L. M. Berger, Fraunhofer Institute for Material and Beam Technology (FhG-IWS), Dresden, Germany; S. Saaro, Fraunhofer Institute for Material and Beam Technology, Dresden, Germany; M. Woydt, Federal Institute for Materials Research and Testing (BAM), Berlin, Germany
In the current work the tribological properties of a variety hardmetal coatings (WC-10%Co4%Cr, WC-20%"CrC"-7%Ni, Cr3C2-25%NiCr, (Ti,Mo)(C,N)-29%Ni, (Ti,Mo)(C,N)-29% Co) in an unlubricated dry sliding wear test in the temperature range from room temperature up to 800°C were studied. Sliding velocities were varied in the range 0.1-3 or 6 m/s with a wear distance 2000-5000 m and a normal force of 10 N. Hard chromium and APS sprayed Cr2O3 coatings were studied in the same conditions for comparison. In order to investigate the influence of the oxide scales on the tribological behavior the the coatings were oxidized at individually selected temperatures. The results between non-oxidized and oxidized coating are compared and are linked with the results microstructural characterization and the formation of oxides formed as layers in result of high-temperature testing in air and tribological reactions. Depending from the sliding speed and temperature the dry wear rates of several coatings were comparable to those typically measured under mixed/boundary conditions.
Summary: In the current study the tribological properties of oxidized and non-oxidized hardmetal coatings in an unlubricated dry sliding wear test in the temperature range from room temperature up to 800°C are compared. Hard chromium and plasma-sprayed Mo-NiCrBSi coatings were studied in the same conditions for comparison.
