非水溶液预镀镍在钛合金电镀前处理中的应用

Application of nonaqueous nickel pre-plating to pretreatment for electroplating on titanium alloys

回顾了多种钛合金电镀前处理的工艺方法。介绍了一种在TC4钛合金、TA1工业纯钛上获得耐磨、可焊的镀镍/金工艺,其流程主要包括除油、酸蚀、活化、预镀镍、电镀镍、化学镍和电镀金。试验了二甲基亚砜、乙二醇–醋酸–乳酸、乙二醇–柠檬酸等3种非水溶液体系预镀镍工艺。结果发现,采用乙二醇–柠檬酸体系预镀镍后所得金、镍镀层与钛基材结合良好,经过5次-65~200°C冲击循环以及多次＂250°C-冷水＂淬火试验后均无起泡、开裂,正常的摩擦试验后镀层没有被破坏。该工艺对解决钛合金材料的可焊性、导电性、耐磨性等问题不失为一种新的尝试,值得进一步的研究。

Several pretreatment processes for electroplating on titanium alloys were reviewed. A process for electroplating wear-resistant and solderable nickel and gold coatings on TC4 titanium alloy and TA1 industrial-grade pure titanium was introduced. The process flow is mainly composed of degreasing, acid etching, activating, nickel pre-plating, nickel electroplating, electroless nickel plating, and gold electroplating. Three nonaqueous nickel pre-plating baths including dimethyl sulfoxide system, ethylene glycol–acetic acid–lactic acid system, and ethylene glycol–citric acid system were tested. The results showed that the gold and nickel coatings obtained after nickel pre-plating in an ethylene glycol–citric acid electrolyte have good adhesion to the titanium-based substrates, can endure thermal shock test from-65 °C to 200 °C for 5 times and 250 °C–cold water quenching test for several times with no bubbling or cracking, and are not destroyed after normal friction wear testing. The process can be regarded as a new attempt to solve the problems of solderability, conductivity, and wear resistance of titanium alloys, being worthy of further study.