Characterization and Wear Response of Magnetron Sputtered W-B and W-Ti-B Coatings on WC-Co Tools

In this work, alpha-WB2 and (W,Ti)B-2 borides were applied as wear-resistant coatings to commercial WC-Co cutting inserts. Properties of coatings deposited by magnetron sputtering on WC-Co tools were studied. The crystal structure and chemical composition were analyzed. Vickers hardness and surface roughness were determined and wear test in semi-dry conditions was performed. The W-B and W-Ti-B coatings deposited on WC-Co substrate were smooth and very hard. However, titanium alloy W-B films with Vickers hardness of 3630 +/- 260 HV0.02 were characterized by lower adhesion to the substrate, influencing the wear mechanism. Turning tests carried out on 304 stainless steel showed that the W-B film caused less wear compared to uncoated insert. Moreover, when W-B coating was applied, flank wear was reduced by 30% compared to uncoated WC-Co insert. Additionally, coating prevented chipping of the edge during cutting under test conditions. The research shows that W-B film deposited by magnetron sputtering has great potential as a coating for cutting tools for difficult-to-cut materials.