SURFACE MODIFICATION OF PURE TITANIUM AND TI-6AL-4V BY INTENSIFIED PLASMA ION NITRIDING

In the present work, ion nitriding of pure titanium and Ti-6Al-4V was conducted at low pressure by intensifying the glow discharge. Plasma intensification was produced by thermionic emission in conjunction with a triode glow discharge system. It was shown that, under the present intensified glow discharge conditions, effective nitriding can be achieved at relatively low temperatures (480-degrees-C) and with significantly enhanced compound layer growth kinetics compared with the conventional techniques. Processed titanium and Ti-6Al-4V developed a surface layer of TiN followed by a Ti2N layer and an interstitial nitrogen diffusion zone. Processed specimens showed a threefold increase in surface hardness. Surface roughness was found to be a function of the degree of plasma intensification. Processing of Ti-6Al-4V resulted in a higher wear, corrosion and wear-corrosion resistance. The present results show that ion nitriding with intensified glow discharge has a great potential as a surface modification method for titanium and titanium alloys.