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

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 Cr3C2–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 Cr3C2–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 Cr3C2–NiCr. Against steel, Colferoloy coatings, with limited delamination and negligible wear loss, were comparable to Cr3C2–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.