SPS Coating Microstructure Controlled by the Surface Topography Using Laser Texturing

Abstract

Abstract Thermal barrier coatings (TBC‘s) being produced at present either by atmospheric plasma spraying (APS) or electron beam physical vapor deposition (EB PVD) are widely used in the hot-temperature sections of turbines to provide thermal and corrosion protections. An emerging technology of suspension plasma spraying has become interesting for the manufacturing of thermal barrier coatings thanks to the useful microstructure including columns similarly to the EB-PVD deposits associated with considerably lower price of production. A narrow window of optimal suspension plasma spraying (SPS) parameters remain an outstanding problem in creating the favorable microstructure. The recent studies demonstrated that the substrate roughness may play an important role in reaching columnar growth of the coatings. This study presents a follow up by showing how the substrate topography obtained by laser surface texturing may be controlled to create regular columnar structure thanks to. The laser generated peaks disposed regularly on the surface can promote columnar structure growth. The formulated suspensions were sprayed onto superalloy substrates coated with powder plasma sprayed bond coats. Optimized previously, plasma spray parameters were selected to generate columnar structures and to find out the influence of the suspension behavior on coating microstructures. The results indicate that columnar SPS coating microstructure can be controlled by optimizing the laser treatment parameters. The control of surface topography may be an important factor to improve the performances of TBC-SPS coatings.