Effect of Interface Coating on High Temperature Mechanical Properties of SiC–SiC Composite Using Domestic Hi–Nicalon Type SiC Fibers

Here we show that when the temperature exceeded 1200 &deg
C, the tensile strength drops sharply with change of fracture mode from fiber pull-out to fiber-break. Theoretical analysis indicates that the reduction of tensile strength and change of fracture mode is due to the variation of residual radial stress on the fiber&ndash
matrix interface coating. When the temperature exceeds the preparation temperature of the composites, the residual radial stress on the fiber&ndash
matrix interface coating changes from tensile to compressive, leading to the increase of the interface strength with increasing temperature. The fracture behavior of SiC&ndash
SiC composites changes from ductile to brittle when the strength of fiber&ndash
matrix interface coating exceeds the critical value. Theoretical analysis predicts that the high temperature tensile strength can increase with a decrease in fiber&ndash
matrix interface thickness, which is verified by experiments.