Deposition of NiCrBSi coatings by atmospheric plasma spraying and dry-ice blasting: Microstructure and wear resistance

Atmospheric plasma spraying (APS) offers a wide range of coatings with very different compositions and properties. Special attention has been paid to NiCrBSi alloys, as promising alternatives to hard chromium plating due to their high wear and corrosion resistance at high temperatures. In this study, dry-ice blasting was combined simultaneously with plasma spraying in order to modify the characteristics of metal alloy coatings. A microstructural and tribological comparison between NiCrBSi coatings obtained by conventional APS and those via dry-ice blasting is carried out. The main wear mechanisms are investigated by the characterization of the wear track and debris using scanning electron microscopy (SEM). It can be observed that coatings using dry-ice blasting consisted of NiCrBSi splats with better flattening and higher percentage of amorphous phase. Oxidation is the main wear mechanism for both coatings. Material transfer takes place between the 100Cr6 ball and the NiCrBSi coating. Better tribological behavior was observed for dry-ice blasted NiCrBSi coatings at diverse sliding velocities.