Detection on the coating peeling of SiC coated C/C composites using infrared thermal-wave tomography

The coating damage of SiC-coated carbon?carbon (C/C) composite is directly influenced on the anti-oxidation attack and ablation performances of carbon?carbon (C/C) composite substrate. It is unprecedentedly reported that infrared thermal-wave tomography (IR-TWT or TWT) approach with laser as external stimulation source is successfully employed for the evaluation of the SiC damage coated on the C/C composite substrate. The stimulation laser intensity is varied according to a chirp-pulsed chain, and employed to induce the chirp-pulsed radar thermal-wave signal. The thermal-wave signals of SiC-coated C/C composite dependence on coating thickness degradation and substrate material are deeply analyzed by using of one dimensional (1D) thermal-wave transfer analytical model. A temporal amplitude of thermal-wave signal as function of delay time is obtained by using of dual-orthogonal demodulation (DOD) algorithms, and it can be employed to represent thermal-wave transmission and to perform tomography. Experimental results confirm that TWT can be used to accurately and reliably assess the SiC coating damage characterization from the C/C composite substrate.