Wear-resistant and low-friction diamond-like-carbon (DLC)-layers for industrial tribological applications under humid conditions

Abstract

Excellent wear and friction properties are important factors in almost all branches of industry. They increase the tool life just as affecting the power consumption, the surface finish of the workpiece and the production rate in a positive way. To facilitate higher productivity at lower operating cost, it is of particular importance to use tools with enhanced wear and friction attributes. Novel amorphous diamond-like-carbon (DLC) coated tools provide these properties in dry and even in humid environment which offers application possibilities in the wood machining industry. The forestry, timber-, and paper-industry in Europe have a production value of approximately 400 billion Euros per year. For this reason, the supplying industry is very conscious to develop highly efficient tools. Especially wear and high friction of cutting tools are limiting factors in the processing of bulk wood. This work is focused on the development of a DLC-system with high wear and friction resistance also under humid conditions which especially exist during the processing of bulk wood. Using the Physical Vapor Deposition (PVD)-process different DLC-coating systems have been deposited, in which the layer properties have been designed related to the humidity conditions. The layer properties and coating parameters have been systematically analyzed with special emphasis on tribological attributes. Tungsten carbide counterparts were used during wear and friction tests to analyse the tribological behaviour of the coatings. Furthermore Raman spectroscopy was applied to characterize the layers microstructure. Correlations between layer structure and corresponding wear and friction properties have been scrutinized.