摘要:采用脉冲电沉积法在镍基合金表面制备Ni-Mo-Al-Y-MoSi2复合镀层。研究了镀液pH、AlCl3浓度、MoSi2浓度、镀液温度、电流密度、脉冲频率、占空比、搅拌速度和电镀时间等参数对该复合镀层中Al和Si含量的影响,得到较佳制备工艺条件为：镀液pH8.2，AlCl3浓度3g/L，MoSi2浓度8g/L，镀液温度40oC，电流密度18.75A/dm2，脉冲频率5000Hz，占空比1/2，搅拌速度400r/min，电镀时间20min；在此条件下制备得到的Ni-Mo-Al-Y-MoSi2复合镀层中Al和Si的含量分别达到8.78%和1.46%。利用电子能谱仪、扫描电镜、X射线衍射仪以及热膨胀仪等测试手段对该复合镀层的组成、微观形貌、晶型结构以及热膨胀系数进行了研究。结果表明，与Ni-Mo-Al-MoSi2复合镀层相比，Ni-Mo-Al-Y-MoSi2复合镀层的表面结瘤更少，更加平整光滑；Ni-Mo-Al-Y-MoSi2复合镀层中Al元素的含量提高了250.65%；Ni-Mo-Al-Y-MoSi2复合镀层衍射峰对应的2θ角发生了不同程度的偏移，说明添加的Y3+进入到了Ni-Mo-Al-MoSi2复合镀层当中。在30-1300oC时，镍合金及镍合金+Y离子复合镀层的热膨胀系数大小排序如下：Tα(镍合金基底)＞Tα(镍合金+Ni-Mo-Al-Y-MoSi2)＞Tα(镍合金+Ni-Mo-Al-MoSi2)。利用电沉积法制备Ni-Mo-Al-Y-MoSi2复合镀层的文献目前还尚未见到报道。62057

毕业论文关键词：脉冲电沉积；稀土；复合镀层；MoSi2；

Study on the Preparation of Ni-Mo-Al-Y-MoSi2 Composite Coating 

Abstract:Ni-Mo-Al-Y-MoSi2 composite coatings were prepared by pulse plating method on the surface of nickel alloy. The effects of the pH value,the concentration of AlCl3 , the concentration of MoSi2 , the temperature of the plating liquid, the current density, the frequency of pulsing, the duty-cycle, the stir speed, as well as the plating time on Al and Si content of composite coatings were also studied, and the optimal operating conditions were explored as following:,the pH value of the bath liquid is 8.2,the concentration of AlCl3 is3g/L,the concentration of MoSi2 is 8g/L,the temperature of the plating liquid is 40oC, the current density is 18.75A/dm2,the frequency of pulsing is 5000Hz,the duty-cycle is 1/2,the stir speed is 400r/min and the plating time is 20min under which conditions the Al and Si content of Ni-Mo-Al-Y-MoSi2 composite coating are 8.78% and1.46% respectively.The morphology surface, the compositions and structure, the crystalline structure and the coeffcients of thermal expansion were analyzed by EDX, SEM, XRD and DIL respectively. From the research, the conclusions were as following:Compared to Ni-Mo-Al-MoSi2, there are fewer nodules on the surface of Ni-Mo-Al-Y-MoSi2 composite coating and the surface is more smooth, the content of Al of the Ni-Mo-Al-Y-MoSi2 composite coating increase by 250.65%, the 2θ of peaks in the Ni-Mo-Al-Y-MoSi2 composite has a different degree of skewing which shows that there has Y in Ni-Mo-Al-Y-MoSi2 composite coating.The thermal expansion curves indicates that from 30 to 1300oC\,the order of the thermal expansion coefficients of Ni alloy and Ni alloy+different composite coatings are as following:Tα(Ni alloy)＞Tα(Ni alloy+Ni-Mo-Al-Y-MoSi2)＞Tα(Ni alloy+Ni-Mo-Al-MoSi2).There has no literature about the preparation of Ni-Mo-Al-Y-MoSi2composite coating by pulse Electro-deposition was seen.

Keywords: Pulse Electro-deposited; rare earth; composite coating; MoSi2;

1  研究背景 1

1.1  前言 1

1.2  热障涂层与热障涂层金属粘结层 1

1.3  二硅化钼在涂层的应用 3

1.4  铝在涂层中的应用 4

1.5  粘结层中稀土的应用 5

1.5.1  稀土元素的定义与特点