The effect of TiN source (i.e., TiN powder, TiO₂ powder and TiO₂ sol) on the phase compositions, microstructures and mechanical properties of hot-pressed Si₃N₄-TiN ceramics was investigated. The results show that only β-Si₃N₄ and TiN phases are detected for the sample with TiN powder. The sizes of β-Si₃N₄ and TiN grains are large, the Vickers hardness, flexure strength, and fracture toughness are (15.6±0.3) GPa, (1 058±78) MPa, and (11.2±0.6) MPa·m^1/2, respectively. However, the O′-Sialon phase appears in the sample with TiO₂ powder in addition to β-Si₃N₄ and TiN phases, and the content of O′-Sialon is 8.7wt%. Due to the relatively fine grains of β-Si₃N₄ and TiN, the Vickers hardness increases to (16.7±0.4) GPa, and the flexure strength and fracture toughness are (986±76) MPa and (11.3±0.4) MPa·m^1/2, respectively. Moreover, the O′-Sialon phase appears in the sample with TiO₂ sol, the content of O′-Sialon is 12.5wt%, and the size of β-Si₃N₄ and TiN grains is finer, having a higher Vickers hardness (i.e., 16.6±0.5 GPa), and relatively lower flexure strength (i.e., 788±94 MPa) and fracture toughness (i.e., 10.2±1.0 MPa·m^1/2). Si₃N₄-TiN ceramics with uniformly fine microstructures and good mechanical properties can be thus obtained with TiO₂ powder.

Results regarding the fabrication of SiC coating layers and other SiC-related materials for nuclear reactor applications are reported herein. A fluidized bed chemical vapor deposition (FB-CVD) method was used to prepare the SiC coatings, and the coating process was simulated using the newly proposed multiscale coupling model to enhance the coating uniformity. Different kinds of SiC series products, such as dense SiC layers, fine-grained SiC coating layers, SiC/C/Si mixed coating layers, porous SiC coating layers, SiC nanowires and SiC nanoparticles, were developed for nuclear energy applications. Postulated accident conditions, such as air ingress, wereconsideredto evaluate the reliability of the SiC coating layer. An irradiation test was also performed in ahigh-flux nuclear reactor, and the results validated the high performance of SiC coating materials in nuclear reactor applications.

The use of zirconia ceramics in humid environments is limited by the phase transformation from the tetragonal phase to the monoclinic phase. In this study, an oscillatory pressure sintering (OPS) technique was developed for the preparation of zirconia ceramics that were characterized by high density, fine grain size and excellent mechanical properties. The hydrothermal aging behaviors of the oscillatory pressure sintered and hot-pressed zirconia were investigated. The Raman analysis showed strong peaks at 178 and 189 cm^-1 in both the oscillatory pressure sintered and the hot-pressed specimens, but the peak intensities of the oscillatory pressure sintered specimen were much weaker than those of the hot-pressed specimen. When the specimens were aged for 18 h, the flexural strength of the oscillatory pressure sintered zirconia reached approximately 1 216 MPa, which is much higher than that of the hot-pressed zirconia. Therefore, the OPS technique is promising for the preparation of zirconia ceramics that are used in the biomedical field.

A preparation method to improve the dispersion of zirconia particles in the slurry and the strength of the ceramic body was proposed. The physicochemical properties of the slurry were analyzed. The ceramic slurry was extruded via micro-flow extrusion forming, and the mechanical properties of the printed body were analyzed. The results show that the size of zirconia particle reaches a minimum value and the zeta potential is maximum after ball milling at 600 r/min for 12 h. The slurry with 5%-6% sodium polyacrylate has the lowest viscosity at pH 8.5. Zirconia slurry prepared under the optimized conditions (i.e., grinding parameters and dispersant content) is smooth in the extrusion process and meets the requirements of micro-flow extrusion. The surface roughness and mechanical properties of sintered printed blank are satisfactory, thus meeting the mechanical performance requirements of denture.

