The Application Of Laser Texturing To Control The Microstructure And Performance Of SPS Thermal Barrier Coatings

Suspension Plasma Spraying has demonstrated to be a suitable technology for the production of Thermal Barrier Coating top coats. But the further improvement of SPS TBCs still need to be done in order to meet high requirements caused by increasing operating temperature of gas turbines.

This work presents the novel idea of using laser texturing as a bond coat pre-treatment technology prior to the top coat deposition. That kind of laser treatment was already proven to enhance the adhesion strength of thermally sprayed coatings or to enable formation of regular columnar coatings. Here, the different laser treated patterns were created on the APS NiCrAlY bond coats. Then, the 14YSZ suspension was used to spray top coats. The investigation of produced thermal barrier coatings has included microstructural characterization made by Scanning Electron Microscopy and X-Ray diffraction. The topography analysis made by Shape from Shading was used to count the column density. Finally, the thermal cyclic tests and thermal oxidation test were performed. The results indicate that the SPS columnar coating microstructure may be controlled by using laser texturing and suggest that the strict control of the bond coat/top coat interface may be an important factor influencing the performances of SPS TBCs.