Optical and electron microscopic studies on indented silicon carbide crystals

Abstract

The static indentation hardness test has been applied to the study of the environment effects on hardness, plastic deformation, and fracture properties of silicon carbide crystals. Measurements of microhardness on the (0001) planes show that the hardness of silicon carbide is significantly lowered by water absorbed from the air. Upon annealing the crystals, at very high temperatures, the hardness is found to increase. A three-dimensional distribution of stress, beneath an indenter, has been evaluated using 'elastic equations'. The mechanics of crack initiation around the contact circle of a spherical indenter with the specimen has been analysed. The crack extension force, for a crack propagating downward from the surface of the specimen, has been evaluated. Evidence of plastic deformation by slip is provided by a number of indentations, specially those with the spherical and double-cone indenters. (1010) is the preferred slip plane.