Investigation of oxidation and hot corrosion behavior of molybdenum coatings produced by high-velocity oxy-fuel coating method

Abstract

Thermal spray coatings methods are frequently used in automotive, aerospace, and marine vehicles. The most obvious damage mechanisms of coating systems, which are exposed to many damages during use, are high-temperature oxidation and corrosion. While the oxygen element coming from the atmosphere creates the high-temperature oxidation damage in the coating systems, the molten salts such as Na2SO4 and V2O5 coming from low-quality fuels constitute the high-temperature hot corrosion damage mechanism. In this study, its behavior against high-temperature oxidation and hot corrosion damage mechanisms was investigated by coating Molybdenum (Mo) on a 316 L stainless steel substrate with the High-Velocity Oxy-Fuel technique, which is an innovative thermal spray coating method. Both damage mechanisms were carried out isothermally at 650 °C. Oxidation tests were carried out for 5, 25, and 50 h, while hot corrosion tests were carried out for 1, 3, and 5 h. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), Elemental mapping, and Energy Distribution Spectroscopy (EDS) analysis was performed on molybdenum-coated samples before and after both tests. The results obtained were evaluated and discussed in light of the literature.