Some New Aspects of Microstructural Design of β-Si3N4 Ceramics

Abstract

Abstract A new possibility in tailoring microstructures and properties of silicon nitride ceramics is demonstrated by the use of fine b-Si3N4 powders. Fine powders were produced by a plasmachemical synthesis and by crystallisation of amorphous Si3N4 in the presence of an oxide nitride liquid. A wide range of microstructures can be obtained depending on sintering and powder characteristics. At low sintering temperatures microstructures consisting of nanosized, equiaxed grains were obtained, whereas at high temperatures or long sintering times microstructures consisting of fine needle like grains were formed. Microstructural analysis revealed a high anisotropic grain growth of the b grains in the fine grained materials.