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| Abstract No.: |
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Scheduled at:
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Friday, June 09, 2017, Hall 27 10:20 AM
Metal Coatings
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| Title: |
Deposition of PVD thin films on thermal barrier coatings for a wear resistant thermal insulation
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| Authors: |
Markus Dildrop* / University of Dortmund, Germany
Wolfgang Tillmann / TU Dortmund University/ Institute of Materials Engineering, Germany
Markus Dildrop/ TU Dortmund University/ Institute of Materials Engineering, Germany
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| Abstract: |
Due to the superposed thermal and mechanical stress profile, thermo-mechanically coupled forming processes require tools and machine components which meet high demands. High forming forces and process temperatures in the contact zone between the tool and the workpiece limit the life span of these tools. A promising approach for protecting such tools is a combination of thermally sprayed coatings and physical vapor deposited layers. This coating system combines the characteristics of the individual layers and leads to superior mechanical, tribological as well as thermal properties under the mentioned coupled stresses.
In this study thermally sprayed alumina (Al2O3) and yttria-stabilized zirconia (ZrO2) were produced by atmospheric plasma spraying. Therefor different coating porosities were adjusted in order to varied the effect of thermal insulation for the substrate made of AISI H11 (1.2343). After the coating process the surface roughness of the thermal barrier coatings were reduced by polishing process in preparation for the PVD top layer. Subsequently, friction reducing, wear and heat resistant hard TiAlSiN and CrAlSiN coatings were deposited on top of the polished coatings by using magnetron sputtering process. The wear resistant of these PVD top layers were determined at different temperatures (20°C, 500°) by using a high temperature tribometer. Titanium and chromium interlayers were applied by PVD technique in different coating thicknesses (50 150 µm) between PVD and thermally sprayed coatings. Afterwards the influence of these metallic interlayers on coating adhesion of PVD coatings were analyzed by performing scratch tests. Hardness and youngs modulus were investigated by means of nanoindentation. The morphology and topography of the coatings were analyzed by scanning electron microscopy, light microscopy and optical three-dimensional surface analyzer. EDX analyses and X-ray diffraction were used to determine the chemical composition and the residual stresses of the PVD coatings.
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