LI Xiao-jing,WEN Shuai,FU Bo-yang,MAO Xin,ZHANG Min,WANG Qi-wei,CHEN Ping.Effect of Negative Voltage on Microstructure and Wear Resistance of MAO Ceramic Coatings on 2A50 Aluminum Alloy[J],48(7):135-141
Effect of Negative Voltage on Microstructure and Wear Resistance of MAO Ceramic Coatings on 2A50 Aluminum Alloy
Received:April 09, 2019  Revised:July 20, 2019
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DOI:10.16490/j.cnki.issn.1001-3660.2019.07.014
KeyWord:micro-arc oxidation  2A50 aluminum alloy  friction and wear  negative voltage
                    
AuthorInstitution
LI Xiao-jing 1.School of Physics & Electronic Technology, Liaoning Normal University, Dalian , China
WEN Shuai 1.School of Physics & Electronic Technology, Liaoning Normal University, Dalian , China
FU Bo-yang 1.School of Physics & Electronic Technology, Liaoning Normal University, Dalian , China
MAO Xin 1.School of Physics & Electronic Technology, Liaoning Normal University, Dalian , China
ZHANG Min 1.School of Physics & Electronic Technology, Liaoning Normal University, Dalian , China
WANG Qi-wei 2.Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China
CHEN Ping 3.School of Chemical Engineering, Dalian University of Technology, Dalian , China
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Abstract:
      The work aims to prepare 2A50 aluminum alloy micro-arc oxidation ceramic layer with higher hardness and better wear resistance by adjusting the negative voltage parameters. With a bipolar pulse power, wear-resistant ceramic coatings with high micro-hardness were fabricated in-situ on 2A50 aluminum alloy by micro-arc oxidation method in silicate electrolyte. The effect of negative voltage on microstructure, phase structure, micro-hardness and wear properties was investigated by changing the negative voltage from 0 to –200 V. The microstructure, phase structure, micro-hardness and wear properties were characterize, measured and evaluated by SEM, XRD, Vikor hardness tester and tribology tester. The phase of the obtained coatings was mainly composed of γ-Al2O3. The coating consisted of the inner dense layer and the outer loose layer. As the negative voltage increased, the quantity and size of the pin holes in the coatings first decreased and then increased. Micro-arc oxidation could greatly strengthen 2A50 aluminum alloy and the micro-hardness increased from 75HV0.5 to 1321HV0.5 after a micro-arc oxidation under a negative voltage of –100 V. The obtained ceramic coatings exhibited good wear resistance and the friction coefficient was in the range of 0.35~0.55. The wear mechanism was deduced to be the combination of abrasive wear and adhesive wear. When the positive voltage is high, the lower negative voltage can well suppress the strong discharge phenomenon in the micro-arc oxidation process to obtain a dense, hard and wear-resistant film layer.
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