【作者】 田丰；

【导师】 张罡；

【作者基本信息】 沈阳理工大学 ， 材料学， 2009， 硕士

【摘要】 化学镀Ni-P合金是利用还原剂在工件表面上自催化还原沉积得到Ni-P镀层,作为提高金属等材料表面耐磨和耐蚀性能的一种表面强化方法,已广泛应用于电子、机械、石油等众多领域。本文在综合分析大量文献的基础上,对化学镀镍的研究现状与进展进行了综述,探讨了化学镀的热力学和动力学机理。以锅炉用钢(20g)及高温合金钢(GH3536)为基体,通过实验,研究了化学镀镍工艺的一般组成和各组分所起的作用。在此基础上,研究了工艺参数对镀速及含磷量的影响,研究高温高磷的化学镀Ni-P合金工艺的最佳方案。并在此配方的基础上,选用超声波和高剪切机结合的分散方法加入第三相粒子SiC(1~5μm)制备了Ni-P-SiC复合镀层。通过实验得出最佳工艺配方(TF)为:硫酸镍30g/L,次亚磷酸钠为28g/L,稳定剂1.0mg/L,10g/L柠檬酸与4g/L乳酸复配络合剂,缓冲剂为10g/L,pH值为4.5,施镀温度为90℃。采用扫描电子显微镜、X射线衍射仪、摩擦磨损试验机及显微硬度仪等对镀层的表面形貌、相结构、耐磨性及硬度等进行表征。TF配方下获得镀速为22.38μm/h、镀态硬度为HV700~750的镀层,该镀层表面平整致密具有银白色金属光泽。XRD实验表明含磷量为13.10%的高磷镀层呈非晶态结构,400℃为Ni-P镀层的晶化温度,此时硬度达到最高值接近HV1800。中性盐雾实验表明镀层的腐蚀速率远低于基体材料,144h中性盐雾实验后镀层表面未发生明显变化,能对基体合金起到防护作用。对Ni-P镀层及Ni-P-SiC复合镀层进行摩擦磨损实验,Ni-P-SiC复合镀层的摩擦系数约为0.2,Ni-P镀层摩擦系数为0.3,表明复合镀层的耐磨性高于镍磷镀层。采用研究出的TF配方和工艺,在高温合金GH3536表面制备了出含磷量为11.33%、硬度为HV503的高磷镀层。常用非晶态镀层耐蚀性好、硬度较低。同常用镀液配方相比,TF配方和工艺获得的非晶态镀层硬度高达HV750,兼顾了高耐蚀和高硬度的优点。TF配方与黎明航空发动机公司工业应用的配方进行对比,TF配方所得镀层硬度提高约30%。对镀液使用周期的研究表明,TF镀液使用寿命可达8MTO。因此,TF配方具有配方构成与工艺参数控制的科学性、生产应用的可行性和技术经济价值。更多还原

【Abstract】 Electroless Ni-P alloy is a surface treatment technology based on an oxidation reduction in which Ni-P alloy deposit onto catalytic metallic substrates in bath that is reduced by Nickle salt and reducer. It have been widely applied to various fields, such as electronics、engineering and petroleum industry, etc.due to its excellent corrosion and wear resistance characters.Current situation and development were reviewed of Electroless Nickel(EN) on the base of massive literature foundation. Moreover, thermodynamics and dynamics mechanism of EN were preliminarily discussed. The ecumenical composition and the function of every composing part of EN plating technology were researched, and selects a basic prescription for producing EN. Then investigates the effects that technical parameter has on plating rate and phosphorus content on the basis of it and choose an optimal prescription. At last introduces a high-phosphorus electroless technology to produce Ni-P alloy on boiler steel and high-temperature alloy steel substrate. SiC(1~5μm) was prepared with the ultrasonic decentralization and ultra-turrax. The particle is well distributed in Ni-P compound plating by electroless plating on this basis formula.The bath compositions and conditions for the electroless coatings of formula TF are as followed: Nickel Sulphate 30g/L, Sodium Hypophosphate 28g/L; Complexing agent: Lactic Acid 4g/L,and Citricacid10g/L, Buffer 10g/L,Ph value 4.5, Temperature 90℃.With the assistance of Scanning electron microscope、friction and wear testing equipment、X-ray diffraction and hardness meter, systematical tests were carried out to measure the surface morphology of the coatings、wear resistance、structure、and deposit hardness.Using the TF prescription of acidic electroless Nickel technology, of which the coating rate is 22.38μm/h and the phosphorus content is 13.10%. The micro-hardness of as-plated coating is between HV700~750, which is then up to HV1800 after being heated at 400℃(crystallization temperature) for an hour. Compared with the substrate, EN coating has excellent corrosion resistivity after 144h in neutral salt spray test. The electroless compound coating of Ni-P-SiC has better wear resistance and lower friction than Ni-P coating.The prescription of TF is apply to high-temperature alloy steel substrate of which the phosphorus content is 13.10% and the micro-hardness is HV503.The prescription of TF has both good corrosion resistivity and high hardness. At the same time the hardness of coating improve 30% contrast with the prescription of Lingming aero-enging corporation.The cycle life of plating solution reaches 8 MTO. It can meet the requirement industry.更多还原