High-volume, fully dense silicon nitride monolith and method of making by simultaneously joining and hot pressing a plurality of RBSN parts

34 34 3High-volume, fully dense, multi-component monoliths with microstructurally indistinguishable joints that can be used as refractory, corrosion and wear resistant components in the non-ferrous metal industry. The SiNmonoliths according to the invention comprise at least 90% by weight β-type SiNand up to 10% by weight of a predominantly amorphous binder phase, said binder phase being formed from compositions of the rare earth metal -Al-Si-O-N, rare earth metal -Mg-Si-O-N or Mg-Si-O-N systems. Preferably the rare earth metal is yttrium (Y). The monoliths have a volume of greater than 250 cm. A method of making the multi-component monoliths is achieved by simultaneously joining and uniaxially hot pressing an assembly of reaction bonded silicon nitride bodies (RBSN bodies). RBSN bodies are placed in contact with each other in the substantial absence of any interlayer or ceramic paste in between.