Evaluation of dry sliding wear behavior of thermally sprayed and microwave post-processed TiO2 reinforced tungsten carbide composite coating

Wear, erosion, and corrosion are among the most common failure mechanisms, depending on the specific application, and these issues are resolved by base metal modifications. Carbide and oxide-based alloys have excellent mechanical and tribological qualities such as hardness, wear, and erosion/corrosion resistance. Thermal spray is one of the best surface modification procedures to prevent the base metal surface from various degradations and withstand their properties even in harsh and high-temperature working environments. Porosity and voids, unmelted or partly melted particles, and residual stress are the common problems. These problems restrict the coating life cycle. Laser treatment, microwave treatment, and electron beam welding are some of the post-treatment methods that could be used to overcome these problems. The composite powder WC12Co+TiO2 was deposited with the high-velocity oxygen fuel (HVOF) spray technique on an AISI 4140 steel alloy base followed by microwave post-treatment. The as-deposited coatings had a heterogeneous microstructure with cracks and holes, as well as poor bonding strength between splats. The worn surface of as-deposited coatings demonstrates splatter separation with extreme distortion, indicating an abrasive wear process. However, microwave-treated coatings become more resistant to wear and friction because of the development of intermetallic phases and a homogeneous microstructure. As a consequence of the fatigue spalling action, microwave-remelted coating has less breadth and smoother wear scars. On the other hand, microwave-treated coatings provide a more homogeneous structure with decreased surface roughness and porosity. The microwave-treated WC12Co+TiO2 coating had better mechanical and tribological properties as compared with as-deposited coating.