Utilization of iron tailings to fabricate foam ceramics is of significant research value in both recycling of waste resources and meeting the demand for high-performance building insulation materials. In this work, foam ceramics were successfully fabricated using iron tailings via a foaming gel-casting method. Precise control of the foaming time could enable an effective tuning of the pore structure in foam ceramics. As-prepared foam ceramics showed a hierarchical porous structure with porosities of 61.82 %-80.07 %, compressive strengths of 3.08-13.02 MPa, and thermal conductivities of 0.184-0.351 W m(-1) K-1. After re-heating at 1150 degrees C for 10 h, the foam ceramics retained their original microstructure with a line shrinkage of 0.96 %. When they were further fired under an alcohol blowtorch at similar to 1105.7 degrees C for 40 min, the backside temperature of the foam ceramic was only 205.6 degrees C. These comprehensive properties make this tailings-based foam ceramic a promising lightweight material for fire-resistant and thermal insulation in construction and industry.

The mass production of potassium niobate powder with high crystallinity and anisometric morphology is crucial for developing advanced photocatalysts or photodevices with heterogenized and composite structures. However, single-phase layered microcrystals for the K-Nb-O system have long been challenging to synthesize by the molten salt method. Here, a strategy was proposed to fabricate layered K4Nb6O17 microcrystals from perovskite KNbO3 in molten KCl salt. It was found that the growth of the layered K4Nb6O17 microcrystals into building blocks was controlled by the oriented attachment mechanism, which was driven by ionic interactions between K+ in the K4Nb6O17 microcrystals and Cl in the KCl salt. The degradation rate of layered K4Nb6O17 microcrystals on methylene blue (MB) solution reached more than 70% under visible-light irradiation. Our findings not only facilitate the development of a series of K4Nb6O17-based composites but also provide a new template for the preparation of textured niobate ceramics. Furthermore, this work opens the research of oriented attachment mechanism for the fabrication of layered microcrystals by controlled self-organization.

Bimetallic composite tubes prepared by hot extrusion are usually assembled in parallel with the billet, which usually results in a low extrusion ratio and reduced production efficiency. In this study, Al/Al bimetallic composite tube with excellent surface quality were successfully prepared using AA6061 aluminum alloy and AA1060 aluminum alloy as the original materials and a special conical assembly form at 450 degrees C and a large extrusion ratio of 21 by hot extrusion process. Macroscopic observation of the distribution of the two materials in the wall of the composite tube shows that the Al/Al composite tube combines well along the extrusion direction, the wall thickness of the inner and outer walls is gradient distribution along the extrusion direction, the stable extrusion stage accounts for 60 % of the total length, about 110 cm, and combines well in the circumferential direction as well. The bonding strength of the Al/Al composite tube is above 120 MPa, which is higher than the ultimate tensile strength (UTS) of the original AA1060 aluminum alloy and achieves metallurgical bonding. In addition, the UTS of the composite tube has reached the requirement of existing Al/Al composite products and has better plasticity. The microstructure near the interface of the composite tube shows no holes and inclusions on the interface, and the grains of the two materials have been refined to a certain extent, and the transmission electron microscope (TEM) results reflect that the two materials are in a coherent relationship. And the simulation of composite tube extrusion was conducted. The influence of the microstructure evolution on the mechanical properties and the bonding mechanism of the composite tube are discussed based on the microstructure evolution at the interface of the composite tube and the simulation results.

This study developed a bauxite-based ceramic microfiltration membrane with a sandwich structure, featuring dual mullite-whisker separation layers surrounding a coarse-particle intermediate layer, fabricated through a simplified sieving and co-sintering process. The separation layers, derived from fine bauxite particles, formed high-aspect-ratio mullite whiskers on their surfaces, imparting superhydrophilic properties. The intermediate layer, built from coarse bauxite particles, enhanced the flow rate due to its macroporous structure. The integrated sandwich design delivered exceptional oil/water separation efficiency (96.9 %) and a high pure water flux of 669.3 L center dot m-2 center dot h-1 , balancing selectivity and permeability. The membrane also showed remarkable durability, retaining a water flux of 547.3 L center dot m-2 center dot h-1 after simple cleaning and recycling, with separation performance for emulsions of varying concentrations dropping by less than 1.5 % after 9 cycle tests. This cost-effective, scalable fabrication method highlights the potential of bauxite-based ceramic membranes for efficient and sustainable oil-in-water separation applications.

