Surface pretreatment of Mg alloys prior to Al electroplating in TMPAC-AlCl_3 ionic liquids

It is difficult to directly electroplate Al on Mg alloys. The effects of pretreatment parameters on the corrosion resistance of films obtained on AZ31 Mg alloy surface were studied by using potentiodynamic polarization curves, to produce a compact interfacial layer as zinc-immersion deposition. After the substrate was pretreated under optimized conditions, aluminum was electrodeposited on AZ31 from TMPAC-AlCl3 room temperature ionic liquids. The depositions were characterized by scanning electron microscope equipped with energy dispersion X-ray. The results show that the traditional pretreatment of Mg alloys was successfully used for the Al-electroplating process from TMPAC-AlCl3 ionic liquids. The entire procedure includes alkaline cleaning, chemical pickling, surface activation （400 mL/L HF acid, 10 min）, zinc-immersion （20 min） and anhydrous treatment. A relatively compact zinc-immersion film was prepared on the substrate surface. A silvery-colored satin aluminum deposition was obtained on AZ31 from TMPAC-AlCl3 using direct current plating.

Progress of electroplating and electroless plating on magnesium alloy

The current research processes of electroplating and electroless Ni-P alloy plating on magnesium alloys were reviewed. Theoretically,the reason for difficulties in electroplating and electroless plating on magnesium alloys was given.The zinc immersion, copper immersion,direct electroless Ni-P alloy plating and electroplating and electroless plating on magnesium alloys prepared by chemical conversion coating were presented in detail.Especially,the research development of magnesium alloy AZ91 and AZ31 was discussed briefly.Based on the analysis,the existing problems and future research directions were then given.

Electroplating process of amorphous Fe-Ni-Cr alloy

A novel process of electroplating amorphous Fe Cr Ni alloy in chloride aqueous solution with Fe(Ⅱ), Ni(Ⅱ) and Cr(Ⅲ) was reported. Couple plasma atomic emission spectrometry (ICP AES), X ray diffractometry(XRD), scanning electronic microscopy(SEM), microhardness test and rapid heating cooling method were adopted to detect the properties of the amorphous Fe Ni Cr deposit, such as composition, crystalline structure, micrograph, hardness, and adherence between deposit and substrate. The effects of the operating parameters on the electrodeposit of the amorphous Fe Ni Cr alloy were discussed in detail. The results show that a 8.7?μm thick mirror like amorphous Fe Ni Cr alloy deposit, with Vicker’s hardness of 530 and composition of 45%～55% Fe, 33%～37% Ni, 9%～23% Cr was obtained by electroplating for 20?min at room temperature(10～30?℃), cathode current 10～16?A/dm 2, pH=1.0～3.0. The XRD patterns show that there only appears a broad hump around 2 θ of 41?°～47?°for the amorphous Fe Ni Cr alloy deposit, while the SEM micrographs show that the deposit contains only a few fine cracks but no pinholes.

Electroplating of Zr-Ti Alloy

The electrodeposition of Zr-Ti alloy has been studied in molten fluoride system consisting of fluorides of both zirconium and titanium dissolved in FLINAK (KF:NaF:LiF = 42.0:11.5:46.5 mol). A coherent dense deposit of the alloy with a smooth surface is obtained on different material substrates. X-ray diffraction has demonstrated that the alloy deposit is a Ti-Zr solid solution with Ti mainly and its preferred orientation is strongly along Ti[110] direction. The properties of the deposit are better than those of a pure zirconium coating. The optimum operating parameters are a temperature of about 800°C, a current density less than 40mA/cm2, a solution about 15wt% ZrF4 and 15wt% K2TiF6 in FLINAK as well as pure zirconium as anode material.

ELECTROPLATING OF AMORPHOUS Al-Mn ALLOYS(Ⅱ) KINETIC FEATURES OF ELECTRODEPOSITION OF Al-Mn ALLOYS

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Electroplating Zn-Al Alloy Technology

The method of controlling separating anode and separating power source was used to perform orthogonal optimization for the parameters in electroplating Zn Al alloy.The electroplating Zn-Al alloy technology was decided, in which the content of Al is about 12%-15% .

