Pencil sketch graphene films as solid lubricant on steel surface: Observation of transition to grapehene/amorphous carbon |
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| Institution: | 1. R&D Center of Lubricating and Protecting Materials, Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China;2. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA;3. School of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, PR China;4. University of Chinese Academy of Sciences, Beijing 100049, PR China;1. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People’s Republic of China;2. School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730000, People’s Republic of China;1. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China;1. School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai, 264209, PR China;2. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, PR China;1. School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia;2. School of Physics and Electronics, Hunan Normal University, Changsha 410081, China;3. School of Physics and Electronics, Central South University, Changsha 410083, China;1. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000,& China and University of Chinese Academy of Sciences, Beijing 100049, China;2. School of Petrochemical Technology, Lanzhou University of Technology, Lanzhou,730050, China |
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| Abstract: | During recent years, graphene as a solid lubrication material have been thoroughly studied under nano or micro scales, but rarely reported at industrial conditions. In present work, graphene films as solid lubricant were prepared on the surface of 201 stainless steel substrates by pencil sketch. And then the friction tests from 5 to 65 N were carried out via a homemade tribo-tester and used GCr15 balls (ø = 5 mm) as friction pairs. Not surprisingly, graphene films cannot bear the loads beyond 5 N, but interestingly, via gradually increasing the loads, graphene films show prominent load performance and steady state of friction coefficients at about 0.12 while the loads varied from 5 to 65 N. Compared with bare steel, the coefficient of graphene films reduced by about 80%, and the wear volume reduced to 1/28 when variable load (from 5 N to 30 N) were applied. Raman spectra shown that the structure of graphene had been changing into diamond-like carbon films with graphene distributed inside, which was confirmed by HRTEM that graphenes were coming with amorphous carbon. Considering the roughness of steel wafers (170 nm), one can speculate that, with graphene films' protection, the steel has no abrasion but plastic deformation instead. It is concluded that the shearing force induced the film densification via sp2 to sp3 changing that enforced cross-linking. This cross-linking carbon matrix was responsible for high load bearing and the graphene exfoliated into graphene under shearing force contribute to low steady-state friction. Benefiting from sketch, one can get a lubrication film on any substrates with complex topography, our results shed light on the growth of graphene films for industrial use. |
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| Keywords: | Graphene Amorphous carbon Lubricant Low friction Low wear |
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