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The capillary and thermal performance of porous Si3N4 ceramics with nearly spherical pore structure has been investigated by altering the addition and diameter of pore‐forming agent polymethyl methacrylate (PMMA) in this work. An exponential model is used to evaluate the liquid uptake capacity of porous Si3N4 ceramics. Porous Si3N4 ceramics fabricated by 5 μm PMMA with 40 wt.% addition possess the lowest capillary time constant and show the best capillary performance owing to the perfect balance between friction resistance and capillary force. The thermal conductivity of porous Si3N4 ceramics is significantly impacted by their porosity. Alexander model with an exponent of.96 is suitable for predicting the thermal conductivity of porous Si3N4 ceramics due to its R‐squared up to.99. Moreover, with the addition and diameter of PMMA decrease, the flexural strength of porous Si3N4 ceramics increases. These results support the application of porous Si3N4 ceramics in the field of mass and heat transfer. [ABSTRACT FROM AUTHOR]

The Si 3 N 4 raw powder, sintering aids, and sintering process are the most critical factors affecting the thermal conductivity and mechanical properties of Si 3 N 4 ceramics. The impact of sintering aids content and powder characteristics on gas pressure sintered Si 3 N 4 ceramics was investigated in this study. Lower aids content facilitated phase transformation prior to densification, promoting a pronounced bimodal microstructure. Based on in-situ shrinkage behavior, liquid phase sintering of Si 3 N 4 ceramics can be divided into three stages without clear boundaries. Between 1200 and 1400 °C, higher oxygen and metallic impurities favored particle rearrangement. Between 1400 and 1800 °C, the dissolution and precipitation process was probably controlled by the α-phase ratio and particle size. Above 1800 °C, subsequent grain growth was primarily facilitated by the Ostwald ripening process, leading to a reduced densification rate. Higher oxygen content leading to greater weight loss during sintering. Higher Fe resulted in a darker color of sintered Si 3 N 4 ceramics. High α-phase content promoted the formation of a bimodal microstructure and ensured superior mechanical properties. Reduced levels of oxygen and aluminum were prerequisites for achieving high thermal conductivity. Powders prepared by silicon nitriding method were cost-effective materials for the preparation of high-performance Si 3 N 4 ceramic substrates. [ABSTRACT FROM AUTHOR]

Porous Si 3 N 4 /SiC ceramics were prepared with Si and SiC as raw materials, Y 2 O 3 as sintering additive and ZrO 2 as nitrided catalyst through a rapid nitration process. The nitriding rate as a function of temperature and duration was investigated. The porous Si 3 N 4 /SiC ceramics with 8 wt% monoclinic ZrO 2 addition that was nitrided at 1400 °C for 2 h exhibited the highest nitridation degree of 95%. The experimental results also demonstrated that the reciprocal formation of ZrO 2 and ZrN can effectively enhance the level of nitridation by suppressing the melting of silicon in micro-regions. The effects of nitriding time on the mechanical properties of the specimens with ZrO 2 as a catalyst was also studied. After nitrided at 1400 °C for various durations from 2 to 8 h, the porous Si 3 N 4 /SiC ceramics with the properties of a porosity over 39.8%, a flexural strength over 88.9 MPa and a linear shrinkage lower than 0.6% were achieved. The systematic investigation reveals the catalytic mechanism of ZrO 2 in the synthesis of Si 3 N 4 /SiC ceramics. [ABSTRACT FROM AUTHOR]

Porous cordierite/ Si C ceramics were fabricated by in situ reaction bonding using α- Si C, α- Al2O3, and Mg O powders as the starting materials. During sintering, part Si C is oxidized to Si O2 and then the latter reacts with Al2 O3 and Mg O to form cordierite. As a result, porous cordierite/ Si C ceramics were obtained, and the ceramics are strengthened by the residual Si C. Due to the large volume expansion introduced by the oxidation of Si C, the ceramics exhibit small sintering-induced dimension variations. In addition, a fine-grained microstructure and good thermal and mechanical properties were obtained for the porous cordierite/ Si C ceramics. [ABSTRACT FROM AUTHOR]

Abstract: Porous Si3N4/SiC ceramics were rapidly prepared with Y2O3 as sintering additive and ZrO2 as nitrided catalyst, using Si and SiC as starting powders. Porous Si3N4/SiC ceramics with 5wt% ZrO2 addition showed a complete nitridation and good mechanical properties (with a high porosity of 34.96%, flexural strength of 150±4.2MPa, linear shrinkage of 0.02%). It was revealed that the reciprocal formation of ZrO2 and ZrN effectively enhanced nitridation by inhibiting the melting of silicon in micro-regions. [Copyright &y& Elsevier]

Abstract: Porous Si3N4/(Si3N4 +BN) sandwich ceramics were fabricated by tape casting and hot pressing. The layer thickness ratio, sintering temperature and sintering pressure affected the fracture strength, dielectric constant and porosity. The Si3N4/(Si3N4 +BN) sandwich ceramics with the layer thickness ratio of 1.5 sintered at 1450°C with 5MPa has a good comprehensive property of the fracture strength of 54.3MPa and dielectric constant of 3.48 (at 1GHz). [Copyright &y& Elsevier]

