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2710 |
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New approach to ceramic / metal - polymer multilayered coatings for high performance dry sliding applications |
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Andreas Rempp* / IFKB University of Stuttgart, Germany Michael Widmann / WITTENSTEIN bastian GmbH, Germany Andreas Killinger/ IFKB University of Stuttgart, Germany Philipp Guth/ WITTENSTEIN bastian GmbH, Germany Rainer Gadow/ IFKB University of Stuttgart, Germany |
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The combination of thermally sprayed hard coatings with a polymer based top coat leads to multilayered coating systems with tailored functionalities concerning wear resistance, friction, adhesion, wettability or specific electrical properties. The basic concept is to combine the mechanical properties of the basic hard coating with the tribological or chemical abilities of the polymer top coat suitable for the respective application. This paper gives an overview of different types of recently developed multilayer coatings and their application in power transmission under dry sliding conditions. State of the art coatings for dry sliding applications in power transmission are mostly based on thin film coatings, like DLC or solid lubricants e.g. MoS2. A new approach is the combination of thin film coatings with combined multilayer coatings. To evaluate the capability of these tribological systems a multi-stage experimental program has been carried out. In the first stage the performance of the sliding lacquers and surface topography of the steel substrate has been evaluated. Therefore case-hardened and ground steel substrates were laser textured and coated with different sliding lacquers. In the following stage thermally sprayed hard coatings were tested under different loads and in combination with different sliding lacquers. For this test stage steel samples were coated with oxide ceramics, metal alloys and hard metals by high velocity flame spraying (HVOF) and high velocity suspension flame spraying (HVSFS). After a grinding process several types of sliding lacquers were applied by air spraying on the coated specimens. Wear resistance and friction coefficients of combined coatings were determined using a twin disc test-bed and a special gear test-bed. |