Fretting behaviour and porosity of Ti2N coatings

Abstract

In today's world, TiN coatings are often used to protect tools from extensive wear. Yet, in recent years, coatings such as TiC, Ti(C,N) and (Ti,AI)N have taken over for certain applications due to their special characteristics. However, when the deposition parameters are changed during TiN deposition, a Ti2N coating with interesting properties of corrosion and wear resistance can be deposited. Thick (e.g. 25 μm) and well adherent Ti2N coatings have been deposited using strictly controlled parameters.

A large amount of literature on the tribological properties of traditional TiN coatings, deposited under different conditions and on various substrate materials, has been published in the past. In this paper, the results of fretting and porosity measurements on Ti2N-coated high speed steel specimens are given. In both cases, the effect of coating thickness has been investigated.

The porosity of the coatings was measured by a coulometric method developed previously. On the basis of these results, it was found that a thick (approximately 20 μm) Ti2N coating was nearly impenetrable.

Fretting tests were performed in the gross slip regime for a number of cycles between 1000 and 100 000 (for the thickest coating) without perforation of the coating. The fretting wear behaviour of the Ti2N coatings was found to be good in comparison with TiN coatings.

The results obtained for these tests are compared with similar tests performed on TiN coatings.