The preparation of TiO2 microspheres by spray drying followed by controlled sintering was investigated. Starting from commercial rutile TiO2 nanoparticles dispersed in water, spherical microspheres with broad size distributions were produced by adjusting key spray-drying parameters, including solid concentration, gas flow, and suspension composition. The results showed that controlling the spray-drying conditions and the subsequent sintering cycle influenced the resulting microsphere size and morphology, grain evolution, and porosity. A tailored multi-step sintering approach was used to control the microstructural evolution of individual TiO2 microspheres while limiting inter-microsphere coalescence. SEM and three-dimensional nano-tomography revealed pronounced grain growth and progressive pore elimination during sintering. The grain size increased from approximately 2–5 µm at 1200 °C to 20–40 µm at 1400 °C, while ex situ nano-tomography showed a decrease in pore volume fraction from 15.9% to 1.3% over the same temperature range. In situ nano-holotomography further confirmed the progressive reduction in the connected pore network during heating. Overall, sintering at 1400 °C provided the best compromise between densification, grain growth, microsphere isolation, and preservation of the spherical morphology.
Prosthetic restorations made of titanium and its alloys are often veneered with ceramics. While Co-Cr or Ni-Cr alloys are subjected to high-temperature oxidation before ceramic application, this is not possible for titanium due to its high reactivity; hence, the resulting layers are thick, porous, and have poor adhesion. An alternative method for obtaining an oxide layer is anodic oxidation, or anodization. This paper presents the shear strength of the titanium–ceramic bond after different anodization variants. The following reagents were used for oxidation: Group A—1 molar phosphoric acid (V), Group B—1 molar sulfuric acid (VI), Group C—1 molar mixture of the above acids, and Group D—2% Na2SiO3 at pH = 13.1. The veneering ceramic was applied to the treated sample surfaces, and the samples were subjected to a shear test. Anodic oxidation was found to increase the joint stress compared to a control group of unanodized samples (Group 0). The highest strength was achieved for samples from groups A and B. Hence, anodic oxidation improved the titanium–ceramic adhesion of polished samples compared to the control group.
The effect of Co3O4 concentration on the phase composition, surface morphology, geometric density, estimated porosity, compressive strength, and resistive superconducting transition of YBa2Cu3O7−δ ceramics was comparatively investigated. Undoped YBa2Cu3O7−δ and Co3O4-modified YBa2Cu3O7−δ ceramics containing 0.1, 0.5, 1.0, and 1.5 wt.% Co3O4 were prepared from the same nonstoichiometric Y–Ba–Cu–O precursor mixture by a solid-state reaction route followed by oxygen annealing. Phase composition was evaluated by X ray diffraction, surface morphology by scanning electron microscopy, geometric density from specimen mass and dimensions, compressive strength by uniaxial compression, and superconducting transition parameters by four probe electrical resistance measurements. The YBa2Cu3O7−δ phase remained the dominant crystalline phase in all specimens. The sample containing 0.1 wt.% Co3O4 exhibited the highest YBa2Cu3O7−δ content among the modified specimens, 65.2 wt.%, the highest measured compressive strength of 1.95 MPa, and the highest onset transition temperature of 95 K. The highest geometric density of 5.36 g/cm−3 and the lowest estimated porosity of 15.3% were obtained at 0.5 wt.% Co3O4. The specimens containing 1.0 and 1.5 wt.% Co3O4 showed lower YBa2Cu3O7−δ phase fractions and lower geometric density, and did not reach the zero-resistance state within the available measurement range. Although the 0.1 wt.% specimen exhibited a higher onset temperature than undoped YBa2Cu3O7−δ, its lower zero-resistance temperature and broader transition indicate that Co3O4 did not improve all superconducting parameters simultaneously. Since only one specimen was tested for each composition, the density and compressive strength trends should be regarded as preliminary.
