Applicability of nitride powders as foaming agents in superplastically foamed ceramics

The applicability of several nitride powders for use as foaming agents in superplastically foaming ceramics was investigated. Ceramic mono-foams were fabricated successfully using AlN and Si₃N₄ foaming agents. By using BN as a foam agent, on the other hand, we cannot fabricated well developed ceramic foams due to cracking and fracture. When the quantity of foaming agent was increased, the porosity increased to a certain amount, then saturated. With equal amounts of Si₃N₄, the porosity from the dispersed foaming agent was higher than that obtained from a monolithic compact without mixing, which was similar to the case of SiC foam agent.