A Novel Automated and Controlled Dual Laser Ablation System for Selective Removal of Thermal Barrier Coatings

Thermal barrier coatings have been widely used to provide thermal protection to superalloy components in gas turbine engines. After certain amount of service time, the coating experiences a reduction in thickness by processes such as wear, erosion and foreign/domestic object damage. When the thickness decreases below a critical value, the thermal barrier effect provided by the coating is no longer adequate, resulting in premature component failure. Repair and rework of such coatings typically require complete removal of the TBC. Currently, the TBC removal is done via a combination of autoclave, caustic and acidic solutions, and grit blast. Such a method is not selective and can not be easily controlled. In this proposal, AlphaSense, Inc. (AI) and the University of Michigan (UM) detail the development of a novel automated and controlled dual laser ablation system for selective TBC removal. With our approach, the merits of the proposed system has the following merits: a) Fast materials removal rate, b) Virtually no collateral damage to the bond coat and substrate, c) Capable of avoiding the cooling holes, d) Fully automatic process, and e) Suitable for a wide variety of coatings and substrates. BENEFIT: The most straightforward military application is to remove the thermal barrier coatings on the turbine engines for maintenance and repair. Since it allows fast materials removal and virtually no collateral damage to the bond coat and substrate, it can also be used to produce precise and superior quality cooling holes in the coating. Such a dual laser ablation system can also be used by commercial turbine engine manufacturers for similar purposes. Other than thermal barrier coatings, the final product can also be used in other materials and coating system, including primer, adhesive materials and paint. Furthermore, the fs- LIBS spectroscopy to be developed under the current program can reveal materials chemical compositions, and provide a virtually non- invasive method for chemical analysis. Therefore, it can be used in wide areas spanning from airport security and border security application(explosive, biological agent, illicit drug and landmine detection), environmental monitoring (soil contaminations, air or water quality surveillance), industrial processing by materials analysis (mineral resources, impurities, quality control, sorting), biomedical studies (teeth and bones), and art works analysis. The potential market for our proposed system is huge. We estimate that the potential market for the above- mentioned market sectors can easily exceed $100M.