Tribological characteristics of titanium nitride and titanium carbonitridemultilayer films Part I. The effect of coating sequence on material and mechanical properties

In this study, the specimens in disc style were prepared by changing the co ating sequence and coating thickness of titanium nitride and titanium carbo nitride films on S45C steel substrate as the top and the second layers of a multilayer system. These arrangements were made in order to investigate th e mechanical properties of the composite films like the adhesion strength, load carrying capacity, hardness, surface topography and surface microstruc ture. The experimental results show that the specimens with the Ti/Ti(C,N)/ TiN him have a relatively higher composite hardness than the Ti/TiN/Ti(C,N) film. The trend exhibited in the coating film hardness of ceramic coating film is similar to the composite hardness. The specimens with the Ti/Ti(C,N )/TiN film have a lower critical friction force and critical track distance compared with the Ti/TiN/Ti(C,N) film. For the specimen with the Ti/Ti(C,N )/TiN film, peaks protruding over the flat surface are quantitatively incre ased by the increase in the coating film thickness. Nevertheless, either th e peak parameter Rz or the amplitude parameter Ry after coating thick films is strongly affected by the Ra value of steel substrate before coating and the uniformity of the surface morphology can thus be improved. However, fo r the specimens with the Ti/TiN/Ti(C,N) film, increasing the total film thi ckness decreased the asperity, but also eliminated the morphological unifor mity. (C) 2001 Elsevier Science B.V. All rights reserved.