Low-Temperature Glass Bonding for Development of Silicon Carbide/Zirconium Tungsten Oxide Porous Ceramics with Near Zero Thermal Expansion Coefficient

Abstract

Near zero thermal expanding porous ceramics are useful in many applications in advanced manufacturing techniques, especially electronics engineering. Zirconium tungsten oxide (ZrW2O8) has been expected to be an excellent negative thermal expansion material for reducing thermal expansivity of composites. However, at 777°C ZrW2O8 decomposes to ZrO2 and WO3, which have positive thermal expansion coefficient and limit applications of ZrW2O8. Therefore, a low temperature sintering technique is required to use ZrW2O8 in zero thermal expanding composite. This work develops a low temperature glassy bonding agent to fabricate near zero thermal expanding SiC/ZrW2O8 porous ceramics. The results show ZrW2O8 reacts with alkali and alkaline earth oxides at lower temperatures than the decomposition temperature of ZrW2O8. Nevertheless, ZrW2O8 is inert with Al2O3, B2O3, and SiO2. By using borosilicate glass (B2O3–SiO2) as a bonding agent, SiC/ZrW2O8 porous ceramics are sintered at temperatures lower than the decomposition temperature of ZrW2O8 and have near zero thermal expansion coefficient (−0.2 × 10−6 K−1). No reaction is found between the glassy bonding agent and ZrW2O8 or SiC.