| TANG Yu-hao,XIANG Dong,LI Dong-hao,WANG Lei,WANG Ping,HAN Pei-dong.Effects of Current Density in Electrolyte Containing Graphene on Properties of 2024 Aluminum Alloy Micro-arc Oxidation Coating[J],47(7):203-208 |
| Effects of Current Density in Electrolyte Containing Graphene on Properties of 2024 Aluminum Alloy Micro-arc Oxidation Coating |
| Received:March 18, 2018 Revised:July 20, 2018 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2018.07.029 |
| KeyWord:2024 aluminum alloy micro-arc oxidation current density graphene hardness abrasive resistance corrosion resistance |
| Author | Institution |
| TANG Yu-hao |
School of Material Science and Enginering, Southwest Petroleum University, Chengdu , China |
| XIANG Dong |
School of Material Science and Enginering, Southwest Petroleum University, Chengdu , China |
| LI Dong-hao |
School of Material Science and Enginering, Southwest Petroleum University, Chengdu , China |
| WANG Lei |
School of Material Science and Enginering, Southwest Petroleum University, Chengdu , China |
| WANG Ping |
School of Material Science and Enginering, Southwest Petroleum University, Chengdu , China |
| HAN Pei-dong |
Southwest Institute of Electronic Telecommunication Technology, Chengdu , China |
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| Abstract: |
| The work aims to study effects of current density on thickness, hardness and wear resistance, corrosion resistance of MAO coating. Graphene nanoplatelets (GNPs) was added to the electrolyte containing sodium hydroxide and sodium silicate, micro-arc oxidation (MAO) treatment of 2024 aluminum alloy was completed at different current density in the mode of pulsed direct current. Morphology and composition of the coating were analyzed using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS); corrosion resistance of the coating was tested using polarization curve; phase composition of the sample was characterized with X-ray diffractometer (XRD); surface mechanical property of the ceramic coating was determined with multi-functional material surface performance testing machine. Current density increased from 1 A/dm2 to 5 A/dm2, thickness of coating containing GNPs increased from 4.2 μm to 5.8 μm, thickness of GNPs-free coating increased from 2.7 μm to 4.5 μm. After MAO treatment at initial current density of 1 A/dm2, the hardness of the coating containing GNPs was up to 163HV, 63% higher than that of GNPs-free coating. Friction coefficient was about 0.5 when current density was 1 A/dm2, and it decreased to 0.3 as current density reached 5 A/dm2, which improved wear resistance of coatings. At the current density of 3 A/dm2, self-corrosion potential increased gradually, and corrosion current tended to decrease, and corrosion resistance of the ceramic coating was the best. Current density had no obvious effects on composition of the ceramic coating. Friction coefficient of compact layer in the sample significantly decreases and wear resistance improves as current density increases. Higher current density can effectively reduce number and size of discharge holes on the coating, and improve corrosion resistance of the coating. The coating exhibits the best corrosion resistance at the current density of 3 A/dm2. Thickness, hardness, abrasive resistance and corrosion resistance of the coating can be improved by adding GNPs. |
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