Revestimentos de nióbio e nióbio-ferro 60% obtidos por HVOF sobre aço API 5L X70

The development of new applications for niobium has aroused interest due to excellent corrosion resistance. Furthermore, Brazil has the world's largest reserves of this metal. In this context, this study aimed to obtain niobium and niobium-iron coatings by the high velocity oxy-fuel (HVOF) process, on API 5L X70 steel substrate. The HVOF thermal spray process is getting increasing importance for obtaining coatings for protection against corrosion and wear. This technique allows obtaining coatings with more cohesion, less porosity, associating the low cost compared to other thermal spray processes. The morphology of the coatings obtained was examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed the formation of oxides during the process, which can lead to increased hardness and wear resistance. Furthermore, it was observed that the coating of niobium-iron 60% showed no regions of porosity, while the presence of such defects was observed for the niobium coating. This can be associated with a further fusion of the particles of niobium-iron 60% mixing compared to pure Nb coating.