Tribological properties and microstructure of monolayer and multilayer Ta coatings prepared by magnetron sputtering

To improve the wear resistance of medical titanium alloy, Ta coatings were prepared by magnetron sputtering method on Ti6Al4V substrates. Phase structure and surface morphology of Ta coatings were characterized by Xray diffraction and atomic force microscope, respectively. The properties of Ta coatings, including adhesion, nano-hardness, and wear resistance, were tested using nano-scratch, nano-indentation and tribometer, respectively. The results show that both stable body-centered cubic (alpha-Ta) phase and metastable tetragonal phase (8-Ta) coexist in a multi-layer structure, and it shows a non-columnar feature. Interestingly, only a pure phase with columnar crystals is found in monolayer Ta coating. A body-centered cubic (alpha-Ta) phase is found in a monolayer prepared under the pulse power bias voltage with low deposition temperature. A pure metastable tetragonal phase (8-Ta) is prepared under the direct current bias voltage, which has the best adhesion and wear resistance compared with other Ta coatings.

Automated summary

Ta coatings were prepared on medical titanium alloy to improve wear resistance, and their phase structure and properties were studied under different preparation conditions. Multi-layer coatings showed a non-columnar feature, while pure phase columnar crystals were found in monolayer coatings. Among the coatings, the one prepared under direct current bias voltage exhibited the best adhesion and wear resistance.