Journal of Ceramics

[Background and purposes]Si3N4 ceramics are widely regarded as one of the most promising advanced engineering ceramic materials,due to their excellent high-temperature mechanical properties,outstanding thermal stability and remarkable thermal shock resistance,with extensive applications in various fields,including electronic power devices,ceramic cutting tools,biomedical implants and aerospace components.However,conventional machining methods often suffer from low efficiency,long production cycles,high costs and difficulties in ensuring precision,when fabricating complex-shaped Si3N4 components,leading to the emergence of additive manufacturing technologies as a viable alternative.Among these,digital light processing(DLP)has attracted widespread attention for its high forming efficiency,superior dimensional accuracy and excellent surface quality,yet the inherent gray color of Si3N4 powder,coupled with its high light absorption and significant refractive index,severely restricts the curing accuracy and penetration depth during photopolymerization,a challenge that has prompted various surface modification strategies,which nevertheless remain relatively scarce in terms of systematically and simultaneously improving the rheological behavior and photopolymerization characteristics of Si3N4 slurries,along with the mechanical performance of sintered bodies.Therefore,this study was motivated to employ low-melting-point glass powder as a coating material for Si3N4 particles,combined with ball milling and sintering processes for surface modification,while utilizing DLP as the shaping technique to systematically investigate the comprehensive effects of this coating on the rheological properties,curing behavior,microstructure and mechanical and thermal properties of the resulting ceramics. [Methods]Si3N4 powder was used as the raw material coated with low-melting-point glass powder,employing MgO and Y2O3 as sintering aids,while the photosensitive resin system consisted of OPPEA and HDDA with Irgacure 819 as the photoinitiator,KMT-3331 and BYK-110 as dispersants and DOP as the plasticizer.The Si3N4 powder was blended with 0-5 wt.％glass powder and sintering aids,then ball-milled,dried,sieved and heat-treated at 700 ℃ to form a uniform coating.The coated powder was mixed with resin and additives through vacuum homogenization to prepare photosensitive slurry,which was layer-wise cured via DLP at 30 μm per layer to obtain green bodies.The samples were subsequently vacuum-debinded at 500 ℃ for 3 h and air-debinded for 4 h,followed by pressureless sintering at 1850 ℃ for 8 h.The slurry's rheology was characterized with a rotational rheometer(MCR301),while curing parameters(Ew,Sw,Ed,Sd)were determined by using single-layer curing tests based on quasi-Beer-Lambert and Beer-Lambert semi-logarithmic models.Phase identification was performed by using XRD,microstructure was examined by using SEM and bending strength of the sintered ceramics was evaluated via three-point bending,along with measurement of Vickers hardness(10 kg,10 s)and Archimedes density. [Results]As the content of low-melting-point glass powder for coating was increased from 0 wt.％to 5 wt.％,the viscosity of the Si3N4 slurry decreased from 0.594 Pa·s to 0.477 Pa·s,indicating effective improvement in rheological properties,while the curing behavior showed systematic changes with increasing depth sensitivity coefficient(Sd)but decreasing critical energy density(Ed),along with reduced width sensitivity coefficient(Sw)yet enhanced critical energy density(Ew)and curing width.XRD analysis results confirmed the negligible influence of the glass powder on phase composition of the final ceramics,due to decomposition at 1850 ℃ during sintering and low Al2O3 content(27.87 wt.％).SEM results revealed high densification and reduction in average grain size from 2.61 μm to 2.29 μm(12.26％),consistent with liquid-phase sintering.The flexural strength increased from(679.5±46.6)MPa to(776.5±54.7)MPa(14.3％improvement),due to grain refinement,while Vickers hardness decreased from(15.90±0.85)GPa to(15.300±0.265)GPa and fracture toughness displayed an initial rise followed by a decline,reflecting the critical effect of glass phase content. [Conclusions]To address the challenge of conventional surface modification methods in synergistically optimizing both the Si3N4 slurry properties and the mechanical performance of the sintered bodies,surface coating modification of Si3N4 powder was implemented by precisely controlling the content of the low-melting-point glass powder,combined with ball milling and sintering processes.This treatment significantly reduced the viscosity of the Si3N4 slurry and improved its curing performance.During sintering,an appropriate amount of glass powder partially volatilized without adversely affecting composition or densification of the ceramics.Furthermore,the glass phase formed during sintering effectively refined the grains,resulting in a maximum increase of 14.3％in flexural strength and 31.1％in fracture toughness for the Si3N4 ceramics,thereby achieving synergistic optimization of printing processability and mechanical properties.

[Background and purposes]Solid oxide electrolysis cells(SOECs)represent a highly efficient technology for energy conversion,playing a pivotal role in integrating renewable energy and achieving carbon neutrality goals.However,their performance and durability are critically limited by the microstructure of porous electrodes,where complex multiphysics processes occur.Non-uniform electric field distributions induced by heterogeneous pore structures can lead to localized current crowding,Joule heating and accelerated material degradation.Traditional design approaches often rely on empirical methods,lacking a systematic understanding of the effect of dynamic pore morphology on electric field behavior.Therefore,this study was aimed to elucidate the relationship between the three-dimensional microstructure of porous electrodes and the electric field distribution in SOECs through a combination of advanced characterization and multiscale modeling. [Methods]SOEC single cells with a NiO/GDC-SSZ-GDC/LSCF configuration were fabricated by using a multi-step ceramic processing route.Microstructural properties of the electrodes were characterized using field-emission scanning electron microscopy(FE-SEM)and X-ray computed tomography(XCT).High-resolution XCT scanning at 500 nm resolution enabled the reconstruction of 3D pore networks,which were processed using anisotropic diffusion filtering and watershed segmentation in Avizo software.Key morphological parameters,including porosity,pore size distribution,tortuosity and shape factors,were quantified.Based on the reconstructed structures,two-dimensional(2D)and three-dimensional(3D)models were developed using a finite element-based platform.These models incorporated coupled charge conservation and electrochemical kinetics to simulate the electric field and current density distributions under SOEC operating conditions.Both idealized particle-based and fiber-based electrode architectures were generated and compared to evaluate their electrochemical characteristics. [Results]The 3D microstructure analysis results revealed that the NiO fuel electrode had a porosity of 0.3214,with interconnected pores accounting for 91.54％of the total porosity.The average tortuosity was calculated to be 1.2,significantly lower than that reported for typical particle-based electrodes(1.8),indicating the presence of more efficient transport pathways.Simulations results demonstrated that pore morphology is a primary cause of local electric field and current density distortion.Both 2D models and 3D idealized models showed significant fluctuations in electric field strength and potential distribution within the porous electrodes.Crucially,simulations based on the real 3D reconstructed structure identified that the local current density at narrow pore throats was significantly higher than those in other regions,directly confirming that complex pore morphology induced current concentration.Furthermore,the fiber-structured electrode model exhibited more uniform potential and current density distributions,as compared with the particle-based structure,benefiting from continuous conductive paths that reduced contact resistance and transport tortuosity. [Conclusions]It is revealed the intrinsic relationship between the 3D microstructure of porous electrodes and the electric field distribution in SOECs was revealed in this study.The findings underscore the necessity of 3D characterization for accurately assessing electrode transport properties.The simulation results confirmed that complex pore morphology,especially narrow pore throats,acted as a hotspot for current concentration,posing a potential risk for localized degradation.Moreover,the fiber structure,with its continuous conduction paths and low tortuosity,was demonstrated to be a superior electrode architecture for achieving uniform electrochemical performance.The insights and methodologies provide a theoretical basis for the rational design of high-performance SOEC electrodes.

[Background and purposes]In extra-high voltage systems,overvoltage and protection have always been one of the key research issues for ensuring the safe and stable operation of power systems.Parallel insertion of closing resistors can convert the L-C oscillating electrical energy in the power grid into thermal energy,which is then dissipated into the external environment,thereby achieving the purpose of suppressing switching overvoltage.Although extensive research has been conducted on materials for closing resistors,the core technology for producing high-voltage closing resistor materials has not been mastered,while there remains a significant gap in key performance indicators between domestically produced resistor discs and foreign products.Carbon-ceramic resistor materials have become the mainstay of high-performance foreign closing resistor products,due to their advantages,such as excellent electrical conductivity,strong pulse resistance,superior overload capacity and efficient heat dissipation.In recent years,research on carbon-ceramic resistor materials has primarily utilized natural minerals as raw materials.However,these raw materials have complex compositions,making the reaction processes during calcination relatively difficult to control.Based on the analysis of a foreign product,a series of samples using high-purity alumina and silica as the main raw materials and graphite as the conductive filler have been designed and prepared. [Methods]Phase composition of the prepared samples was analyzed,while their microstructure is observed and their porosity,bulk density,and electrical resistivity were characterized.Combined with the analysis and test results,the effects of the alumina/silica mass ratio,type of sintering aid,graphite particle size and content of graphite on phase composition and properties of the samples are studied. [Results]When 300-mesh graphite is added at 15％and iron oxide(Fe2O3)at 5％,the alumina/silica mass ratio in the range of 2∶1 to 3∶1 has almost no effect on bulk density of the samples,but significantly influences the open porosity and electrical resistivity.This is mainly attributed to the change in the content of corundum phase with the proportion of alumina.When the alumina/silica mass ratio is fixed at 3∶1 and 15％300-mesh graphite is used as the conductive filler,and the effect of sintering aid types was studied. [Conclusions]As compared with Fe2O3,CaCO3 is more conducive to promote the transformation of quartz to cristobalite and the formation of mullite.Samples prepared with 3％CaCO3 as the sintering aid are mainly composed of corundum,mullite,cristobalite,and graphite.When the alumina/silica mass ratio is fixed at 3∶1,3％CaCO3 is used as the sintering aid,11％-15％of 800-mesh graphite are added as the conductive filler,composite resistor materials with corundum,cristobalite,mullite,and graphite as the main phases are successfully prepared.The prepared samples exhibit an open porosity of 33.2％-35.5％,a bulk density of 1.99-2.10 g·cm-3,and an electrical resistivity of 0.11-4.66 Ω·m.The research results of this paper provide data support for the study of carbon-ceramic composite resistor materials.

