Combined Low Coherence Interferometry/Raman Spectroscopy for Non-destructive Characterization of High Temperature Composite Surfaces and Coatings

During this proposed research, Physical Sciences Inc. (PSI) will develop a high throughput, non-destructive technology for characterizing the surface and the coatings of high temperature ceramic matrix composites (CMCs) used for hypersonic applications. At velocities above Mach 5, CMCs are exposed to high heat flux and wind shear and thus special post-manufacturing coatings are required to protect them from oxidation and ablation. We propose to develop a structural and chemical analysis tool that will assess the quality of the CMCs and these coatings in a manufacturing environment. Currently, non-destructive evaluation techniques are available only for laboratory use and thus are not suitable for use during the manufacturing processes. To address this need, we propose to develop a technology suitable for characterizing CMC roughness and surface chemistry during various phases of the manufacturing process. This technology will combine the high resolution surface roughness measurement capability of Scanning Low Coherence Interferometry (SLCI) with the powerful surface chemistry characterization capability offered by Raman spectroscopy. We will demonstrate this approach during the Phase I program using CMC parts manufactured at PSI, while testing during various phases of the CMC manufacturing will be performed during Phase II.