To solve thermal mismatch problem in the bonding process of RB-SiC ceramic using borosilicate glass braze (BS), β-eucryptite/BS composite braze (BSL) was designed. The effect of β-eucryptite addition on a) the characteristic temperature, thermal expansion coefficient and wettability of composite glass braze, as well as b) the microstructure and mechanical properties of joints was investigated. The thermal expansion coefficient of BSL decreases and its rate increases with the increase of β-eucryptite amount. Also, the characteristic temperature of BSL and its rate both increase with the increase of β-eucryptite amount. The apparent contact angle of BSL increases at the same temperature, and the variation of apparent contact angle along with temperature becomes slow. The RB-SiC/composite glass solder (BSL3)/RB-SiC joint has the similar interface to the RB-SiC/BS/RB-SiC joint bonded at 850 ℃ for 10 min. However, in the glass seam, β-eucryptite turns into massive gray KAlSiO₄ crystals (i.e., kaliophilite). The massive KAlSiO₄ crystals with a negative expansion characteristic can reduce the thermal expansion coefficient and prevent the crack propagation, thus strengthing the joint. The shear strength of the joint after reinforcement increases from 5.2 MPa to 10.9 MPa.

The insulating ceramic plate was sintered and surface-decorated using molybdenum tailings as the main raw material (55%) with kaolin, red sludge, feldspar, glass powder and blowing agent incorporated. The water absorption, bulk density, compressive strength and thermal conductivity of the insulating ceramic plate were measured, and the microstructure was observed and the pore diameter was counted. The effects of firing temperature, slurry fineness and addition of blowing agent on the pore size of insulating ceramic plates were studied. The results show that the addition of blowing agent has the most significant influence on the pore structure, pore size and distribution of the insulating ceramic plate, and is the key to obtain low thermal conductivity. In this study, the prepared molybdenum mine tailings-based insulating ceramic plate has high solid content, excellent thermal insulation performance and light weight, and is surely a new building insulation material with broad market prospects.

The thermal stability of the stack repeating unit and short stacks was investigated for a flat tube anode-supported solid oxide fuel cell based on double-sided cathodes under rapid cycling condition from room temperature to operating temperature. The cell can experience a secondary pressure on cathode sides due to its anti-destructive characteristics, and the performance of the stack repeating unit and short stack can be improved slightly or keep stable during rapid thermal cycles. The cell characteristics of experiencing rapid thermal cycling and secondary pressure give a foundation for its rapid start-up and reuse, indicating a new feature of large-scale solid oxide fuel cell and having broad potential applications.

Hard carbon material was extracted from an expired composite donkey-hide gelatin pulp via hydrothermal carbonization pelletizing and subsequent pyrolysis reaction. The corresponding micro-morphology, element composition, structure and Na-storage performances were investigated. The results show that the obtained carbon material manifests a smooth microsphere-like morphology with the mean diameter of 4.3 μm, and N and S elements evenly distribute in carbon micro-spheres with a low degree of graphitization. The reversible discharge specific capacities are 225 and 180 mAh/g at 0.5 and 1.0 A/g for 500 cycles, respectively, and the reversible discharge specific capacity remains 108 mAh/g even at 2.0 A/g for 1 000 cycles, indicating the electrochemical Na-storage cycling performances at the large current density. The results could facilitate to promote the development of the circular economy mode of expired waste medicine and the green energy.

Two kinds of CuS counter electrodes with different morphologies applied to QDSC were prepared by a solvothermal method and an in-situ method, respectively. The prepared counter electrodes were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy (EIS) and current-voltage (J-V) curve measurement, respectively. According to the results by morphology analysis, CuS nanoparticles with a size of 20 nm can be agglomerated into larger and irregular particles in CuS counter electrode prepared by the in-situ method, and CuS counter electrode prepared by the solvothermal method consists of nanorods and nanoparticles in microstructrue. The results reveal that two kinds of CuS counter electrodes are superior to Pt counter electrode in the electrical performance. CuS counter electrode prepared by the in-situ method yields the maximum power conversion efficiency (i.e., 1.840%) and the charge transfer resistance R_ct is 3.346 Ω. CuS counter electrode prepared by the solvothermal method yields a power conversion efficiency of 1.450% and R_ct is 2.609 Ω. The corresponding parameters of Pt counter electrode are 0.940% and 11.680 Ω, respectively.

The performance of direct internal reforming of ethanol as a fuel in a flat tube solid oxide fuel cell based on double-sided cathodes was investigated. The results show that the cell can operate stably for 100 hours with a power density of 0.137 W/cm²@0.8 V when ethanol is injected into the cell at a constant water to carbon ratio. A slight carbon deposition only occurs inside the cell. The structure cell can be applied for direct internal reforming of carbon-containing fuels, indicating a promising potential for use.