Effect of fiber coating thickness on the interfacial properties of a continuous fiber ceramic matrix composite

摘要

The interfacial properties (coefficient of friction, residual clamping stress, residual axial stress, and debond stress) of a continuous fiber ceramic composite were determined by means of single-fiber push-out tests. The composite consisted of Nicalon(trademark) fibers, that had been coated prior to matrix infiltration with carbon layers ranging in thickness from 0.03 to 1.2 (mu)m, and a SiC matrix. It was found that the effective interfacial frictional stress decreased as the thickness of the carbon layer increased, from 24.6 (plus minus) 9.9 MPa for a thickness of 0.03 Jim to 5.8 (plus minus) 1.4 MPa for a thickness of 1.25 (mu)m. It was also found that both the coefficient of friction and the residual clamping stress decreased as the thickness of the carbon layer increased. These results are explained in terms of the state of residual stresses in this composite and the role of the fiber surface topography during fiber sliding.