Frictional Characteristics of Oxide-Treated and Untreated Tungsten-Carbide Tools

The role of surface oxide layers in the tungsten carbide tool wear was investigated by treating the tools with titanium dioxide and by performing friction tests. The friction tests were performed using both the oxide-treated and untreated tools at various temperatures, loads, and sliding speeds. The oxide-treated tools were prepared by coating tungsten-carbide tools with titanium dioxide and heating them to temperatures above 1525 deg F in a vacuum of 10⁻⁴ torr to induce mass diffusion. The oxide-treated tools which contained titanium, tantalum, and niobium in addition to tungsten carbide and cobalt have higher hardness and lower coefficient of friction, especially at high temperatures. Structural changes take place at the subsurface layer during the oxide treatment, which lower the coefficients of friction of the tool and enhance the steel cutting properties of tungsten-carbide tools.