Porous silicon nitride (Si3N4) ceramics with high porosity were prepared via nitridation of Si powder, using Si3N4 as filler and Y2O3 as sintering additive. After nitridation, samples with high Si3N4 filler content showed high porosity, low flexural strength, and low grain size. A porosity of 50-62% a flexural strength of 16-49 MPa were obtained. After postsintering at 1750°C, sample with Si3N4 filler content of 50% exhibited a bimodal grain size distribution of elongated β-Si3N4 grains with high aspect ratio embedded in fine-grained matrix. Porous Si3N4 ceramics with a porosity of 48-60% and a flexural strength of 100-145 MPa were obtained. [ABSTRACT FROM AUTHOR]

Abstract: Porous silicon nitride (Si3N4) ceramics were prepared from water-based Si3N4 slurries via a freeze-casting process. The green body shows good replica of ice dendrites with uniform pore channels. The microstructure of porous Si3N4 ceramics could be controlled by the freezing temperature. After sintering, porous Si3N4 ceramics with uniform microstructure was obtained. At low freezing temperature, the pore size distribution was narrower and concentrated with pore morphology from tree-like to vimineous channels. Porous Si3N4 ceramics with a porosity of 51%, flexural strength of 77MPa, and aspect ratio (AR) of 5.20 was obtained at 1850°C with 3% sintering additives. [Copyright &y& Elsevier]

Abstract: Porous Si3N4 ceramics were prepared using PMMA as pore former, and the mechanical and dielectric properties were investigated, as a function of porosity. Higher porosity was achieved at lower sintering temperature with lower sintering additive and more PMMA. The flexural strength decreased exponentially with increasing the porosity and the pore size. The dielectric constant decreased with increasing the porosity and the frequency has less effect on the dielectric constant. [Copyright &y& Elsevier]

Abstract: Fe3+ and Ni2+ (5 at.%) doped In2O3 single-crystalline nanocubes showed distinctly different magnetic properties before and after 4T high magnetic field treatments. Fe3+ doped In2O3 nanocrystals were transferred from paramagnetic to super-paramagnetic by treating them in high magnetic field while Ni2+ doped In2O3 nanocubes obviously improved primary ferromagnetism. These special phenomena may open up a way to endow nanomaterials with novel and special functions. In addition, their magnetic properties were not caused by impurities or changes of morphologies and crystalline structures. [Copyright &y& Elsevier]

Abstract: Porous hydroxyapatite (HAP) ceramics with different morphologies were fabricated by the freeze casting method. The morphologies of HAP ceramics were modified by adjusting the concentration of polyvinyl alcohol (PVA) additive in the HAP slurries. HAP ceramics without PVA additive were composed of non-interconnected macroscopic lamellar pores and porous ceramic walls. With PVA additive, the HAP ceramics were made up of small lamellar pores or three-dimensional reticulate pores and porous ceramic walls. PVA additive had no effect on the phase composition of HAP ceramics. The open porosity and pore connectivity were improved because of the addition of PVA. [Copyright &y& Elsevier]

Abstract: For the interest of the practical application, porous TiO2 sheets were prepared by a novel freeze tape-casting method, in order to improve the photocatalytic activities of these TiO2 sheets, p-type NiO was loaded by chemical solution deposition. The samples were characterized by a series of physical means, including XRD, SEM, EDS, XPS, ICP-OES, and UV-vis spectroscopy. The photocatalytic activities of the samples were evaluated by the degradation of methyl orange solution. The results showed that the photocatalytic activity of the TiO2 sheet was greatly enhanced by the NiO loading, and the photocatalytic efficiency increased with increasing the NiO loading, the extraordinary performance for the NiO-loaded sample with 0.1M precursor dipped was related to its unique morphology. The sample annealed at 600°C showed the better photocatalytic activity than the sample annealed at 400°C and 800°C. The improvement of the photocatalytic activity was attributed to the formation of p–n junctures at the interface of the NiO/TiO2, which facilitates the photoinduced electron/hole pairs'' separation by the inner electric field, thus leading to the higher photocatalytic activities for the NiO-loaded TiO2 sheets. [Copyright &y& Elsevier]

Abstract: Cordierite-bonded porous SiC ceramics were fabricated with and without CeO2 addition in air by an in situ reaction bonding technique. The effects of CeO2 addition on the phase composition, microstructure and properties of porous SiC ceramics were investigated. It was found that the CeO2 addition strongly promotes the phase transformation towards cordierite while inhibits the formation of spinel. With CeO2 addition, the neck growth was enhanced, and the mechanical properties of porous SiC ceramics were improved. When 2.0wt.% CeO2 was added, a flexural strength of 35.3MPa was achieved at an open porosity of 42.1%. Pore size distribution characterization by mercury porosimetry indicated that 2.0wt.% CeO2 addition enlarged the average pore size of porous SiC ceramics and introduced a bigger homogeneity in pore size. In addition, it was found that higher permeability was obtained after adding 2.0wt.% CeO2. Moreover, the thermal shock resistance of cordierite-bonded porous SiC ceramics was also improved by the addition of CeO2. [Copyright &y& Elsevier]

Abstract: Borophosphosilicate bonded porous silicon nitride (Si3N4) ceramics were fabricated in air using a conventional ceramic process. The porous Si3N4 ceramics sintered at 1000–1200°C shows a relatively high flexural strength and good dielectric properties. The influence of the sintering temperature and contents of additives on the flexural strength and dielectric properties of porous Si3N4 ceramics were investigated. Porous Si3N4 ceramics with a porosity of 30–55%, flexural strength of 40–130MPa, as well as low dielectric constant of 3.5–4.6 were obtained. [Copyright &y& Elsevier]

