Isothermal and Cyclic Plasma Nitriding of Titanium Alloys

Plasma nitriding of two titanium alloys was carried out in a specially designed glow discharge chamber with a titanium cathode. The experiments were performed isothermally at 930 and 730°C, and also cyclically over the same temperature range. The tribological characteristics of the surfaces after treatment were evaluated using a modified four ball wear test. It is shown that materials processed at 730° C, which possess a complex titanium nitride based surface structure, have the best wear resistance. This result is attributed to the lower proportion of brittle TiN that is produced at low treatment temperatures.