1992 Volume 32 Issue 2 Pages 250-256
The hard surfacing of mild steel substrate was carried out by thermal spraying of commercially available nickel base tungsten carbide powder under oxy-acetylene flame. The influence of pre and post spray heating on the morphology, hardness and wear characteristics of the coating were studied. The increase in preheating upto 400°C and post spray heating upto 900°C was found to enhance the hardness and wear resistance of the coating. However, the properties of the coating were found to vary across the coating showing a maximum hardness and wear resistance in the region somewhere in between its surface and the interface with the mild steel. The possibilities of occurring of various kinds of transformation during spraying as well as during post spray heat treatment have been analysed as a cause of variation in distribution of property across the coating.