阴极电流密度对酸性液电镀Zn-Ni合金质量的影响

复合电镀是制造复合材料的一种新方法,在过去30多年里取得了极大的发展,关于电镀工艺和镀层性能的研究也较为深入.锌镍合金是近20多年发展起来的一种新型防护性镀层,具有极高的耐腐蚀性、低氢脆性、可焊性和机械加工性等优良特性,极具发展前景.锌镍合金镀层具有优良的耐腐蚀性,可以满足不断提高的防护性能要求.文章介绍了一种酸性锌镍合金电镀工艺.研究了电流密度的增加,镀层中的镍含量增加;获得了最佳工艺参数:100-120 g/L NiSO4·H2O,60-80g/L znC12,200-220 g/L NH4C1,20～35 g/L硼酸,0.05～0.5 g/L十二烷基硫酸钠,0.3 g/L香草醛,pH=5,温度/.C=20～25,电流密度/(A/dm2)=1.     

降低镀锌钢板镀层缺陷的方法

这种方法系由日本川崎钢铁公司研究发明。该镀锌钢板镀层由三部分组成：表层为锌或锌合金、中间层为含铁较少的镀层，底层含铁浓度较高。镀锌层底层的化学成分为，％：硅≥0．1，钛≥0．1，镍≥0．1，铜≥0．1，铝≥0．1，钒≥0．1，锰≥0．5，磷≥0．05，铝（或铌）≥0．05，硼≥0．001。钢中含硅0．1％～2．0％，锰0．5％～4．0％，磷0．05％～0．2％。镀锌的方法为电镀，电镀锌槽中电镀液含FC3+0．1～20g／L。镀液，此外，电镀液中还含有羧酸或强碱羧酸盐。镀层重量为0·1～10g／m2，整个镀层含氧量为0．1％～10％。采取这种方法生产的…     

金-银合金电镀液

本发明公开了一种金-银合金电镀液，其中含有以金含量计1．0～30g／L的氰化金钾和以银含量计1．0×10^-6～200×10^-6的氰化银钾。该电镀液最好添30～100g／L的焦磷酸钾、20—50g／L的硼酸、0．05-150g／L的乙二胺或者其衍生物。该电镀液是适合连接器等的电气接点零件的电气接点形成用的电镀液。     

Al／β-PbO2-WC-ZrO2复合电极材料的制备

研究了电镀液中固体微粒质量浓度及工艺条件对Al／β／-PbO2-WC-ZrO2复合电极材料的表面化学组成及稳态析氧极化曲线的影响规律,对工艺条件进行了优化,优化后的工艺条件如下：WC：50g／L,ZrO2浓度为50g／L,电流密度为3A／dm^2,温度：20℃,电沉积时间：2．5h．该新型电极用于锌电积可使槽电压降低,电流效率提高。     

碱性电沉只低镍锌镍合金镀层

从碱性镀液中电沉积得到镍合量小于１ｗｔ％的锌镍合金镀层。电镀液组成，氧化锌、氯化镍、氢氧化钠、络合剂和光亮剂，镀层具有优良的耐蚀性能。     

钢丝连续电沉积锌镍合金及其耐蚀性

研究了在硫酸盐型镀液中连续电沉积镍含量为７￣９％ｗｔ的锌镍合金镀层工艺，讨论了镀液的Ｚｎ＾２＋／Ｎｉ＾２＋比及阴极电流密度对合金镀层中镍含量的影响；通过」中性盐雾试验、周浸试验、电化学试验研究锌镍合金镀层的耐蚀性。     

