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Tetrahedral amorphous carbon coatings for friction reduction of the valve train in internal combustion engines

: Götze, Andreas; Makowski, Stefan; Kunze, Tim; Hübner, Matthias; Zellbeck, Hans; Weihnacht, Volker; Leson, Andreas; Beyer, Eckhard; Joswig, Jan-Ole; Seifert, Gotthard; Abrasonis, Gintautas; Posselt, Matthias; Fassbender, Jürgen; Möller, Wolfhard; Gemming, Sibylle; Krause, Matthias


Advanced engineering materials 16 (2014), No.10, pp.1226-1233
ISSN: 1438-1656
ISSN: 1615-7508
European Commission EC
13857/2379; ECEMP-D1
Journal Article
Fraunhofer IWS ()

Tetrahedral amorphous carbon (ta-C) is studied as a tribological coating for the valve train's exhaust camshaft of a combustion engine. The coated camshafts were installed in a non-fired engine, tested in a computerized component test bench under practice-relevant conditions and analyzed for their frictional behavior. A notable reduction of the valve train's drive torque on the test bench is demonstrated. Namely, on a roller cam system with ta-C-coated camshaft the reduction is about 15% in average within the entire engine-map. The ta-C coatings were extensively characterized under laboratory conditions before and after the investigations on the test bench. Mechanistic understanding of the tribological behavior of ta-C coatings under dry or starving lubricated conditions was achieved by atomistic simulations of the tribological contact. Industrial utilization of these results would lead to a significant increase of the energy efficiency of combustion engines.