SEDL / STP / STP1080-EB / STP25396S

Comparison of Methods for Determining Fiber/Matrix Interface Frictional Stresses in Ceramic Matrix Composites

Cranmer, DC
Group leader, National Institute of Standards and Technology, Gaithersburg, MD

Deshmukh, UV
Research associate, Drexel University, Philadelphia, PA

Coyle, TW
Research associate, Ecole Nationale Supeneure de Mechamque, Nantes,

Pages: 12    Published: Jan 1990

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Abstract

In this study, several experimental methods including indentation push-in, in dentation push-out, and single-fiber pull-out tests were employed to measure the strength of the fiber/matrix bond in two continuous fiber reinforced ceramic matrix composites. The composite systems examined were a silicon carbide (SiC) monofilament reinforced borosilicate glass matrix and a SiC fiber tow reinforced glass-ceramic matrix Single-fiber pull out test results gave debond strengths (τ^d) of 11.1 ±3.2 MPa and interface frictional stresses (τ^f) of 3.6 ± 0.7 MPa for the SiC/borosihcate system. In the push out test, τ^d for the SiC/borosihcate system appears to be about 10 MPa while ts between 1 and 55 MPa were obtained in the SiC/glass-ceramic composite. The push-in test gave values of τ^f, between 2 and 34 MPa for the SiC/glass-ceramic system. Variability in τ within a specimen is due to differences in bonding between the fibers and matrix at various locations. The discrepancies in τ both within a test and between test methods are explained in terms of fiber/matrix bonding and test geometry. The most versatile test method appears to be the indentation push-out test.