Surface modification of air plasma spraying WC-12%Co cermet coating by laser melting technique

Tungsten carbide cermet powder with 12%Co was deposited on stainless steel substrate by air plasma spraying method. Two types of coatings were produced i.e. thick (430 mu m) and thin (260 mu m) with varying porosity and splat morphology. The coated samples were treated with CO2 laser under the shroud of inert atmosphere. A series of experimentation was done in this regard, to optimize the laser parameters. The plasma sprayed coated surfaces were then laser treated on the same parameters. After laser melting the treated surfaces were characterized and compared with as-sprayed surfaces. It was observed that the thickness of the sprayed coatings affected the melt depth and the achieved microstructures. It was noted that phases like Co3W3C, Co3W9C4 and W were formed during the laser melting in both samples. The increase in hardness was attributed to the formation of these phases. (C) 2013 Elsevier Ltd. All rights reserved.