A novel lithium disilicate glass-ceramic modified with Pyrex-derived borosilicate glass and antimony oxide was developed to improve mechanical performance while maintaining chemical stability. The material was fabricated by oxide mixing, melt-quenching, casting, and controlled crystallization, followed by structural and microstructural characterization using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Flexural strength, Vickers hardness, and chemical solubility were evaluated according to the relevant ISO standards and compared with those of a commercial lithium disilicate glass-ceramic (IPS e.max CAD; Ivoclar Vivadent, Schaan, Liechtenstein). Statistical analyses were performed using independent-samples t-tests at a significance level of α = 0.05. Structural characterization demonstrated a multiphase crystalline glass-ceramic containing reflections consistent with lithium disilicate, while FE-SEM revealed elongated, partially interlocking crystals distributed within the residual glassy matrix, confirming the development of the intended glass-ceramic microstructure. The experimental material exhibited significantly higher flexural strength than the commercial reference (560.41 ± 53.31 MPa vs. 371.39 ± 14.48 MPa; p < 0.05), whereas Vickers hardness and chemical solubility did not differ significantly between the materials (p > 0.05). These findings suggest that the incorporation of Pyrex-derived borosilicate glass as a glass-network modifier, together with antimony oxide, may provide a viable approach to producing lithium disilicate glass-ceramics with enhanced flexural performance while maintaining hardness and chemical durability, supporting their potential for dental restorative applications.
A CMY palette of ceramic pigments was synthesized using both microwave-assisted firing (800 W, 30 min) and conventional electric firing (1000 °C for 3 h). For the allochromatic vanadium-zircon system (including the non-mineralized green and halide-mineralized blue compositions), as well as the chromium-doped scheelite yellow pigment, microwave firing does not outperform conventional calcination. Although comparable reactions occur during synthesis, microwave firing produces powders with lower colour performance. Nevertheless, these differences become visually negligible after incorporation into glazes. This behaviour can be attributed to the low dopant concentration and the localized, selective heating characteristic of microwave irradiation. In the vanadium-zircon system, the microwave-mineralized sample exhibits features similar to those of the non-mineralized compositions, including lower reactivity, smaller crystallite size, and enhanced blue colour development when applied in glazes. In contrast, for the idiochromatic Zn(Al1.3Fe0.5Cr0.2)O4 spinel red-brown pigment, microwave firing yields superior colour performance compared with conventional electric firing, producing higher chroma and greater colour intensity. In idiochromatic pigments, the relatively high proportion of chromophore components promotes more homogeneous microwave absorption and heating throughout the precursor mixture. The enhanced colour properties achieved through microwave synthesis may indicate the presence of a beneficial non-thermal microwave effect, leading to improved chromatic performance.
Perovskite solar cells (PSCs) have emerged as one of the most rapidly advancing photovoltaic technologies of the past decade, progressing from the initial demonstration of 3.8% power conversion efficiency (PCE) in 2009 to certified single-junction efficiencies exceeding 26% and perovskite–silicon tandem efficiencies exceeding 33.9% as of 2024. Their appeal resides in the combination of a broadly tunable bandgap achieved through compositional engineering of the ABX3 perovskite crystal structure, compatibility with low-temperature solution processing, and the potential for manufacturing costs substantially below those of silicon photovoltaics. However, the translation of laboratory-scale performance to commercially viable modules at industrial throughput remains the central challenge in the field. This review provides a comprehensive and critically organized account of PSC manufacturing, spanning device architectures and material requirements, scalable deposition and coating technologies, charge transport layer integration and interface engineering, process control and crystallization strategies, post-treatment methods, artificial intelligence and machine learning-assisted manufacturing, module fabrication and encapsulation, advanced tandem and flexible device configurations, green chemistry and circular lifecycle strategies, and the critical barriers to commercialization. The review concludes with a strategic assessment of the technological, regulatory, and economic requirements for PSC technology to transition from pilot-scale demonstration to utility-scale deployment.
This in vitro study evaluated the effect of two silane coupling agent application techniques (dry air and thermally activated warm air) on the interfacial properties and shear bond strength (SBS) of lithium disilicate veneers fabricated with two designs: incisal overlap and window. Materials and Methods: The interfacial characteristics of lithium disilicate specimens were evaluated using contact angle measurements and ATR–FTIR spectroscopy to investigate the effect of different silane application techniques. Forty lithium disilicate veneer specimens were divided by preparation design (incisal overlap or window) and silane application technique (dry air or warm air) (n = 10). Forty flat lithium disilicate specimens were prepared for contact angle and ATR–FTIR analyses. Wettability was assessed using the sessile drop method, while SBS was measured using a universal testing machine. ATR–FTIR evaluated chemical changes within the silane layer. Results: Warm-air silane application significantly improved SBS and wettability compared with dry-air application. The incisal overlap/warm-air group exhibited the highest SBS (19.3 ± 1.7 MPa), whereas the window/dry-air group showed the lowest (12.5 ± 1.4 MPa). Contact angle measurements demonstrated significantly lower values following thermal activation (p < 0.001). ATR–FTIR analysis suggested modifications in carbonyl-containing organic species at the interface following thermal activation. Conclusions: Thermal activation of silane improved interfacial properties and bond strength. Incisal overlap preparations demonstrated superior bonding performance, while warm-air silane application enhanced adhesion across both designs.
