Effect of applied load on the tribological properties of MoS2–TiL/MoS2–TiH nano-multilayer coating

Abstract

MoS2–TiL/MoS2–TiH coating (L and H are low and high power of the sputtered Ti target) possesses excellent tribological properties owing to its nano-multilayer structure. In this study, the tribological properties of MoS2–TiL/MoS2–TiH coating were extensively analyzed at different loads. Relative to the MoS2–Ti monolayer coating, the nano-multilayer structure not only improved the wear resistance but also increased the critical load at which the coating began to peel off. The MoS2–Ti coating maintained its lubrication only in the early stage of the test even at a load of 2 N. In contrast, the friction coefficient and wear rate of the multilayer coating were small and stable until the load reached 20 N. The critical load of the optimized MoS2–TiL/MoS2–TiH coating was 10 times that of the MoS2–Ti coating. At excessive loads, the multilayer coating lost its lubrication in the early stage of the test because the coating was completely worn off under such loading.

Effect of Modulation Periods on the Mechanical and Tribological Performance of MoS2–TiL/MoS2–TiH Multilayer Coatings

“…Our previous studies proved that the mechanical and tribological performance of MoS 2 -Ti coatings could be effectively enhanced using MoS 2 -Ti L /MoS 2 -Ti H multilayer structures [10][11][12]. The growth of columnar structures could be prevented by the multilayer structure, thus the MoS 2 -Ti L /MoS 2 -Ti H coating had a compact structure and exhibited excellent mechanical and tribological properties.…”

“…In order to solve the above drawbacks, MoS 2 -based coatings with incorporated additives have been developed, with the resultant doped MoS 2 -based coatings exhibiting improved performance compared with their undoped counterparts. The doped additives can be classified into four main categories: metals (Ti [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], Au [22], Pb [16,20,21,23], Sn [24], Ta [25], W [26], Zr [27],…”

“…First, adding Ti contributes towards the compactness of the coating, thereby reducing the concentration of defects in the material. This is the main reason why such coatings have better mechanical and tribological performance [5][6][7][8][10][11][12][13][14][15][16]21,38] compared with their undoped counterparts. In contrast, pure MoS 2 coatings exhibit a columnar structure, which is porous and loose.…”

“…Another effective approach to improving the performance of the coating is to build a multilayer microstructure [10][11][12]19,37]. The multilayer structure effectively inhibits the growth of a column-like structure and makes the coating more compact as the multilayer structure effectively slows dislocation movement and grain boundary slippage [10][11][12]19].…”

“…Another effective approach to improving the performance of the coating is to build a multilayer microstructure [10][11][12]19,37]. The multilayer structure effectively inhibits the growth of a column-like structure and makes the coating more compact as the multilayer structure effectively slows dislocation movement and grain boundary slippage [10][11][12]19]. In addition, the multilayer interface effectively inhibits the infiltration of oxygen elements into the inner coating, thus the oxidation resistance of the coating can be improved [37].…”