Yb:fiber laser surface texturing of stainless steel substrate, with MCrAlY deposition and CO2 laser treatment

Abstract

Ceramic coatings are employed to avoid the oxidation effect on turbine blade metallic substrate and as well as, increase turbine work temperature, improving its performance on metallic substrates to increase their lifetime. A bond coat (BC) base of particulate material of Ni–Al powders is necessary to assure a good adherence and gradual decrease in thermal expansion coefficient between the blade metallic substrate and the ceramic top coating. This research aims to study the influence of the laser surface texturing on the deposition of particulate materials of MCrAlY (BC) on AISI 316L stainless steel substrate. The laser texturing was applied on the stainless steel surface by an Yb–fiber laser beam and further the BC powder was pre-deposited by a sedimentation technique and irradiated by a CO2 laser beam. Analyses of textured substrates and NiCrAlY coatings were carried out by different characterization techniques. These analyses showed that the LT was efficient to form a homogenous dense layer, without cracks or pronounced imperfections, leading to a metallurgical bonding between the substrate and the coating. The LST promoted the same metallurgical bond observed for LT. In addition, the coating showed higher thickness, aluminum segregation toward the surface and higher interdiffusion between the coating and underlying substrate elements.