Abstract: In2O3–SnO2 nanocomposites with controllable morphologies were prepared via a co-precipitation method. The experimental results indicated that variation of In/Sn ratios facilitated the modification of In2O3–SnO2 morphology from nanoparticles to nano-toasts and nanorods that possess ultrahigh response and selectivity to ethanol. The results demonstrate the possibility to synthesize one-dimensional and two-dimensional oxide nanocomposites under mild conditions, showing that a soft chemistry route is a promising route for rationally and structurally designing nanomaterials. [Copyright &y& Elsevier]

Abstract: Highly porous and open interconnected pore structural TiO2 were prepared by a novel freeze casting method. In the experiment, the well-dispersed aqueous slurries were first frozen, and then dried at a reduced vacuum. Since the sublimation of ice crystals developed in the freezing process, the green bodies with highly porous were obtained. The phase composition and the microstructure of the sintered samples were characterized by XRD, SEM, porosity and the pore size distribution was measured by mercury porosimetry. The results demonstrated that the PVA concentration in the slurries remarkably affect the microstructure of TiO2 ceramics. The pore morphology of TiO2 ceramics with 3wt.% polyvinyl alcohol (PVA) addition was dendritic, and however, the pore morphology of TiO2 ceramics with 6wt.% PVA addition changed into columnar. The reason for the variation of the pore morphology was ascribed to the effect of the PVA gelation on the growth behavior of the ice crystals. [Copyright &y& Elsevier]

Abstract: A reaction bonding technique was used for the preparation of cordierite-bonded porous SiC ceramics in air from α-SiC, α-Al2O3 and MgO, using graphite as the pore-forming agent. Graphite was burned out to produce pores and the surface of SiC was oxidized to SiO2 at high temperature. With further increasing the temperature, SiO2 reacted with α-Al2O3 and MgO to form cordierite. SiC particles were bonded by the cordierite and oxidation-derived SiO2. The reaction bonding characteristics, phase composition, open porosity, pore size distribution and mechanical strength as well as microstructure of porous SiC ceramics were investigated. The pore size and porosity were strongly dependent, respectively, on graphite particle size and volume fraction. The porous SiC ceramics sintered at 1350°C for 2h exhibited excellent combination properties, the flexural strength of 26.0MPa was achieved at an open porosity of 44.51%. [Copyright &y& Elsevier]

Abstract: Porous TiO2 sheets obtained by aqueous tape casting were modified with Ag deposition. The results showed that Ag-deposited TiO2 sheets had better photocatalytic activity than the pure TiO2 sheets, the optimum deposition time was found to be 2min and the corresponding Ag loading was 1.48mg/cm2 TiO2 sheet. The valid mechanism of the enhancement for the photocatalytic activities was attributed to the interaction between the Ag particles and the TiO2 sheet, which made Ag particles act as electron traps to efficiently separate the photogenerated electron-hole pairs. From an application point of view, this process shows a high practical interest. [Copyright &y& Elsevier]

Abstract: In order to investigate the effect of organic additives on the zeta potential of PLZST (Pb0.97La0.02Zr0.66Sn0.25Ti0.09), the zeta potential of PLZST powder with addition of dispersant, binder, plasticizer were performed. The experimental results indicated that the zeta potentials of PLZST without any organic addition were tightly related to the titration sequence and their IEPs (isoelectric point) were also not constant. The zeta potentials of PLZST with organic additives were strongly dependent on the structure, polarity and weight of the added organic additives. The dispersant did not greatly reduce the zeta potential of PLZST due to its good polarity and ionization. Compared to the IEP of PLZST without dispersant addition, the IEP of PLZST with dispersant addition switched from 8.7 to 3.5. The zeta potential of PLZST with binder addition seriously decreased due to electrostatic screening. Since dispersant is a highly polar polyelectrolyte, the zeta potential of PLZST mixed with dispersant, binder and plasticizer addition was dominated by the dispersant. pH variation has great effect on the viscosity of PLZST slurries without organic addition; however, pH variation did not show an obvious influence on the viscosity of PLZST slurries with organic additives. [Copyright &y& Elsevier]

Abstract: Porous SiC ceramics were prepared by an in-situ reaction bonding process from SiC, Al2O3 and graphite in air at 1400–1550 °C. The reaction bonding behavior during the sintering was studied. The surface of SiC particles is oxidized to amorphous silica above 750 °C. When the sintering temperature reaches 1100 °C, the amorphous silica begins to be crystallized to cristobalite. After 1400 °C, the oxidation-derived silica reacts with Al2O3 to form mullite. Porous SiC ceramics are bonded by the silica and mullite. In addition, the effects of sintering temperatures on the reaction bonding behavior, open porosity and flexural strength were investigated. [Copyright &y& Elsevier]

Abstract: Cr-doped ZnO single-crystalline nanowires are fabricated by a facile wet-chemical route. The nanowires show stable room-temperature ferromagnetic behavior. Calculations indicate that most of the magnetic moment is induced by Cr 3d and O 2p exchange interactions. The initial adsorption of dopants on the specific nanocrystal surface and the following oriented attachment of preformed nanocrystals play key roles in the doping process. [Copyright &y& Elsevier]

