Increased Hardness and Wear Resistance of Commercially Pure Titanium by a Plasma Nitrocarburizing

Abstract

The tribological properties of commercially pure titanium need to be improved when applied as a friction component. This research investigated the effect of plasma nitrocarburizing process on the hardness and wear resistance of commercially pure titanium. The plasma nitrocarburizing process was carried out with a ratio of the composition of N2 gas and CH4 gas of 1:1, 1:2 and 1:3. Metallographic test by scanning electron microscopy was carried out to observe phase modifications on the surface of the material. Compounds formed in a thin layer on the surface of the commercially pure titanium were observed by X-Ray Diffraction testing. Furthermore, Vickers hardness and wear testing were carried out to determine the effect of the plasma nitrocarburizing process. The results showed an increase in hardness and wear resistance. The surface hardness of the untreated commercially pure titanium was 105.75 VHN and increased to 156.76, 211.12 and 236.32 VHN after the plasma nitrocarburizing process was carried out with a ratio of N2 gas and CH4 gas composition of 1:1, 1:2 and 1:3, respectively. The reduction in specific wear rate was experienced by commercially pure titanium. The specific wear rate of the untreated commercially pure titanium was 4.468E-8 mm2/kg. The plasma nitrocarburizing process, which was carried out with a ratio of N2 gas and CH4 gas composition of 1:1, 1:2 and 1:3, reduced the specific wear rate to 2.812E-8, 1.176E-8 and 6.14E-9 mm2/kg, respectively.