The Elevated Temperature Tribological Performance of Tough and Superhard TaMoN–Ag Films With Solute and Nanocomposite Structures

Abstract

Films have been prepared with not only high hardness to guarantee excellent wear resistance but also high toughness to prevent brittle fracture at low to middle-high temperatures. On the basis of ternary transition metal nitrides with significantly improved hardness and toughness, TaMoN–Ag films with solute and nanocomposite structure were prepared by direct current (DC) magnetron sputtering technology. Friction wear tests were performed between room temperature (RT) and 700 °C. When doping with trace amounts of Ag atoms (∼1.12 at%, 4 W), TaMoN–Ag film maintain solid solution structure. TaMoN–Ag films with the Ag target power is 4 W show the highest hardness (H ∼ 62.1 GPa), which is 58% higher than TaMoN film and 44% better than that of TaMoN films. Meanwhile, a lower wear rate (KIC ∼ 5.87 × 10−7 mm3/N·m) is obtained. The tribological properties of TaMoN–Ag films at room temperatures are related to the H3/E2 and lubricious Ag phase, while the tribological properties at high temperatures are mainly due to the formation of lubricating binary metal oxides (AgxTMyOz (Magnéli phases)). The composite films generally have good resistance to plastic deformation.