Characterization of C<sub>f</sub>/SiC Composite Fiber Bundle Surface Based on an Optical System

Abstract

The traditional contact devices measure material's surface roughness by scratching its surface, which may cause surface damage and sampling error. In order to avoid these troubles, an optical measurement system is used in this paper. Considering the anisotropic and inhomogeneous surface structure of Cf/SiC composite, a multi-scale measure system must be established. Fiber bundle is the first scale to be studied, whose appropriate measurement parameters are studied here. When sampling area is 150μm×150μm and sampling step is from 0.1μm to 0.5μm, the values of 3D surface parameters Sa, Sq, Ssk and Sku are steady and their relative changes are small. 2D surface roughness Ra is adopted to select the proper sampling length. The results show that as long as the sampling length is more than 112μm, the mean value of 2D surface roughness Ra are relatively stable. The critical sampling length is about 1/7 of the standard minimum sampling length in ISO 468-1982. According to the results obtained, the research provides a useful guideline for determination on the appropriate sampling conditions of Cf/SiC composite fiber bundle surface measurement.