TC4钛合金电镀Ni-P镀层工艺及性能研究

发布时间：2018-03-19 21:40

  本文选题：TC4钛合金　切入点：电镀　出处：《兰州理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：钛合金因其密度小、比强度高、耐蚀性及生物相溶性好等特点受到人们的青睐,使其在汽车、医疗器械及航空航天国防事业中得到了广泛应用。然而,钛合金表面硬度低,易氧化的特点使钛合金在工业应用中表现出较差的耐磨性,大大限制了其应用范围,因此对钛合金表面进行改性处理就显得尤为重要。Ni-P镀层因其简单的操作工艺和良好的耐磨耐蚀性等特点常被用于金属表面的改性处理,本文拟采用电镀Ni-P镀层的方法对TC4钛合金表面进行改性处理,提高钛合金的表面性能。通过对电镀镍磷制备工艺及研究现状的总结,在次磷酸-镍盐体系中对TC4钛合金电镀Ni-P工艺进行了研究,通过设计正交试验对工艺配方和参数进行了优化,获得的最佳工艺配方为:NiSO_4·6H_2O 140g/L、电流密度4A/dm2、pH值3.5、NiCl_2·6H_2O 16g/L、温度65℃、NaH_2PO_2·H_2O 8g/L、H_3PO_4 35g/L。TC4钛合金在该工艺条件下电镀Ni-P镀层,不仅镀速快硬度高,而且获得的镀层表面光亮平整、致密度高。在正交试验的基础上,采用单因素实验,研究了各工艺参数对Ni-P镀层沉积速度、硬度及磷含量的影响规律。为了改善钛合金表面Ni-P镀层的性能,对钛合金表面预处理工艺进行了研究。通过对不同预处理工艺下获得的镀层的表面形貌、硬度和结合强度的对比分析,确定了最佳预处理工艺:打磨→化学除油→酸洗活化→化学预镀。对镀层的微观形貌、物相组成、硬度及耐磨耐蚀性进行了研究分析,结果表明:镀层表面呈均匀分布的胞状结构,表面致密光滑,主要成分为Ni和P;随着热处理温度的升高,镀层结构由非晶态逐渐转化为晶态,热处理温度在400℃时,镀层中有Ni_3P相析出;镀层的硬度与P含量和热处理温度有关,镀层硬度随着P含量的增加呈现先增大后减小的趋势,当P含量在8%时镀层硬度有最大值;镀层硬度随热处理温度的升高先增加后减小,经过400℃热处理后镀层硬度达到最大;镀层经400℃热处理后耐磨耐蚀性显著增强。
[Abstract]:Because of its low density, high specific strength, corrosion resistance and good biocompatibility, titanium alloy has been widely used in automobile, medical device and aerospace industry. However, the surface hardness of titanium alloy is low. The characteristic of easy oxidation makes titanium alloy exhibit poor wear resistance in industrial application, which greatly limits its application scope. Therefore, it is very important to modify titanium alloy surface. Ni-P coating is often used to modify metal surface because of its simple operation technology and good wear resistance and corrosion resistance. In this paper, the surface of TC4 titanium alloy is modified by electroplating of Ni-P coating to improve the surface properties of titanium alloy. The TC4 titanium alloy electroplating Ni-P process was studied in the system of hypophosphoric acid and nickel salt. The formulation and parameters of the process were optimized by designing orthogonal test. The best technological formula obtained is: 1: NiSOS 4 路6H _ 2O 140 g / L, current density 4 A / m ~ (2 / 2) pH 3.5 / NiCl _ 2 路6H _ 2O 16 g / L, temperature 65 鈩，

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