Tribological performance of CrN and CrN/GLC coated components for automotive engine applications

Modern automotive systems strictly demands increased mechanical and thermal loads, a longer service life and the weight reduction. Low friction hard coatings are extensively used in power train and engine applications by wear inhibition and friction reduction. The present study evaluates friction and wear responses of CrN and CrN/GLC coatings in different lubricated conditions. Results showed that, the presence of GLC surface not only lowered friction significantly by 67% under oil-starved or even dry conditions, but also obtained a pronounced decrease in wear by 70% for the opposite surface in the oil-lubricated environment, as compared to CrN coating. GLC application thus allowed the engine components to operate more reliably and durably when improper conditions happened. A tribochemical layer with the responsive character accounted for superior performance of GLC/CrN coating, which derived from the interactions of the additive in oil with the rubbing surfaces. The information on the correlation of performance with physics and chemistry of the rubbing interface was provided. (C) 2016 Elsevier B.V. All rights reserved.