Quantitatively non-destructive detection for the laser-induced damage in ceramic matrix composite by using polarized laser scattering method

Abstract

Ceramic matrix composites (CMCs) have emerged as ideal materials for next-generation aero-engine hot-section components due to their excellent high-temperature resistance and low density. However, the lack of effective non-destructive testing (NDT) methods for quantitatively evaluating laser–induced thermal damage in ceramic matrix composites (CMCs) poses a significant challenge for their reliable application in aero–engine hot components. To address this gap, this study develops a polarized laser scattering (PLS) detection system that exploits the sensitivity of polarized light to subsurface damage distributions. The developed method decouples surface scattering from subsurface scattering, enabling simultaneous detection of surface and subsurface laser-induced damage, including surface oxides, subsurface microcracks, interfacial gaps, and bubbles encapsulated within oxide layers, across scales from sub–micrometer to millimeter. The PLS approach is systematically validated against conventional characterization techniques and corroborated by in situ focused ion beam (FIB) cross–sectional imaging on a laser–machined CMC part. Quantitative comparison with destructive benchmarks yields an average relative error of 9 % for damage size determination, confirming the accuracy and practicality of the PLS method. This work establishes, for the first time, a quantitative NDT paradigm for laser–induced damage in CMC, providing a quantifiable tool for low–damage laser machining of film–cooling holes of CMCs.