铝锂合金表面氧化膜的制备及性能研究

发布时间：2018-05-29 09:18

本文选题：2060-T8铝锂合金 + 阳极氧化　；参考：《南京航空航天大学》2017年硕士论文

【摘要】：作为满足航空航天领域结构轻量化要求的最理想材料之一,铝锂合金具有较低的各项异性、高强可焊性及抗疲劳裂纹等优点,广泛应用于商用、民用飞机或直升机的蒙皮、机身框架、襟翼翼肋、水平安定面、尾翼安定面、舱门、进气道唇口、燃油箱上,提高铝锂合金表面性能的研究具有重要意义。本文研究了2060-T8铝锂合金在硫酸电解液中的阳极氧化行为和在硅酸盐电解液中的微弧氧化行为。首先,分析了直流稳压条件下电压、时间、电解液浓度等参数对铝锂合金阳极氧化膜表面微观特性、粘结性能及摩擦磨损性能的影响。其次,分析了脉冲电流条件下,正脉冲电压、时间、占空比、脉冲频率等对微弧氧化膜表面微观特性、粘结性能及摩擦磨损性能的影响。在硫酸电解液中铝锂合金进行恒压阳极氧化,制得的氧化膜表面呈银灰色,与铝锂合金基体没有明显变化。经过SEM和EDS分析,铝锂合金阳极氧化膜表面含有微量孔洞和胞状突起,表面较为平整,膜层主要元素成分为Al、C、O、S等,其中O和S主要来源于硫酸电解液。在硅酸盐电解液中对铝锂合金进行单脉冲微弧氧化,制得的氧化膜表面呈红棕色,氧化膜越厚颜色越深。经过SEM和EDS分析,铝锂合金微弧氧化膜表面含有大量孔洞和菜花状突起,表面起伏不平,膜层主要元素成分为Al、C、O、Si、Na等,其中O、Si和Na主要来源于硅酸盐电解液。拉剪试验表明,铝锂合金阳极氧化膜的粘结性能总体低于微弧氧化膜的粘结性能,但两者均高于基体合金的粘结性能。阳极氧化过程中,电解液硫酸浓度10%时制得的铝锂合金试样粘结强度最高,可达23.2MPa,较基体合金提高73%;微弧氧化过程中,氧化时间45min制得的铝锂合金试样粘结强度最高,可达28.2MPa,较基体合金提高111%。摩擦磨损试验表明,铝锂合金微弧氧化膜的摩擦磨损性能明显高于阳极氧化膜,阳极氧化膜的摩擦磨损性能又高于基体合金。阳极氧化过程中,铝锂合金的摩擦磨损性能随电压的升高而先升后降,电压为10V时制得的阳极氧化膜耐磨性能最好,较基体提高7.2倍。微弧氧化过程中,正脉冲电压过高或过低均不利于合金耐磨性能的提高,正脉冲电压为400V时制得的微弧氧化膜耐磨性能最好,较基体合金试样提高20倍。
[Abstract]:As one of the most ideal materials to meet the requirements of lightweight structure in aerospace field, Al-Li alloy has the advantages of low heterogeneity, high strength solderability and fatigue crack resistance, and is widely used in commercial, civil aircraft or helicopter skin. It is of great significance to improve the surface properties of Al-Li alloy in fuselage frame, flaps, horizontal stabilizer, tail stabilizer, hatch, inlet lip and fuel tank. The anodizing behavior of 2060-T8 aluminum-lithium alloy in sulphuric acid electrolyte and micro-arc oxidation in silicate electrolyte have been studied in this paper. Firstly, the effects of voltage, time and electrolyte concentration on the surface microcosmic properties, bond properties and friction and wear properties of Al-Li alloy anodic oxide film were analyzed. Secondly, the effects of positive pulse voltage, time, duty cycle and pulse frequency on the surface properties, adhesion properties and friction and wear properties of micro-arc oxide films are analyzed. Aluminum-lithium alloy was anodized at constant voltage in sulphuric acid electrolyte. The surface of the film was silver gray and had no obvious change with the base of Al-Li alloy. By SEM and EDS analysis, the surface of the anodic oxide film of Al-Li alloy contains a small number of pores and cellular processes, and the surface is flat. The main elements of the film are Al _ 2O _ 4 / O _ S, among which O and S are mainly derived from sulphuric acid electrolyte. Aluminum-lithium alloy was oxidized by single pulse micro-arc in silicate electrolyte. The surface of the oxide film was red-brown, and the thicker the film was, the darker the color was. By SEM and EDS analysis, a large number of pores and cauliflower protrusions were found on the surface of Al-Li alloy micro-arc oxide film. The tensile and shear tests show that the bonding property of the anodic oxide film of Al-Li alloy is generally lower than that of the micro-arc oxide film, but both of them are higher than that of the base alloy. In the process of anodizing, the bonding strength of Al-Li alloy sample made from the electrolyte with sulfuric acid concentration 10 is the highest, up to 23.2MPa, which is 73% higher than that of the base alloy, and the bond strength of Al-Li alloy sample prepared by oxidation time 45min is the highest in the process of micro-arc oxidation. It can reach 28.2MPa, which increases 111% compared with the base alloy. The friction and wear tests show that the friction and wear properties of Al-Li alloy micro-arc oxide film are obviously higher than those of anodic oxide film, and the friction and wear properties of anodic oxide film are higher than that of base alloy. During anodic oxidation, the friction and wear properties of Al-Li alloy increased first and then decreased with the increase of voltage, and the wear resistance of the anodic oxide film was the best when the voltage was 10 V, which was 7.2 times higher than that of the substrate. In the process of micro-arc oxidation, the high or too low positive pulse voltage is not conducive to the improvement of the wear resistance of the alloy. When the positive pulse voltage is 400V, the wear resistance of the micro-arc oxide film is the best, which is 20 times higher than that of the base alloy sample.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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