Influence of the α/β-SiC phase transformation on microstructural development and mechanical properties of liquid phase sintered silicon carbide

摘要: The transformation kinetics and microstructural development of liquid phase sintered silicon carbide ceramics (LPS-SiC) are investigated. Complete densification is achieved by pressureless gas pressure sintering in argon nitrogen atmospheres with Y2O3 AlN as additives. Studies the from β to α-SiC reveals a dependency on initial β-content atmosphere. rate decreases an increasing starting powder presence nitrogen. completely supressed for pure β-SiC powders when additive system consists 10.34 wt % 2.95 AlN. Materials without showed homogeneous microstructure equiaxed grains, whereas microstructures elongated grains were developed SiC high α/β-ratio (> 1 : 9) occurs. Since predominantly intergranular fracture mode, grain size shape has significant influence mechanical properties. toughness materials platelet-like about twice grains. exhibiting show also higher bending strength after post-HIPing.