Abstract: Silica (SiO2) bonded porous silicon nitride (Si3N4) ceramics were fabricated from α-Si3N4 powder in air at 1200–1500 °C by the oxidation bonding process. Si3N4 particles are bonded by the oxidation-derive SiO2 and the pores derived from the stack of Si3N4 particles and the release of N2 and SiO gas during sintering. The influence of the sintering temperature and holding time on the Si3N4 oxidation degree, porosity, flexural strength and dielectric properties of porous Si3N4 ceramics was investigated. A high flexural strength of 136.9 MPa was obtained by avoiding the crystallization of silica and forming the well-developed necks between Si3N4 particles. Due to the high porosity and Si3N4 oxidation degree, the dielectric constant (at 1 GHz) reaches as low as 3.1. [Copyright &y& Elsevier]

Abstract: Porous silicon carbide (SiC) ceramics were prepared by an in situ reaction bonding process. Their thermal shock resistance to cooling was evaluated as a function of the quenching temperature, quenching cycles and specimen thickness by the water-quenching technique. It is shown that the residual strength of the quenched specimens decreases with increasing the quenching temperature and specimen thickness, but the residual strength is hardly affected by the quenching cycles. Moreover, the thermal shock resistance to heating was investigated by the instantaneous heating method. It was found that the residual strength of the heated specimens decreases gradually with increasing the heating temperature. The thermal shock damage was proposed to originate from the propagation of cracks at the necks (the bonded parts between SiC particles). However, the pores may arrest the propagating cracks and then impair this damage. Therefore, the in situ reaction bonded porous SiC ceramics exhibit excellent thermal shock resistance. [Copyright &y& Elsevier]

A well-dispersed aqueous slurry for tape casting of PLZST (Pb0.97La0.02Zr0.66Sn0.23Ti0.11) was prepared. Properties of PLZST slurries with and without polyelectrolyte dispersant were characterized by zeta potential, sedimentation etc. The experimental results show that the pH value of the slurries is changing with ball-milling time, and that the polyelectrolyte dispersant has a significant effect on the isoelectric point of PLZST. TGA analysis indicates that the organic additives in the green tapes can be completely removed by heat treatment at 600 °C. The density of PLZST ceramics is tightly related to the plasticizer and the sintering temperature. However, the results demonstrated that it is possible to prepare a dense PLZST thick film through aqueous slurry tape casting. [Copyright &y& Elsevier]

In order to decrease the Al2O3 sintering temperature and modify the bioactivity of implant, the low melting point A/W bioglass was selected to prepare Al2O3–A/W bioglass coating through tape casting process. The experiment showed that A/W bioglass react with water during ball milling and the pH value of slurries is always changed. Although some compositions of bioglass evaporate at sintering temperature, 99.17% relative density of Al2O3–10 wt.% A/W tape sintered at 1300 °C was achieved. The result indicated that it was possible to prepare the bioactivity A/W–Al2O3 coating layer by tape casting. [Copyright &y& Elsevier]

Studies the fabrication and properties of tape-cast laminated and functionally gradient alumina-titanium carbide materials. Bending strength of the Al[sub 2]O[sub 3] composites; Attribution of increased toughness to stress distribution caused by variations in the composition of the composite layers.

Si 3 N 4 ceramics now face new applications and challenges in the semiconductor field. The preparation of h-BN/Si 3 N 4 machinable ceramics incorporating 5–30 vol% h-BN via hot-pressing was carried out. This study systematically explored how the varying h-BN content influenced the composite's microstructure, mechanical attributes, and machinability. The results showed that some of the h-BN was encapsulated by growing Si 3 N 4 grains to form an intragranular structure during the process of hot-pressing, while the remaining h-BN exhibited uniform distribution along grain boundaries. The Si 3 N 4 phase transition in composites was inhibited by excessive h-BN, accompanied by a higher decrease in densification. The sample containing 20 vol% h-BN exhibited the best comprehensive performance, with high mechanical strength and excellent machinability. The bending strength and fracture toughness remained high at 862 MPa and 10.3 MPa m1/2, and could be effortlessly machined with cemented carbide drills. Additionally, the machinability of the composites was systematically characterized through observations of crack propagation paths, fitting of R-curves, and mechanical drilling tests. [ABSTRACT FROM AUTHOR]