[Background and purposes]Blue-and-white porcelain,as a distinguished representative of Chinese ceramic art,holds a prominent place in the global history of decorative arts.Its unique cobalt-based underglaze technique and iconic blue-and-white palette not only demonstrate exceptional craftsmanship but also embody profound cultural symbolism.The color characteristics of blue-and-white porcelain have evolved over time under the combined influence of raw material composition,glaze formulation,firing conditions and prevailing aesthetic values,forming distinctive historical trajectories.However,most existing studies have focused on qualitative explorations from aesthetic,semiotic and archaeological perspectives,with limited application of systematic quantitative methods,thus constraining objective comparisons and the identification of developmental patterns across different periods.With the rapid advancement of digital imaging,computer vision and machine learning,it has become possible to analyze artifact colors with precision using non-contact,repeatable and quantifiable techniques,offering new pathways for heritage preservation and revitalization.In this study,the K-means++clustering algorithm was integrated with the Natural Color System(NCS)to digitally extract and parameterize the color features of blue-and-white porcelain from the Yuan,Ming and Qing dynasties,aiming to reveal the historical evolution of its hue,blackness and chromaticness,and hence establish a structured color database that can support heritage conservation,design innovation and cross-media application. [Methods]A total of 223 representative blue-and-white porcelain sherds from various historical periods were collected from the Tao Xi Chuan Ceramic Shard Museum in Jingdezhen and private collections.Compared with complete vessels,sherds offer flatter surfaces that minimize light distortion and facilitate accurate color capture,while their accessibility broadens the sample base for quantitative studies.Each sample was photographed in a controlled studio environment using a Canon EOS 6D camera at a resolution exceeding 300 dpi and 2000×2000 pixels.Lighting was maintained between 5000K and 6000K to simulate natural daylight,with diffusers and black light-absorbing cloth to eliminate direct glare,shadows and environmental reflections.A standard color card was included in each frame,while the images were color-corrected in Adobe Lightroom through white balance adjustment and matching to reference values,ensuring high fidelity between digital and physical color.The corrected images were processed using the K-means++clustering algorithm.Unlike standard K-means,K-means++optimizes the selection of initial centroids through probabilistic dispersion,thereby avoiding local minima and improving clustering stability.RGB values of each pixel were extracted,normalized and grouped into clusters,with the optimal cluster number determined by combining the elbow method,to identify the inflection point in the SSE curveand silhouette coefficient analysis,which measures cluster cohesion and separation.Both metrics consistently indicated K=5 as optimal for most periods.RGB values of the five dominant colors from each sample were then converted to the NCS parameters of hue(H),blackness(S)and chromaticness(C)for further statistical and comparative analysis. [Results]The analysis revealed a consistent concentration of hues within the NCS range R90B-R60B across all three dynasties,indicating a strong bias toward cool blue tones with occasional shifts toward purpleblue.In the Yuan Dynasty,colors were characterized by high blackness(50-70)and low chromaticness(10-30),producing deep blue-gray tones.These visual attributes correspond with the use of both domestic and imported cobalt sources containing higher impurity levels,resulting in muted saturation.In the Ming Dynasty,particularly during the Yongle and Xuande reigns,the refinement of imported cobalt and improved firing techniques led to increased chromaticness(20-50,occasionally exceeding 60)and reduced blackness(30-60),producing purer brighter blues.Later Ming wares incorporated domestic cobalt,expanding the tonal range to include both light azure and intense deep blues.In the Qing Dynasty,especially during the Kangxi,Yongzheng and Qianlong reigns,colors exhibited greater hue diversity,with shifts toward R60B purpleblue tones.Blackness was moderate(30-50)and chromaticness frequently ranged from 40 to 70,producing vibrant saturated blues.These patterns confirm the correlation between technological refinement,material purity and aesthetic diversity,as well as the influence of court tastes and production scale on color variability. [Conclusions]It is demonstrated that integrating K-means++clustering with the NCS system provides a precise,replicable and non-invasive approach for quantifying the color characteristics of ceramic artifacts.By revealing the historical trajectory of blue-and-white porcelain,from the Yuan Dynasty's deep,restrained palette,through the Ming Dynasty's balanced and refined blues,to the Qing Dynasty's diverse and saturated tones,a robust color reference framework was established,which is applicable to digital heritage archiving,cultural product development and cross-media design translation.Furthermore,the workflow presented here addresses a broader methodological gap in heritage studies,by bridging computational analysis with perceptual color systems.This enables not only the preservation of color data in standardized formats but also its transformation into actionable design strategies.Such strategies can inform visual identity systems,spatial design schemes and product color planning,ensuring that the cultural essence of traditional palettes is retained,while adapting to contemporary design languages.Ultimately,this approach advances both the academic study and practical application of historical color knowledge,fostering new avenues for innovation in the digital humanities and creative industries.

[Background and purposes]Recrystallized silicon carbide(R-SiC)porous ceramics are pivotal advanced refractories utilized in high-temperature applications,such as kiln furniture and thermal exchangers,due to their exceptional thermal stability,chemical inertness and mechanical strength at elevated temperatures.Recrystallization sintering process,following the evaporation-condensation mechanism without sintering aids,is favored for producing high-purity SiC ceramics.However,a significant challenge lies in balancing the material's porosity with its mechanical performance.In traditional approaches,powders with bimodal or multimodal particle size distributions were used to enhance densification,but often at the cost of complex processing and possible uncontrolled grain growth.The introduction of silicon carbide fibers(SiCf)into ceramic matrices is a well-established strategy for toughening and strengthening.However,its application and mechanistic understanding within a single-particle-size R-SiC system,where the reinforcement mechanism differs fundamentally from dense composites,remain unexplored.This study was aimed to systematically explore the influence of SiCf and sintering temperature on phase evolution,microstructural development and resultant mechanical properties of single-particle-size R-SiC porous ceramics,seeking to identify the optimal processing parameters and elucidate the underlying mechanisms. [Methods]The green bodies were prepared using a single-size 6H-SiC powder(D50=1.07 μm)as the matrix.Silicon carbide fibers(SiCf,diameter of 5-10 μm,length of 50-100 μm)were incorporated as a reinforcing phase at a concentration of 20 wt.％.The powder and fibers were homogenized via ball-milling in an ethanol suspension for 4 h.The mixed batches were subsequently dried,mixed with 2 wt.％of a binder solution(hydroxyethyl cellulose and polyvinyl alcohol)and uniaxially pre-pressed at 10 MPa,followed by cold isostatic pressing(CIP)at 180 MPa,to form green compacts with dimension of 40 mm× 8 mm×6 mm.The binder was removed at 600 ℃ for 3 h in Ar.The final recrystallization sintering was conducted in a high-temperature furnace in Ar,at temperatures ranging from 1600 ℃ to 2200 ℃ for 1 h.Phase composition was determined by using X-ray diffraction(XRD)with Rietveld refinement.Microstructure,grain size and sintering neck development were analyzed by using scanning electron microscopy(SEM).Apparent porosity and bulk density were measured according to the Archimedes principle.The cold modulus of rupture(CMOR)was evaluated by using three-point bending test. [Results]XRD analysis results confirmed that the primary phases were 6H-SiC,with additional 4H-SiC and 3C-SiC polymorphs.The introduction of SiCf,which contained a fraction of the metastable 3C-SiC polytype,influenced the phase evolution during sintering.At the optimal temperature of 2100 ℃,the SiCf-added sample(PSC2)exhibited an increase in the content of 4H-SiC and 3C-SiC,as compared with the pure SiC sample(PSC1),which was attributed to the evaporation-condensation and phase transformation of the SiCf-derived 3C-SiC.At 2100 ℃,the addition of SiCf resulted in a more uniform distribution of finer grains and a narrower size distribution of sintering necks,as quantified by a lower SPAN value(1.30 for PSC2 vs.1.67 for PSC1).This indicated that SiCf promoted homogeneous neck development by providing additional vapor sources and nucleation sites.Consequently,the mechanical properties were significantly enhanced.The sample with 20 wt.％SiCf sintered at 2100 ℃ demonstrated optimal performance,with an apparent porosity of(45.5±0.8)％,a bulk density of(1.80±0.03)g·cm-3 and a CMOR of(43.44±4.75)MPa.This represented a 35.7％increase in flexural strength over the baseline sample[PSC1:(32.02±6.89)MPa]at the same temperature.However,a critical finding was the temperature-dependent behavior of SiCf.When the sintering temperature was elevated to 2200 ℃,the beneficial effect of SiCf was negated.Excessive grain growth,particularly abnormal or exaggerated grain growth,was observed in the SiCf-containing sample.This microstructural degradation led to a precipitous drop in mechanical strength,with the CMOR of PSC2 decreasing to(23.62±1.47)MPa,a 45.6％reduction from its peak value at 2100 ℃ and lower than that of the pure SiC sample at 2200 ℃[(26.85±0.82)MPa].This suggests that,beyond a critical temperature,the enhanced mass transport facilitated by SiCf becomes detrimental,triggering unstable grain coarsening. [Conclusions]High-porosity and high-strength SiC porous ceramics were prepared using a single-particle-size SiC powder and SiC fibers(SiCf)as the raw materials,at sintering temperatures in the range of 2100-2200 ℃.At 2100 ℃,the decomposition of SiCf occurred,leading to a decrease in the content of 4H-SiC and 3C-SiC polytypes.This indicates a phase transformation process from the metastable 3C-SiC to the more stable 4H-SiC and 6H-SiC polytypes.When the sintering temperature was elevated to 2200 ℃,abnormal grain growth was observed.The addition of SiCf further promoted secondary recrystallization,which resulted in a significant degradation of mechanical properties,as evidenced by the decrease in the cold modulus of rupture from(26.85±0.82)MPa to(23.62±1.47)MPa.The optimal comprehensive performance of the recrystallized SiC porous ceramic was achieved with the addition of 20 wt.％SiCf and sintering temperature of 2100 ℃,yielding an apparent porosity of(45.5±0.8)％,a bulk density of(1.80±0.03)g·cm-3 and a superior cold modulus of rupture of(43.44±4.75)MPa.

