Micromechanical properties and sliding wear behaviour of HVOF-sprayed Fe-based alloy coatings

Abstract The tribological performance of two Fe–Cr–Ni–Si–B–C (Colferoloy) alloy coatings manufactured by HVOF thermal spraying was studied by rubber-wheel dry particle abrasion test and ball-on-disk sliding wear tests. The results were compared to those obtained on Ni–Cr–Fe–Si–B–C and Cr 3 C 2 –NiCr layers (also manufactured by HVOF-spraying), hard chromium electroplating and bulk tool steel. At room temperature, the sliding wear loss of the Colferoloy coatings against alumina counterpart, caused by a mix of mild abrasion, delamination and tribo-oxidation, was larger than that of Cr 3 C 2 –NiCr and tool steel but lower than that of Ni–Cr–Fe–Si–B–C and hard chromium plating. At 400 °C and 700 °C, Colferoloy coatings mainly suffered abrasive grooving: they were still superior to Ni–Cr–Fe–Si–B–C but inferior to Cr 3 C 2 –NiCr. Against steel, Colferoloy coatings, with limited delamination and negligible wear loss, were comparable to Cr 3 C 2 –NiCr and superior to Ni–Cr–Fe–Si–B–C, tool steel and electrolytic hard chromium, although they inflicted quite significant wear to the steel counterbody. Colferoloy coatings were therefore validated as alternatives to Ni-based alloys and electroplated chromium under sliding wear conditions, but appeared unsuitable for particle abrasion resistance. The different sliding wear behaviours of HVOF-sprayed coatings could be explained by coupling micro- and nano-hardness to scratch testing, which reflected cracking resistance and plastic deformability.