Microstructure Evolution and Friction Properties of TiN-Ag Coating with a TiN Diffusion Barrier Layer
摘要
In general, the lubrication of transition metal nitride coatings has been enhanced by the soft metal Ag doping. However, the quick diffusion of Ag at high temperature could deteriorate the coating properties. In order to control the diffusion of the soft metal Ag, depositing a barrier layer on the coatings has been an effective method. In this study, TiN-Ag coating was prepared by magnetron sputtering method and TiN barrier layers with different thickness (100-290 nm) were deposited on its surface. The microstructure and friction properties of TiN-Ag coating with TiN barrier layer was investigated, and the diffusion mechanism of Ag was also discussed. Similar to TiN-Ag, TiN-Ag/TiN double-layer coatings were also composed of TiN and Ag phases, and the phases shared a nanostructure. For TiN-Ag coating, the coverage of silver were 92.00% (at 500 °C for 5 min) and 95.70% (at 500 °C for 15 min). The coverage of silver decreased gradually with the increase in the TiN barrier layer thickness. For TiN-Ag/TiN(290 nm) coating, the coverage of silver decreased to 42.51% (at 500 °C for 5 min) and 49.00% (at 500 °C for 15 min). The coverage of silver increased with the increase in the temperature and holding time. Both the room and high-temperature friction coefficient of the TiN-Ag coating decreased by the TiN layer design. After sliding at 500 °C, the wear rate of TiN-Ag coating was 4.76 × 10−5 mm3/(N m) and that of TiN-Ag/TiN(290 nm) coating was 2.99 × 10−5 mm3/(N m). The TiN barrier layer enhanced the high-temperature friction properties of the TiN-Ag coating by controlling Ag diffusion.