[Background and purposes]With the rapid rise of strategic emerging industries,such as 5G communications,artificial intelligence and new energy vehicles,electronic devices are rapidly evolving toward high performance,multifunctionality and extreme environmental adaptability.This places increasingly demanding challenges and requirements on the performance of dielectric materials for multilayer ceramic capacitor(MLCC).The Ba6-3xLn8+2xTi18O54 ceramic system,with tungsten bronze structure,has emerged as a highly promising dielectric material for MLCC,due to its high dielectric constant,low dielectric loss and excellent temperature stability.In this study,a two-step sintering method was employed to prepare Ba(Sm0.1La0.5Bi0.4)2Ti3.8(Al0.5Nb0.5)0.2O12(BST-BLAN)ceramics.Using COMSOL software,the electric field distribution and breakdown path evolution of the ceramics with different microstructures were simulated,systematically revealing the influence of sintering processes on material structure and performance. [Methods]The raw materials were mixed and ball-milled for 4 h with a planetary ball mill,dried and pre-sintered at 1100 ℃for 4 h.After secondary ball-milling for 8 h,the powder was granulated and pressed into 10 mm×2 mm green bodies.The green bodies were sintered with a two-step method.They were first heated at 5 ℃·min-1 to 650 ℃ and held for 2 h to remove PVA,then heated at 10 ℃·min-1 to T1,held for 1 min,and cooled to T2(170 or 200 ℃ below T1).After holding for 2 h,12 h,or 24 h,the samples were cooled down with the furnace.The sintered ceramic samples underwent grinding,polishing,ultrasonic cleaning,electrode coating and powder milling before characterization with XRD,SEM,dielectric property and breakdown strength.Simultaneously,COMSOL software was employed to simulate electric field distribution and breakdown path evolution of the ceramics with different microstructures. [Results]Average grain size of the two-step sintered samples decreased significantly.With increasing T1,the density first increased then decreased,reaching maximum value at 1230 ℃.At 1260 ℃,the second phase disappeared,due to the fostered Bi3+volatilization.With increasing T1,the dielectric constant exhibited a parallel trend to the variation of density,peaking at 157 at 1230 ℃,higher than that of the conventionally sintered samples.Conversely,dielectric loss followed an opposite pattern,reaching a minimum of 0.04％at 1230 ℃.The absolute value of the temperature coefficient decreased slightly with rising T1.Breakdown strength was significantly improved when using the two-step sintering method.It is first increased and then decreased with rising T1,reaching the maximum value of 10.2 kV·mm-1at 1230 ℃.Increasing T2 and prolonging holding time both cause Bi3+volatilization to outweigh grain growth effects,reducing relative density.The maximum relative density of 98.7％is achieved in the sample sintered at T2=1030 ℃ for 12 h.Dielectric constant exhibits a similar trend to density,reaching the maximum value of 161 at T2=1030 ℃ for 12 h.Conversely,dielectric loss follows an opposite trend,reaching the minimum value of 0.028％at T2=1030 ℃ for 12 h.Temperature stability showed slight improvement at T2=1030 ℃ for 12 h.With varying T2 and holding times,density and porosity were the primary factors influencing breakdown strength.Breakdown strength followed the same trend as density,reaching the maximum level of 13.0 kV·mm-1at T2=1030 ℃for 12 h. [Conclusions]Two-step sintering did not cause significant changes in phases of the ceramics.Compared to conventional sintering,it resulted in finer,more uniform grains and higher grain boundary density.Appropriately increasing T2 temperature and holding time reduces internal defects and enhances density,thereby improving dielectric properties and breakdown strength.However,excessive increases in these parameters lead to adverse effects due to the accelerated volatilization of Bi3+.

[Background and purposes]Ceramic art is not only an object for collection and appreciation but also a vital medium for cultural exchange.However,traditional display methods are often confined to static presentations,failing to fully realize the effective communication of its artistic value and cultural connotations.The"spatial turn"in aesthetics during the latter half of the 20th century,along with Gernot Böhme's theory of"atmospheric aesthetics,"emphasizes the significance of the"presence"of artworks,proposing that artistic experience is a"common reality"co-constructed by the work and the viewer within a specific environment.Against this theoretical backdrop,this study is aimed to delve into how to synergistically use the two key elements of lighting design and atmospheric ambiance to construct an immersive exhibition field.This approach seeks to transcend mere visual presentation,deepen the audience's aesthetic experience and emotional resonance and thereby provide a systematic theoretical and practical guide for ceramic art exhibitions. [Methods]Based on the theory of atmospheric aesthetics,this study is attempted to construct an integrated practical framework.Firstly,four core principles are proposed for creating atmospheric ambiance:Holism(unifying the space with the artwork's style),thematicity(highlighting the core imagery of the work),comfort(meeting the physiological and psychological needs of the audience)and cultural resonance(embedding historical and cultural context).Secondly,practical methods are systematically elaborated. (1)Space and Color.partitions and screens are utilized for dynamic zoning,while colors that resonate with the artwork's theme(e.g.,cool tones for natural themes,warm tones for classical themes)are employed to shape the spatial narrative. (2)Core Lighting Techniques. For material adaptation,lighting schemes are customized according to the physical properties of ceramics(e.g.,glaze reflectivity,body translucency,crackle texture).For instance,soft diffused or side light is used for high-gloss glazes to avoid glare and backlighting is employed for highly translucent white porcelain to highlight its delicacy. For precision parameter control,the angle,intensity,color temperature and projection method of light are flexibly adjusted,based on the artwork's theme.For example,the artistic conception of Song Dynasty porcelain requires soft diffused light,while the beauty of Jun porcelain's kiln transformation necessitates adjustable color temperature lighting to showcase its color flow. For sensory integration,in contemporary experiential exhibitions,lighting could be combined with sound,interactive projections,and other multi-dimensional sensory stimuli to construct an enveloping immersive space. [Results]A profound"interconstructive relationship"between lighting and ambiance is revealed.They are not merely in an applied relationship but form a symbiotic mechanism of bidirectional construction.This relationship manifests concretely on three levels,in terms of interconstruction,including intentionality and technicality,space and perception,and object and subject.With the guidance of this theory,practices are demonstrated. (1)Artistic expression is significantly enhanced.Precise lighting design(e.g.,using low-angle side light for carved patterns)can intensify the texture,feel and form of ceramics,allowing their artistic characteristics to be fully displayed. (2)Audience experience undergoes a profound shift.Successful atmospheric ambiance effectively guides audience behavior and psychology.For instance,soft and tranquil lighting shifts the audience from"cursorily viewing flowers while passing on horseback"to"calmly observing and appreciating details,"thus leading them into a contemplative state.whereas dynamic exploratory lighting stimulates the audience to become active"discoverers"of the space. (3)Cultural communication efficacy is strengthened.By constructing a complete"artistic conception"(Yijing),the exhibition moves beyond a simple display of objects to become an aesthetic activity that evokes empathy,enabling the audience to deeply perceive the profound cultural implications and philosophical connotations of ceramic art through immersion. [Conclusions]It is demonstrated that,in ceramic art display,lighting design and the creation of atmospheric ambiance form an inseparable bidirectional empowerment system.Lighting has transcended its role as a mere technical tool to become aesthetics itself,the direct source of ambiance,while ambiance provides the carrier of meaning for lighting.Working together,they ultimately aim to realize an aesthetic experience of"fusion of object and self."Future ceramic art exhibitions should be moved beyond the mere accumulation of techniques,striving for the harmonious unity of light,object,space and the viewer's body.New lighting concepts and technologies should be actively explored to construct more impactful and interactive spaces of artistic conception,thereby promoting effective communication and innovative development of ceramic art in the contemporary context.

[Background and purposes]Blue-and-white porcelain is the essence of traditional Chinese ceramic culture.However,during the preparation and firing of blue-and-white porcelain,due to the influence of the formula composition and preparation process of the blue pigment,uneven coloration occurs in the blue and white decoration,while the lines of the blue and white decorative materials may show varying degrees of"color dispersion"(the length of the spread of blue and white decorative lines is called"color dispersion"),resulting in blurred outlines and lines in the blue and white picture,which destroys the bright,clear and layered expression effect of blue and white.In order to identify the reasons for this phenomenon,this paper is aimed to explore the influence of BaO/CaO ratio in the glaze on the coloration and"color dispersion"behavior of blue-and-white porcelain,thereby revealing the effect of the glaze layer structure on the coloration mechanism and"color dispersion"behavior of blue-and-white porcelain. [Methods]To clarify the extensive color variations and the"color dispersion"phenomenon of blue-and-white porcelain,the effects of the BaO/CaO ratio in the glaze on the chromaticity value,"color dispersion"distance,microstructure,glaze network structure and Co2+concentration,in the glaze of blue-and-white porcelain,were analyzed using field emission scanning electron microscopy(FE-SEM),Fourier transform infrared spectroscopy(FTIR),electron probe microanalysis(EPMA)and optical microscopy(OM). [Results]It is experimentally demonstrated show that,as the BaO/CaO ratio in the glaze increases,the strength of the Si-O-Si bonds in the glaze network structure decrease,while the"color dispersion"distance of the blue-and-white porcelain lines first increases(60-100 μm).However,when the BaO/CaO ratio is increased to 1.71,stable octahedral Co-spinel crystals exist in the reaction layer at the interface between the blue pigment and the glaze,whereas the"color dispersion"distance decreases to about 60 μm,while the b*value first increases(-33.65 to-29.38)and then decreases to-33.1. [Conclusions]With increasing ratio of BaO/CaO in the glaze,the strength of the Si-O-Si bonds in decreases.The viscosity of the glaze decreases,while the"color dispersion"distance of the blue-and-white porcelain increases.However,when the ratio of BaO/CaO reaches 1.71,stable Co-spinel crystals exist in the interface layer of the blue-and-white porcelain,whereas the"color dispersion"distance of the blue-and-white porcelain decreases again.Therefore,it is concluded that the size of the"color dispersion"distance of the blue-and-white porcelain is related to the viscosity of the glaze and the stability of the crystal structure of the blue pigment.The result lays a solid physical and chemical foundation for the technological development of blue-and-white porcelain decoration and points out the direction of development.

