AZ91D镁合金表面超声化学镀工艺及性能研究

发布时间：2018-07-08 14:16

  本文选题：AZ91D镁合金 + 超声场　； 参考：《江苏大学》2017年硕士论文

【摘要】：镁及其合金是目前工业应用中最轻的金属结构材料,我国镁资源丰富,储量为世界第一,镁合金产量和出口量也名列前茅,广泛应用于国防军工、航空航天、汽车等领域。但镁合金表面生成的氧化膜不致密,在溶液中不稳定,耐腐蚀性能差,限制了其应用。表面改性技术是改善镁合金的耐腐蚀性能的重要手段。化学镀是目前发展最快也是应用最广的表面处理技术之一。本文在AZ91D镁合金化学镀过程中引入超声场,通过单因素试验法优化预处理工艺参数;通过正交试验法优化超声化学镀工艺参数;通过单因素试验法优化热处理工艺参数;最后采用间隔取液法延长镀液寿命。借助扫描电子显微镜、X射线衍射仪、电化学工作站和摩擦磨损试验机等仪器对化学镀层的表面形貌、成分、结构、膜厚、耐蚀性、耐磨性、沉积速率、结合力等性能进行系统研究。结果显示,超声场能显著提升化学镀沉积速率,改善预处理表面质量,提升结合力,制备的化学镀层厚度均匀、完整致密,沉积速率提升了0.2083μm/min。在本试验条件下其最佳预处理工艺参数是:酸洗时间30 s,活化时间10 min;最佳化学镀工艺参数是:温度85℃,时间60 min,超声功率80 W,pH值6.0;最佳热处理工艺为300℃×1 h。经过超声化学镀处理后镁合金的自腐蚀电位比基材正移了0.902 V,显著提高了镁合金的耐蚀性;超声化学镀处理后镀层表面均匀、致密、平整,其摩擦系数由基材的0.23降低到0.14,显著提升镁合金的耐磨性。经300℃×1 h热处理处理后,试样结合力比未经热处理试样显著提升近一倍,此时镀层的硬度达到峰值为890 HV。老化性试验中,镀液的寿命为4 h;利用间隔取液补充溶液法可以延长镀液的施镀时间至9 h。
[Abstract]:Magnesium and its alloys are the lightest metal structural materials in industrial application at present. China is rich in magnesium resources, its reserves are the first in the world, and its output and export are among the highest in the world. It is widely used in the fields of national defense, aerospace, automobile and so on. However, the oxidation film formed on magnesium alloy surface is not dense, unstable in solution and poor corrosion resistance, which limits its application. Surface modification technology is an important means to improve corrosion resistance of magnesium alloys. Electroless plating is one of the most widely used surface treatment technologies. In this paper, ultrasonic field was introduced into the electroless plating process of AZ91D magnesium alloy. The pretreatment process parameters were optimized by single factor test method, the ultrasonic electroless plating process parameters were optimized by orthogonal test method, the heat treatment process parameters were optimized by single factor test method. In the end, the bath life is prolonged by the method of interval liquid extraction. The surface morphology, composition, structure, film thickness, corrosion resistance, wear resistance, deposition rate of the electroless coating were studied by means of scanning electron microscope (SEM), electrochemical workstation and friction and wear tester. The properties such as binding force were studied systematically. The results show that the deposition rate of electroless plating can be improved by ultrasonic field, the surface quality of pretreatment is improved, and the adhesion is enhanced. The thickness of the electroless coating is uniform and compact, and the deposition rate is increased by 0.2083 渭 m / min. The optimum pretreatment process parameters are as follows: pickling time 30 s, activation time 10 min, optimum electroless plating process parameters 85 鈩，

本文编号：2107707