Influence of process parameters on the quality of thermally sprayed X46Cr13 stainless steel coatings

Thermally sprayed metallic coatings have been frequently applied over low carbon steel components, aiming at protecting against corrosion and wear. However, these coatings always contain pores, oxides and cracks in the microstructure, which affect the protection performance. The spraying process employed determines not only the amount and distribution of these defects, but also several coating properties (e.g. thickness, hardness and adhesion to the substrate). Therefore, the final coating quality is strongly related to the spray parameters definition, such as: fuel gas type, oxygen pressure, particle velocity and spray distance. This research aims at verifying the efficiency of the High Velocity Combustion Wire spray process (HVCW) for the deposition of X46Cr13 stainless steel coatings. This process submits the particles to higher velocities than those in conventional processes (e.g. flame spraying (FS) and arc spraying (AS)), normally producing more refined microstructures with better properties. The influence of spray parameters has been investigated considering characteristics of the microstructure and mechanical properties, as well as, with respect to the corrosion behavior in synthetic marine solution. The results have confirmed the favorable performance of the HVCW process, which has produced a sufficiently dense coating to prevent damages to the substrate. Additionally, the absorbed oxygen content has been considered adequate to obtain optimized mechanical properties, including wear resistance.