Chemical vapor deposited SiC (SCS-0) fiber-reinforced strontium aluminosilicate glass-ceramic composites

Abstract

Unidirectional SrO · Al2O3 · 2SiO2 glass-ceramic matrix composites reinforced with uncoated chemical vapor deposited (CVD) SiC (SCS-0) fibers have been fabricated by hot-pressing under appropriate conditions using the glass-ceramic approach. Almost fully dense composites having a fiber volume fraction of 0.24 have been obtained. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase observed in the matrix by x-ray diffraction. No chemical reaction was observed between the fiber and the matrix after high temperature processing. In three-point flexure, the composite exhibited a first matrix cracking stress of ∼231 ± 20 MPa and an ultimate strength of 265 ± 17 MPa. Examination of fracture surfaces revealed limited short length fiber pull-out. From fiber push-out, the fiber/matrix interfacial debonding and frictional strengths were evaluated to be ∼17.5 ± 2.7 MPa and 11.3 ± 1.6 MPa, respectively. Some fibers were strongly bonded to the matrix and could not be pushed out. The micromechanical models were not useful in predicting values of the first matrix cracking stress as well as the ultimate strength of the composites.