ME-C:H coatings in motor vehicles

The trends in the automotive industry are towards higher performance, improved reliability and tolerances, less lubricants and more environmental friendly products. In addition, there is a strong demand for decreased fuel consumption. All this is a tough challenge for the automotive designers who will need new ways of thinking and occasionally unconventional solutions. A solution is to improve the wear resistance and lower the friction of the tribological system by deposition of a low friction diamond like carbon (DLC) coating on critical components. Me-C:H is a DLC type of coating which has been tested on a large number of automotive components during the last 10 years. Today, parts coated in serial production are mainly to be found in diesel injection systems. However, the use of Me-C:H coatings in vehicles increases rapidly. Nearly 30 million coated parts are delivered to the automotive industry every year with an annual increase of approximately 50%. In this paper, an overview of results from laboratory testing as well as real applications are presented and discussed. Emphasis will be put on the aspects of design to optimise the tribological system; e.g, what is required of the substrate to ensure a successful use of the coated component. The majority of the results are positive; friction has decreased drastically and lifetime, wear resistance and resistance to seizure has increased significantly. The high performance of Me-C:H coatings and the high potential of an optimised tribological system predict a further rapid growth of these coatings in the automotive industry. (C) 2001 Elsevier Science B.V. All rights reserved.