高性能镍基厚涂层的制备工艺及强化

发布时间：2018-04-15 18:15

本文选题：磨损 + 高性能　；参考：《东华大学》2017年硕士论文

【摘要】：据国际有关部门的初步统计,2%-4%国民生产总值的损失是由于零件表面磨损问题所导致的。在我国,因为零件磨损而导致的机器、设备失效或报废的问题也是十分严峻的。仅就机械、矿山、电力和建材等工业部门的不完全统计,每年因为零件磨损问题而导致的钢材损耗约为100万吨。本课题将针对高接触应力下的磨损问题,将电刷镀技术与电接触强化技术相结合,研究制备了一种高性能厚涂层的工艺。其中,分析列举了影响镀层增长与镀层质量的原因,根据影响因素,制定了切实可行的研究方案,研究制备了镀层厚度达到0.5mm左右的镍基镀层,并掌握了相应的实验规律。然后,对制备的镀层通过电接触强化,经分析可知,强化后两种镀层的硬度、镀层与基体的结合力、抗热疲劳性等均得到了较大的提升。通过对电接触强化后的镀层进一步分析可知,经过电接触强化后,镀层表面上的缺陷减少,这是由于电接触强化过程中,电极轮与工件镀层的紧密压合,并由电接触强化机输入高达20KA的大电流,导致电极轮产生巨大的电阻热,工件镀层产生了熔合与扩散现象,填补了缝隙,通过电极轮与工件的相对转对,压合了凹陷,修复了部分缺陷;在冷却液与瞬间高温的作用下,对靠近结合处的基体起到了淬火效果,改变了靠近结合处基体的组织形貌,提升了硬度。通过扫描电镜观察,强化后镀层与基体组织形貌发生了改变,结合处产生了扩散、融合等现象。通过XRD分析可知,电接触强化细化了晶粒,产生了再结晶效果。
[Abstract]:According to the preliminary statistics of relevant international departments, the loss of gross national product (GNP) of 2% to 4% is caused by the wear problem on the surface of parts.In our country, the problem of machine, equipment invalidation or scrapping caused by wear and tear of parts is also very serious.Incomplete statistics for the mechanical, mining, electric and building industries alone account for about 1 million tons of steel per year due to wear and tear.In order to solve the wear problem under high contact stress, a kind of thick coating with high performance was prepared by combining brush plating technology with electrical contact strengthening technology.Among them, the reasons that affect the growth and quality of the coating are analyzed and listed. According to the influencing factors, the feasible research scheme is established, and the nickel base coating whose thickness is about 0.5mm is researched and prepared, and the corresponding experimental law is grasped.The hardness of the two coatings, the adhesion between the coating and the substrate, and the thermal fatigue resistance of the two coatings were greatly improved.Through the further analysis of the electrocontact strengthened coating, it can be seen that the defects on the surface of the coating are reduced after the electric contact hardening, which is due to the close pressing of the electrode wheel and the coating of the workpiece during the electric contact strengthening process.The high current of up to 20KA is input from the electric contact intensifier, which leads to the great resistance heat of the electrode wheel, the phenomenon of fusion and diffusion of the coating of the workpiece, filling the gap, and pressing the depression through the relative rotation between the electrode wheel and the workpiece.Under the action of the coolant and the instantaneous high temperature, the matrix near the bond was quenched, the microstructure of the matrix near the bond was changed, and the hardness was increased.Scanning electron microscopy (SEM) showed that the morphology of the coating and the matrix changed, and diffusion and fusion occurred at the bonding point.XRD analysis shows that the grain is refined by electric contact strengthening and recrystallization effect is obtained.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.44

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