[Background and purposes]Fiber-reinforced ceramic matrix wave-transmitting materials have become the main selection for aircraft radar radome & antenna windows.With the rapid development of guidance technology,the design,materials and preparation of multi-functional integrated radome & antenna windows,such as wave transmission,broadband and stealth performance,have become one of the bottlenecks that limit the development of weapons and equipment.With single medium radome & antenna windows,it is unable to meet the above requirements.Frequency selection surface(FSS)can regulate electromagnetic waves effectively,thereby achieving the above-mentioned purpose.However,the preparation of FSS radome& antenna window materials serving with high temperature(≥800 ℃)based on fiber-reinforced ceramic matrix composites mainly faces two major technical problems,which are(i)preparation of conductive coating with high temperature resistance and high bond strength and(ii)high-precision FSS structure processing for complex curved surfaces.The latter can be solved by the laser etching and other methods,while the former has exposed the surface fibers of the material and broken the matrix due to mechanical processing.When the metal layer is coated directly,it is difficult to create a strong bond between the two layers.Polysilazane(PSZ)is one of the important ceramic precursors with the characteristics of in-situ ceramic transformation.It has rarely been reported in the use of surface reinforcement material for fiber-reinforced ceramic-based wave-transmissive materials.In this paper,SiO2f/SiO2 ceramic matrix composite was studied,whereas the PSZ precursor was used to perform surface strengthening treatment,which then coated with a high-temperature resistant metal coating to prepare Pt-SiO2f/SiO2 composites.The preparation and performance of the composites were studied,aiming to propose a method to enhance the binding force of metal-ceramic matrix composites effectively and explore the preparation method of new ceramic-based FSS radome & antenna window materials. [Methods]The SiO2f/SiO2 composite was prepared by using liquid phase penetration combined with sol-gel methods,while the preform had a needle punched structure.The first round of the immersion was liquid infiltration,while the second round was sol-gel method,using silica sol with mass fraction of 25％and 40％.The PSZ precursor was mixed with self-made ceramic fillers and sprayed onto surface of the SiO2f/SiO2 composite.After that,the Pt slurry was sprayed and sintered at different temperatures.The internal quality of the composites was analyzed by using the Carl Zeiss Metrotom 1500 CT scanning system.Microstructure and morphology of the composites were characterized using Thermo Fisher Apero S scanning electron microscopy.Macroscopic morphology of the sample was analyzed by using Japanese KEYENCE VK-X2000 laser confocal microscope.The TG analysis on the sample using the German FTA449 F5 synchronous thermal analyzer.The EDX 600PLUS film thickness gauge and FT-341 four probe tester were used to measure the thickness and conductivity of metal coatings.A quartz lamp radiation heating system was used to assess temperature resistance of the composites,while the adhesion of the coating was evaluated by using the grid cut method(GB/T 9286-2021). [Results]Density of the SiO2f/SiO2 composite material is 1.73 g·cm-3,in which the internal voids of the preform are effectively filled with SiO2 matrix.Volume defect rate of the composite material is only 0.08％.The exposed fibers and fracture of the matrix occurred due to the mechanical processing.The PSZ precursor undergoes ceramic transformation after 600 ℃.With increasing content of self-made ceramic filler,the PSZ precursor can form a fully encapsulated porous interface layer on the SiO2f/SiO2 composite materials.When the ceramic filler content is greater than 20％,defects,such as pits and cracks,will be present in the PSZ interface layer.As PSZ interface layer was subjected to 1000 ℃ for 300 s with quartz lamp heat treatment,it bonded well with the SiO2f/SiO2 substrate.With increasing sintering temperature,square resistance and conductivity of the Pt coating decreases and increases,respectively,over the same thickness range.When the coating thickness varies from 20 μm to 30 μm,the sheet resistance is(30±5)mΩ·□-1,while the electrical conductivity reaches 106 S·m-1.The Pt-coating prepared at sintering temperatures of 850-950 ℃ can withstand quartz lamp thermal assessment at 1000 ℃ for 300 s,while the adhesion remained at the highest-level 0.Finally,FSS periodic patterns can be obtained by using the laser processing on the surface of Pt-SiO2f/SiO2 composite materials. [Conclusions]The PSZ precursor significantly improved the condition of composites and bonding strength of Pt-coating,thereby realizing the application in frequency selective surface(FSS)radome & antenna windows.The optimal temperature for the Pt-coating is in the range of 850-900 ℃.When the coating thickness varies from 20 μm to 30 μm,the sheet resistance is(30±5)mΩ·□-1,while the electrical conductivity reaches 106 S·m-1.The Pt-coating adhesion remained at the highest-level 0,when subjected to 1000 ℃ for 300 s of quartz lamp thermal treatment,while the electrical conductivity remained unchanged.Moreover,the Pt-SiO2f/SiO2 composites had a high laser machinability.

[Background and purposes]During the Song and Yuan dynasties,Jingdezhen Kiln was an important production area for celadon-white porcelain.With the exchange and dissemination of porcelain-making techniques,especially the southward spread of porcelain sculpture techniques from the Northern Ding Kiln,the craftsmanship of celadon-white porcelain human-figure statues in Jingdezhen Kiln achieved significant progress and development.A large number of kiln sites were used to produce a considerable quantity of celadon-white porcelain wares and human-figure statues.In the Southern Song Dynasty,the types of human-figure statues were diverse,covering various categories,such as Buddhist and Taoist statues,zodiac porcelain figurines and so on.During the Yuan Dynasty,influenced by the prevalence of Tibetan Buddhism,as well as the changes in ceramic materials and technological innovations,large-scale and mature celadon-white porcelain human-figure statues were fired in Jingdezhen Kiln.Their themes and functions gradually expanded to opera stories,folk culture and other fields,showing a trend of literati orientation and secularization,with the related craftsmanship also becoming increasingly mature.This paper was aimed to systematically sort out the innovative developments in various aspects,such as the body and glaze material system,forming techniques,decorative methods and kiln furnace technologies of celadon-white porcelain human-figure statues,from Jingdezhen Kiln during the Song and Yuan dynasties.The internal logic of their technological evolution was explored,an in-depth analysis of the social and cultural factors that drove technological innovation,such as material development,consumer culture and religious dissemination,were conducted.It is intended to comprehensively clarify the development context and cultural connotations of the craftsmanship of celadon-white porcelain human-figure statues during this period. [Methods]Firstly,ancient literatures,such as Tao Ji(Record of Ceramics)and Jingdezhen Tao Lu(Record of Jingdezhen Ceramics)are consulted,while modern academic works,such as Chinese Ceramics to obtain relevant records of Jingdezhen Kiln's celadon-white porcelain sculptures during the Song and Yuan dynasties,are referred,to sort out their development clues from historical documents.Secondly,the physical objects collected in major museums,such as the Song-Dynasty White and Green Glazed Unglazed Porcelain Bodhisattva Guanyin and the Yuan-Dynasty Blue-White Glaze Water Moon Guanyin,were analyzed.By comparing the differences in modeling,decoration and techniques of the statues from different periods,it is attempted to visually demonstrate the development and changes of the techniques.Finally,referring to the archaeological excavation results of sites,such as Hutian Kiln Site and Luomaqiao Site,the unearthed fragments of celadon-white porcelain and ceramic molds were analyzed to study the development and evolution of material formulas and forming techniques from an archaeological perspective,thus providing physical evidence for the research. [Results]In terms of material technology,the material formula evolved from the"single-component formula"to the"two-component formula".In the Yuan Dynasty,adding kaolin to porcelain stone was used to improve the refractoriness of the body and reduced the deformation rate,significantly increasing the size of Yuan-Dynasty statues and breaking through the size limitations of Song-Dynasty statues.Regarding the forming technology,initially influenced by other kilns,molding techniques and a production model combining molding and hand-shaping were later developed in Jingdezhen Kiln.There was a wide variety of molds,including positive molds and negative molds,where the negative molds were further divided into single-piece molds,combined molds and multi-piece molds.The combination of molding and hand-shaping enabled improvement in production efficiency while taking into account the flexibility of artistic creation,and promoted the maturity of porcelain-sculpture techniques.Concerning the decorative techniques,multiple decorative processes,such as the combination of"section-molding"and"hand-shaping",line-carving and open-work carving,were integrated.By precisely controlling the glaze color of the celadon-white porcelain,the decoration became rich and diverse,skillfully integrating religious and secular elements and reflecting the characteristics of multi-cultural integration.In the aspect of kiln firing technology,the kiln type was evolved from the dragon kiln to the gourd kiln and then the mantou kiln.Although the dragon kiln had certain advantages,it had limitations,such as rapid cooling and uneven temperature distribution.The gourd kiln and the mantou kiln were more controllable.The mantou kiln was especially suitable for firing complex-shaped porcelain sculptures,effectively reducing the risk of deformation and collapse and hence promoting the development of firing techniques. [Conclusions]The celadon-white porcelain human figurines of Jingdezhen Kiln during the Song and Yuan dynasties were the product of the in-depth integration of porcelain-making craftsmanship and social culture.They not only carry religious and folk significance but also embody the exchanges and mutual learning with other kilns,reaching a new height in terms of artistry and craftsmanship.Through material innovation,improvement of forming techniques and innovation of decorative methods,a dual breakthrough in art and technology was achieved.These figurines not only reflect the superb porcelain-making skills of the time but also contain profound historical,cultural,aesthetic and humanistic connotations,becoming important witnesses to the social religious beliefs,cultural traditions and aesthetic pursuits of that era.The study of the celadon-white porcelain human figurines of Jingdezhen Kiln during this specific period of the Song and Yuan dynasties is expected to be helpful for the restoration of ceramic sculpture techniques of Jingdezhen Kiln and the inheritance and protection of cultural heritage.

