复合化学镀几个关键工艺因素研究

为使化学镀镍-磷合金镀层具有更高的硬度,进一步提高其耐磨、耐蚀的性能,利用化学复合镀技术制备出镍-磷-纳米Al2O3复合镀层,并研究了pH值、温度、固体颗粒含量等几个关键工艺因素对镀液的稳定性、镀速和镀层磷含量的影响,特别是对固体颗粒的分散方法进行了较深入的研究.结果表明,在合适的工艺条件下,即当镀液的pH值为4.4～4.6,施镀温度(90±2)℃,颗粒含量12～14g/L,采用机械搅拌加超声波分散,机械搅拌转速200～250r/min,超声波分散频率40kHz时,可获得性能良好的复合镀层.     

光纤光栅表面化学镀镍及影响镀层性能的因素

目的通过优化化学镀工艺,在光纤光栅表面获得综合性能优良的镀镍层。方法利用化学镀置换还原反应,在非金属表面沉积金属镀层。改变镀镍液温度、pH值并优化敏化活化处理,得到连续光滑的镍层。通过金相显微镜对镀层进行形貌观测,用高低温交变试验箱和万能试验机对镀层附着力和镀镍后光纤光栅的抗拉力进行测试。结果与未优化时沉积镍层对比,优化化学镀工艺沉积的镍层连续光滑,说明镀液稳定干净,镍原子沉积速率合理。优化条件为:过滤敏化液和活化液,并在敏化、活化后各进行超声清洗30 s,镀镍液温度92℃,pH值3.2。该条件下可得到稳定干净的镀液和连续光滑的镀层。经测试,镀层无开裂脱落,镀镍光纤光栅的抗拉力在5.5 N以上。而未优化时,镀液不稳定,镀层不连续或连续部分不光滑,且超声清洗时部分脱落。结论优化化学镀工艺中敏化活化处理和镀镍液温度、p H值后,镀液干净稳定,镍原子沉积速率合理,所得镀层连续致密、厚度均匀,从而力学性能得到改善。     

以硫酸镍为主盐的镁合金化学镀镍

以硫酸镍为主盐,采用正交实验确定了镁合金"无氟绿色环保"碱性化学镀镍镀液成分及操作条件.选择适合镁合金化学镀的缓冲剂,考察了镀液参数对化学镀的影响.结果表明:缓冲剂Na2CO3适合镁合金化学镀镍,它不仅能提高化学镀镍速度,而且可以调节镀层与基体间的结合力,缓冲化学镀过程中pH值的变化;碱性化学镀的pH值范围为8.5～11.5;络合剂柠檬酸钠的最佳浓度为30 g/L;所得镀层均匀致密,孔隙率少,属于晶态特征明显的低磷镀层,耐蚀性较好,化学镀层与镁合金基体结合良好.     

pH值对中温化学镀镍-磷的影响

化学镀镍-磷技术作为表面强化的一种途径,已经得到越来越广泛的应用和不断的发展.为了研究pH值对镀层性能的影响,采用中温化学镀镍工艺,以醋酸钠为缓冲剂,以乳酸为络合剂,在酸性体系中化学沉积镍-磷合金.研究了溶液的pH值对化学镀镍-磷合金的沉积速度、镀层性能的影响.结果表明:pH值对镀速的影响较大,随着pH值的升高,镀速逐渐增加,镀层磷含量逐渐降低;在一定范围内硬度和腐蚀速度随pH值的升高而增加,在pH值为5.1时,镀层的综合性能达到最好.     

不锈钢化学镀镍工艺研究

采用主要含硫酸镍、次磷酸钠、表面活性剂、醋酸钠及柠檬酸钠的镀液对不锈钢试片进行化学镀镍,研究了硫酸镍和表面活性剂的浓度、镀液pH值及温度对沉积速度的影响,确定了这几项参数的较佳取值.结果表明:硫酸镍25g/L、表面活性剂0.1g/L、温度85℃、pH值4.6较为适宜,在该工艺条件下所得的镀层样品经弯曲、热浸和人工汗实验均合格.     

