TECHNIQUES FOR REMOVING A CONTAMINANT LAYER FROM A THERMAL BARRIER COATING AND ESTIMATING REMAINING LIFE OF THE COATING

摘要

Systems and techniques are disclosed for removing contaminants from a surface of a thermal barrier coating (TBC) and, optionally, estimating the remaining lifetime of the TBC. Laser induced breakdown spectroscopy (LIBS) is one method that may be used to remove contaminants from a surface the TBC prior to performing photo luminescence piezo spectroscopy (PLPS) or another spectroscopic technique on a thermally grown oxide (TGO). LIBS may facilitate monitoring substantially in real-time the chemical composition of the material removed. LIBS may be used to remove substantially only the contaminants with minimal effects on the underlying TBC. One technique for determining when to stop removal of material from the TBC is cross-correlation between a spectrum collected from the ablated material and a reference spectrum collected from a reference substrate. In some embodiments, the same system may be used to perform LIBS to remove impurities and PLPS to measure stress in the TGO.