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 degrees C and 700 degrees 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. (C) 2011 Elsevier B.V. All rights reserved.