Joining of reaction sintered silicon nitride ceramics

Adhesives prepared by mixing the silicon powder, clay and silica sol were used to join the pre-nitridized silicon nitride ceramics by pressureless reaction sintering method at 1390°C. The results indicated that clay could enhance the plasticity of the adhesives, form a compact joint and obtain a bonding strength of 40 MPa. The sintered adhesive is mainly composed of S₃N₄ and O′-sialon, which have good physical chemistry compatibility with the parent material. Sialon acerous crystal has formed at the interface between the adhesive and parent material and formed an interlocking network, which integrated these two parts, providing good interface bonding. Analysis indicated that the mechanism of the adhesive sinter and interface reaction is a dissolution-precipitation process.