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

Near zero thermal expanding porous ceramics are useful in many applications in advanced manufacturing techniques, especially electronics engineering. Zirconium tungsten oxide (ZrW 2 O 8 ) has been expected to be an excellent negative thermal expansion material for reducing thermal expansivity of composites. However, at 777°C ZrW 2 O 8 decomposes to ZrO 2 and WO 3 , which have positive thermal expansion coefficient and limit applications of ZrW 2 O 8 . Therefore, a low temperature sintering technique is required to use ZrW 2 O 8 in zero thermal expanding composite. This work develops a low temperature glassy bonding agent to fabricate near zero thermal expanding SiC/ZrW 2 O 8 porous ceramics. The results show ZrW 2 O 8 reacts with alkali and alkaline earth oxides at lower temperatures than the decomposition temperature of ZrW 2 O 8 . Nevertheless, ZrW 2 O 8 is inert with Al 2 O 3 , B 2 O 3 , and SiO 2 . By using borosilicate glass (B 2 O 3 –SiO 2 ) as a bonding agent, SiC/ZrW 2 O 8 porous ceramics are sintered at temperatures lower than the decomposition temperature of ZrW 2 O 8 and have near zero thermal expansion coefficient (−0.2 × 10 −6 K −1 ). No reaction is found between the glassy bonding agent and ZrW 2 O 8 or SiC.