(K, Na)NbO3 materials with piezoelectric effect are considered to be very competitive compounds in the field of optoelectronics. The low crystallinity and stability of the raw materials have limited the development of the (K, Na)NbO3 materials. In this work, a new strategy combining solid phase reaction and molten salt methods has been designed to synthesize (K, Na)NbO3 powder. Uniform-sized (K, Na)NbO3 nanocrystallines were obtained in the K0.5Na0.5NbO3-KCl system at 900 degrees C. The electric properties of the (K, Na)NbO3 ceramics suggested that the chemical composition of the nanocrystalline closed to the stoichiometric ratio of K0.5Na0.5NbO3. It was found that the degradation rate of (K, Na)NbO3 nanocrystallines on methylene blue (MB) solution reached 68 % under visible light irradiation. This study shows that (K, Na)NbO3 has great potential in the environmental remediation of polluted water.

The origin of pinched ferroelectric loops in perovskite materials is attributed to the pinning effect of defect dipoles, but its applicability to tetragonal tungsten bronze-structured ceramics remains unconfirmed. In the present paper, textured KSr2Nb5O15 ceramics doped with Bi2O3 was prepared by a tape casting technique using heterogeneous microcrystals as raw materials. The formation mechanism of microcrystals in molten salt was investigated in detail. The effects of Bi2O3 content on microstructure and electric properties were investigated. It was found that the obtained ceramics had a heterogeneous grain structure and induced polarization could produce at the interface with the increase of temperature or external electric field. The shape of polarization-electric field (P-E) hysteresis loop was independent of the Bi3+-doping amount and pinched behavior occurred spontaneously in the samples without requiring prior aging treatment. Our results suggested that the heterogeneous grain structure was mainly responsible and the pinning effect of interface dipoles was the governing mechanism for the pinched loops in the textured KSr2Nb5O15 ceramics.

Near-alpha high-temperature titanium alloys suffer from low ductility due to silicide and alpha 2 (Ti3Al) precipitates. This study explores how adjusting the Al/Zr ratio affects these precipitates and their impact on ductility. Dispersed silicide precipitates activate the pyramidal (c + a) slip systems, enhancing ductility by limiting basal (a) slip. Conversely, alpha 2 nanoparticles promote basal (a) slip, resulting in planar dislocations and reduced ductility. These findings offer a new strategy for balancing strength and ductility in near-alpha high-temperature titanium alloys through controlled precipitation.

High strength beta titanium matrix composites (TMCs) exhibit complex deformation mechanisms, with the shear band being particularly prevalent. However, the underlying mechanism of shear band formation remains unclear. In this article, we systematically investigated its mechanism and the evolution of texture during cold rolling in a TMC - 2 vol% TiC/Ti-4Al-1Sn-2Zr-5Mo-8 V-2.5Cr, which was cold-rolled after solution treatment in the two-phase and single-phase zones. The results reveal that a typical gamma-texture configuration, characterized by specific compositions of (111) (1-10) and (111) (0-11), gradually develops within the TMC matrix with increasing rolling deformation, storing greater strain energy. Notably, fewer shear bands formed in the coldrolled plate matrix after solution treatment in the two-phase zone, attributed to the presence of alpha p phase. The diffusely distributed alpha p, in conjunction with TiC particles, effectively hinders dislocation movement, thereby reducing dislocation entanglement density and subsequent lattice distortions. This reduction in lattice distortion minimizes shear band formation. Importantly, the presence of precipitated alpha p and reduced shear band density result in superior mechanical properties in the cold-rolled plates solution treated in the two-phase zone.

Dense KSr2Nb5O15 (KSN) ceramics were prepared by tape casting process using the powder as raw materials, which was fabricated by the traditional solid-state reaction method. It was found that the high density of pure KSN ceramics was attributed to the presence of connected pores and formation of a large number of low-energy grain boundaries. The Bi2O3 dopant into the KSN ceramics could reduce the anisotropy of grain boundary energy and form liquid phase during sintering, which had a direct effect on the elimination of pores and grain growth behavior. The room-temperature permittivity increased linearly and the dielectric peak broaden accordingly with the increase of Bi2O3 content. In addition, pinched ferroelectric hysteresis loops were observed in the pure KSN ceramics, which only occurred in the ferroelectric ceramics doped with high-valent ions. A possible mechanism related reversible domain switching process was proposed. This work give the guidance for the preparation of dense ferroelectric ceramics, also provide the experimental basis for the development of the pinning effect on ferroelectric domain wall.

