Bodycote international prize paper competition: Joint second prize tinitron process for low pressure nitriding of titanium and its alloys

Abstract

Titanium has been known for nearly 200 years and in mineral form is the fourth most commonly occurring element. Although titanium is such a common element, the pure metal is still expensive. Nevertheless, titanium is being more and more extensively used in a wide range of applications, from aerospace components to leisure products. In fact the main drawback of titanium, despite its cost, is that it usually needs additional treatments to enhance its wear resistance capabilities. These treatments are usually expensive, which limits their use to high added value parts. The Tinitron process is a gaseous treatment giving excellent wear resistance to titanium parts at the lowest possible cost for a wide range of applications. This thermochemical treatment is based on nitrogen diffusion into titanium without the use of a plasma. The diffusion of nitrogen creates a compound layer of TiN+Ti₂ N and a diffusion layer of Ti(N) underneath. As the treatment is based on diffusion there are no adhesion problems. The compound and diffusion layers harden the surface of the material and the compound layer increases its wear resistance. Furthermore, the treatment is performed under vacuum at low pressure, thus minimising gas consumption and environmental impact. Tinitron permits homogeneous bulk treatment of complex shaped parts (grooves, holes, etc.) and it can be used in the medical field as the process is 100% biocompatible. Finally, Tinitron is less expensive than standard titanium surface treatments.