| As a solid lubricant,WS2 shows the merits of high bearing capacity,low friction and good wear resistance when it serves in vacuum.But in the atmosphere,especially in damp environment,the poor friction performance of pure WS2 limits its applications.The recent researches have shown that the construction of the composite or multilayer films with WS2 is an effective ways to improve the friction performance of WS2 in atmospheric environment.In this paper,WS2/a-C nanoscale multilayer films with various layer thickness ratios?modulation period50 nm?were prepared on monocrystalline silicon substrate by magnetron sputtering method.The composition,microstructure and morphology of the multilayer films with lay thickness ratio of 1:39,1:19,1:9,3:20 and 1:4 were studied.The tribological properties of the multilayer films in vacuum,in atmosphere?RH?70%?and in water were investigated also.The results show that an increasing layer thickness ratio(La-C/LWSx)leads to the increase of the film's S/W ratio from 1.38 to 1.62,the reduced size of WS2,and the increasing relative density and flatness,but nearly no change is found in phase structure of a-C and WSx layer.The hardness of the multilayer films shows a trend of increase then decrease,the multilayer film with La-C/LWSx ratio of 1:9 exhibits the maximum hardness of 2.15GPa;The adhesion strength of the multilayer films shows a trend of reduce then increase,the adhesion strength of the multilayer film with La-C/LWSx ratio of 1:39 is best.In vacuum environment,the friction coefficient of multilayer films shows a trend of decrease then increase and is lower than that of pure WSx film;the wear rate follows the same trend.The multilayer film with La-C/LWSx ratio of 1:9 has a friction coefficient of 0.066,wear rate of 5.7×10-15 m3 N-1m-1 and exhibits the best wear resistance.In atmospheric environment,the friction coefficient of the multilayer films shows a trend of gradually reducing and higher than that of pure WSx film,but the wear rate of the multilayer films shows a trend of increase then decrease and significantly lower than that of pure WSx film,the multilayer film with La-C/LWSx ratio of 1:39 has a wear rate of 3.27×10-14 m3 N-1m-1 and exhibits the best wear resistance.In water environment,the friction coefficient of the multilayer films shows a reduced trend and is lower than that of pure WSx film,and the wear rate follows the same trend.The multilayer film with La-C/LWSx ratio of 1:4 has a friction coefficient of0.188,wear rate of 1.16×10-13 m3 N-1m-1 and exhibits the best wear resistance. |
PDF Full Text Request