锌镍合金用于载体支撑超薄铜箔剥离层的研究

在35μm载体铜箔上电镀一层高锌低镍合金镀层作为剥离层,再在焦磷酸盐液中电沉积超薄铜箔层,最后制得载体支撑超薄铜箔。考察了镀液硫酸锌和硫酸镍的配比、焦磷酸钾络合剂及明胶添加剂等对剥离层性能的影响。结果表明,在剥离层镀液中Zn2+∶Ni 2+=4∶1,焦磷酸钾0.5mol/L,明胶0.2g/L,十二烷基苯磺酸钠0.2～0.3g/L条件下,锌和镍能够共同沉积,该镀层作为剥离层后剥离效果良好,载体箔和超薄铜箔间的剥离强度较稳定,可以达到4.7N/cm。     

电沉积钨钴合金的工艺研究

研究了W-Co合金电镀工艺,讨论了电流密度、主盐浓度、阳极、pH值和温度对电镀的影响,并对在不同基体材料上的电镀钨合金的难易程度进行了比较。结果表明,电流密度在4～6A/dm2,镀液的pH=4～5.5,室温下就能获得较好的合金镀层。在不同基体金属上电镀W-Co合金时,基体金属的电位要正于镀层金属的电位,才能获得结合力良好的镀层。     

碳纤维电镀Cu/Ni双镀层及其性能表征

碳纤维经过脱胶和活化预处理后,表面活性大大增加,碳纤维表面由疏水性转变为亲水性,电镀过程中能很好地在镀液中润湿、分散,可解决碳纤维电镀常易出现的"黑心"问题。通过对照实验,确定最佳电镀工艺:镀Cu温度为45℃,电流密度为0.7 A/dm2;镀Ni温度为25℃,电流密度为0.8 A/dm2。碳纤维经连续电镀后得到Cu/Ni双镀层。测试结果表明:双镀层均匀致密,界面结合良好,镀层纯度高,结合力强。电镀前后单丝拉伸性能基本无改变,可很好地保持碳纤维的力学性能。电镀后碳纤维电阻率急剧下降,导电能力显著增加。     

镀液中硫酸镍浓度对镍钨合金镀层电镀质量的影响

研究了通过电镀的方法在钢基体上获得镍钨合金镀层的方法,通过镀层成分和镀层形貌研究了硫酸镍浓度对镍钨合金镀层电镀质量的影响．结果表明当硫酸镍浓度为40g／L时,镀层形貌最好,电镀质量最高．     

Synergistic Effect of Gelatin and Glycerol on Electrodeposition of Zn-Ni Alloy

The use of organic compounds which improves corrosion resistance has attracted growing interest in electroplating technology. In this direction, this article presents the experimental results of electrodeposition of Zn-Ni alloy on mild steel (MS) from acid chloride bath using gelatin and glycerol as additives. The bath composition and operating parameters have been optimized by the conventional Hull cell method. The effect of gelatin and glycerol, individually and in combination on the deposition process, was identified by a cyclic voltammetry (CV) study at different scan rates. Bright deposition of Zn-Ni alloy was found at optimal current density (c.d.) due to the preferential deposition of gelatin and glycerol by controlling the Ni content of the alloy. The CV study demonstrated that alloy deposition is diffusion controlled when additives were used individually and is adsorption controlled when used in combination. Corrosion behaviors at different current densities (c.d.s) were evaluated by potentiodynamic polarization and electrochemical impedance (EIS) methods. The surface morphology and phase structure of the coatings were analyzed by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) studies. The experimental results revealed that both gelatin and glycerol have synergistic effects in improving the electrocrystallization process and, hence, the corrosion stability of the coatings. At an optimal c.d. (3.0 A dm^?2), the Zn-Ni alloy coating showed peak performance against corrosion with the least corrosion rate. Better corrosion protection at optimal c.d., which was attributed to specific Zn(101), γ-(411,330), and Zn(103) reflections, is evidenced by the XRD study.     

