Measuring Interphase Recession by Fiber Push-In Testing

Abstract

A novel technique for measuring interphase recession in ceramic-matrix composites (CMCs) due to oxidation is described. The technique involves fiber push-in testing and analysis of the load-displacement curves. Fiber push-in tests were conducted on carbon-coated Hi-Nicalon SiC fibers in a CVI SiC matrix, where the carbon interphase had recessed due to oxidation. Estimates of interphase recession distances from analysis of fiber push-in tests are in reasonable agreement with measurements made by optical microscopy. Besides measuring the recession distance, the fiber push-in test can be used to investigate environmental effects on fiber bridging.