Dense Ce,Pr-doped YAG transparent ceramics (YAG:Ce,Pr) with enhanced red emission were fabricated by pressureless sintering in air at 1600 °C. Fine YAG powders containing 0.2 mol% Ce and varying amounts of Pr (0.04–0.32 mol%) were synthesized using a glycine–nitrate combustion method. The emission and excitation spectra were analyzed to investigate the influence of Pr doping on red emission. The results indicate that YAG: Ce,Pr ceramics are a promising candidate for blue-to-yellow light conversion. The strongest red emission component was measured in samples containing 0.16 mol% Pr. It was confirmed that electron transfer from Ce to Pr enhances the red emission component (609 nm), primarily by increasing the population of electrons relaxing from the 1D2 excited state to the 3H4 ground state. Further increasing the Pr concentration beyond 0.16 mol% resulted in a reduction in the red emission intensity due to concentration quenching. Microstructural analysis of YAG:Ce,Pr revealed a dense and homogeneous microstructure composed of equiaxed grains.
This in vitro study evaluated the effects of simulated gastric acid exposure on surface roughness, color change, translucency, and mass change in four monolithic CAD/CAM restorative materials with different microstructural compositions. Rectangular specimens (12 × 14 × 1 mm; n = 12/group) were prepared from a polymer-infiltrated ceramic network material (VITA Enamic), a zirconia-reinforced lithium silicate glass-ceramic (Celtra Duo), a resin nanoceramic (Cerasmart), and a lithium disilicate glass-ceramic (IPS e.max CAD). After standardized finishing and polishing, baseline measurements of surface roughness, color coordinates, translucency, and mass were obtained, and the specimens were then individually immersed in simulated gastric acid (0.06 M HCl, pH 1.2) at 37 °C for 96 h, with the solution renewed every 24 h. Post-exposure measurements were performed using the same protocols. Data were analyzed using the Shapiro–Wilk test, Kruskal–Wallis test with Dunn’s post hoc comparisons, and Wilcoxon signed-rank test (α = 0.05). Significant changes were observed after acid exposure, and the magnitude of these changes varied among materials. Surface roughness increased significantly in all groups, with the greatest increase detected in Celtra Duo and VITA Enamic. Measured mass also changed significantly in all groups; VITA Enamic showed a slight increase, whereas Celtra Duo, Cerasmart, and IPS e.max CAD showed slight decreases. Although statistically significant differences in color change and translucency were identified among the groups, all color changes remained below the clinically perceptible threshold, indicating limited optical impact under the present model. IPS e.max CAD exhibited the lowest color change, whereas Cerasmart showed the highest ΔE00 values. Within the limitations of this accelerated in vitro model, simulated gastric acid exposure caused material-dependent alterations in surface roughness, limited optical changes, and small measured mass changes in monolithic CAD/CAM restorative materials.
Crystalline solids melt at well-defined material-specific temperatures Tm via first-order phase transitions, whereas glasses undergo continuous transformations from solid to molten states at glass transition temperatures Tg, resembling second-order transitions. Despite extensive study, the microscopic origin of this distinction remains unveiled. In this work, both melting and glass transition are described within a unified framework based on analysis of thermally activated breakings of chemical bonds, treated as elementary excitations of condensed matter, termed configurons. The increasing concentration of configurons leads to a percolation transition corresponding to loss of mechanical rigidity of an elastic solid whose atoms are connected via chemical bonds. Configurons are delocalized and mobile in crystals, enabling their condensation and consequent latent heat release, whereas in glasses they are localized (Anderson localization), suppressing condensation and yielding a continuous transition from solid to molten states. The proposed framework provides a unified physical interpretation of phase transitions.