Complex liquid–solid reactions occur during brazing. A deep understanding of brazing liquid evolution is therefore of important concern for the bonding between filler and substrates. The joining of gas‐pressure‐sintered silicon nitride (Si3N4) ceramic to oxygen‐free copper (OFC) foil was prepared using Ag–Cu–TiH2 filler at 875°C for 0.5 h. The effect of the Ag:Cu ratio on the interfacial microstructure and peeling strength of the joints was analyzed. The reaction of brazing liquid with Si3N4 ceramic includes reactions with both the β‐Si3N4 and the grain boundary phases (Y–Si–Mg–O–N). The resulting interfacial reaction products include TiN, Ti5Si3, and potential Cu3Ti3O. Based on the phase composition and three‐dimensional morphology of the interfacial reaction products in the Si3N4 ceramic/OFC foil joints, a model for the evolution of the brazing liquid as the reaction proceeds was proposed. Peeling test results indicated that the peeling strength of the joints rises unilaterally with the increase of the Ag:Cu ratio in the filler until reaching the peak value of 24.3 N/mm at the maximum Ag:Cu ratio of 90:10. The mechanisms of the joint peeling fracture were discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: β-Mn2V2O7 microtubes with the range of 15–25 μm in length, 2.5–3.5 μm in external diameter, and ca 0.4 μm of the wall in thickness, as well as β-Mn2V2O7 hollow microspheres with an average outer diameter of 2 μm were successfully synthesized in a suitable molar ratio of NH4VO3 and MnCO3 powders via a hydrothermal process. XRD and FESEM were used to characterize the products, and the magnetic susceptibility curve was also measured. In the whole process, the concentration of Mn2+ cations derived from MnCO3 dissolution plays a crucial role in the formation of β-Mn2V2O7 microtubes and hollow microspheres. [Copyright &y& Elsevier]

Abstract: Single-crystalline Pb2+ doped ZnO nanorods were synthesized by a hydrothermal method in the presence of cetyltrimethyl ammonium bromide (CTAB). The obtained Pb2+ doped ZnO nanorods were in diameters of ∼150 nm and in lengths of ∼3 μm. The nanorods grow along the [011¯0] direction. The Pb2+ doped ZnO nanorods show violet and blue emission bands centered at 415, 438 and 467 nm, respectively. The possible growth mechanism of the Pb2+ doped ZnO nanorods was also discussed. [Copyright &y& Elsevier]

Vacuum pyrolysis is mostly employed to extract liquid biofuels from biomass in industry, but the potential application of its by-product (biochar) is seldom studied. The wood biochar monoliths were prepared by pyrolyzing cotton rose stem under vacuum conditions and a common nitrogen atmosphere, respectively. The effects of vacuum conditions on the physicochemical properties of biochar monoliths were investigated by various techniques, such as Raman, FTIR, XPS, TG, BET, CO2 adsorption and SEM methods. The results showed that the vacuum pyrolysis biochar, in comparison with nitrogen atmospheric pyrolysis biochar, features a higher degree of graphitization, a richer micro-porosity (57.2% vs. 33.9%), and a more reactive surface. The comparison of electrochemical performance suggested that the electrode prepared by vacuum pyrolysis overtakes that by nitrogen atmosphere pyrolysis with a specific capacitance of 161 F g−1 versus 133 F g−1 and an ease ion delivery capacity. Moreover, 125% of initial capacitance was retained over 10000 cycles at 50 mA cm−2. The vacuum conditions are more favorable for the preparation of biochar as well as the biochar derived activated carbon materials for application as electrodes. [ABSTRACT FROM AUTHOR]

Magnéli phases are an important class of transition metal oxides widely utilized in fields such as batteries, electrocatalysis, and photocatalysis. However, there are no reports on the use of Magnéli phases as additives in ceramic sintering. In order to explore the impact of the Magnéli phase as an additive on the sintering process, self-made Magnéli phase Ti 4 O 7 powder was added to the graded mixture of titanium dioxide (TiO 2) coarse powder and nanopowder, and sintered under atmospheric conditions in this study. The sintering characteristics, microstructure, and mechanical properties of TiO 2 ceramics with different content of Ti 4 O 7 were characterized. The results revealed that the addition of Ti 4 O 7 contributed to the reduction of the densification temperature of TiO 2 ceramics. Compared to the undoped sample, the addition of 1 wt% Ti 4 O 7 powder significantly improved the flexural strength and Vickers hardness of TiO 2 ceramics by 13.5% and 24.8%. According to the results of thermal analysis, UV–Vis–NIR, and XPS, the mechanism of Ti 4 O 7 in the sintering process of TiO 2 ceramics under atmospheric conditions was systematically discussed. This work not only obtained TiO 2 ceramics with improved performance but also showed the tremendous potential of Magnéli phases in the field of ceramic sintering. [ABSTRACT FROM AUTHOR]

Solar-driven interfacial evaporation has emerged as a promising way for renewable energy-driven clean water production, due to its ability to concentrate heat on the evaporation surface and facilitate the evaporation process. Nevertheless, the weak interaction between solar-absorbing materials and porous support substrates has posed a significant challenge in achieving the necessary combination of light absorption, mechanical strength, and long-term stability required for practical solar-driven water evaporation. In this work, we prepared porous black ceramics with both high light absorption and strong structural support, exhibiting a remarkable light absorption of 94% in the solar spectrum. Afterward, inspired by the water transport and evaporation process of mushrooms, we developed an energy-efficient bionic system. The resulting system demonstrates an evaporation rate of 1.41 kg/m2/h under 1 sun illumination (1 kW/m2) and 25 °C, attributable to the heat localization effect. Furthermore, under natural sunlight with an average solar intensity of 0.44 kW/m2, the bionic system exhibits an evaporation rate of 0.7 kg/m2/h. This work not only developed a highly stable, regenerable photothermal material and an energy-efficient bionic system for practical solar-driven water evaporation, but also highlights the immense potential of porous ceramics in advancing the field of solar-driven interfacial evaporation. [ABSTRACT FROM AUTHOR]

