Some New Aspects of Microstructural Design of β-Si₃N₄Ceramics

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.

Evaluation of Silicon Nitride Ceramic Cutting Tools with Diamond Coatings

“…It is well known that the anisotropic growth of β-Si 3 N 4 grains is related to the different growth rate on the basal plane and the lateral planes of the hexagonal β-Si 3 N 4 prism (12). The growth rate in the c-axis is higher that in the a-axis, which leads to the anisotropic growth of these grains [10,11]. As reported in previous work, [4] samples sintered with high amounts of Al 2 O 3 -Y 2 O 3 additives resulted in larger grains due to smaller degree of steric hindrance [12].…”