Mechanism of current efficiency improvement of Zn-Fe alloy electroplating by hydrogen inhibitor

The effect of hydrogen inhibitor on partial current densities ofZn, Fe and differential capacitance of electrode/electrolyte interface, and adsorbing type of hydrogen inhibitor were studied by the methods of electrochemistry. The mechanism of current efficiency improvement were explained from the point of valence electron theory. The results indicate that the partial current density of Fe increases in addition of hydrogen inhibitor, which reaches the maximum of 0.14 A/dm^2 when current density is 0.2 A/din〈 Differential capacitance of electrode/electrolyte interface decreases obviously from 20.3μF/cm^2 to 7 μF/cm^2 rapidly with the concentration varying from 0 to 20 mL/L, because hydrogen inhibitor chemically adsorbs on active points of Fe electrode surface selectively. Element S in hydrogen inhibitor with negative electricity and strong capacity of offering electron shares isolated electrons with Fe. The adsorption of H atom is inhibited when adsorbing on active points of Fe electrode surface firstly, and then current efficiency of Zn-Fe alloy electroplating is improved accordingly.

Electroplating zinc transition layer for electroless nickel plating on AM60 magnesium alloys

Electroplating zinc coating as transition layer of electroless nickel plating on AM60 magnesium alloys was investigated. The zinc film can be deposited in a pyrophosphate bath at 50-60℃under current density of 0.5-1.5 A/dm2. A new fore treatment technology was applied by acid cleaning with a solution containing molybdate and phosphorous acid, by alkaline cleaning in a bath containing molybdate and sodium hydroxide. The subsequent electroless plating was carried out in nickel sulfate bath. The SEM observation shows that the deposition is uniform and compact. The polarization curve measurements show that the corrosion potential of the zinc plating in 3.5% NaCl is about -1.3 V(vs SCE) which is noble than that of magnesium substrate. The zinc electroplating can be applied as the pretreatment process for electroless nickel plating on magnesium alloys.

Preparation of Amorphous Film on Ni-S Alloy by Electroplating Method

Beginning from the formation of amorphous alloy film and its use of proAnse, this paper obtains the Ni-S amorphous alloy film by electroplating method using a bath containing Na2S2O3, and considers the deposition conditions in detail. The composition of Ni-S alloy film changes with the cathodic current density, Na2S2O3 content in the bath solution and bath pH, but the structure of the film is detendned by the sulphur content in the deposit. X-ray diffraction (XRD) patterns show that films containing about 15-30% sulphur consist of amorphous alloy. In addition, the process of Ni-S alloy film deposition and the relation between the plating conditions and deposits were studied.

Surface quality, microstructure and mechanical properties of Cu-Sn alloy plate prepared by two-phase zone continuous casting

Cu-4.7%Sn （mass fraction） alloy plate was prepared by the self-developed two-phase zone continuous casting （TZCC） process. The relationship between process parameters of TZCC and surface quality of the alloy plate was investigated. The microstructure and mechanical properties of the TZCC alloy plate were analyzed. The results show that Cu-4.7%Sn alloy plate with smooth surface can be obtained by means of reasonable matching the entrance temperature of two-phase zone mold and the continuous casting speed. The microstructure of the TZCC alloy is composed of grains-covered grains, small grains with self-closed grain boundaries, columnar grains and equiaxed grains. Compared with cold mold continuous casting Cu-4.7%Sn alloy plate, the room temperature tensile strength and ductility of the TZCC alloy plate are greatly improved.

Microstructure and dry sliding wear behavior of Cu-Sn alloy reinforced with multiwalled carbon nanotubes

Multiwalled carbon nanotubes （MWCNTs） reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocomposites were subjected to density, hardness, electrical conductivity, and friction and wear tests. The results reveal that the density of nanocomposite decreases with the increase of the mass fraction of CNTs. A significant improvement in the hardness is noticed in the nanocomposite with the addition of CNTs. The developed nanocomposites show low coefficient of friction and improved wear resistance when compared with unreinforced alloy. At an applied load of 5 N, the coefficient of friction and wear loss of 2%CNTs reinforced Cu-Sn alloy nanocomposite decrease by 72% and 68%, respectively, compared with those of Cu-Sn alloy. The wear mechanisms of worn surfaces of the composites are reported. In addition, the electrical conductivity reduces with the increase of the content of CNTs.

