铝合金化学镀镍预处理新工艺

为了改进铝合金化学镀镍工艺,避免浸锌法对化学镀镍液的污染,研究了铝合金活化-预化学镀镍工艺.利用SEM观察了活化膜和预化学镀镍层的表面形貌.通过结合力、孔隙率和耐蚀性试验,确定了活化工艺最佳pH值为9～10,预化学镀镍最佳厚度为0.6μm左右.结果表明,活化-预化学镀镍工艺可代替浸锌法.镀层质量达到GB/T13913-92技术要求.为铝合金镀镍提供了新的预处理技术.     

铝合金化学镀Ni-P前处理工艺条件的优化

化学镀Ni-P可以改善铝合金易产生晶间腐蚀、表面硬度低、不耐磨损等缺陷,欲使镀层与铝合金基体具有很好的结合力,前处理工艺则显得尤为重要。采用正交试验,用极差法分析了活化和预镀镍各工艺参数对后续化学镀Ni-P镀速影响的主次顺序,确定了活化和预镀镍镀液的最佳配方及各工艺条件,并利用金相显微镜、扫描电镜能谱、增重法、热震实验和失重法等测试了采用最佳活化、预镀镍工艺所得镀层的形貌和性能,结果表明:所确定的活化、预化学镀镍前处理工艺可显著提高镀层的硬度、沉积速率及其与基体的结合强度,镀层组织致密均匀,耐蚀性优良。     

金属粉末制备透射电镜薄膜样品的方法

用化学镀镍方法将金属粉末颗粒包埋、经磨片及离子减薄制成的透射电镜薄膜样品有宽阔的薄区视场。观察了粉末颗粒的显微组织。对镀前粉末颗粒的活化处理及化学镀镍方法进行了分析。结果表明:用化学镀镍的方法可以将高硬度的粉末颗粒制成透射电镜薄膜样品。     

镁合金微弧氧化层化学镀镍的镍盐活化工艺研究

通过差热分析、扫描电镜?斓仁侄?对镁合金微弧氧化层化学镀镍的镍盐活化工艺进行了研究,并与钯盐活化的效果进行了对比。结果表明:用镍盐对镁合金微弧氧化陶瓷层进行化学镀镍的活化是可行的,活化需要通过活化液室温浸泡和热还原两个步骤完成,活化液配方和热还原工艺是影响活化效果的重要因素;与钯盐活化相比,镍盐活化后化学镀镍的镀速低,最终形成的镀层厚度小,但有利于保持化学镀液在施镀过程中的稳定性。     

模具锌合金表面化学镀镍前处理工艺

采用两种不同化学除油溶液和浸蚀活化溶液以及一种碱性预镀镍工艺作为模具锌合金化学镀镍的前处理工艺,并研究了工艺与性能的关系,结果表明,化学除油溶液应为弱碱性,浸蚀活化工艺采用稀酸+有机酸溶液较为合适,预化学镀镍最佳时间为30分钟.经实验确定的前处理工艺的模具锌合金试样在化学镀镍后镀层均匀、致密,且结合良好.     

钛合金化学镀镍结合力探讨

对钛合金化学镀镍增强结合力的几种方法作了一些实验,试验结果表明:胶体钯活化工艺是铁及其合金在化学镀镍(镀)前处理生产中既实用又有效的方法。胶体钯活化工艺适用性广,化学镀镍沉积速度快,经热处理扩散大大提高镀层强度。     

化学镀镍活化或诱发方法

综述了化学镀镍中的钯活化法、N型半导体氧化物活化法、镍有机酸盐热解活化法以及用于导体的诱发方法.并选择黄铜作为基体,通过实验比较了几种活化或诱发方法.     

碳纤维表面化学镀镍研究

在碳纤维表面进行化学镀镍研究,探讨了碳纤维的去胶方法,并对粗化、敏化、活化配方进行了研究,优化了化学镀镍配方.结果表明:在400℃下灼烧30 min,去胶效果比较好;用硝酸溶液进行除油,同时还能起到粗化作用;用硝酸银进行活化处理,可得到致密镀层,镀层厚2μm.     

