Hot and cold erosive wear of thermal sprayed NiCr-based coatings: Influence of porosity and oxidation

In this work, the hot and cold erosive wear mechanisms of HVOF and plasma-sprayed NiCr-based coatings are evaluated. Erosion tests were carried out in specially developed equipment, with possible variations in temperature and attack angle. The effects of erodent incrustation (SEM/EDS mapping) and oxidation of metallic coating (mass weight) were considered. The results were associated with the microstructural characteristics of the coatings (porosity, size of lamellae) and with the mechanical properties, such as microhardness and elasticity modulus. The obtained results showed that NiCr coatings are ductile, a property similar to monolithic metallic materials. The porosity influenced both the amount of incrusted alumina particles and oxidation. The increase in temperature caused higher oxidation and erodent incrustation.