The tape casting combined with lamination process was developed to prepare dense (K, Na)NbO3 ceramics without any sintering additives by alignment of columnar NaNbO3 template in a matrix of K0.5Na0.5NbO3 powder. A phase separation phenomenon was observed in matrix due to the induction of template epitaxial growth. The effects of template layer content on densification process and electric properties of the (K, Na) NbO3 ceramics were investigated in detail. It was found that the relative density increased with the increase of template content. Multiple peaks appeared in the dielectric temperature spectrum and Curie temperatures of the (K, Na) NbO3 ceramics increased from 306 ℃ to 343 ℃ with the decrease of template content. The high piezoelectric constant (165 pC/N) and remanent polarization (22 µC/cm2) could mainly attributed to the response of interface polarization between K-rich and other phases. This work provides a new way for the preparation of high-performance piezoelectric ceramics by inducing heterogeneous interface.

The piezoelectric properties of multi-element doped (K, Na)NbO3 ceramics are close to that of lead-based systems and expected to become environmentally friendly substitutes. To reduce the types of doped elements and achieve the repeated preparation of high-performance ceramics, we synthesized the Li-doped (K, Na)NbO3 particles with high crystallinity and chemical stability by molten salt method. Different from the traditional method, the microcrystals were obtained by recrystallization of the Li-doped (K, Na)NbO3 powder synthesized by solid state reaction in molten KCl and NaCl salts. The effects of the calcination temperature on phase structure, size and morphology of microcrystals were investigated. It was found that doping of Li+ could stabilize the crystal structure of (K, Na)NbO3 so that no other heterophase was formed in the molten salts. The crystallization growth of microcrystals was controlled by oriented attachment mechanism. The thermal hysteresis loops of dielectric properties confirmed that the synthesized microcrystals had high chemical stability. This work will provide ideal raw materials for the development of high performance potassium sodium niobate ceramics.

The anisometric templates with the same composition as the matrix is the key to the preparation of textured high entropy or multi-element doped ferroelectric ceramics. Here, we designed the A-site disordered niobate ((Na0.5K0.5)(Sr0.4Ba0.3Ca0.3)2Nb5O15) with tetragonal tungsten bronze structure and fabricated the needle-like microcrystals with a high aspect ratio by molten salt synthesis. The effects of process parameters (calcination temperature and molten salt content) on the morphology and chemical composition of products were investigated. It was found that a single tetragonal tungsten bronze structure phase could be obtained at calcination temperatures up to 1200 ℃. With the increase of molten salt content, the size of product particles become more uniform. The TEM results suggested that the obtained needle-like particle was a single crystal and had a uniform distribution of elements. In addition, the photocatalytic properties of the microcrystals were evaluated by degrading the organic dye methylene blue (MB) under simulated sunlight conditions. The present work shows the potential of the A-site disordered niobate microcrystals with tetragonal tungsten bronze structure for the solar-driven remediation of polluted water.

Metal-organic frameworks (MOFs) have been considered as promising adsorbents for eliminating organic contaminants from wastewater. However, their inherent fragile and particulate form renders them challenging to handle and recycle in practical applications. Herein, millimeter-sized porous mullite beads composed of interlocked mullite whiskers were selected as the substrate materials. ZIF-8 was synthesized in situ on the mullite whisker to create millimeter-sized ZIF-8@porous mullite composite beads. After three cycles of in-situ growth, the ZIF-8 fully enveloped mullite whiskers, forming a homogeneous core/shell structure. Furthermore, the loading mass of ZIF-8 in ZIF-8@Mullite-3 beads reached 22.18 wt%. The BET surface area of the ZIF-8@Mullite-3 porous beads samples is 244.23 m(2)/g. The obtained millimeter-sized ZIF-8@Mullite porous beads exhibited satisfactory adsorption of Congo red (61.29 mg/g) and displayed exceptional reusability and stability. The CR removal efficiency of the ZIF-8@Mullite beads remained above 90%, even after the fifth reuse. The MOFs based beads with enhanced mechanical strength can be recycled and easily handed, highlighting their superiority compared to MOF powders in water treatment applications.

