【作者】 张道军；

【导师】 邵红红；

【作者基本信息】 江苏大学 ， 材料学， 2008， 硕士

【摘要】 镁合金具有比重小,比强度和比刚度高,铸造性能、机械加工性能和阻尼性能良好,以及抗电磁干扰、抗震和易回收等优点,在航空航天、汽车、机械、电子等领域正得到日益广泛的应用。但是镁合金的耐腐蚀性能比较差,这一直是阻碍其进一步开发使用的一个主要因素。化学镀镍.磷作为镁合金表面处理的一种方法,由于集耐腐蚀、耐磨、镀层均匀、导电、导热、钎焊等多种性能于一身,一直吸引着人们的注意力,但目前这一工艺不够成熟和完善,镀层的防护作用不能满足要求。本课题以AZ91D镁合金为研究材料,研究了化学镀Ni-P前处理工艺,并采用正交优化设计的方法,研究了碱式碳酸镍、次亚磷酸钠、柠檬酸、pH值、温度等对镀层沉积速度和镀层表面结构及形貌和各种性能的影响,获得了最佳工艺参数。借助扫描电镜、能谱仪、X射线衍射仪、显微硬度计、划痕仪及盐雾试验等设备对化学镀层热处理前后的表面状态、组织结构及性能进行了综合分析。分析结果表明,通过正交优化设计所得到的最佳工艺参数可以实现在AZ91D镁合金上直接化学镀镍,镀层表面光亮、均匀致密,镀层的显微硬度比镁合金基体有了大大的提高,镀层与基底的结合力也比较优良,并且表现出了良好的耐腐蚀性能。更多还原

【Abstract】 Magnesium alloys have a number of desirable features,including low density,high strength-to-weight ratio,excellent castability,good machinability and damping characteristics,and its use in a variety of applications,particularly in aerospace, automobile,mechanical and electronics components,is now growing rapidly.However, poor corrosion resistance has often prevented it from further exploitation. Electroless-nickel-plating（EN）,being one of the surface treatments of magnesium alloys, has attracted much attention due to the possession of a combination of properties,such as good corrosion and wear resistance,deposit uniformity,electrical and thermal conductivity,and solder-ability etc.However,this process is now far from completeness, particularly in corrosion resistance aspects.Therefore,this dissertation is aimed at optimization procedure by orthogonal design ways.In this paper,temperature,pH value, and 2NiCO₃·3Ni（OH）₂·4H₂O,NaH₂PO₂·H₂O,H₈C₆O₇·H₂O was researched to understand that the factors influencing direct-electroless-plating on magnesium alloys,and the optimization parameters were obtained.Using the scan electronic microscope equipped with energy dispersive,and X-ray diffraction,micro-hard tester,salt spray tester etc,the surface morphology and microstructure,micro-hardness,adherence between the plating and matrix,and the corrosion resistance of the plating were observed.The result showed that the optimization parameters were fit to direct electroless plating on magnesium alloys.The morphology of the plating was very nice and the adherence between the plating and matrix was choiceness,and the corrosion resistance of the plating was outstanding.更多还原