Background: Nonalcoholic steatohepatitis (NASH) progresses from simple nonalcoholic fatty liver (NAFL) and has a poor prognosis. Abnormal lipid metabolism is closely related to the occurrence and development of nonalcoholic fatty liver disease (NAFLD). This study aimed to study the relationships between serum lipid metabolites and NASH, and to improve the early diagnosis of NASH. Methods: This study included 86 NAFLD patients (23 NASH and 63 NAFL), and 81 unaffected individuals as controls from West China Hospital between October 2018 and May 2019. With lipid metabolites as the focus of the study, the differences in lipid metabolites were compared between the control group, NAFL patients, and NASH patients. Logistic regression analysis was used to examine the risk factors of NASH. Finally, receiver operating characteristic curve (ROC curve) was used to analyze the efficacy of the metabolites in NASH prediction. Results: The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lipoprotein A (LPA) increased with the severity of NAFLD. In NAFLD patients, LPA (OR:1.61; 95%CI: 1.03–2.52) was a potential risk factor for NASH, and ROC analysis showed that the combination of LPA, ALT, and AST had a greater predictive efficiency for NASH. Conclusions: Abnormal apolipoprotein/lipoprotein is closely related to lipid metabolism disorder in patients with NAFLD. In NAFL, the combination of LPA, ALT, and AST contributes to predicting the occurrence of NASH. LPA may be a potential biomarker and therapeutic target for diagnosing and treating NASH. [ABSTRACT FROM AUTHOR]

In order to enhance the interfacial bonding between aluminum and β-Si3N4 whiskers in Al matrix composites (AMCs), Ni coating was deposited on the surface of β-Si3N4 whiskers using an electroless plating method. The interfacial test results showed that Ni coating was successfully deposited on the surface of β-Si3N4 whiskers and the whiskers were well bonded with Al matrix without pores. In addition, the whiskers were homogeneously dispersed in the Al matrix. The effect of Ni-coated β-Si3N4 whiskers on the mechanical properties of composites was investigated in detail. Densification and the mechanical performance of AMCs reinforced by Ni coated β-Si3N4 whiskers (NSAMCs) were improved comparing to that of AMCs reinforced by uncoated β-Si3N4 whiskers (USAMCs). The maximum value of tensile strength and bending strength reached up to 290 MPa and 487 MPa, when the Ni content was 0.9 vol.% and the β-Si3N4 whiskers content was 20 wt.%, respectively. However, excessive Ni content weakened the strengthening effect. Medium Ni coating on β-Si3N4 whiskers significantly optimized the interface and improved the performance of the composites. [ABSTRACT FROM AUTHOR]

Gas-pressure sintered silicon nitride (Si 3 N 4) ceramic was brazed to oxygen-free copper (OFC) foil using 20.22 ± 0.93 mg/cm2 of Ag-Cu-TiH 2 filler at 875 ◦C for 0.5 h. The effect of TiH 2 content on the 3D morphology, including the cross-section microstructure and etched surface morphology of Si 3 N 4 ceramic/OFC foil joints, was analyzed. An evolution model of the interfacial microstructure for joints was proposed based on 3D morphological analysis. The reaction between the brazing alloy and Si 3 N 4 ceramic formed the interfacial reaction layer and the inside reaction zones during brazing. The growth mechanism of the interfacial reaction layer was discussed in detail. The peeling test was used to evaluate the bonding strength of the Si 3 N 4 ceramic/OFC foil joints, and the optimum peeling strength of 25.1 N/mm was achieved at 5 wt% TiH 2 content. The interfacial microstructure of the joints changed with TiH 2 content, leading to different main fracture mechanisms and corresponding peeling strengths. [ABSTRACT FROM AUTHOR]

The poor wettability between the ceramic reinforcements and the metal matrix makes it difficult to realize the densification process of composites, which is severely detrimental to their mechanical properties. To improve the mechanical properties of Al matrix composites (AMCs) reinforced by β-Si3N4 whiskers (β-Si3N4w), we prepare TiN coating on the surface of β-Si3N4w via molten salt process, remarkably strengthening the interface bonding between Al matrix and β-Si3N4w. By optimizing the coating layer thickness, the bending strength of AMCs reinforced by TiN-coated β-Si3N4w reaches 439 MPa at 850°C, exhibiting remarkable enhancement relative to the composites without TiN coating (335MPa). Meanwhile, the interfacial test shows that TiN-coated β-Si3N4w is well bonded with the Al matrix, and no interfacial defects were detected. Moreover, the TiN coating with appropriate thickness can efficiently alleviate the agglomeration of β-Si3N4w, promote the densification of AMCs, and modify the Al/β-Si3N4w interface. [ABSTRACT FROM AUTHOR]

Lithium–Sulfur battery is deemed as one of the most promising next-generation energy storage systems. Identifying the reduction of soluble lithium polysulfides (LiPSs) is critical for rational material designs for Lithium–Sulfur batteries. In this work, a simple molten-salt method is applied to synthesize titanium nitride/silicon nitride (TiN–Si 3 N 4) core-shell nanoparticles to inhibit soluble polysulfides shuttling. This Ti-reacted strategy has outstanding advantages such as facile and recyclable preparation process, tunable TiN morphology, and good polysulfide adsorption. With the modified separator, Li–S cells exhibit an outstanding initial capacity of 1243 mA h g−1 at 0.5C, good rate capacity of 782 mA h g−1 at 2C, and high capacity retention of 49.2% after 500 cycles. This low-cost and eco-friendly Ti-reacted strategy provides a practical route for the actual application of separator modification in the field of lithium-sulfur battery. [ABSTRACT FROM AUTHOR]