Production of short-fiber-reinforced carbon/carbon composites (SF-C/C composites) is typically based on the pyrolysis of short-fiber-reinforced plastics (CFRPs) produced by compression molding. The production of C/C composites is generally a highly time- and energy-intensive process, particularly for complex geometries. Injection molding can offer an attractive alternative due to its high level of automation, cost efficiency, and ability to produce complex geometries. However, in contrast to compression molding, the shorter fiber lengths resulting from the compounding process and the parameter/geometry-dependent cavity-filling behavior in injection molding lead to a complex three-dimensional fiber orientation distribution. This can profoundly affect both the pyrolysis behavior of the CFRPs and the properties of the resulting SF-C/C composites. In this study, CFRP plates (150 × 150 × 4 mm3) were injection-molded at varying injection rates and mold temperatures. The influence of these parameters on the properties of the resulting SF-C/C composites was systematically investigated. Characterization included shrinkage and warpage behavior, porosity, microstructure via light microscopy and X-ray computed tomography, and flexural properties. The results show that the homogeneity of fiber orientation within the component is critical for controlling warpage during pyrolysis. In particular, asymmetric flow-line formation leads to non-uniform shrinkage across the thickness and promotes warpage. Therefore, achieving a homogeneous and/or symmetric distribution of the fiber orientation is essential for producing warpage-free SF-C/C composites by injection molding.
Ceramics, as a handicraft, is the crystallization of art and science. In order to study the firing process of ceramics, improve their density, mechanical properties, viscosity, and surface tension, and enhance the surface quality of the shaft, this article uses first-principles methods to study the electronic properties of ceramic colorants Al2O3, Fe2O3, TiO2, CaO, MgO, Na2O, KO2, and ceramic body SiO2. Research has shown that these seven color-developing agents exhibit anisotropy and have stable crystal structures. The bandgap values of Al2O3, CaO, Fe2O3, KO2, MgO, Na2O, TiO2, and ceramic SiO2 are 6.325 eV, 3.654 eV, 0 eV, 0 eV, 4.731 eV, 1.972 eV, 2.18 eV and 6.002 eV, respectively. In Al2O3/SiO2, Fe2O3/SiO2, TiO2/SiO2, CaO/SiO2, MgO/SiO2, Na2O/SiO2, and KO2/SiO2 systems, due to the influence of the potential field in the SiO2 system, the charge characteristics exhibit obvious interfacial and non-periodic characteristics. The research results revealed the charge transfer and distribution patterns at the interface between ceramic colorants and ceramic ligands, elucidating the influence mechanism of different colorants/embryo components on firing temperature, shrinkage rate, and finished product defects. This mechanism can be used to predict the advantages and disadvantages of alkali metals, iron, titanium, and aluminum components in raw materials, optimize low-temperature rapid firing formulas, suppress firing deformation, control pore defects, and improve the mechanical properties of finished products. It provides micro theoretical support for the industrialization, stabilization, and high-quality production of local ceramics in southwestern China.
Ceramics are widely evaluated for their extreme hardness, high-temperature stability, and corrosion resistance, which enable applications in harsh service environments. However, these same properties, high melting points, brittleness, and low thermal shock resistance, make conventional manufacturing of complex ceramic components difficult and expensive. Traditional processes often require costly diamond tooling or energy-intensive sintering and tend to produce only simple geometries, with significant waste material and risk of defects. Additive manufacturing (AM) has recently emerged as a promising route to fabricate intricate, near-net-shape ceramic parts without these drawbacks. By building components layer by layer, AM reduces the need for extensive machining and enables the fabrication of geometrically complex, near-net-shape ceramic structures with reduced material waste, although challenges such as porosity, interlayer defects, and cracking during post-processing remain. Nonetheless, ceramic AM technologies lag behind their metal and polymer counterparts, and significant challenges remain in achieving fully dense parts with reliable mechanical properties. This review provides an in-depth overview of the state of the art in ceramics and ceramic composite additive manufacturing. We detail the most widely used AM processes (stereolithography, binder jetting, material extrusion, powder bed fusion, inkjet printing, and direct energy deposition) and typical feedstock formulations for each technique. We examine the resulting mechanical properties (strength, toughness, hardness, wear resistance) and functional properties (thermal stability, dielectric behavior, biocompatibility) of additively manufactured ceramics, and discuss their current and potential engineering applications in the aerospace, defense, automotive, biomedical, and energy sectors. Persistent challenges, including porosity, shrinkage and cracking during sintering, achieving uniform microstructures, high process costs, and scalability issues, are analyzed, and we highlight promising future directions such as multi-material grading, integration of machine learning for process optimization, and sustainable manufacturing approaches. Despite significant progress, challenges remain in achieving fully dense structures, improving process reliability, and scaling ceramic AM for industrial applications, highlighting the need for further research in process optimization, material design, and multi-material integration.
