| LIU Jin-long,LI Hong-xuan,JI Li,LIU Xiao-hong,ZHANG Ding-jun.Tribological Properties of TiB2 Doped WS2 Composite Films in Wide Temperature Range[J],52(6):235-245 |
| Tribological Properties of TiB2 Doped WS2 Composite Films in Wide Temperature Range |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.06.020 |
| KeyWord:WS2/TiB2 composite film wide temperature range mechanical properties friction and wear crystal orientation |
| Author | Institution |
| LIU Jin-long |
School of Material Science and Engineering, Lanzhou University of Technology, Lanzhou , China;State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou , China |
| LI Hong-xuan |
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou , China |
| JI Li |
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou , China |
| LIU Xiao-hong |
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou , China |
| ZHANG Ding-jun |
School of Material Science and Engineering, Lanzhou University of Technology, Lanzhou , China |
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| Abstract: |
| The work aims to investigate the effect of TiB2 sputtering current (the content of TiB2) on tribological properties of WS2/TiB2 composite films in wide temperature range (25-500 ℃). WS2/TiB2 composite films were prepared by non-equilibrium magnetron sputtering. The morphology and structure of the films were observed by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscope (HRTEM). The structure of the films was characterized by X-ray diffractometer (XRD) and X-ray photoelectron spectrometer (XPS). The mechanical properties of the films were evaluated by nanoindentation instrument (Anton Paar, NHT2). The tribological properties of the films were tested by a high temperature ball disc friction and wear tester (THT01, 03591). Optical microscope (Olympus, STM6) and three- dimensional profilometer (Micro XAM-800) were used to observe the morphology of wear tracks and wear scars, and HRTEM was used to analyze the structure of wear tracks and wear scars. TiB2 doped WS2 films changed from highly crystalline to amorphous state, and the surface morphology of composite films changed from "worm-like" to "island-like", improving the density and mechanical properties. With the increase of TiB2 sputtering current, the friction coefficient and wear rate of the composite films decreased firstly and then increased. In addition, as the test temperature rose, the friction coefficient of the composite films firstly decreased and then increased, but the wear rate was gradually increasing. Among them, sputtering current of TiB2 with 1.5 A contributed to the lowest friction coefficient and wear rate in wide temperature range (25-500 ℃). The friction coefficients of composite films at 100 and 300 ℃ at sputtering current with 0-2.5 A were lower than those at 25 and 500 ℃, while the friction coefficient of composite film prepared with TiB2 sputtering current of 4.0 A was opposite. By analyzing the wear tracks and corresponding wear scars of composite films prepared with sputtering current of 1.5 A at different experimental temperature, it was found that the furrow on the surface of wear tracks was obvious at 25 ℃. When the temperature rose to 100 and 300 ℃, the furrow on the surface of the wear tracks became shallow, and the friction coefficient decreased and remained stable, respectively to about 0.015 and 0.021. However, the depth, width and wear rate of wear tracks slightly increased, and the friction mechanism was mainly abrasive wear and adhesive wear. When the experimental temperature reached 500 ℃, the plastic deformation of the film surface and subsurface increased, the damage was serious, there was a wide furrow, and the film was basically invalidated. However, the friction coefficient was kept at about 0.08, which was typical of the transfer film lubrication, occurring in part of the oxidation wear during friction. With the increase of the experimental temperature, the size of the debris on the pair ball became larger, the transfer film on the pair ball moved from the edge of the wear scars to the center gradually, and a continuous and dense transfer film was formed at 300 ℃. In order to further investigate the structure evolution of composite films at high temperature, the wear tracks and wear scars of composite film with TiB2 sputtering current of 1.5 A at 300 ℃ were prepared by FIB and observed by transmission electron microscope. Under the frictional shear force, the crystal plane orientation of WS2(002) parallel to the sliding direction and the crystal plane orientation of TiB2(101) was formed. Meanwhile, the crystal plane structure of lubricated TiO2(001) was formed by oxidation under high ambient temperature and frictional heat. The composite films prepared at TiB2 sputtering current of 1.5 A have excellent tribological properties in wide temperature range. The dense amorphous structure, high hardness and elastic modulus, and recrystallization orientation under frictional shear force and high temperature oxidation are the key factors for low frictional wear. |
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