Improving the Corrosion Resistance of the Nickel–Tungsten Alloy by Optimization of the Electroplating Conditions

Nickel–tungsten (Ni–W) alloy coating was electrodeposited on the copper substrate by direct current voltammetry. The optimization of a free-ammonium bath for electrodeposition of Ni–W alloy coating was investigated. Experiments were focused on elucidating the effect of W concentration and operating conditions on the corrosion performance of the obtained Ni–W alloy coating. The corrosion behavior of the coatings was investigated by potentiodynamic polarization (Tafel) test. Experimental data such as corrosion current density, corrosion rate and polarization resistance indicated that the operating conditions used during the electroplating had significant effects on the corrosion parameters of the Ni–W alloy coating. The results showed that the highest corrosion resistance was obtained for the coating with 56.7 wt% tungsten (Ni/W ratio of 1:2.5) which was prepared at the current density of 3.8 A dm^?2. The increase in the corrosion resistance at the optimum current density was attributed to the lower interferences of the hydrogen evolution reaction. Energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) techniques were used to characterize the electrodeposited Ni–W alloy with the best anti-corrosion parameters.

     

Optimization of bright zinc-nickel alloy bath for better corrosion resistance

Optimization of an acid chloride bath for electrodeposition of smooth Zn-Ni alloy on to mild steel was studied using thiamine hydrochloride (THC) as brightener. The influence of deposition current density, temperature, composition, and corrosion properties of Zn-Ni alloy coatings was investigated. The effect of bath composition and operating parameters on deposits characters like composition, micro-hardness, thickness and adhesions were tested. Under no conditions of current density employed in the present study, the anomalous type of co-deposition has changed to normal type. Electrolytically deposited Zn-Ni alloys were characterized by electrochemical AC and DC techniques. The experimental results revealed that coatings having ∼ 3.16 wt. % Ni at 3.0 A/dm² was the most corrosion resistant. The better corrosion resistance at optimal current density was attributed to the formation of n-type semiconductor film at the interface using Mott-Schottky (M-S) analysis. The effect of THC on plating process was investigated through cyclic voltammetry techniques. X-ray diffraction (XRD) studies of the coatings showed the presence of γ-Phase with composition of Ni₅Zn₂₁, responsible for it extended orrosion resistance. The change in the surface morphology of the coatings, with current density was analyzed using scanning electron microscopy (SEM).     

锌-铁-磷电镀技术研究

研究了电流密度值对Zn-Fe-P合金镀层形貌及耐蚀性能的影响.结果表明,随着电流密度的增加,且在Dk=2 A/dm2 时,Zn-Fe-P合金镀层具有很好的耐蚀性能和较高的硬度.     

Ni-SiO2复合镀层电沉积制备及组织性能研究

利用直流电沉积方法在Zr-4合金表面制备了Ni-SiO₂复合镀层,采用场发射扫描电镜、显微硬度计、电化学工作站、摩擦磨损试验机等研究复合镀层的表面形貌、显微硬度、耐腐蚀性及摩擦磨损性能。研究结果表明:与单一的Ni镀层相比较,Ni-SiO₂复合镀层的显微硬度值有所提升,表面更为均匀,Ni-SiO₂复合镀层的耐腐蚀性能和耐磨性能也得到明显提升。且当SiO₂颗粒添加量为10 g/L时,复合镀层的综合性能较优。      

Corrosion Resistance of Sintered NdFeB Permanent Magnet With Ni-P/TiO2 Composite Film

The Ni-P/TiO2 composite film on sintered NdFeB permanent magnet was investigated by X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), and energy dispersive X-ray spectrometer (EDX).The corrosion resistance of Ni-P/TiO2 film coated on NdFeB magnet, in 0. 5 mol/L NaCl solution, was studied by potentiodynamic polarization, salt spray test and electrochemical impedance spectroscopy (EIS) techniques. The selfcorrosion current density (icorr) and the polarization resistance (Rp) of Ni-P/TiO2 film are 0. 22 μA/cm2 (about 14% of that of Ni-P coating), and 120 kΩ·cm2 (about 2 times of that of Ni-P coating), respectively. The anti-salt spray time of Ni-P/TiO2 film is about 2.5 times of that of the Ni-P coating. The results indicate that Ni-P/TiO2 film has a better corrosion resistance than Ni-P coating, and the composite film increases the corrosion resistance of NdFeB magnet markedly.     

