Fe-Cr and Fe-Cr-Ni based HVOF coating systemscustomised for wear and corrosion protection

Iron-based coating systems are being considered as replacements for traditional coatings such as WC-Co and hard chrome plating when wear resistance and corrosion protection are required. A number of iron-based powder alloys comprising Fe-Cr-Ni and Fe-Cr respectively have been developed to provide engineering surfaces with high resistance to dry wear and corrosion. Specific coating properties may be enhanced further, for example, by blending with hard wear resistant materials such as tungsten carbide. This paper compares the wear and corrosion resistance of a number of Fe-Cr based coatings with WC-Co (88% WC, 12% Co). Results show that the performance of Fe-Cr coatings can compare favourably with WC-Co layers. Metallurgical techniques including optical metallography, scanning electron microscopy and EDAX were used to characterise the coatings. The properties observed have been related to the underlying microstructures and alloy composition.