汽车轮毂用铝合金表面镍镀层的耐蚀性能研究

在汽车轮毂用的铝合金表面上电镀镍。研究镀液pH值、电流密度、镀液温度等因素对镀层耐蚀性能的影响。用线性扫描伏安法研究镍镀层在3.50%NaCl溶液中的耐蚀性能,用SEM和XRD表征了镍镀层的形貌和结构。结果表明,电镀的最佳工艺条件为:镀液pH为4.2,电流密度为30mA/cm2,镀液温度为58℃;在该条件下获得的镍镀层有很好的耐蚀性能,其结构为立方晶系。     

镀液pH值和钼酸根浓度对化学镀Ni-Mo-P沉积速度及镀层结构的影响

确定了化学镀获得不同结构Ni—Mo-P镀层的最佳工艺参数及镀液配方，探讨了络合剂、pH值、钼酸根浓度以及添加剂等参数对化学镀Ni—Mo—P合金镀层成分及结构的影响。结果表明，以柠檬酸钠作为主络合剂、醋酸钠作为辅助络合剂的络合剂体系对Ni、Mo实现共沉积有着较好的作用；Ni—Mo-P合金镀层中Mo和P含量有一定的制约关系，随着镀层中Mo含量的提高，镀层结构由非晶态向晶态转变；镀液pH值在一定范围内(pH值6．5～10)时，pH值的升高可提高沉积速度；镀液的钼酸根浓度和pH值对沉积速度的影响呈波浪形，存在一个极大值；随着沉积速度的提高，镀层的耐蚀性能也会有所改善。     

化学镀法制备SiCp-Ni复合粉体

研究了酸性化学镀在SiCp陶瓷粉末表面涂覆Ni-P合金,考察了镀液的温度、pH值及粉末粒度对镀液稳定性和镀层性能的影响.结果表明,粉体越细,稳定施镀温度越低;合理选择工艺参数可使粒径从200μm～10μm的SiCp粉末得到均匀镀层;镀层P含量随pH值升高而降低,镀层结构为非晶态.     

基于三元复合络合剂的高磷Ni-P化学镀

针对单一络合剂难以兼顾镀液稳定性、镀速和镀层质量等多重要求,现有复合络合剂或成本过高、或工艺稳定性欠佳等问题,采用柠檬酸钠-乳酸-乙酸钠三元复合络合剂,借助增重法、扫描电子显微镜(SEM)、能谱仪(EDS)和材料耐蚀性快速检测专利技术,系统研究了络合剂及还原剂用量、镀液初始pH值及施镀温度对化学镀Ni-P施镀效果的影响,探明镀速、镀层硬度及其P质量分数、镀层腐蚀防护性能随工艺参数的变化规律。结果表明:利用基于三元复合络合剂的镀液,不仅可获得P质量分数最高为18.41%的高磷Ni-P镀层,而且工艺稳定性优异。在适宜的镀液初始pH值区间(4.0~5.5),镀层P质量分数受其它工艺参数的影响甚微,能始终稳定在11.12%~14.52%的高位。典型试样SEM分析表明:镀层表面平整、均匀,结构致密,镀层与基体结合紧密且厚度分布均匀。     

pH 值对碳化硅粉体表面镀镍的影响

对碳化硅表面进行化学镀镍,研究了镀液的pH值对镀速、镀层组织及形貌的影响。结果表明:镀液pH值低于8.5时,无反应发生,粉体未镀上镍;pH值为10～11时,粉体的增重接近理论值,XRD图谱中的镍衍射峰较强,镀层完全覆盖基体;pH值高于11时,随着pH值的升高,气体生成越发明显,反应速度明显加快,镀液由深蓝色变为无色的时间明显缩短。在pH值10～11范围内对粉体进行二次化学镀,镀层厚度明显增大且显得凸凹不平,镀层中的镍颗粒大小不均匀。     

Effect of citrate additive on the electrodeposition and corrosion behaviour of Zn–Co alloy

The electrodeposition of Zn–15Co alloy on a stainless steel substrate from a citrate bath has been investigated as a function of pH and citrate concentration in the electroplating bath. UV–vis results and speciation diagrams of zinc and cobalt in aqueous citrate solution were used to select deposition baths with different dominant Zn–Co citrate complexes. Voltammetry and potentiostatic methods were used to study the codeposition mechanism. The corrosion behaviour of electrodeposits of Zn–15Co alloys was studied by means of electrochemical experiments in a solution of 3.5% NaCl using potentiodynamic polarisation and open circuit potential. The results showed that the corrosion resistance of the deposits was highly influenced by the presence of citrate in the electroplating bath.     

表面活性剂对纳米氧化物分散稳定性的影响

采用分光光度计研究了表面活性剂对纳米Al2O3颗粒在电刷镀液中分散稳定性的影响.试验结果表明,表面活性剂聚乙二醇2000,磷酸二氢钠,乙酸铵,聚羧酸铵和柠檬酸三铵的添加对纳米Al2O3粒子在特快镍电刷镀液中的分散稳定效果不同,其中柠檬酸三铵的分散效果在单一表面活性剂中效果最佳,而表面活性剂的复合添加,分散稳定效果更好.电刷镀层显微硬度结果表明,添加表面活性剂不仅能提高纳米粒子的分散稳定性,而且能提高纳米电刷镀层的显微硬度.     