[Background and purposes]The evolution of protective armor,driven by advancing weaponry,has shifted towards multi-material composites.Ceramics,notably alumina(Al2O3),silicon carbide(SiC)and boron carbide(B4C),are pivotal components,due to their low density,high hardness,modulus,melting point,and strength,significantly enhancing ballistic protection for personnel and vehicles.While Al2O3 is denser and B4C is costlier,SiC ceramics have emerged as a primary choice owing to their combination of low density,cost-effectiveness and superior ballistic performance.Understanding the dynamic response of ceramics under extreme impact loading,characterized by GPa-level stresses,millisecond durations and localized effects,is crucial but remains challenging.Research focuses on ballistic mechanisms,dynamic damage evolution and constitutive relationships under such high-strain-rate conditions,yet limitations in testing methods hinder full comprehension of transient dynamic behavior.Given SiC's critical role,investigating its stress response and failure mechanisms under dynamic impact is paramount.This study was aimed to specifically examine the influence of interface types within SiC ceramics on their impact resistance.By fabricating SiC ceramics with varied interfaces and employing Split Hopkinson Pressure Bar(SHPB)testing,it was attempted to elucidate the dynamic mechanical behavior and damage mechanisms under impact,thereby revealing how interface characteristics govern the material's anti-penetration performance. [Methods]SiC ceramics were fabricated with SiC,B4C,C,B,Al2O3 and Y2O3 powders(1-3 μm,＞99％purity),with specific sintering additive ratios.The powders were ball-milled for 12 h in a solvent mixture of alcohol and methyl ethyl ketone,with TEP as dispersant,PVB as binder and glycerol as plasticizer,to form a homogeneous slurry.A slurry with 40 wt.％solid content was tape-cast using doctor blade set at 0.6 mm and 0.9 mm.The dried tapes were cut,stacked and laminated at 30 MPa and 120 ℃.After debinding,the samples were sintered.The sintered ceramics were characterized by using Archimedes'method for density,SEM for microstructure,Vickers hardness testing at 9.8 N and three-point bending for strength and fracture toughness.Dynamic mechanical properties were evaluated using a split Hopkinson pressure bar to obtain stress-strain curves and analyze strain rate effects,energy absorption and damage evolution mechanisms. [Results]Liquid-phase sintered(L-SiC)ceramics exhibited the highest fracture toughness,due to energy absorption by weak grain boundary phases.Both L-SiC and reaction sintered(R-SiC)ceramics showed higher flexural strength than the solid-phase sintered samples(S-SiC),which suffered from reduced mechanical properties related to the closed pores and large grains.S-SiC,with strong interfaces and fewer grain boundary phases,had the highest hardness.Microstructural analysis revealed that L-SiC consists of SiC grains and YAG intergranular phase,failing primarily through intergranular fracture and YAG phase failure.S-SiC,containing SiC grains,residual carbon and closed pores,failed mainly by transgranular fracture.R-SiC,composed of SiC,B4C and Si,failed primarily through fracture of the Si phase and intergranular fracture.Under dynamic compression,all ceramics showed significant strain rate strengthening.The flow stress increased with strain rate,with S-SiC having the highest strength,followed by L-SiC and R-SiC.The failure time decreased with increasing strain rate.Energy absorption analysis indicated that transmitted energy decreased while reflected and dissipated energy generally increased with strain rate.The variation was attributed to the rapid loss of structural integrity.S-SiC demonstrated the strongest ability to maintain structural integrity at low strain rates.Dynamic damage analysis showed that,at low strain rates,breaking produced larger fragments,while high strain rates resulted in fine debris.S-SiC and R-SiC fragments exhibited more pronounced prismatic morphology than L-SiC,where weak interfaces caused crack deflection.Microscopic examination of fracture surfaces revealed intergranular fracture with grain pull-out in L-SiC,transgranular fracture in S-SiC and brittle fracture of the Si phase with limited crack extension in R-SiC.Under ultra-high strain rates,micro-cracks are formed within S-SiC grains,indicating internal damage and plastic deformation,due to the residual stresses from elastic anisotropy. [Conclusions]Three types of SiC ceramics with distinct interfaces were fabricated,each exhibiting characteristic failure modes.The liquid-phase sintered sample(L-SiC)failed mainly through intergranular fracture and failure of the YAG grain boundary phase,the solid-phase sintered sample(S-SiC)failed primarily via transgranular fracture and the reaction sintered(R-SiC)one failed through fracture of the Si phase combined with intergranular fracture.All the three ceramic types exhibited a significant strain rate strengthening effect.The interface type influenced the flow stress,i.e.,weak interfaces reduced the flow stress but increased the failure strain,whereas strong interfaces enhanced the flow stress but decreased the failure strain.The interfacial type,together with the material's ability to maintain structural integrity,jointly influenced the kinetic energy dissipation.Energy was dissipated through mechanisms including particle fragmentation,friction and ejection.Based on the dynamic damage process,the failure of SiC ceramics can be categorized into a three-stage progression.

[Background and purposes]In the history of Chinese ceramics,the phrase"Southern Green and Northern White"has often been used to summarize the ceramic production landscape during the mid-to-late Tang Dynasty.However,historical documents and archaeological evidence reveal that,despite this conventional framework,there were substantial instances of northern kilns producing celadon and southern kilns producing white porcelain.This paper was aimed to explore the production conditions of southern white porcelain during the Tang and Five Dynasties periods,with a focus on white porcelain artifacts unearthed in Changsha,and to investigate the relationship between southern white porcelain production and the transmission of northern whiteware techniques. [Methods]In this paper,historical literature was combined with archaeological data,particularly focusing on the analysis of white porcelain artifacts unearthed in the Changsha region from the Tang and Five Dynasties periods.Through comparative studies of key southern kilns such as the Fanchang and Jingdezhen kilns,the production techniques,circulation routes and the influence of northern white porcelain technology on southern production were examined. [Results]During the Tang and Five Dynasties periods,the production of white porcelain in southern China,though geographically dispersed,was primarily concentrated in the Xu-Huai area,southern Anhui,the Changsha region and northeastern Jiangxi.These kilns were typically situated in areas with accessible water transportation and strong foundational ceramic industries,producing mainly everyday wares,such as bowls,plates,saucers and jars.The production of southern white porcelain was significantly influenced by the migration of northern populations to the south,reflecting a southward transmission of northern whiteware techniques.Furthermore,with comparative studies of the Fanchang and Jingdezhen kilns,it is suggested there is a close relationship between the emergence of Qingbai(bluish-white)porcelain and the production of white porcelain in southern China. [Conclusions]The production of white porcelain in southern China during the Tang and Five Dynasties periods disrupted the traditional"Southern Green and Northern White"framework,demonstrating that northern white porcelain technology spread to the south through population migration and evolved into a unique southern production system.The results of this study not only enriched our understanding of Tang Dynasty ceramic production but also provided new insights into the rise of Qingbai porcelain during the Song Dynasty.

