Comparative study on the influence of bias on the properties of Si-DLC film with and without Si interlayer on NBR: The role of Si interlayer

Abstract

Si doped diamond-like carbon (Si-DLC) film was prepared on nitrile-butadiene rubber (NBR), and the effects of substrate bias on the microstructure, adhesion and tribological properties of Si-DLC films with and without Si interlayer were studied. The principal purpose of this study is to explore how bias leads to structural and performance differences of films with and without interlayer, and to further clarify the role of Si interlayer by comparing the difference in the above obtained results. The results show that bias does not influence the structure of the films without Si interlayer on NBR, but the introduction of Si interlayer has a significant effect on the growth mechanism and microstructure of Si-DLC top layers under the different bias. However, Si interlayer does not play a positive role in improving the adhesion of films in this work. Furthermore, the results of tribological study show that the presence or absence of Si interlayer has little effect on the friction and wear of the films when the bias voltage is low (≤500 V), but the wear mechanism is completely different. However, when the bias voltage is high enough (≥700 V), the friction coefficient and wear of the films with Si interlayer are lower than that of films without Si interlayer. Finally, it must be pointed out that there is a huge risk when the brittle interlayer is chosen once the top layer fails. Therefore, the ductile interlayer should be selected as the load-bearing layer without sacrificing the adhesion, and more efforts should be made to improve the mechanical and tribological properties of the top layer.