電參數及電解液濃度對鎂合金微弧氧化膜層性能的影響及應用

摘要： 為研究電參數和電解液濃度對鎂合金微弧氧化膜層性能的影響，以Mg-Zn系鎂合金為研究載體，采用硅酸鹽體系電解液，在鎂合金表面制備了微弧氧化膜，通過改變電參數及電解液濃度，研究了不同參數對微弧氧化膜層性能的影響。結果表明：隨著電壓的升高、占空比的增加、頻率的減小，提供的能量增加，膜層生長速率加快，膜層厚度隨之增加；隨著電流密度的增加，膜層厚度先增加后減小，電流密度對膜層厚度的影響取決于生長速率和反應時間。膜層厚度與電解液濃度成正比，但電解液濃度過高將引起局部燒蝕，導致膜層脫落。微弧氧化膜層能夠顯著提高鎂合金的耐腐蝕性，膜層厚度增加和膜層孔徑減小均可提高鎂合金的耐腐蝕性。微弧氧化試樣采用質量分數為3.5%的氯化鈉溶液浸泡120 h，腐蝕速率僅為0.24 mm/a。在鎂合金汽車電池箱體表面制備了微弧氧化+電泳復合膜層，微弧氧化膜層厚度約為13.7 μm，電泳涂層厚度約為25 μm，中性鹽霧試驗720 h后無明顯銹蝕。

關鍵詞：鎂合金 微弧氧化 電參數 電解液濃度 耐蝕性

中圖分類號：TG174.4" "文獻標志碼：B" "DOI： 10.19710/J.cnki.1003-8817.20240380

The Effect and Application of Electrical Parameters and Electrolyte Concentration on the Properties of Micro-Arc Oxidation Coating on Magnesium Alloy

Bi Yong1， Wang Pengyue2， Sun Wei1， Wang Chenggang2， Wang Tianhua2， Qiu Xin1

（1.Changchun Institute of Applied Chemistry， Chinese Academy of Sciences， Changchun 130022; 2.FAW Foundry Co.， Ltd.， Changchun 130011）

Abstract： To investigate the effect of electrical parameters and electrolyte concentration on the properties of Micro-Arc Oxidation （MAO） coatings on magnesium alloys， Mg-Zn series magnesium alloys are used as the research substrate. Silicate-based electrolyte is employed to prepare MAO coatings on the surface of the magnesium alloy. By varying the electrical parameters and electrolyte concentration， this paper studies the influence of different parameters on the performance of the MAO coatings. The results show that with the increase of voltage and duty cycle， and the decrease of frequency， the energy provided increases， leading to an accelerated coating growth rate and an increase in coating thickness. With the increase in current density， the coating thickness initially increases and then decreases， as the effect of current density on coating thickness depends on the growth rate and reaction time. The coating thickness is directly proportional to the electrolyte concentration; however， excessively high electrolyte concentrations can cause localized ablation， resulting in coating detachment. The MAO coatings significantly enhance the corrosion resistance of the magnesium alloy， and both increased coating thickness and reduced pore size can improve the corrosion resistance. MAO samples immersed in a 3.5% sodium chloride solution for 120 h exhibits a corrosion rate of 0.24 mm/a. A composite coating of MAO followed by electrophoretic deposition is prepared on the surface of a magnesium alloy automotive battery case. The MAO coating thickness is approximately 13.7 μm， and the electrophoretic coating thickness is about 25 μm， withstanding a neutral salt spray test for 720 h.

Key words： Magnesium alloy， Micro-arc oxidation， Electrical parameter， Electrolyte concentration， Corrosion resistance

1 前言

鎂合金具有密度低、比強度高、導電導熱性好、阻尼減振性好及可回收利用等優點，廣泛應用于航空航天、電子通信、汽車制造、生物醫學及能源等領域[1-3]。鎂合金表面氧化膜疏松多孔，在腐蝕介質中無法有效保護基體，導致鎂合金的耐蝕性較差[4-5]。鎂合金化學性質活潑，與其他常用金屬材料相比，具有較高的電負性，當與異種金屬接觸時，由于存在電位差而發生電偶腐蝕，鎂合金部件作為陽極會加速腐蝕[6-9]，腐蝕問題已成為限制鎂合金應用的最大障礙。……