[Background and purposes]The Yixing uniform pottery is a kind of glazed pottery fired near the Dingshu Town area of Yixing City,generally known as"uniform pottery"or"Yijun".Yijun has not been interrupted since it was fired in the middle and late Ming Dynasty,among the five"golden flowers"of Yixing ceramics.Yijun was first recorded in the Ming Dynasty in the Jiajing period in the book"Museum Essentials".There are many kinds of Yixing pottery,including sky blue,sweet white,light green and dozens of glaze colors,among which the gray-blue glaze is outstanding.Gray-blue glaze is a kind of split-phase glaze with yellowish-white markings on the surface caused by kiln changes.Yijun gray-blue glaze kiln change is mainly attributed to the use of lime kiln sweat as the raw materials.The lime kiln sweat in the CaO and P2O5 components of the glaze surface has a corresponding role in promotingYijun gray-blue glaze phasing,in line with the Rayleigh scattering and Mie scattering laws,resulting in glaze milky blue and milky white.At the same time,in the oxidizing atmosphere,glaze melts contained Fe3+,Cu2+,Co3+,leading to glaze melt color in the visible light region.Therefore,the gray-blue glaze coloration is mainly produced,due to the coupling of structural coloring and ionic coloring.This work was aimed to study the effect of divalent alkali metal oxides,with different MgO/CaO molar ratios,on phase precipitation and crystallization of the Yixing pottery gray-blue glazes,so as to analyze the internal mechanism of their color changes.When the multilevel phase precipitation is generated,both the nucleation and the crystal growth are influenced. [Methods]Yixing mud,lime kiln sweat,Longyan kaolin,quartz,limestone and chemically pure iron oxide,copper oxide,zinc oxide,dicobalt trioxide were used as the raw materials.The two main components had particle size of 397 μm and 81 μm,with the mass ratio of 1∶3.Then,other raw materials were weighed and mixed according to the ratio of material,ball,and water of 1.0∶2.0∶0.8,by using ball milling(YDM-1 rapid ball mill)at 1400 r·min-1 for10 min.The glaze slurry was passed through a 100-mesh sieve.The molar ratios of MgO/CaO included 0.10/0.78,0.15/0.73,0.29/0.59,0.44/0.44,0.59/0.29.The color parameters of the samples were analyzed by using colorimeter,while the sample glaze was subjected to stereomicroscopic analysis under 250× magnification with a VHX-6000 super depth-of-field three-dimensional microscope.X-ray diffractometer and laser Raman spectrometer were used to analyze phase compositions of the samples.A micro-area X-ray fluorescence spectrometer(M4 TORNADO)was employedto examine surface elemental profiles.The samples wereetched in 5 wt.％HF solution for 35s,followed by ultrasonic cleaning for 20 min and drying at 80℃ for 2 h.Microstructures ofthe glaze were observed using a field emission scanning electron microscope(JEM-6700FSEM),while the microstructure map was constructed using an Image-Pro Plus image processing software. [Results]With the change of MgO/CaO molar ratio from 0.10/0.78 to 0.44/0.44,the overall L*value shows a decreasing trend and surface brightness of the glaze gradually decreases.Meanwhile,with the increasing MgO/CaO molar ratio,the split-phase droplets gradually become smaller and the glaze Rayleigh scattering was weakened,so the blue part of the glaze surface gradually becomes smaller.For the mottled part of the glaze surface,with decreasing MgO/CaO molar ratio,the split-phase droplets also gradually become smaller.The glaze surface mottled at the Mie scattering is correspondingly weakened,with lower the degree of milkyness.When the MgO/CaO molar ratio is 0.59/0.44,the L*value shows an overall decreasing trend and the brightness of the glaze surface gradually decreases.At ratio of 0.59/0.29,the glaze surface has silver blocky mottling,with metallic luster,resulting in a higher L*value.Due to the high temperature viscosity ofthe glaze,the generated O2 escapes on the surface of the glaze and forms a certain number of pits.In this case,the glaze surface has a high content of iron,which is enriched with iron phases in the pits.After cooling due to the supersaturation,it precipitates into crystals in the form of magnetite,hematite and other forms,creating crystalline films that produce a full-wave band of strong reflections on the visible light,thus resulting in silvery-white patina.With increasing molar ratio of MgO/CaO,the degree of glassiness of the enamel gradually decreases,leading to a gradual decrease in the gloss of the glaze. [Conclusions]The molar ratio of MgO/CaO has a significant effect on the coloration of gray-blue glaze of Yixing uniform pottery.In oxidizing atmosphere,the glaze coloration is mainly produced through the co-coupling of structural color and ionic coloring.With increasing molar ratio of MgO/CaO,the generation and growth of split-phase droplets are suppressed,while the glaze color changes from blue-green to blue to brown,due to the effects of the Rayleigh scattering and the Mie scattering.When the molar ratio of MgO/CaO is 0.59/0.29,the glaze forms uneven silvery-white mottles,which is ascribed to the high temperature viscosity of the glaze caused by the high molar ratio of MgO/CaO,making the glaze surface uneven.High molar ratio of MgO/CaO inhibits the generation and growth of the phased droplets.The structure of the glaze surface produces multi-stage phase separation,which promotes the nucleation and crystal growth of the glaze,making the glaze surface easier to precipitate the crystals of iron oxide,the formation of crystal thin film and strong reflection of light,thus resulting in silver-white color.

[Background and purposes]Due to its high hardness,high thermal conductivity,outstanding corrosion resistance and strong chemical stability,silicon carbide(SiC)has been widely used in high-tech material manufacturing fields,such as aerospace,national defense,nuclear industry and space technology.Nevertheless,the high hardness and brittleness of SiC ceramics render them extremely difficult to be processed into complex shapes by using the traditional mechanical processing techniques.Introducing a second phase with high mechanical properties and high electrical conductivity into the silicon carbide matrix is considered as an effective approach to enhance the comprehensive and processing performances of SiC ceramics. [Methods]SiC-TiB2-ZrN composite ceramics were prepared by using β-SiC,ZrB2 and TiN as the raw materials at 2000 ℃ and 40 MPa.The effects of the content of the additives on phase composition,microstructure,mechanical properties and electrical conductivity of the SiC-based composite ceramics were studied.ZrB2 and TiN reacted in-situ to form TiB2 and ZrN.The in-situ reaction improved the sintering performance of SiC ceramics.The generated TiB2 and ZrN possess excellent electrical conductivity and mechanical properties,thus significantly improving the electrical conductivity and mechanical properties of the final products. [Results]SiC-TiB2-ZrN composite ceramics were obtained from the raw materials with different formulations,while no ZrB2 and TiN residues were retained after sintering.During the sintering process,the generated TiB2 and ZrN were mutually dissolved,causing the XRD diffraction peaks of the two phases to shift.With increasing content of the additive,the porosity of the ceramic composites decreased from 12.96％to 0.07％,indicating that the in-situ reaction of ZrB2 and TiN significantly enhanced the sintering activity of SiC.When the contents of TiB2 and ZrN were 30 mol％,the hardness and fracture toughness of the ceramic composites ceramics were 25.19 GPa and 5.68 MPa·m1/2,respectively.The SiC grains experienced transgranular fracture mode dominantly.The presence of TiB2 and ZrN in the ceramic composites leads to the occurrence of intergranular fracture mode.Moreover,when the cracks propagated in TiB2 with higher mechanical properties,the crack propagation path was significantly tortured.Electrical conductivity of the ceramic composite with 30 mol％TiB2 and ZrN was 3.3× 103 Ω-1·cm-1. [Conclusions]SiC-TiB2-ZrN ceramic composites were successfully fabricated using β-SiC,ZrB2 and TiN as raw materials.The TiB2 and ZrN phases in the ceramic composites inhibited the phase transformation of β-SiC to α-SiC.The addition of additives was beneficial to densification and mechanical properties of the SiC ceramic composites.When the contents of TiB2 and ZrN were 30 mol％,the apparent porosity,Vickers hardness and fracture toughness of SiC ceramic composites were 0.07％,25.19 GPa and 5.68 MPa·m1/2,respectively.The improvement of mechanical properties was attributed to the increase in density and the change in fracture mode.Due to the high electrical conductivity of TiB2 and ZrN and their inhibition of the crystal phase transformation of β-SiC,the STZ30 sample had high electrical conductivity of 3.3×103 Ω-1·cm-1,making the SiC-TiB2-ZrN ceramic composites suitable for EDM processing technology,which has advantages in improving processing efficiency and realization of complex shapes.

[Background and purpose]At present,the synthesis of FDCA from HMF mainly relies on the traditional liquid-phase catalytic reaction system.This reaction process requires the use of not only noble metal catalysts,such as platinum(Pt),gold(Au)and palladium(Pd),but also toxic strong oxidants,such as potassium dichromate(K2Cr2O7)or potassium permanganate(KMnO4).The reaction conditions are rather harsh,usually requiring relatively high temperatures(100-200 ℃)and high pressures(＞5 bar)to effectively achieve the conversion of HMF.Therefore,efforts have been constantly made to seek more environmentally friendly and economical methods.Electrocatalysis,as an emerging technology,can be used for the conversion of HMF under milder conditions,while avoiding the use of toxic oxidants and noble metal catalysts.Noble metal catalysts exhibit certain performance in the electrocatalytic conversion of HMF,but their high cost and scarce raw materials are significant drawbacks.Therefore,the development of highly efficient and inexpensive non-noble metal catalysts has become a research hotspot in the field of biomass conversion. [Methods]Electrodeposition method was used to synthesize the catalysts.In an electrolyte with a total metal salt concentration of 50 mmol·L-1,hydroxides of nickle-cobalt and other elements(Ni-Co-OH)were formed on titanium mesh substrate.After electrodeposition for 10 min,a blue-cyan NiCo hydroxide sample was obtained.Subsequently,the sample was calcined at 250 ℃ for 2 h in air,at a heating rate of 1 ℃·min-1,converting the bimetallic cobalt-based hydroxide into NivCoyO4.Electrocatalytic oxidation activity of HMF of the Ni1.5Co1.5O4 catalyst could be optimized by adjusting the ratio of nickel.The regulation of Ni content could be used to enhance the conductivity of the catalyst,increase the number of active sites and adjust the electron density and energy-level distribution in the spinel structure,thereby improving the HMFOR activity.In situ Raman and in-situ EIS were combined to explore the mechanisms and roles of Ni and Co in Ni1.5Co1.5O4 during the catalysis of HMFOR. [Results]Benefiting from the flexible metal-ion substitution mechanism and structural stability of the Co-based spinel,Ni1.5Co1.5O4 exhibited nanosheet morphology and large specific surface area.There is an inter-ionic charge transfer between Ni and Co.In Ni1.5Co1.5O4,electrons transfer from Ni to Co,making Co an electron-rich center and Ni an electron-deficient center.Secondly,the introduction of Ni increased the electrochemical active surface area of Ni1.5Co1.5O4 and the charge-transfer efficiency inside the electrode,thus improving the performance and efficiency of HMFOR.Eventually,a HMF conversion rate of 99.77％,a FDCA yield of 98.10％,and a Faradaic efficiency of 97.86％were achieved. [Conclusions]For Ni1.5Co1.5O4,on one hand,the Co-based spinel structure inherently possessed high structural stability.With the substitution of Ni ions,no significant lattice distortion or structural collapse occurred.On the other hand,Ni ions and Co ions are similar in size and charge,Ni ions can flexibly replace Co ions at different sites without disrupting the overall lattice structure.As a result,the nanosheet structure of the Co-based spinel is well-maintained,thus leading to increase in electrochemical specific surface area and number of active sites.There is an inter-ionic charge transfer between Ni and Co,rendering Co an electron-rich center and Ni an electron-deficient center.At applied voltages,Co3+is more likely to be oxidized to generate highly active Co4+for HMF.This active species key to the-OH—-CHO reaction.The results of in-situ Raman spectra indicated that the surface of Ni1.5Co1.5O4 underwent reconstruction at applied voltages.The formation of Ni3+/Ni4+at relatively high applied voltages led to a competitive reaction between the oxygen evolution reaction(OER)and HMF.In the synergistic effect of Ni and Co,apart from contributing catalytic activity,Co also played a role in maintaining the structural stability of the catalyst.

