Structure and Mechanical Properties of Ti-Al-Ta-N Coatings Deposited by Direct Current and Middle-Frequency Magnetron Sputtering

Abstract

Ti-Al-Ta-N coatings are characterized by attractive mechanical properties, thermal stability and oxidation resistance, which are superior to ternary compositions, such as Ti-Al-N. However, because of their open columnar microstructure, the Ti-Al-Ta-N coatings deposited by conventional direct current magnetron sputtering (DCMS) exhibit insufficient wear resistance. This work is focused on obtaining the Ti-Al-Ta-N coatings with improved microstructure and mechanical and tribological properties by middle-frequency magnetron sputtering (MFMS). The coatings are deposited by the co-sputtering of two separate targets (Ti-Al and Ta) using pure DCMS and MFMS modes as well as hybrid modes. It is found that the MFMS coating has a denser microstructure consisting of fragmented columnar grains interspersed with equiaxed grains and a smaller grain size than the DCMS coating, which is characterized by a fully columnar microstructure. The modification of the microstructure of the MFMS coating results in the simultaneous enhancement of its hardness, toughness and adhesion. As a result, the wear rate of the MFMS coating is less than half of that of the DCMS coating.

Effect of Plasma-Electrolytic Nitrocarburizing of Medium Carbon Steel Surface on Friction and Wear in Pair with Tin-Lead Bronze

“…Various technologies are used to improve the wear resistance of various materials [1,2]. Technologies of plasma electrolytic treatment have found application in applying protective ceramic coatings on the surfaces of metals of the valve group, polishing metal surfaces, and also forming hardened diffusion layers on steels and titanium alloys [3][4][5][6][7][8][9][10][11][12][13][14].…”