Influence of both surface roughness and surface morphology on frictional behavior of ceramics during run-in period under dry sliding was investigated simultaneously. Similar average surface roughness (Ra = 0.01–0.02 µm) was produced for the three ceramics: monolithic boron carbide ceramics, boron carbide-silicon carbide composite ceramics and monolithic silicon carbide ceramics. Surface roughness parameters show some influence on friction processes, however, surface morphology is considered as a more important competitive factor. Lower friction coefficient during run-in period and shorter sliding distance up to the steady state condition were observed for the B4C–SiC composite ceramics, which has a different surface morphology from those of monolithic B4C ceramics and monolithic SiC ceramics.

Developing thermal storage materials is crucial for the efficient recovery of thermal energy. Salt-based phase-change materials have been widely studied. Despite their high thermal storage density and low cost, they still face issues such as low thermal conductivity and easy leaks. Therefore, a new type of NaCl-Al₂O₃@SiC@Al₂O₃ macrocapsule was developed to address these drawbacks, and it exhibited excellent rapid heat storage and release capabilities and was extremely stable, significantly reducing the risk of leakage at high temperatures for industrial waste heat recovery and in concentrated solar power systems above 800 °C. Thermal storage macrocapsules consisted of a double-layer encapsulation of silicon carbide and alumina and a self-standing core of NaCl-Al₂O_3. After enduring over 1000 h at a high temperature of 850 °C, the encapsulated phase-change material exhibited an extremely low weight loss rate of less than 5% compared with NaCl@Al₂O₃ and NaCl-Al₂O₃@Al₂O₃ macrocapsules, for which the weight loss rate was reduced by 25% and 10%, respectively, proving their excellent leakage prevention. The SiC powder layer, serving as an intermediate coating, further prevented leakage, while the use of Al₂O₃ ceramics for encapsulation enhanced the overall mechanical strength. It was innovatively discovered that the Al₂O₃ particles formed a network structure around the molten NaCl, playing an important role in maintaining the shape and preventing leakage of the composite thermal storage phase-change material. Furthermore, the addition of Al₂O₃ significantly enhanced the rapid heat storage and release rate of NaCl-Al₂O₃ compared to pure NaCl. This encapsulated phase-change material demonstrated outstanding durability and rapid heat storage and release performance, offering an innovative approach to the application of salt phase-change materials in the field of high temperature rapid heat storage and release and encapsulating NaCl as a high-temperature thermal storage material in a packed bed system. Compared with conventional salt-based phase-change materials, the developed product is expected to significantly improve the reliability and thermal efficiency of thermal storage systems.

Frictional characteristics of carbide ceramics (SiC, B4C–SiC, and B4C) sliding against SiC balls in water were measured over a wide range of test conditions. Carbide ceramics can obtain hydrodynamic lubrication with low friction coefficients at 20 and 40 N; however, carbide ceramics cannot obtain hydrodynamic lubrication with low friction coefficients at 5 N. Carbide ceramics exhibit lower friction coefficients at 20 and 40 N than those at 5 N in each lubrication regime. Carbide ceramics can exhibit a wider application range with low friction at high loads (20 and 40 N). The low friction of carbide ceramics is achieved by the combination of hydrodynamic lubrication and tribochemical reactions. The products of tribochemical reactions of carbide ceramics improve the viscosity of water at or near the worn surfaces of carbide ceramics, promoting the hydrodynamic lubrication for carbide ceramics. B4C ceramic shows lower friction coefficients than those of SiC and B4C–SiC ceramics in boundary lubrication and mixed lubrication at 20 and 40 N.

Inorganic phase-change materials (PCMs) with high melting points have great potential for thermal energy storage systems. Sodium chloride (NaCl) has a high melting point (801 °C) and high latent-heat-storage density (482 kJ/kg). However, it is difficult to encapsulate NaCl using a sintered ceramic shell because of its good wettability against ceramics and high volume-expansion capacity during melting. In this study, a novel NaCl/Al₂O₃ powder-composite structure was developed as highly stable PCM core material for highly stable encapsulation. The shape-retention performance and the mechanism of NaCl/Al₂O₃ powder-composite structure during melting were investigated. We have successfully fabricated a NaCl/Al₂O₃ powder-composite structure, which has a higher NaCl volume ratio of 80 vol% than conventional techniques. The gel-like network structure of Al₂O₃ particles in molten NaCl was a key structure to keep the shape of the composite ball and to prevent the evaporation of molten NaCl.

Coating technology is decisively important for metallization of ceramic materials and ceramic metal sealing technology. Previous studies have shown that the network-like structure after penetration of molten aluminum can significantly improve the strength of joint components. However, the direct aluminum coating method is limited by the shape of the substrate. To obtain a dense aluminum film on the surface of B₄C, in this study, aluminum was deposited by pulse electroplating in EMIC–AlCl₃ ionic liquid. The deposited metals were observed and analyzed by SEM–EDS and XRD. A Vickers hardness tester was adopted as an auxiliary equipment to clarify the film quality. The results show that frequency and duty cycle have significant effects on crystal orientation. The content of oxides in the contact gap reduces the bonding strength of the deposited metal, which provides experimental basis for metal electrodeposition on B₄C.