[Background and purpose]The improvement in the degree of industrialization,the continuous development of machining,steel,minerals and other industries have led to increasing demand for emulsified oil in the industry.With the expanded application of emulsified oil,the environmental problems caused by wastewater discharge become more and more aggravated.Such wastewaters contain high concentration CODCr,with complex composition and difficulty in degradation,which poses a threat to the ecological environment and human health.Conventional treatment processes,such as electrolysis,precipitation and flocculation,have encountered problems,such as low removal efficiency,high cost and secondary pollution.Ceramic membranes have strong anti-pollution performance,long cleaning cycle,easy maintenance and no need of chemical agents,thus being in line with the concept of environmental protection.Therefore,it has been widely used in the treatment of emulsified oil wastewater.In this study,the efficient interception of emulsified oil in wastewater by using flat ceramic membrane was realized,aiming to provide theoretical basis for the application of flat ceramic membrane in the treatment of wastewater containing emulsified oil. [Methods]The rationality of the experimental design was verified by analyzing the characteristics of the emulsified oil and the characterization properties of the flat ceramic membrane.The influences of influent CODCr concentration,pH value,aeration and other factors on the treatment effect of the flat ceramic membrane were explored.In order to obtain the optimal process conditions for treating wastewater containing emulsified oil,GPC was used to detect the emulsified oil,so that the molecular weight and distribution of the components were determined.SEM and EDS were used to characterize the ceramic membranes and observe their surface morphology.CODCr was determined according to HJ/T 399-2007 Determination of Water Chemical Oxygen Demand by Rapid digestion Spectrophotometry.In order to ensure the accuracy of the experiment,each group of experiments were repeated three times and the arithmetic average of the three experiments was taken as the test result. [Results]According to the gel permeation chromatography(GPC)diagram of the emulsion oil,the size of the emulsified oil molecule is larger than 1/10 of the aperture of the flat membrane(100 nm),so that the emulsion oil can be completely trapped by the flat membrane.As revealed by SEM images,the inner surface of the flat ceramic membrane(i.e.,the interception surface)became obviously rough,suggesting that the emulsion oil molecules were trapped on the surface.EDS indicated that,after the interception of emulsified oil,there are obviously a large number of carbon-containing substances on the surface of the plate ceramic membrane,implying that the ceramic membrane can effectively intercept the emulsified oil.As the concentration of CODCr in wastewater increases,the removal rate increases gradually.This indicates that the concentration of the emulsified oil wastewater has a great influence on the treatment efficiency.The higher the concentration of the wastewater,the more the organic molecules are trapped by the plate ceramic membrane.As the pH value of the wastewater increases,the removal efficiency of CODCr gradually increases.This is because NaOH solution,as a regulator and demulsifier,forms a mixed membrane with the film-forming substances in the emulsified oil of the original wastewater,which has lower strength than the original interface membrane,resulting in the destruction of the interface membrane.In this case,the water was wrapped in the membrane,whereas the water droplets collide one another to form large water droplets,eventually settling down to the bottom.Aeration has little effect on the removal of CODCr in effluent.This is mainly because the oil droplets in the waste emulsified oil are stably dispersed in the water by the emulsifier,which not only includes oil substances,but also may contain other organic substances,such as emulsifiers,undecomposed additives,etc.,to form a stable emulsion,thus making it difficult for the oil droplets to gather and float or separate through simple aeration.In aerating state,the processing capacity of the equipment is significantly higher than that in non-aerating state.This is because the aeration forms cross-flow on the membrane surface,which would wash the membrane surface,remove the material on the membrane surface and reduce the concentration polarization,thus reducing the occurrence of irreversible membrane pollution,effectively minimizing the probability of membrane pollution and improving the continuous processing capacity. [Conclusions]A new process-short flow plate ceramic membrane process-is proposed for the treatment of emulsified oil wastewater from mine hydraulic supports.The plate ceramic membrane can effectively retain emulsified oil and reduce the CODCr in water.Under the conditions of an influent CODCr of 120 mg-L-1,a pH of 9 and aeration,the treatment efficiency of the plate ceramic membrane was optimized.Specifically,the effluent CODCr is reduced to 57 mg·L-1,corresponding to a removal rate of 52.5％.Meanwhile,aeration can effectively reduce the degree of membrane pollution and extend the service life of the plate ceramic membrane.

[Background and Purpose]The construction of large-span steel suspension bridges has increased demand for fire protection materials that can withstand the harsh conditions,including potential fires and humid environments.Traditional fire protection materials often fail to meet the specific requirements of bridge cables,such as lightweight,flexibility and maintaining performance in humid conditions.Fiber-reinforced SiO2 aerogel composites offer a promising solution,due to their superior thermal insulation and mechanical properties.However,the long-term performance of these composites under hygrothermal aging conditions,which are critical for their application in bridge cables,remains unexplored.This study was aimed to address this issue by evaluating the hygrothermal aging behavior of fiber-reinforced SiO2 aerogel composites,thus predicting their service life in natural environments. [Methods]Three types of SiO2 aerogel composites were prepared,with glass fiber,glass fiber-basalt fiber composites,and basalt fiber as matrices,by using sol-gel technology and supercritical ethanol drying processes.The composites were subjected to hygrothermal aging tests at 60 ℃ and 90％relative humidity for up to 180 days.Microstructure,mechanical properties and thermal insulation performance of the composites before and after aging were characterized by using scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),universal testing machine and thermal conductivity measurements.The degradation of mechanical and thermal insulation performance was analyzed,while a prediction model for the service life of the composites under natural environmental conditions was proposed based on the Hallberg-Peck model. [Results]It is found that the fiber was bonded with the aerogels well in the initial state of the composites,with aerogels uniformly filling the fiber-formed framework.After hygrothermal aging for 180 days,some fibers detached from the aerogel,leading to partial fracture of the aerogel blocks.The tensile strengths of the glass fiber/aerogel composite,glass fiber-basalt fiber/aerogel composite and basalt fiber/aerogel composite decreased by 4.9％,11.7％and 10.3％,respectively,while their thermal conductivities increased by 5.6％,9.2％and 8.4％.The Hallberg-Peck model was used to predict the service life of the composites in Guangzhou natural environments,while the failure criteria was set to be that the degradation of tensile and heat insulating properties was no more than 10％.As a result,the predicted service lives of the glass fiber/aerogel composite,glass fiber-basalt fiber/aerogel composite and basalt fiber/aerogel composite were 18.7 years,10.4 years and 11 years,respectively. [Conclusions]The three types of fiber-reinforced SiO2 aerogel composites exhibit sufficiently high stability and performance retention under hygrothermal aging conditions,making them suitable for long-term service in the humid environments of bridges.These composites showed significant potential in the application on bridge cable fire protection,contributing to enhanced safety and durability of bridge structures.The findings also provide valuable insights into the design and optimization of fiber-reinforced aerogel composites for various engineering applications,highlighting the importance of understanding the aging mechanisms and predicting the service life of such materials.

[Background and purpose]With the vigorous development of the cultural industry around the world,the economic value of intangible cultural heritage is increasingly being discovered and recognized.As a typical traditional craft with the nature of production,ceramic intangible cultural heritage has economic attributes from the date of birth and has broad prospects for industrialization.However,during the process of industrialization,it is very easy for enterprises to harm its artistic authenticity owing to the pursuit of maximizing profits.As a novel business model using market-based strategies to solve complex social issues,social entrepreneurship provides new ideas for the inheritance of intangible cultural heritage.Specifically,social entrepreneurship offers considerable benefits in the inheritance of ceramic intangible cultural heritage,such as achieving the integration of commercial and cultural value,engaging a diverse range of stakeholders,promoting ceramic cultural identity and dissemination,advancing the innovation and sustainable development and so on.However,in the process of fulfilling social mission,enterprises meet challenges in aggregating resources and creating value simply by its own strength,so that it is necessary to collaborate with stakeholders to allocate and integrate resources.Therefore,value co-creation represents the core logic embedded in the process of social entrepreneurship.This study is aimed to explore the realization path of social entrepreneurship to promote the inheritance of ceramic intangible cultural heritage under the participation of multiple stakeholders with case studies. [Methods]Huangyao Group and Chengdexuan Porcelain Co.,Ltd.were selected as the samples for case study.The two companies have insisted on adopting traditional handmade porcelain techniques from the beginning of their founding,who have made outstanding contributions to the inheritance and development of the ceramic intangible cultural heritage.Their efforts also have received profound recognition.The grounded theory was used to analyze both primary and secondary data,totaling more than 160,000 words.The data set encompasses the following sources:(1)records of in-depth interviews,encompassing company executives,company staff,inheritors,and government personnel;(2)internal company documents;(3)information published on the company's official platforms;(4)relevant news reports;(5)government documents;(6)related papers from CNKI;(7)consumer feedback from various platforms.The data analysis process includes four parts:open coding,axial coding,selective coding and theoretical saturation test.Following systematic inductive analysis,the concepts and categories were progressively refined from the primary data,which was initially vague and cluttered.Ultimately,the realization path of social entrepreneurship to promote the inheritance of ceramic intangible cultural heritage was formulated. [Results]In the open coding session,61 concepts were obtained through the initial refinement of the primary data.Subsequently,the related concepts were categorized into the same category and 19 categories were refined,such as profit-driven,social mission and personal experience.In the axial coding session,the 19 categories were integrated into 4 main categories through a process of further clustering and summarization:conceptual consensus,environmental co-construction,cooperation symbiosis and value win-win.In the selective coding session,through repeated analysis of the 19 categories and 4 main categories,the core category was finally summarized as"value co-creation of social entrepreneurship in ceramic intangible cultural heritage industry".The four main categories serve as the process of the core category,in which the conceptual consensus forms the foundation,the environment co-construction serves as the guarantee,cooperation symbiosis is the key and the value win-win is the goal.One-third of the original data were set aside as a saturation test sample.Following the coding process,no additional concepts or categories emerged.Consequently,the theoretical saturation test was passed and the model had reached saturation. [Conclusions]Social entrepreneurship is an effective way to promote the inheritance of ceramic intangible cultural heritage.Guided by the theory of value co-creation,the realization path of social entrepreneurship to promote the inheritance of ceramic intangible cultural heritage was thoroughly explored.Social entrepreneurship establishes a value co-creation network through four distinct processes,i.e.,conceptual consensus,environmental co-construction,cooperation symbiosis and value win-win.This value co-creation network encompasses the involvement of various stakeholders,including government,enterprises,inheritors,local residents,universities,research institutes and consumers.In the collaborative creation of value by stakeholders,social entrepreneurship effectively activates the cultural value and economic potential of ceramic intangible cultural heritage,thus realizing its living heritage in the process of industrialization.Finally,the study was concluded with four implications to help optimizing the development of social entrepreneurship in ceramic intangible cultural heritage industry.

