Influence of architecture and doping of diamond-like carbon coatings on coating properties

Ursula Selvadurai, LWT, TU Dortmund University, Dortmund, Germany

In order to increase the service life and performance of cutting tools, multiple different approaches are pursued. One highly promising approach is the use of diamond-like carbon coatings which reduce the friction and increase the hardness of cutting tool surfaces that are used in the wood industry. Diamond-like carbon (DLC) consists of amorphous carbon with a significant fraction of sp3 C–C bonds and exhibits properties such as a high mechanical hardness, high corrosion resistance as well as low friction and wear coefficients. In comparison to this material (a:C), the hydrogenated amorphous carbon (a-C:H) exhibits a lower friction and wear coefficient.

Based on these findings, the coatings will be modified by varying the layer architecture and the doping of the coatings with hydrogen, silicon, silver, and tungsten in order to obtain optimized diamond-like carbon coatings for the use under cyclic-mechanical load conditions. Thus, the influence of different designs of multilayer coatings containing DLC-layers on the properties such as hardness, the Young´s modulus, and wear coefficients will be investigated in a recently started research project.

Additionally, the behaviour of the coating against impact loads will be analyzed in-situ. For that purpose, an apparatus has to be constructed which makes it possible to analyze the time-resolved change of the microstructure of the coating during the impact test in-situ in a large chamber SEM and to determine the failure mechanisms. Subsequently, a correlation of the coating properties will allow the deposition of diamond-like carbon coatings on wood cutting tools with a long lifetime.

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