Effects of TiC addition on properties of laser particle deposited WC-Co-Cr and WC-Ni coatings

The mechanisms by which titanium carbide (TiC) improves the properties of tungsten carbide (WC) coatings deposited on duplex stainless steels using laser particle injection technique were investigated. The relationships between laser process parameters and the synthesized composite were studied. The morphologies and microstructures of the feedstock powders and composite coatings were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques. Surface hardness of the composite layers was determined using the Vickers microhardness tester while its corrosion behaviour in 3.5% NaCl solution was investigated by potentiodynamic polarization curve measurement method. As a result of the laser treatment, microstructures characterized by hard ceramic particles with strong bonding to substrate were formed on the surface layer of the steels. The addition of TiC to WC resulted in microstructures free from cracks, pores and intermetallics which could be detrimental to the properties of the composites. High microhardness was observed and most of the coatings shifted the corrosion potential to more noble values with the pseudo-passive curve.