前处理工艺对钛合金化学镀镍层结合力的影响探讨

化学镀镍作为一种经济适用的材料表面处理技术,已经广泛应用于各个领域,钛及钛合金表面化学镀镍可提高其表面硬度、耐蚀性及耐磨性。镀层与基体材料的结合力是衡量化学镀件质量的重要指标之一,而前处理工艺对化学镀镍层结合力起到决定性的影响。本文结合近期研究成果,探讨了除油、酸洗、活化及其它特殊前处理工艺对钛合金化学镀镍层结合力的影响。     

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。     

The analysis of corrosion performance of car bodies coated by no nickel and low nickel zinc phosphating processes

In today's automotive industry in order to protect car bodies from corrosion, spray or immersion type zinc phosphating processes are applied. In both types, nickel and chromium are widely used though they are harmful to human health and environment. In this study, car body's corrosion performance, coated by no nickel (0 ppm) and low nickel (100, 200, 300 ppm) immersion type zinc phosphating (without chromium passivation) processes, are compared to the bodies that are coated by spray and immersion type processes including nickel (500–700 ppm) and chromium. After analyzing coating weight, composition, morphology of the crystals and salt spray test corrosion performance of car bodies specimens coated by no nickel and low nickel processes are as good as the ones coated by spray and immersion phosphating processes including nickel and chromium. In developing environment consciousness, it is inevitable to favor no nickel or low nickel processes since they give no harm to nature and human health.     

Investigation of high-performance acid zinc nickel electrolyte

Zinc nickel alloy coatings are increasingly demanded by the automotive industry due to their highly improved corrosion protection over pure zinc and other zinc alloy coatings. To produce zinc nickel coatings with a nickel incorporation of 12 to 16%, mainly alkaline zinc nickel electrolytes are used in the plating industry. Continuous improvements in the field of acidic zinc nickel alloy electrolytes now meet the needs of the automotive industry while being advantageous in specific fields of application.In this paper, zinc nickel coatings deposited from alkaline as well as from ammonium-free acid zinc nickel electrolytes are investigated. The morphology is evaluated by scanning electron microscopy; the texture is investigated by focused ion beam, and X-ray diffraction patterns identify the structure of the coating. The corrosion protection of the zinc nickel coatings and the adhesion of the zinc nickel coatings have been bench-marked. For applications on fasteners, the coefficients of friction have been measured and compared.     

The Effect of Addition Agents upon the Conductivity,Cathodic Polarisation and Grain Size of Deposits Obtained from the Cell: Cu/CuSo4, H2So4/Cu

The outdoor corrosion resistance of chromium plated, polished Watts nickel is compared with that of bright nickel, and the following systems of composite plates are also reviewed. 1. Bright, crack-free chromium in thicknesses of 0·03 to 0·08 mil (0·75 to 2 micron) on nickel or copper+nickel plate. 2. The usual 0·01 mil chromium on dual or duplex nickel plate consisting predominantly of a thin overlay of bright nickel on a deposit of soft, semi-bright, sulphur-free nickel. 3. Dual or duplex microscopically cracked bright chromium plate of 0·03 to 0·1 mil thickness deposited on nickel or copper+nickel. 4. Chromium+nickel+chromium composite deposits. Systems 2 and 3 are the best in use to date. System 2 is well established and in more widespread use than the newer system 3. The latter system appears to offer considerable promise, but the outdoor exposure tests (1 year) are not yet of sufficient duration for its proper evaluation. System 4 has not yet been tried under production conditions, but the results of extended outdoor exposure tests (4 years) indicate that it is capable of showing the best overall corrosion resistance. Combinations of all these systems are also discussed.     

Nickel Electroplating

NICKEL ELECTROPLATING has been practicallyused for decades.There is an unknown part in theplating,although this is easy to plate.Applications ofthe plating are described from the practical viewpoint.Purpose of Nickel Electroplating(1)Decorative,and corrosion resistanceNickel electroplating is deposited on iron,cupper,zinc and aluminum substrate etc.,and chromiumplating is usually deposited on nickel plating.Hexavalent chromium plating has an important effecton the corrosion resisitan…     

Ni-Ti纤维的化学镀镍工艺研究

对Ni-Ti纤维进行了化学镀镍。镀液的基本成分为硫酸镍18.7 g/L,次磷酸钠15 g/L,柠檬酸钠33 g/L,pH8.5,温度50℃前处理工序依次为超声清洗、粗化、敏化、活化和还原。研究了化学镀镍层的形貌,测定了镀层与基体的结合力结果表明,Ni-Ti纤维的镀镍层均匀、完整,与基体结合牢固。此外,前处理是Ni-Ti纤维化学镀镍的关键     

