INTERFACIAL BEHAVIOR OF NICALON-FIBER-FEINFORCED GLASS-CERAMIC MATRIX COMPOSITE DUE TO CREEP-CONDITIONING

Abstract

Creep-conditioning had been shown to be effective in inducing a compressive residual stress in the matrix of SiC-fiber-reinforced BMAS glass-ceramic matrix composite. The increase in the compressive stress in the matrix manifested in the increase in the proportional limit of the crept specimens, as compared to that of the as-received. The change of residual stresses in the composite due to creep-load transfer was evaluated through mechanical testing and X-ray diffraction. Microstructural studies on the fracture surfaces and fiber/matrix interface showed that no interfacial reaction or any significant change in the failure behavior of the composite was observed. Interfacial sliding stress at the interface, obtained from a fiber push-out test, revealed that essentially there was no change in the normal clamping stress. The results confirmed that creep-conditioning treatment, intended to increase the matrix cracking stress, could be successfully applied to composite materials without sacrificing the "composite-like" fracture behaviors.