Enhancing the adhesion and tribological performance of Si-DLC film on NBR by Ar plasma pretreatment under a high bias

Li Qiang,Aimin Liang,Changning Bai,Junyan Zhang

doi:10.1063/1.5063365

Abstract

Silicon-containing diamond-like carbon (Si-DLC) films were successfully deposited on nitrile-butadiene rubber (NBR) via magnetron sputtering Si target in Ar and CH4 mixture atmosphere. The influence of Ar plasma pretreatment bias on the adhesion and tribological properties of the Si-DLC coated NBR were investigated systematically. The results indicated that the surface roughness of NBR substrate decreased monotonously with the increase of bias. Compared with the virgin NBR, the surface topography did not change significantly under a low bias, but a shallow layer and considerable chain scission could be observed by SEM and FTIR analysis under a high bias. As a consequence, the excellent adhesion could be obtained by Ar plasma pretreatment under a high bias (&gt;-500 V), while the adhesion of the samples pretreated by a low bias (≤-500 V) were even worse than that of untreated samples. Furthermore, the samples pretreated at a relatively high bias of -1000 V exhibited the lowest and stable friction coefficient of 0.25 and outstanding wear resistance, while the tribological performance of the samples pretreated with a low bias (≤-500V) were even worse than that of untreated ones. The research results of this work are of great surface engineering significance for the design and fabrication of hard films with a high adhesion and excellent tribological performance on rubber substrates.

Highlights

Nitrile-butadiene rubber (NBR) is widely used in the automotive, aerospace industries as seal materials due to their moderate cost, excellent elastic properties and the existence of strong polar groups (C≡N) in its molecular chain for superior oil resistance.1,2 NBR presents the high friction coefficient and wear rate sliding against the engineering materials, resulting in the loss of its function and failure of the sealing system
For reduction of friction and enhancement of wear resistance of NBR, Si doping diamond-like carbon (Si-DLC) film has been prepared on NBR via magnetron sputtering Si target in Ar and CH4 mixture atmosphere
The surface roughness of NBR is reduced monotonously with the increase of bias, and the virgin structure of NBR shows not much change under a low bias, but a shallow layer and considerable chain scission could be measured by SEM and FTIR analysis under a high bias, which attributed to ion-etching effect during the Ar plasma treatment under a high bias

Summary

Introduction

Nitrile-butadiene rubber (NBR) is widely used in the automotive, aerospace industries as seal materials due to their moderate cost, excellent elastic properties and the existence of strong polar groups (C≡N) in its molecular chain for superior oil resistance. NBR presents the high friction coefficient and wear rate sliding against the engineering materials (ceramic, steel, etc), resulting in the loss of its function and failure of the sealing system. Nitrile-butadiene rubber (NBR) is widely used in the automotive, aerospace industries as seal materials due to their moderate cost, excellent elastic properties and the existence of strong polar groups (C≡N) in its molecular chain for superior oil resistance.. NBR presents the high friction coefficient and wear rate sliding against the engineering materials (ceramic, steel, etc), resulting in the loss of its function and failure of the sealing system. A variety of considerable efforts have been directed toward reducing friction and wear of NBR and increasing lubrication. Diamond-like carbon (DLC) films can be considered to be one of the ideal protective coatings for improving friction and wear properties of rubber. Because the promising protective film combines chemical inertness, low friction coefficient, high wear resistance properties.. The chemical composition of DLC film (mainly composed by C and H) exhibits a good compatibility with NBR rubber Because the promising protective film combines chemical inertness, low friction coefficient, high wear resistance properties. Especially, the chemical composition of DLC film (mainly composed by C and H) exhibits a good compatibility with NBR rubber

Objectives

Results

Conclusion