Electrodeposited nickel/alumina composite coating on NdFeB permanent magnets

NdFeB magnets are highly susceptible to corrosion in various environments. A nickel/alumina composite coating for NdFeB magnets was investigated in this paper. The microstructures of electrodeposited nickel coating and nickel/alumina composite coating were determined by scanning electron microscope (SEM). The corrosion behavior of nickel coating and nickel/alumina composite coating in 3.5 wt% sodium chloride solution was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the nickel coating and nickel/alumina composite coating can both provide adequate protection to the NdFeB substrate. Furthermore, the free corrosion potential of nickel/alumina composite coating is more positive and the passivation region is more obvious compared with nickel coating, and the capacitance loop diameter of nickel/alumina composite coating is significantly larger than that of nickel coating. With the increase in immersion time, a flat of passivation film is formed on the surface of nickel/alumina composite coating, resulting in excellent corrosion resistance after 288 h immersion in 3.5% sodium chloride solution according to EIS testing.     

Excellent mechanical properties of three-dimensionally ordered macroporous nickel photonic crystals

High quality three-dimensionally ordered macroporous (3DOM) nickel photonic crystals (PCs) are fabricated using the polystyrene template-assisted electrodeposition method on nickel alloy substrate. The Ni²⁺ in solution will firstly arrive in the electrode (nickel alloy substrate) and occupy the interstices among the PS template spheres; when enlarge the deposition time to 5 min, 3DOM nickel PCs will be achieved. The 3DOM nickel PCs grow firmly on the substrate due to the similar bounds between the PCs and substrate. Excellent mechanical properties are observed in the 3DOM nickel PCs, which may promote the practical applications of PCs.     

‘Nickel Allergy’ arising from decorative nickel plated and alloyed articles: prevention at source

This work builds on papers published in Transactions during 2015 and 2018 reporting research into low-cost commercial methods for the prevention of nickel release from decorative nickel plated articles, rendering them suitable for placement on the European market in accordance with the requirements of REACH. ‘Nickel Allergy’ sometimes occurs when nickel-containing articles are in direct and prolonged contact with the skin, leading to corrosion of elemental nickel by sweat, liberating sufficient nickel ions to be absorbed through the skin and initiate an allergenic effect. The EU ‘Nickel Restrictions’ impose limits on the amount of nickel released from articles intended for use in this application, but permits a non-nickel surface coating that can ensure the rate of nickel release does not exceed 0.5?µg?cm^?2 week^?1 after 2 years of normal use. The official tests for coated items are simulated wear and corrosion under EN 12472 followed by determination of nickel release under EN 1811. Earlier work concluded that suitable barrier coatings over bright electrodeposited nickel are regular chromium deposited from a hexavalent electrolyte, microporous trivalent chromium from a chloride electrolyte and UV cured PU electrophoretic coatings. Further tests reported here focused on nickel release from examples of wearable articles such as costume jewellery and watch cases. A typical flash coating of gold over bright nickel is thin and porous and being more noble, causes the rate of nickel release to be accelerated; but this can be prevented by an intermediate barrier coating of electrodeposited palladium. To round out the relevance of this study on wearable articles, nickel release tests were also conducted on nickel-containing Grades 304 (UNS S30400) and 316 (UNS S31600) austenitic stainless steels, plus a typical gold alloy containing nickel. All passed the nickel release tests satisfactorily.     

The electrochemical recovery of nickel from plating residues

In view of the increasing demand for nickel and its compounds, the recovery of nickel values from any secondary source is of great importance, particularly in countries such as India where there is no domestic source of the metal. The buildups (or nodules) that accumulate during the nickel plating processes are one secondary source of metal. To take advantage of this resource, an electrochemical approach has been attempted to recover the nickel from plating wastes in the form of nickel sulfate. The approach involves selective anodic dissolution of the nickel nodules in a sulfuric acid medium and crystallization of the resultant nickel sulfate. Acidity, nickel concentration in the electrolyte and the extent of dissolution of the nodules have been examined with the intent of avoiding the loss of nickel at the cathode and reducing copper contamination in the electrolyte.     

The Properties of Nickel Electrodeposited from a Sulphamate Bath

The properties of nickel electrodeposited from a nickel sulphamate bath and the effect of some experimental variables upon them are described. The optimum conditions for minimum internal stress are defined. The tensile properties of sulphamate nickel deposits and their effect on the fatigue strength of En 25 (Ni/Cr/Mo) steel of 80 ton/in² U.T.S. are directly compared with the properties of nickel deposited from a Watts type solution.