| LIU Yong,ZHANG Ziyu,FU Jingguo,LIU Xue,CHAO Haibin,MA Chunsheng.Effect of Electrolyte Additives on Bonding Strength and Preparation of Aluminum-tin-copper Alloy Microarc Oxidation Ceramic Layers[J],54(5):265-275 |
| Effect of Electrolyte Additives on Bonding Strength and Preparation of Aluminum-tin-copper Alloy Microarc Oxidation Ceramic Layers |
| Received:December 12, 2024 Revised:January 31, 2025 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.05.021 |
| KeyWord:aluminum-tin-copper alloy micro-arc oxidation bonding strength additives sodium carbonate sodium tungstate |
| Author | Institution |
| LIU Yong |
Dalian Maritime University, Liaoning Dalian , China |
| ZHANG Ziyu |
Dalian Maritime University, Liaoning Dalian , China |
| FU Jingguo |
Dalian Maritime University, Liaoning Dalian , China |
| LIU Xue |
Wafangdian Bearing Group Co., Ltd., Liaoning Dalian , China |
| CHAO Haibin |
CNPC Eastern Geophysical Exploration Co., Ltd., Marine Geophysical Exploration Branch, Tianjin , China |
| MA Chunsheng |
Dalian Maritime University, Liaoning Dalian , China |
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| Abstract: |
| In order to meet the demand of higher load resistance and longer service life of bearing bushing materials proposed by the continuous progress of internal combustion engine technology, achieve the popularization and application of micro-arc oxidation surface treatment technology on the surface of aluminum-tin-copper alloy, this work focuses on the effect of electrolyte additives sodium tungstate and sodium carbonate on the preparation and bonding strength of micro-arc oxidation ceramic layers on the surface of AlSn20Cu alloy. The results of this study can lay an important foundation for the promotion and application of micro-arc oxidation treatment technology on the surface of AlSn20Cu alloy. Aluminum tin copper alloy, with aluminum as the matrix, added with tin and copper and other elements, has high strength, hardness and excellent corrosion resistance, and is widely employed in a variety of light industry, large and heavy machinery bearings. AlSn20Cu alloy is widely employed in main bearings and connecting rod bearings of internal combustion engines. In the working process of internal combustion engines, the bearing bush needs to withstand the harsh conditions brought by high load and high-speed movement, so the bearing bush is required to have excellent wear resistance. In order to improve the wear resistance of the aluminum-tin-copper alloy surface, many scholars have studied the surface strengthening treatment technology of aluminum-tin-copper alloy. However, the traditional surface treatment technology still has some shortcomings in terms of cost and coating performance. Micro-arc oxidation, also known as liquid phase plasma electrolytic oxidation, is an advanced metal surface treatment technology. It generates a micro-arc discharge at the interface of metal and electrolyte through a precisely controlled pulse current, which promotes the formation of an oxide film with high bonding strength and dense structure on the metal surface. The micro-arc oxidation technology has the advantages of low cost, green pollution, no need for strict surface pretreatment, and can control the surface morphology of ceramic layers by technological parameters, therefore it is easy to prepare functional coatings with other technologies. Hence, in 2023, a research group proposed to apply the micro-arc oxidation technology to the surface strengthening treatment of AlSn20Cu alloy. Based on the obtained micro-arc oxidation ceramic layer, the composite coating with anti-friction and wear-resisting properties was prepared by combining with electrophoretic deposition technology. Previous studies have shown that the bonding strength of the micro-arc oxidation ceramic layer plays a crucial role in the wear resistance of the composite coating. However, the existing research on the preparation of micro-arc oxidation ceramic layers on the surface of AlSn20Cu alloy is still not comprehensive, and the influence of electrolyte parameters on the preparation and bonding strength of ceramic layers is lacking.. Under constant pressure mode, sodium carbonate and sodium tungstate were selected as the additives for micro-arc oxidation electrolyte. Firstly, the effect of sodium carbonate concentration on the growth process, basic characteristics and bonding strength of micro-arc oxidation ceramic layer was investigated. Based on the optimization results of sodium carbonate concentration, the effect of sodium tungstate concentration on micro-arc oxidation ceramic layers was further analyzed. The concentration of sodium carbonate was set to 8, 10, 12, 14 and 16 g/L, and the concentration of sodium tungstate was set to 2, 4, 6, 8 and 10 g/L. The software of micro arc oxidation power supply was employed to collect the current data in the reaction. A scanning electron microscopy was employed to characterize the microstructure of the ceramic layer and measure the thickness of the ceramic layer. The surface porosity and average pore size of the ceramic layer were analyzed by SEM images and Image J software. The surface roughness of the ceramic layer was measured by optical profile instrument. The reaction process of micro-arc oxidation was analyzed with the current curve. The bonding strength of the ceramic layer was tested by scratch test. The hardness of the ceramic layer was measured by Micro-vickers hardness tester. The phase composition of the ceramic layer was analyzed by X-ray diffractometer. The stress state of the ceramic layer was analyzed by X-ray method. The elastic modulus of the ceramic layer was analyzed by micro and nano-mechanical test system. Both sodium carbonate and sodium tungstate have certain effects on the process of micro-arc oxidation. With the increase of concentration, the thickness and surface roughness of the ceramic layer increase gradually, but the changes of surface micro-morphology, porosity and average pore size are not significant. Sodium carbonate has little influence on the bonding strength of the ceramic layer, but the change of sodium tungstate concentration makes the bonding strength of the ceramic layer increase first and then decrease. The micro-arc oxide ceramic layer prepared with sodium carbonate concentration of 10 g/L and sodium tungstate concentration of 4 g/L shows the highest bonding strength due to its good bonding state, lower average grain size, elastic modulus and surface stress. |
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