Sintering additives play a decisive role in the densification behavior, mechanical properties, and thermal conductivity of silicon nitride ceramics. In this study, Mg2Si and YH2 were used as sintering additives for gas pressure sintering of silicon nitride based on the synergistic mechanism of "silicide silicon extraction-hydride dehydrogenation". The regulation rules of the additives on ceramic densification, mechanical properties, and thermal conductivity were systematically investigated. Two optimization strategies were proposed for the technical route of replacing traditional oxide additives with non-oxide systems. (i) Rare-earth hydride YH2 was used to replace traditional rare-earth oxides. It reacts with SiO2 to achieve strong deoxidation and precisely regulate the liquid phase composition. (ii) Metal silicide Mg2Si was used to replace metal oxides. It promotes the preferred growth of beta-Si3N4 grains, consumes oxygen in the system, and reduces lattice defects. Mg2Si introduces Si into the liquid phase, increasing the Si/O ratio, which lowers lattice oxygen content and supports higher thermal conductivity. YH2 consumes SiO2 on the Si3N4 surface, which reduces liquid phase oxygen content and inhibits lattice oxygen incorporation, promoting a liquid phase with a high N/O ratio. Compared with traditional Y2O3, YH2 increases the Y2O3/SiO2 ratio in the liquid phase. It promotes grain growth, reduces SiO2 activity, and further improves the thermal conductivity of ceramics. Silicon nitride ceramics prepared by gas pressure sintering at 1750 degrees C with 3 wt.% Mg2Si and 4 wt.% YH2 composite additives exhibit the highest thermal conductivity of 87 W/(m & centerdot;K), with a Vickers hardness of 14.36 GPa and a flexural strength of 643.15 MPa. This study provides an innovative idea for the preparation of high-performance silicon nitride heat dissipation substrates.
This study evaluates the durability of Self-Compacting Sand Concrete (SCSC) incorporating Windshield Glass Aggregate (WGA) as a sustainable replacement for natural sand, utilizing Blast Furnace Slag (BFS) as a constant filler component. Eleven mixtures were investigated: a control mix and ten variants with WGA substitution levels ranging from 10% to 100% in 10% increments. The specimens were exposed to elevated temperatures of 200-800 degrees C and to 240 freeze-thaw cycles between -18 degrees C and +9 degrees C. Under heating, mass loss increased with temperature, but WGA-rich mixtures generally showed lower mass loss and higher residual mechanical performance than the control. At 400 degrees C, WGA100 reached about 96 MPa in compressive strength and 15 MPa in flexural strength, corresponding to residual values of approximately 110.34% and 166.7%, respectively. After freeze-thaw cycling, all mixtures showed limited surface deterioration and mass loss below 1%, decreasing from about 0.76% for the control mixture to about 0.05% for WGA100. The improved durability is mainly attributed to the physical effect of WGA replacement and the baseline matrix refinement associated with BFS.
Samples made from illitic clay were investigated using thermogravimetry (TG), thermodilatometry (TD) and dynamic mechanical analysis (DMA) during heating from room temperature to 300 degrees C. TG revealed three steps of mass loss: (a) the release of weakly bound H2O (with the maximum rate at similar to 120 degrees C) from the pores, (b) a small mass loss event around 215 degrees C, (c) a small mass loss event near similar to 300 degrees C related to dehydration when H2O molecules located in K-free sites of the illite interlayers are removed. TD indicated very small dimension changes for 20 degrees C -> 300 degrees C. This behavior may result from two competing mechanisms, where the first one is regular thermal expansion and the second one is particle rearrangement caused by the removal of physically bound water. Young's modulus initially decreases during heating up to approximately 70 degrees C. Young's modulus subsequently increases exponentially, which may be explained by mechanisms analogous to those observed in the TD measurements. The activation energies derived from the exponential dependence E(t) are 5.66 kJ/mol for the temperature interval 130-200 degrees C and 10.96 kJ/mol for the 200-280 degrees C range.
