Sliding friction and wear behaviour of ion nitrided and TiN coated AISI 4140 steel

This work studies the friction and the sliding wear behaviour of surface treated SAE 4140 steel. The performance of ion nitriding and PVD TiN coatings applied by means of industrial processes as single or duplex treatments was evaluated. Although the deposited TiN coatings (0.7 µm thick) resulted thinner than most of the typically employed for sliding situations, the present work shows that they can provide very good protection. The use of ion nitriding as a pretreatment proved to be beneficial when combined with such a thin coating. However, in the pin on disc sliding tests the coated discs developed the highest friction coefficients and boosted the damage in the steel pins.