硫酸盐酸性光亮镀锡铋合金工艺

采用赫尔槽试验研究了硫酸盐酸性电镀锡铋合金工艺。以改善镀层的光亮性以及镀液的稳定性为目的,讨论了镀液组分及工艺条件对镀液和合金镀层性能的影响,检测了镀液和镀层的相关性能。结果表明:镀液中加入光亮剂和稳定剂后,可获得一种铋含量达2.5%,且耐蚀性、可焊性优良的光亮Sn-Bi合金镀层。镀液的覆盖能力和分散能力良好,镀液稳定性也得到较大提高。     

连续电镀锌-镍合金技术的研究

提出了连续电镀锌镍合金的高氯化氨-弱酸型镀液工艺参数,对镀液成分、pH值、温度、阴极电流密度对镀层镍含量的影响及连续电镀锌镍合金的镀速控制等问题进行了研究.得到外观良好、镍含量在13%～15%的锌镍合金镀层.     

高稳定性酸性光亮镀锡工艺研究

采用霍尔槽试验成功了一种高稳定性酸性光亮镀锡工艺,所得镀层结晶细致,光亮度好,镀液稳定性优良,并探讨了各成分和操作条件的影响,检测了镀液,镀层性能。     

添加剂在电沉积非晶态Cr-C合金工艺中的作用

对有机添加剂在电沉积非晶态Cr-C合金工艺中的作用进行了研究.结果表明,添加剂是镀层 形成非晶态Cr-C结构的决定性组成,能提高Cr电沉积电流效率,对镀液的稳定性有显著影响 .     

Effect of Metal Finishing Wastes on Sewage Purification

The through-hole plating of printed circuits is essentially a method of electroplating non-conductors, and can be divided into four basic sections—cleaning, activation, metallization and electroplating. Activation consists of the absorption of tin compounds and a precious metal from either two separate solutions or one single solution; a comparison is drawn between these two methods indicating the advantages to be gained from the single stage solution. Electroless copper solutions are generally used for metallization and the working parameters of these are considered. Build up of the electroless film is carried out in copper electroplating solutions of which several types are available. A comparison is drawn between these solutions, with respect to throwing power, stability and grain structure of the deposit. Other electroplating systems used to deposit etch resists and solderable surfaces are also discussed.     

Improvement of stability of trivalent chromium electroplating of Ti based IrO2+Ta2O5 coating anodes

The preparation process and properties of the thermally prepared Ti anodes coated with IrO2+Ta2O5 was studied. The structure and morphologies of the IrO2+Ta2O5 coatings were determined by XRD and SEM. Their electrochemical properties were studied by polarization curve and cyclic voltammetry. Trivalent chromium electroplating using Ti/IrO2+Ta2O5 anodes is carried out and the results were analyzed. Results show that this anode exhibits excellentelectrochemical activity and stability in sulfate electrolysis. The electrocatalytic activity is determined not only by the content of IrO2 but also the structure and morphology of the anode coatings. The electroplating results indicats that Ti/IrO2+Ta2O5 anodes have excellent capabilities and merits in improving the stability of trivalent chromium electroplating in sulfate system.     

不锈钢表面镀铝-热氧化处理制备氧化铝膜及其性能

采用无机熔融盐电镀铝、热浸镀铝工艺联合的方法在钢基材表面制备了一层平整、连续的铝镀层,研究了铝镀层在不同氧化时间下的氧化行为。利用X射线衍射仪(XRD)、扫描电镜(SEM)和能谱分析(EDS)对氧化层的形貌和成分进行分析,并考察了氧化层的硬度和耐腐蚀性能。结果表明:将无机熔融盐电镀铝法和热浸镀铝法相结合可获得良好的铝镀层;铝镀层在900℃下热处理20 h后,可获得连续致密的Al2O3膜;Al2O3层有效提高了钢基材的表面硬度和耐腐蚀性能。     

Characterization of Zinc-Cobalt Electrodeposits

The structure and morphology of electrodeposits depend on many factors including temperature, current density, time of deposition and composition of the bath. The properties of an electrodeposit depend on its micro structure. For example corrosion and wear resistance, hardness, internal stress, strength, brightness, electrical conductivity, magnetic properties and leveling are all affected by structure.

The relationships between electroplating parameters such as current density, temperature, bath agitation and electrolyte composition have been investigated for the zinc-cobalt system. It was found that electrolyte composition and temperature affect both deposit composition and morphology. The cathodic current efficiency decreased with current density and hardness was raised with increasing cobalt content in the deposit.

Three powerful techniques were used to access the microstructure of zinc-cobalt deposits: scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results show that the alloy is constituted of a single phase of a solid solution of cobalt dissolved in zinc within an hexagonal crystal system. The deposit is porous and changes from dendritic to nodular with increasing cobalt content.