Sintered reaction‐bonded silicon nitride (SRBSN) with high thermal conductivity was obtained using (Y0.96Eu0.04)2O3 and MgO as sintering additives. Green compacts were nitrided at 1400°C for 4 h. Post‐sintering was carried out at 1850 and 1900°C for 4 h, respectively. In reaction‐bonded silicon nitride (RBSN) doped with Y2O3 and MgO, the β‐Si3N4 content and nitridation degree were 51.1% and 93.8%, respectively. However, the β‐Si3N4 content and nitridation degree were 72.6% and 96.7% in a nitrided compact doped with (Y0.96Eu0.04)2O3 and MgO. After post‐sintering, the phase composition, microstructure, mechanical properties, and thermal conductivity were investigated. After sintering at 1900°C for 4 h, the thermal conductivity of SRBSN doped with (Y0.96Eu0.04)2O3 and MgO was increased by 16.5% compared to that of the samples doped with Y2O3 and MgO. The highest hardness of 1639 HV and the good flexural strength of 776.4 MPa were also achieved in the sample doped with 2‐mol.% (Y0.96Eu0.04)2O3 and 5‐mol.% MgO. [ABSTRACT FROM AUTHOR]

The permeability performance of porous ceramics from particle-stabilized foams is closely associated with the connectivity between bubble-evolved pores. In order to regulate the connectivity of pore structure, the zirconia ceramic foams were fabricated by direct foaming with mixed surfactants of cetyltrimethyl ammonium bromide (CTAB) and sodium N-lauroyl sarcosinate (SLS). Different solid loadings and CTAB:SLS mixing ratios were used in this study. The results indicate that the pore structures of zirconia ceramic foams were interconnected by open windows on the cell walls, and the porosity and average size of cell and cell windows could be tailored by adjusting the solid loading and CTAB:SLS mixing ratio. The decrease in solid loading and CTAB:SLS mixing ratio caused larger porosity and size of cells and cell windows, and thus resulted in the obvious augment of Darcian (k 1) and non-Darcian (k 2) permeability constants. The ranges of k 1 and k 2 of the as-fabricated zirconia ceramic foams are 6.92 × 10−13-4.05 × 10−10 m 2 and 2.09 × 10−5-3.19 × 10−9 m respectively. [ABSTRACT FROM AUTHOR]

In this work, the effects of Y2O3/MgO ratio on the densification behavior, phase transformation, microstructure evolution, mechanical properties, and thermal conductivity of Si3N4 ceramics were investigated. Densified samples with bimodal microstructure could be obtained by adjusting the ratio of Y2O3/MgO. It was found that a low Y2O3/MgO ratio facilitated the densification of Si3N4 ceramics while a high Y2O3/MgO ratio benefited the phase transformation of Si3N4 ceramics. Best mechanical properties (flexural strength of 875 MPa, and fracture toughness of 8.25 MPa·m1/2, respectively) and optimal thermal conductivity of 98.04W/(m·K) were achieved in the sample fabricated with Y2O3/MgO ratio of 3:4 by sintering at 1900°C for 4 h. [ABSTRACT FROM AUTHOR]

Porous β-SiAlON ceramics are fabricated by pressureless sintering with Y-α-SiAlON ceramic powders obtained by the combustion synthesis method as the main additives. The microstructure and composition of porous β-SiAlON ceramics are tailored by changing the addition of the synthesized Y-α-SiAlON ceramic powders. The formation mechanism of porous β-SiAlON ceramics illustrates that their bimodal grain size distributions are determined by the β-SiAlON seed crystals which are derived from the starting synthesized powders and the first precipitates in the liquid phase, respectively. A small addition of Y-α-SiAlON is conducive to the reduction of the thermal conductivity of porous β-SiAlON ceramics. Furthermore, the higher the addition of Y-α-SiAlON ceramics powders, the lower the open porosity, columnar grain size, and dielectric loss, but the larger the density, flexural strength, dielectric constant, and thermal conductivity. [ABSTRACT FROM AUTHOR]

The target of the present research is to fabricate single-phase β-Sialon porous ceramics by self-propagating high-temperature synthesis (SHS). Samples with composition of Si 6-z Al z O z N 8-z (z = 0.5) were prepared by the spontaneous reaction of initial mixture of Si, Si 3 N 4 , Al, and Al 2 O 3 at high-pressure N 2 gas atmosphere. The impacts of Si content on the porosity, phase composition, microstructural morphology, and flexural strength of the fabricated materials were studied in detail. Anticipative target was achieved by adjusting Si content of initial materials and resultant reaction temperature of SHS process. Sample prepared with 35 wt% Si presented single phase of β-Sialon, homogeneous and elongated morphology, and high flexural strength of 150 MPa. To the best of our knowledge, it is the first report to synthesize single-phase β-Sialon porous ceramics by such a rapid and cheap method. [ABSTRACT FROM AUTHOR]

