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The running-in of amorphous hydrocarbon tribocoatings

A comparison between experiment and molecular dynamics simulations
 
: Pastewka, L; Moser, S.; Moseler, M.; Blug, B.; Meier, S.; Hollstein, T.; Gumbsch, P.

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International journal of materials research 99 (2008), Nr.10, S.1136-1143
ISSN: 1862-5282
Englisch
Zeitschriftenaufsatz
Fraunhofer IWM ()
amorphous hydrocarbon coating; atomistic material modelling; molecular dynamic; tribology; running-in mechanism

Abstract
Amorphous hydrocarbon (a-C: H) films have enormous potential as low friction, wear resistant coatings. Here. we present a plasma assisted chemical vapour deposition process for a-C: H that exhibits growth rates of 100 nm min(-1) and higher. The tribological performance of the resulting a C : H films has been studied experimentally by reciprocating sliding of all a-C: H-coated Si3N4 ball oil all a-C: H-coated 100Cr6 steel substrate and by subsequent micro Raman spectroscopy of the wear track. Running-in of the coatings is observed and characterised by it rapid decrease ill the friction coefficient accompained by a significant increase ill sp(2) hybridisation ill the wear track. Ill order to gain a deeper understanding of the underlying running-in mechanisms the sliding of two a-C: H films under a load of 5 GPa has been studied by classical molecular dynamics employing a range-corrected Brenner bond-order potential. The simulations reproduce the experimental trends and explain the running-in by a combination of smoothing and chemical passivation of both tribosurfaces. Consequently, both mechanisms should be controlled in order to produce tribological coatings for applications with optimum energy-efficiency.

: http://publica.fraunhofer.de/dokumente/N-87207.html