MICROSTRUCTURE DESIGNING OF SILICON-NITRIDE

A new concept of materials design that allows simultaneous control of the morphologies and distribution of the structural elements at plural scale levels to create a new family of advanced ceramics was proposed . The validity of the concept was experimentally demonstrated using si licon nitride ceramics as model materials. Controlling anisotropic gra in growth by seeding of small amounts of morphologically regulated, be ta-silicon nitride single crystals (micro-scale level control), combin ed with alignment of the seed particles by tape casting followed by st acking of laminates (macro-scale level control) allows compatibility o f high strength and high fracture toughness in this material, with a h igh degree of reliability for the mechanical strength. (C) 1997 Elsevi er Science Limited.