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 silicon nitride ceramics as model materials. Controlling anisotropic grain growth by seeding of small amounts of morphologically regulated, beta-silicon nitride single crystals (micro-scale level control), combined with alignment of the seed particles by tape casting followed by stacking of laminates (macro-scale level control) allows compatibility of high strength and high fracture toughness in this material, with a high degree of reliability for the mechanical strength. (C) 1997 Elsevier Science Limited.