[Background and purpose]Solid oxide fuel cell(SOFC)is a highly efficient electrochemical device that can be used to directly convert chemical energy of hydrogen and hydrocarbon fuels into electricity in an environmentally friendly manner.While the typical operating temperatures of SOFCs have been reduced to 600-850 ℃,ferritic stainless steels(FSS),such as ZMG 232,AISI 441,SUS430,etc.,can be utilized as interconnect materials,due to their high electrical conductivity,low material/manufacturing cost,excellent mechanic strength and similar coefficient of thermal expansion(CTE)to other cell components.However,it still exists several issues during their operation at 600-850 ℃,including continuous growth of Cr2O3 scale,Cr migration to cathode and dimensional tolerance at interconnect-cathode interface.These issues will cause serious performance degradation for stacks.To solve these problems,a dense protective coating and a porous contact layer are typically prepared between the metallic interconnect and the cathode.The dense protective coating is utilized to inhibit the growth of Cr2O3 scale and prevent Cr migration to the cathode,while the porous contact layer can provide better electrical pathway to decrease the power losses and compensate for the dimensional tolerance between the interconnect and the cathode. [Methods]In this study,MnCoNiFeCu alloy powder was selected as the precursor materials for dense protective coating and porous contact layer.A coating/contact dual-layer structure was fabricated through reactive co-sintering in the simulated SUS 430 interconnect/coating/contact/cathode/cathode support test cells.The precursors were calcined in air at 900 ℃ for 2 h to study phase evolution and microstructure of the protective coating and the contact layer.The phases in the sintered layers were characterized by using X-ray diffraction(XRD),whereas scanning electron microscopy(SEM)featured with energy-dispersive spectroscopy(EDS)was utilized to analyze the microstructure and obtain the compositional information.The test cells were fabricated to examine the electrical performance of the dual-layer structure via Area-Specific Resistance(ASR).After the initial sintering,the furnace temperature was then dropped to 800 ℃ for isothermal oxidation for 1000 h and ten thermal cyclic test.The tested samples were then epoxy-mounted,sectioned,and polished for examining cross-sectional microstructure after oxidation.EDS line scans near at the interconnect-coating and contact-LSM cathode interfaces were obtained to identify the possible interdiffusion between the cell components.Furthermore,the effectiveness of the dual layer in inhibiting the growth of the Cr2O3 layer and blocking Cr migration from the interconnect to cathode was also assessed. [Results]XRD results of the protective coating and contact layer after thermal conversion revealed that the sintered samples predominantly consisted of spinel phase,with minor oxides,while no metallic phases were detected.Specifically,the protective coating exhibited a majority of the spinel phase along with CuO and CoO,as confirmed by EDS mappings,indicating the aggregation of Cu and Co on the surface.In contrast,the contact layer primarily contained the spinel phase and CuO,with EDS mappings indicating uniform distribution of Fe,Co,Ni,Mn and Cu,while no delamination was observed.In ASR measurements,the tested sample exhibited stable behavior with an ASR of only 22.04-22.71 mΩ·cm2 during the 1000 h isothermal oxidation,while the thermal cycling led a dramatic increase in ASR.Once the ASR measurement was completed,the sample cross-sectional surface was characterized.For isothermal oxidation,a dense protective coating and a relatively porous contact layer were observed between the interconnect and cathode.The dual-layer structure was well-boned with the interconnect and cathode after the isothermal oxidation,indicating that the double-layer structure exhibited exceptional thermal compatibility with the adjacent cell components.Importantly,no Cr was detected within both the contact layer and cathode,further confirming the effectiveness of the double-layer structure in inhibiting the migration of Cr from the interconnect to cathode.Conversely,the thermal cycling test sample exhibited serious cracking at the interface between the porous contact layer and the LSM cathode,which was responsible for the rapid increase in ASR during thermal cycling testing. [Conclusions]In this study,MnCoNiFeCu alloy powder was utilized as the precursor material to develop a dense protective coating and a porous contact layer simultaneously through reactive co-sintering,forming a(Mn,Co,Ni,Fe,Co)3O4-based dual-layer structure.The sample exhibited stable behavior with an ASR of only 22.04-22.71 mΩ·cm2 after 1000 h of isothermal oxidation,while the thermal cycling led a dramatic increase ASR in.Notably,the growth of the Cr2O3 scale was dramatically suppressed,while no Cr was detected in the LSM cathode,confirming the effectiveness of the thermally converted dual-layer structure in blocking the migration of Cr.The HEA used as the dense protective coating and porous contact layer offers several advantages,including uniform microstructure,improved electrical performance,exceptional Cr-blocking capability and simple fabrication process.In the future study,more efforts should focus on optimizing the elements in the precursor alloy to further enhance the uniformity and CTE matching of the dual-layer structure after sintering.

[Significance]Amorphous calcium carbonate(amorphous CaCO3,ACC)is the amorphism of CaCO3 with molecular formula of CaCO3·nH2O.It is termed as anhydrous ACC for n=0,which is unstable,and as hydrous ACC for n＞0,which is stable to a certain extent.The value of n in hydrous ACC is also variable,leading to a series of amorphous CaCO3 with different water contents,which is referred to as polyamorphism.ACC has been identified in diverse biological structures and synthesized in laboratory under certain conditions.Due to its thermodynamic instability,ACC serves as a crucial precursor for both geologic CaCO3(calcite)and biologic CaCO3(vaterite and aragonite).Particularly,it plays very important roles in biomineralization.ACC has been widely applied in the fields of calcium supplement,bone regeneration,biological medicine,drug carrier and protein adsorption.Despite decades of study,challenges persist regarding the preparation and conservation of ACC.Furthermore,comprehensive reviews on ACC remain insufficient,especially for the development in recent years.This paper is aimed to provide a comprehensive review on ACC,covering structural model,preparation routes and stability. [Progress]Several structural models of ACC were derived from simulations with different methods,such as Reverse Monte Carlo(RMC),Classical Molecular Dynamics(CMD)and Ab initio molecular dynamics(AIMD).However,it is still debatable on the real structure of ACC.ACC can be synthesized with two basic systems,Ca2+-H2O-CO 32-and Ca2+-H2O-CO2,referred as to double decomposition reaction and carbonation reaction,respectively.The reaction between calcium salt and carbonate in aqueous solution is the most commonly used to synthesize ACC,in which high pH,high concentration and additive,e.g.Mg2+,PO43-,amino acid and protein,are the key factors to obtain ACC with desirable stability.In Ca2+-H2O-CO2 reaction system,the sources of CO32-are diverse,including pure CO2,CO2 in air,CO2 released from(NH4)2CO3 or NH4HCO3,CO2 released from organic matter,CO2-storage materials and so on.Based on double decomposition reaction,the reaction between calcium salt and carbonate in alcohol-water binary solvent even in water-free solvent has been developed in the past decades.Moreover,the solid reaction between CaCl2 and Na2CO3 via mechanochemical method has been employed to prepare ACC.ACC-polymer hybrid materials have also been synthesized based on the two basic systems.The crystallization of ACC occurs through two mechanisms:direct crystallization or dissolution-diffusion-crystallization.The first crystallization takes place in solid state,accompanied by the loss of structural water,while the second one occurs in aqueous media through two or three steps:dissolution(diffusion)and crystallization.In direct crystallization happens due to the dehydration of molecular water,induced by temperature or pressure.However,ACC powder will crystalize in humid environment.In aqueous reaction systems,the crystallization of ACC is inevitable.Therefore,reducing the water content of reaction system is a frequently used method to inhibit the crystallization of ACC and enhance its stability,even in a water-free system.In addition,some cations,e.g.,Mg2+,some anions,e.g.OH-,PO43-and organic molecules can be used to stabilize ACC in aqueous media. [Conclusions and Prospects]The Ca2+-H2O-CO32-system with high pH or/and high concentration is the prevalent method to obtain ACC in early studies.The efficiency of this approach could be enhanced in the presence of organic additives,which is known as biological mineralization.The introduction of organic solvent in Ca2+-H2O-CO32-system can promote the formation and improve stability of ACC.However,the presence of water proves to be disadvantage for long-term stability of ACC.Water-free systems exhibit distinct advantages in both ACC preparation and long-term stability.The ADM method in aqueous medium has additional advantage in ensuring product purity by minimizing impurities in ACC.Beyond addressing structural water concerns,the introduction of Mg2+,PO43-,OH-and organic molecules emerges as a strategy to enhance the stability of ACC.Furthermore,ACC has been formed on the template of polymers and proteins.Achieving long-term stability of ACC has been hot spot of research,leading to various innovative protocols in the past decades.