Porous silicon nitride (Si 3 N 4) ceramics were fabricated by self-propagating high temperature synthesis (SHS) using Si, Si 3 N 4 and sintering additive as raw materials. Effects of different types of sintering additives with varied ionic radius (La 2 O 3 , Sm 2 O 3 , Y 2 O 3 , and Lu 2 O 3) on the phase compositions, development of Si 3 N 4 grains and flexural strength (especially high-temperature flexural strength) were researched. Si 3 N 4 ceramics doped with sintering additive of higher ionic radius had higher average aspect ratio, improved room-temperature flexural strength but degraded high-temperature flexural strength. Besides, post-heat treatment (PHT) was conducted to crystallize amorphous grain boundary phase thus improving the creep resistance and high-temperature flexural strength of SHS-fabricated Si 3 N 4 ceramics. Excellent high-temperature flexural strength of 140 MPa~159 MPa and improved strength retention were achieved after PHT at 1400 °C. [ABSTRACT FROM AUTHOR]

Abstract: Slip casting process combined with reaction bonded silicon nitride (RBSN) was used to prepare porous Si3N4 ceramic with near-net and complex shape. A butyl stearate (BS) coated process was introduced to restrain the hydrolysis of Si, and ammonium polyacrylate (NH4PAA) was used to enhance the dispersion of coated Si. The measured oxygen content showed that the hydrolysis of Si was strongly prohibited by BS coating, and relatively low viscosity was obtained with the addition of 0.25–1.5wt% NH4PAA to the 60wt% solid load slurry. 40–60wt% solid load slurries were used for slip casting in the experiment. After vacuum degassing, slip casting, debindering and nitridation, a density of 1.57–1.92g/cm3 (porosity 50.9–40%) and a flexural strength of 47–108MPa were obtained. The samples without vacuum degassing showed a large number of nanowires grown in the large pores. [Copyright &y& Elsevier]

Abstract: There were interconnected small lamellar pores, big spherical pores and ceramic walls in the hydroxyapatite (HAP) ceramics fabricated by a freeze casting/pore-former method. As keeping the content of polymethyl methacrylate (PMMA) constant and decreasing the size of PMMA, the size of spherical pores and length of ceramic wall both decreased, and the compressive strength increased. As keeping the size of PMMA and decreasing the content of PMMA, the open porosity decreased and compressive strength increased. The shapes of pores caused by ice crystals were reticular, lamellar and treelike, in turn. The HAP ceramics with the spherical pores of 150–250μm, open porosity of 62.13% and compressive strength of 7.01MPa are prospective to have biomedical application. [ABSTRACT FROM AUTHOR]

Abstract: Three-dimensional (3-D) hierarchical nanostructures of γ-Fe2O3 are prepared by a solvothermal process combined with subsequent thermal treatment in air at 500 or 350°C with the aid of a high magnetic field. The experimental results indicate that γ-Fe2O3 instead of α-Fe2O3 forms in air at 500°C in a 12T field. The products are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The magnetization curves measured at room temperature exhibit superparamagnetic characteristics. [Copyright &y& Elsevier]

Abstract: Porous hydroxyapatite (HAP) ceramics was prepared by freeze casting and gelatin was used to adjust the pore morphology and microstructure of the porous HAP ceramics. With the gelatin concentration increase, the viscosity of HAP slurry was increased, and the linear shrinkage ratio of the specimen sintered at 1300°C was also increased. The gelatin addition had great effects on the pore size and pore morphology of the porous HAP ceramics. The experimental results showed that the pore morphology of HAP ceramics was changed from a two-dimensional flat pore to a three-dimensional reticulated pore after gelatin addition. [Copyright &y& Elsevier]

Abstract: An in situ reaction bonding technique was developed to fabricate mullite-bonded porous silicon carbide (SiC) ceramics in air from SiC and α-Al2O3, using graphite as the pore-former. Graphite is burned out to produce pores and the surface of SiC is oxidized to SiO2 at high temperature. With further increasing the temperature, the amorphous SiO2 converts into cristobalite and reacts with α-Al2O3 to form mullite (3Al2O3·2SiO2). SiC particles are bonded by the mullite and oxidation-derived SiO2 to obtain porous SiC ceramics. The reaction bonding behavior, open porosity, pore size distribution and mechanical strength of porous SiC ceramics were investigated as a function of the sintering temperature, forming pressure and graphite content. In addition, the phase composition and microstructure were also studied. [Copyright &y& Elsevier]

The aim of present work is to fabricate porous Si 3 N 4 ceramics with considerable dimensions and homogeneous microstructure by self-propagating high temperature synthesis (SHS) using Si, Si 3 N 4 diluent and Y 2 O 3 as raw materials. The results indicate that Si 3 N 4 diluent with coarse particle sizes and appropriate β-phase content is beneficial to obtain porous Si 3 N 4 ceramics with homogeneous microstructure and excellent mechanical property by controlling the shrinkage inside the sample. The produced Si 3 N 4 ceramics possessed excellent flexural strength of 168 MPa∼259 MPa, and high Weibull modulus of 11.0∼17.2. Additionally, BN and SiC are added as second phase to modify the properties of Si 3 N 4 -based ceramics. Optimum flexural strength of 170 MPa and 137 MPa were obtained with 10 wt.% addition of BN and SiC respectively. After oxidation at 1100 °C∼1300 °C, second phase-doped Si 3 N 4 ceramics also presented higher residual strength than pure Si 3 N 4 ceramics. [ABSTRACT FROM AUTHOR]