WC复合镀层耐腐蚀性能研究

采用复合电沉积工艺制备了Ni-WC复合镀层,通过SEM、EDS和金相显微镜对其表面和断面形貌进行了观察,并借助电化学手段研究了Ni-WC复合镀层在3.5%NaCl腐蚀液中耐蚀性能。结果表明:WC微粒随着电沉积过程逐步埋入复合镀层并均匀分布,镀层与基体间结合良好,在3.5%NaCl腐蚀液中,复合镀层比纯镍镀层相比,腐蚀电位正移而腐蚀电流减少,耐腐蚀能力得到提高。     

Microcracking of flash coatings and its effect on the Zn-Ni coating adhesion of electrodeposited sheet steel

In light of its excellent corrosion resistance, Zn-Ni alloy coated steels could be one of the major coated sheet products used in the automobile industry, provided that the Zn-Ni coating layer is adherent to the sheet steel after various press-forming processes or during service at subzero temperatures. In this study, a flash-coating preplating treatment, made from a chloride bath using a high-speed flow cell, is performed to enhance the adhesion of Zn-Ni electrodeposited sheet steels. A Ni-rich flash coating was deposited first as under-layer, at a low current density of 12 A/dm², in the same electrolyte used to plate the major overlay at a current density of 70 A/dm². The flash coating was then immersed in the hydrochloride acid for time periods ranging from 10 to 40 seconds. Upon immersing, Zn-preferential dissolution was observed; meanwhile, numerous microcracks formed. The density of microcracks increases with immersion time, reaching a saturated state around an etching time of 40 seconds. A similar tendency was also observed for the increase of the Ni content of the flash coating. The internal stress of the as-deposited flash coating is in compression and changes to tension at the very beginning of acid immersion. Cross-sectional transmission electron microscopy (TEM) revealed that microcracks formed on the surface of the flash coating propagate perpendicularly to the coating/substrate interface and stop at a distance of 0.03 μm ahead of the interface, even after a 40-second immersion. The flash coating, after proper etching, is shown to enhance the interfacial shear strength, formability, and adhesion of the coated sheet steels. The development of microcracks and the reduction of the thickness of the flash coating upon acid immersion account for the existence of an optimal extent of etching. The TEM observations on the morphological change of the microcracks upon acid immersion and the structural morphology of the steel/flash coating/major overlay interfaces further support the present strengthening mechanism.     

Surface Modification With Zinc and Zn-Ni Alloy Compositionally Modulated Multilayer Coatings

Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited on to a steel substrate by the successive deposition of zinc and Zn-Ni alloy sublayers from dual baths. The coated samples were evaluated in terms of the surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The microstructural characteristics that were examined using the field emission gun scanning electron microscopy （FEGSEM） confirmed the layered structure, grain refinement of the zinc and Zn-Ni alloy CMM coatings, and revealed the existence of microcracks caused by the internal stress in the thick Zn-Ni alloy sublayers. The corrosion resistance that was evaluated by means of the salt spray test shows that the zinc and Zn-Ni alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy of the same thickness. The possible reasons for the better protective performance of Zn-Ni/Zn CMM coatings were given on the basis of the analysis on the micrographic features of zinc and Zn-Ni alloy CMM eoatings after the corrosion test. A probable corrosion mechanism of zinc and Zn-Ni alloy CMM coatings was also proposed.     

Preparation and Corrosion Resistance of Rare Earth Conversion Coatings on AZ91 Magnesium Alloy

Magnesiumalloysarewidelyusedinweaponin dustry,spacenavigationandhavegoodpotentialof applicationanddevelopmentindailycommunication facilitiesduetotheirpropertiesoflightweightandhighstrength[1].Appliedasstructuralmaterials,mag nesiumalloysmayeasilycrackduet…