Zirconia-toughened alumina (ZTA) ceramics are promising for load-bearing biomedical applications because they combine the hardness, chemical stability, wear resistance, and biocompatibility of alumina with the transformation-toughening capability of zirconia. Grinding is indispensable for achieving dimensional accuracy and surface quality, yet it inevitably introduces surface and subsurface cracks, residual stresses, and a local tetragonal-to-monoclinic transformation of zirconia. These changes can degrade fracture toughness, increase reliability scatter, and reduce long-term service stability. Annealing is therefore often considered a post-grinding recovery strategy because it can relax residual stresses, blunt crack tips, and partially restore the zirconia phase state. However, the extent of recovery depends strongly on the initial damage state, ZTA microstructure, and thermal schedule. This review systematically summarizes the current understanding of grinding-induced damage and annealing-assisted recovery in ZTA ceramics, with particular emphasis on the coupled relationships among subsurface damage, residual-stress evolution, phase transformation, and fracture toughness. Particular attention is given to distinguishing direct ZTA-specific evidence from mechanistic interpretations inferred from related zirconia-containing ceramic systems, because datasets based exclusively on ZTA remain relatively limited. By integrating the existing evidence, this review proposes a coupled processing-damage-recovery framework and identifies the key knowledge gaps that must be addressed to achieve more reliable process optimization in advanced ZTA components.
The use of zirconia as a material in the base of modern restorative dentistry is due to its high strength, biocompatibility, and improved aesthetic performance. The aim of this review is to provide an integrated and coherent overview of the recent developments in zirconia crowns by focusing on the development of materials, microstructure, digital fabrication processes, optical capabilities, and clinical performance. A survey of literature in the form of a narrative literature review was conducted in the most significant databases, such as PubMed, Scopus, Web of Science, and Google Scholar, including publications published since 2000, with a focus on systematic reviews, meta-analyses, clinical studies, and materials science studies. The results show that zirconia materials have developed beyond traditional 3Y-TZP systems, characterized by high strength and fracture toughness to high-translucency and multilayer zirconia (4Y 6Y-PSZ) systems, which provide better aesthetics at the cost of lower mechanical reliability. The implementation of CAD/CAM technologies has enhanced the accuracy of fabrication, marginal fit and reproducibility and the development of sintering, surface modification and bonding protocols has enhanced clinical performance. Recent clinical results have shown high survival rates (around 85–95 percent over 5–10 years), and the results depend on the design of the restoration, the zirconia generation, and the functional loading circumstances. Despite these developments, there are still concerns about the durability of bonding, trade-offs between translucency and strength, and long-term performance of high-translucency zirconia. The development of new technologies, such as additive manufacturing, design-aided artificial intelligence, and bioactive surface modification, is a promising avenue toward improving clinical reliability and performance.
This study investigates the development of sustainable ceramic materials using industrial and agricultural waste from the Kyzylorda region of Kazakhstan. The research focuses on the combined use of local clay, ash from the Kyzylorda thermal power plant (TPP), and rice husk ash (RHA). Experimental investigations included the evaluation of chemical composition, linear and volumetric shrinkage, water absorption, bulk density, and compressive strength of ceramic samples fired at 950-1050 degrees C. Microstructural (SEM) and phase composition (XRD) analyses were performed to explain the observed behavior. The results showed that the optimal composition was 70% clay, 20% TPP ash, and 10% RHA, which demonstrated the highest compressive strength (15.45 MPa), reduced water absorption, and improved densification. The enhanced performance is attributed to partial vitrification and viscous-phase-assisted densification and the formation of crystalline phases such as mullite, cristobalite, and anorthite. The study confirms that the combined use of TPP ash and RHA enables effective recycling of local waste materials and improves the physical and mechanical properties of ceramic products.
Herein, we report a method to additively manufacture carbon fiber-reinforced siliconized silicon carbide composites. The process involves the pyrolysis of a 3D-printed carbon fiber-reinforced poly-ether-ether-ketone (PEEK) composite to produce a porous carbon fiber-reinforced carbon matrix composite preform, which is subsequently infiltrated with molten silicon to obtain a carbon fiber-reinforced siliconized silicon carbide composite. A key aspect of the method is limiting polymer melt flow during pyrolysis of PEEK, which is achieved by thermally annealing the 3D-printed carbon fiber-reinforced PEEK preform in air at a temperature below PEEK’s melting temperature. Rheological and differential scanning calorimetry (DSC) measurements demonstrate that the thermal annealing treatment altered the melting behavior of PEEK, while NMR and FTIR measurements provided a mechanistic explanation for the structural changes responsible for the behavior. It was also found that dimensional changes during pyrolysis were anisotropic with greater shrinkage in the stacking direction of the material.
