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Date of Publication:2022-10-07

Journal:表面技术

Volume:48

Issue:7

Page Number:135-141

ISSN No.:1001-3660

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 �C200 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 ��-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 �C100 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. ? 2019, Chongqing Wujiu Periodicals Press. All rights reserved.

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