Analysis of degradation processes of C/C composites and coating layers with tracer elements in an air-acetylene flame by two-dimensional atomic absorption spectrometry

This paper describes a novel measurement technique for in-situ monitoring of the degradation processes of coated C/C composites (carbon fiber-reinforced carbon composites) in combusting fields. The samples tested in this experiment were C/C composites with double coating layers of SiC and glass materials doped with Ca and/or Mg as tracer elements. These samples were exposed in an C₂H₂/air flame emitted the diatomic molecules, and the light from the Mg-Ca hollow cathode lamp passed through the flame around the sample. The spectrally and spatially resolved images of emission were observed with a spectro CCD camera developed by our group. In this work, two-dimensional atomic absorption spectrometry by using the spectro CCD camera was applied to in-situ monitor the degradation processes of each coating layer and the substrate. The results indicated that the temporal changes in the spatial distribution of atomic absorption caused by Ca and Mg atoms proved to be a good measure for in-situ monitoring of the degradation processes of coated C/C composites in a high temperature flame.