Friction and wear resistance of plasmapolymeric coatings applied on elastomers
Keywords:
plasmapolymeric coating, elastomer, friction reduction, wear resistance, energy savingAbstract
Using plasmapolymeric coatings on flat elastomer plates as well as on dynamic sealing components a significant reduction of friction was determined in the past [1-4]. Quantifying the improvement of wear resistance enhanced lifetime tests were performed as a function of the applied film thickness. The flat elastomer plates were coated with a plasmapolymeric film (SiOxCyHz) in a plasma enhanced chemical vapor deposition (PECVD) process. The film thickness was varied from 0.7 µm to 4.0 µm approximately. The investigated elastomeric substrate material was acrylic rubber (ACM). The friction of elastomers was investigated using an Universal Material Tester (UMT3) system with oscillating pin-on-plate contact geometry. The counterpart in the tribological tests was a 100Cr6 steel ball with a diameter of 10 mm. The tribological tests were run dry in ambient conditions with a velocity of 200 mm/s with a stroke length of 11 mm. Different normal forces between 2 N and 40 N were used. The oscillating measurement setup was chosen to save test time subjecting premature wear. The tests were performed until the coatings were rubbed through to determine the lifetime. It was found that the set in of the wear depended on the film thickness. The set in of wear was detected at the steep rise of the coefficient of friction. The wear resistance increased with increasing film thickness. A minimum film thickness is required depending on the applied load. The load bearing capacity was increasing with increasing film thickness. The beneficial wear resistance of the plasmapolymeric coating depicts the improved lifetime in combination with reduced friction. The film deposition is available at low costs due to the scalable PECVD process. The coefficient of friction was in the range of 0.15 to 0.25. It revealed that the coefficient of friction was independent of the film thickness. Even in the worst case the determined wear rate was below 0.70 µm/km.
