镍基自润滑涂层的摩擦学性能

Tribological Performance of Nickel-Alloy Matrix Self-Lubricating Coatings

镍基自润滑复合粉末(NiCrMoAl-Ag-BaF_2/CaF_2)采用高能球磨结合喷雾造粒法制备,镍基自润滑涂层利用等离子喷涂技术制备.涂层摩擦磨损性能利用HT-1000型销-盘摩擦试验机在不同摩擦速度(0.2~1.0 m/s)及不同试验温度(25~800℃)条件下测试.涂层微观组织、物相组成及摩擦磨损机理利用SEM、EDS和Raman等表征分析.结果表明:在25℃到800℃,涂层的摩擦系数随着温度的增加呈先增加后降低的趋势,400℃时摩擦系数达到最高值0.37;800℃时摩擦系数降至最低值0.17.涂层摩擦系数随摩擦速度的增加呈现先降后增的趋势,0.8 m/s时摩擦系数最低,约在0.17~0.29范围内;1.0 m/s时摩擦系数升高至0.20~0.27范围内.涂层优异的自润滑性能得益于软金属Ag的低剪切性,以及600~800℃范围内BaF_2/CaF_2、Ag与钼酸盐、铬酸盐等高温产物的协同润滑效应.

Nickel-alloys matrix self-lubricating composite powder（NiCrMoAl-Ag-BaF2/CaF2） was prepared by highenergy ball milling combined with spray dry granulation method,and a nickel-alloys matrix self-lubricating coating was prepared by plasma spraying technology. A pin-on-disk HT-1000 friction-meter was used to test the friction and wear properties at different rubbing speeds（0.2-1.0 m/s） and under different testing temperatures（25-800 ℃）. The microstructures,phase compositions and wear mechanism of the coating were analyzed by scanning electron microscopy,energy dispersive spectroscopy and Raman. The results indicate that at a wide temperature range from 25 ℃to 800 ℃,the friction coefficient of the coating firstly increased and then decreased with the increasing temperature. The friction coefficient reached the maximum value of 0.37 at 400 ℃; and then reduced to a minimum value of 0.17 at800 ℃. The friction coefficient of the coating decreased firstly and then increased with increasing sliding speed. The lowest friction coefficient of the coating was about 0.17-0.29 at 0.8 m/s,and then increased to 0.20-0.27 at 1.0 m/s. The favorable lubricating properties of the coating could be attributed to the low shear of the soft metal Ag,and especially the synergistic lubrication effects of BaF2/CaF2,Ag and high-temperature products such as molybdate and chromate rendered the coating with excellent lubricity properties under temperature range of 600-800 ℃.