The Examination of Microstructure and Thermal Oxidation Behavior of Laser-Remelted High-Velocity Oxygen Liquid Fuel Fe/Al Coating

Aluminide intermetallics with superior mechanical and thermal properties can be produced using various techniques. Laser-remelted coating surfaces provide lower porosity and superior adhesion to the substrate. In the present study, Fe and Al powders were sprayed on the 316L stainless steel substrate using high-velocity oxygen liquid fuel (HVOLF) technique. The produced composite coating was subjected to laser heat treatment for the remelting of the coating layer. HVOLF Fe/Al coating, the remelted coating and the substrate were exposed to isothermal oxidation tests at 950 degrees C for 5, 25, 50 and 100 h. Before and after the oxidation tests, the samples were characterized using x-ray diffraction, scanning electron microscopy (SEM) and SEM elemental mapping analysis. Fe and Al were alloyed with the substrate via laser melting, and thus, an alumina-forming surface layer was obtained. Besides, the surface hardness of the substrate was increased by the remelting process. After the oxidation tests, the obtained results showed that the laser-remelted coating exhibits better oxidation performance compared to the substrate material and HVOLF Fe/Al coating with the effect of the formation of the protective alumina oxide layer.