Synergistic Antifriction Mechanism of Surface Micro-textured Graphite Coating on Aluminum Alloy Surface

LIU Si-si, LIU Qiang, LIU Jin-gang, JIANG Sheng-qiang, LIAO Jun-hui, YU Jin, HE Jian-guo

Surface Technology ›› 2019, Vol. 48 ›› Issue (8) : 29-38.

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Surface Technology ›› 2019, Vol. 48 ›› Issue (8) : 29-38. DOI: 10.16490/j.cnki.issn.1001-3660.2019.08.005
Special Topic—Preparation, Properties and Mechanism of Surface Texture

Synergistic Antifriction Mechanism of Surface Micro-textured Graphite Coating on Aluminum Alloy Surface

  • LIU Si-si1, LIU Qiang1, LIU Jin-gang1, JIANG Sheng-qiang1, LIAO Jun-hui2, YU Jin3, HE Jian-guo3
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Abstract

The synergistic effects of micro texture and solid lubricating coating on the anti-friction and anti-wear performances of aluminum alloy surface were studied, which provided references for the anti-friction and anti-wear design of the aluminum alloy piston outer surface of internal combustion engine. The square-shaped micro pits array with regular morphology on the surface of the test pieces were fabricated by pulsed Nd:YAG laser, and the textured surfaces were modified by the thermal spraying solid graphite. Moreover, the tribological performances were study by the HSR-2M type high speed reciprocating friction and wear testing machine under the condition of oil shortage, and the worn surfaces of test pieces were analyzed by scanning electron microscopy and three-dimensional microscope. Furthermore, the synergistic effect and the influence mechanism of micro-texture geometric parameters, relative sliding speeds and coating properties on anti-friction and anti-wear performances were studied. The experimental results show that, under the limited lubrication condition, the friction coefficients of substrate surfaces covered with graphite coating are reduced by 44% compared with the smooth surfaces. On the contrast, the surfaces of the friction pair modified by micro-texture also have friction coefficients significantly smaller than that of smooth surfaces, and the micro-textured surface has a minimum coefficient of friction of 0.074 when the density of micro-texture is 8.2%, which is 67.4% lower than that of the smooth surface. When the frictional coefficient is further reduced to 0.07 under the synergistic effect of the micro texture and graphite coating, no significant wear is observed on the surface of the aluminum alloy substrate. What’s more, a higher sliding speed facilitates a further reduction in the coefficient of friction. Under the synergistic effects of micro-texture and graphite coating, they can effectively improve the tribology performance of aluminum alloy friction pair under the condition of oil shortage. Moreover, reasonable geometric parameters can effectively reduce the friction and anti-wear effect.

Key words

aluminum alloy; laser micro-texture; graphite coating; oil shortage lubrication; synergistic mechanism of antifriction

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LIU Si-si, LIU Qiang, LIU Jin-gang, JIANG Sheng-qiang, LIAO Jun-hui, YU Jin, HE Jian-guo. Synergistic Antifriction Mechanism of Surface Micro-textured Graphite Coating on Aluminum Alloy Surface[J]. Surface Technology. 2019, 48(8): 29-38

Funding

National Natural Science Foundation of China (51405413), Natural Science Foundation of Hunan Province (2018JJ4055), Special Projects of Changsha Zhuzhou Xiangtan National Independent Innovation Demonstration Zone (2018XK2302, 2017XK2107)
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