Microwave Induced Plasma (MIP) Nitriding of Titanium Alloy

Abstract

ABSTRACTTitanium alloys possess several attractive properties such as light weight, high strength and excellent corrosion resistance. However, wider application of these alloys, especially for load bearing components operating under sliding conditions, are restricted due to poor tribological (friction and wear) behaviour. It has been shown previously [1] that nitriding of titanium by using DC plasma is an effective means of increasing the hardness and reducing friction and wear. In this work nitriding response of titanium alloy (Ti-6A1–4V) was investigated using a Microwave Induced Plasma (MIP). The plasma was generated in a TM012 stainless steel cylindrical cavity using 1.5 kW power supply operating at 2.45 GHz. The cavity was water cooled and tuned by two sliding shorts. Nitriding experiments in nitrogen-hydrogen mixture at 70 to 100 torr pressure established that MIP provides an excellent mass transfer medium for nitriding titanium alloy. Furthermore, significant advantages over DC plasma have been discerned. For instance, reduced sputtering, uniformity of treatment and temperature stability can be cited. In this work, preliminary results of characterisation of MIP nitrided surfaces by x-ray diffraction and optical microscopy will be presented to demonstrate the effectiveness of MIP for nitriding titanium.