The piezoelectric properties of multi-element doped (K, Na)NbO3 3 ceramics are close to that of lead-based systems and expected to become environmentally friendly substitutes. To reduce the types of doped elements and achieve the repeated preparation of high-performance ceramics, we synthesized the Li-doped (K, Na)NbO3 3 particles with high crystallinity and chemical stability by molten salt method. Different from the traditional method, the microcrystals were obtained by recrystallization of the Li-doped (K, Na)NbO3 3 powder synthesized by solid state reaction in molten KCl and NaCl salts. The effects of the calcination temperature on phase structure, size and morphology of microcrystals were investigated. It was found that doping of Li+ + could stabilize the crystal structure of (K, Na)NbO3 3 so that no other heterophase was formed in the molten salts. The crystallization growth of microcrystals was controlled by oriented attachment mechanism. The thermal hysteresis loops of dielectric properties confirmed that the synthesized microcrystals had high chemical stability. This work will provide ideal raw materials for the development of high performance potassium sodium niobate ceramics. (c) 2024 The Society of Powder Technology Japan. Published by Elsevier BV and The Society of Powder Technology Japan. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The rapid growth of platelet templates with a large volume results in poor density and repeatability for textured Na0.5K0.5NbO3 (KNN) ceramics. To synthesize needle-like templates with small volume, a heterogeneous microcrystalline transformation method was proposed. Acicular heterogeneous microcrystalline were synthesized from the precursor with tungsten bronze structure. The experimental results suggested that the perovskite phase on the surface of these particles could undergo epitaxial growth and complete texture evolution in the matrix. Dense textured KNN ceramics were prepared by templated grain growth method using the obtained heterogeneous microcrystalline as templates. In addition, the KNN nano-powder was synthesized with a high crystallinity when the precursor was completely transformed, which was an ideal raw material for the preparation of ultrafine-grain KNN ceramics. This work provides a new way for the preparation and microstructure control of high-performance lead-free piezoelectric ceramics.

Compared with conventional semiconductor materials, the Zeolitic imidazolate framework (ZIF-8) has a low photocatalytic activity due to its wider band gap and low electron discharge capacity. To enhance the photocatalytic activity of ZIF-8, we synthesized ZIF-8@AgNWs complexes via the in-situ growth method using AgNWs as the photo-enhanced material. The results of the characterization show that the fully encapsulated shell-core structure of ZIF-8-AgNWs was successfully achieved by the in-situ growth method. And the UV-Vis diffuse reflectance spectroscopy (DRS) analysis showed that the band gap of the ZIF-8@AgNWs complexes was 2.9 eV, with a significant decrease compared to pure ZIF-8 (4.96 eV). The ZIF-8@AgNWs-2 achieves the best photocatalytic activity for methylene blue (MB) degradation. Its degradation efficiency reached 94%, and its apparent rate constant was 0.04371 min −1 . This work might provide a novel strategy for the synthesis of MOF-based photocatalytic materials with higher photocatalytic activity.

Nanoporous metals are considered as the ideal catalysts owing to their open pore structure and high surface area. In the present work, a series of nanoporous Cu-based metamaterial (nano-Cu/MM) catalysts with triply periodic minimal surface (TPMS) were developed by the selective laser melting (SLM) and chemical dealloying process. The TPMS structure endowed the porous metamaterial with an excellent mechanical property and an abundant pathway for mass transfer. The as-prepared nano-Cu/MM was applied as a Fenton-like catalyst in the advanced oxidation process, and the degradation rate of methylene blue (MB) was as high as 99 % in 10 min. In addition, the catalyst showed a good applicability, which could effectively degrade the complex dyes and tetracycline drugs. To meet the practical application, a TPMS-structured coaxial circular with nanoporous structure was designed and prepared by the same process, which could be simply assembled with an electric motor to achieve a continuous catalytic degradation, demonstrating its potential for the industrial applications.

Porous Al2O3 ceramic beads with a small-scale lamellar pore structure were prepared by the dripping-ice templating method. The densification behavior of lamellar walls and the attrition resistance of porous Al2O3 beads were investigated. For the two-dimensional structural lamellar walls, the intrinsic pores shrunk, and the necking area grew during the sintering process, leading to the densification of lamellar walls and the shrinking of porous beads. In addition, the two-dimensional lamellar walls and three-dimensional Al2O3 bulk are compared and possibilities of elaborating of the discrepancy in grain size and pore morphology are discussed. Attrition resistance was determined by a grinding test. The dominant attrition mechanism of porous Al2O3 beads is abrasion. High sintering temperature led to a decrease in the attrition rate due to a wider necking area and denser pore walls.

Zeolite imidazole framework-8 (ZIF-8), serving as a promising adsorbent for wastewater treatment, is limited in practical wastewater treatment due to its polycrystalline powder form resulting in poor recoverability. Herein, the millimeter-scale ZIF-8@porous mullite beads were prepared by the seeded-secondary growth method. The surface of the porous mullite beads is fully encapsulated by nanoscale ZIF-8 crystals, and the ZIF-8 crystals are anchored by mullite whiskers. This composition provides ZIF-8 with a stable macroscopic structure and maintains the exposure of its adsorption sites. Therefore, the ZIF-8@porous mullite beads exhibited good adsorption performance toward methyl orange (MO) and orange G (OG) in the aqueous solution. The analysis of adsorption kinetics indicating the adsorption efficiency of ZIF-8@mullite-w on MO and OG is influenced by the concentration of adsorbates and the adsorption sites. The maximum adsorption of ZIF-8@porous mullite beads on MO and OG was 16.5289 and 5.111 mg/g, respectively.