THE PREPARATION AND APPLICATION OF ELECTROPLATEDSHEET CONTAINING RS ALUMINUM ALLOY POWDERS

Baded on the study of nickel electroplating technology at room temperature, the plated sheet containing rapidly solidified Al-Fe-Cu- V-Si-Ni-Ce-Zr aluminum alloy powders is constructed successfully. The powders and nickel matrix are combined well in the sheet. It can be used to prepare the observation specimen for TEM and determine the hardness of single powder particle as solidified and after heat-treated. The advantages of this method are the realization of heat treatment of powders and the TEM observation of non-interfered microstructure of powders in the size of several microns.

Electron beam braze-welding of vanadium alloy to stainless steel with electroplated Cu/Ag coatings

Cracks may easily occur in the fusion weld between vanadium alloys and stainless steel due to the brittle intermetallics and welding stress. The high vacuum electron beam braze-welding has been successfully used to join vanadium alloy（V-5Cr-STi） to stainless steel （HR-2） with electroplated Cu and Ag coating. To investigate the effects of electroplated coating on the weldability, the joint appearaace, the microstrueture and the mechanical properties of the joints have been thoroughly analyzed. The results show that the joint surface configuration was good and root reinforcement was full and smooth. A reaction zone （RZ） was gained on the interface between the V-5 Cr-5 Ti alloy and HR-2 stainless steel base metals. The width of reaction zone at the top of the joint was up to O. 65 mm, wider than that in the bottom of the joint （ 0.46 mm）. The reaction zone consisted of considerably smaller dendritic structures with an average grain size of less than 10μm. Element Ag and Cu almost enriched the interface between V-SCr-5Ti alloy substrate and RZ, serving as a physical barrier which decreases or avoids the formation of intermetallics. The maximum tensile strength of vanadium alloy^stainless steel dissimilar alloy joint was more than 300 MPa. The joint was defects free.

Effect of Co-Deposited Iron on Microstructures and Properties of Electroplated Nanocrystalline Nickel-Iron Alloys

Nickel-iron nanocrystalline alloys with different compositions and grain sizes were fabricated by electroplating for MEMS devices. The iron content of the deposits was changed by varying the nickel/iron ion ratio in the electrolyte. X-ray diffraction (XRD) analysis was applied for measuring the strength of the texture and grain size of the deposits. The nickel/iron atom ratio of the deposits was analyzed by EDS. The hardness of the alloys was evaluated by Vickers hardness indenter. The internal stress of the deposits was measured by thin film stress measurement using Stoney's formula. Surface morphology and roughness were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Hardness and internal stress mechanism of the electroplated structure as a function of Fe ion content and current density were revealed. With increasing the iron content, the hardness and internal stress of the deposits increase. An excellent correlation between the increase in the internal stress and the loss of (200) texture were found.

A Mssbauer Study on the Mechanically Alloyed Cu-Sn Alloys

Nanocrystalline E and η electron compounds and supersaturated solid solution of the Cu-Sn system have been prepared by mechanical alloying of elemental Cu and Sn powders. The atomie alloying and microstructure of the resultant alloys have been investigated by XRD, DSC and 119Sn Mossbauer spectroscopy. A little amount of SnO2 was detected by Mossbauer spectroscopy, although no trace of diffiaction peaks occurred in the XRD pattern. Thus the spectra for all the milled samples should be fitted using two quadrupole-splitting doublets: one corre sponding to SnO2, the other corresponding to the resultant alloys. The composition dependence of the hyperfine parameters has been eXtensively discussed and explained well with respect to oxidation, sudece effect resulting from grain refinement, coordination environment asymmetry and distortion caused or/and induced by mechanical alloying.

Corrosion resistance of electroplated Zn-Co alloy coating

By the NSS test and the test in SO 2 gas atmosphere and detecting the  corr - t curves, R p- t curves and the cyclic voltammogram curves, the corrosion resistance of the electroplated Zn Co alloy coating was studied. The corrosion resistance of the electroplated Zn Co alloy coating is three times higher than that of the galvanized coating. Because the corrosion resistance of the Zn Co alloy coating is especially remarkable in SO 2 gas atmosphere, it is particularly fit to be used as a protective coating in industrial atmosphere. The reason why the Zn Co alloy coating has such a high corrosion resistance is that its corrosive product has a comparatively great role in depressing the corrosive process.

氯化钾滚镀锌关键技术的开发研究

在氯化钾滚镀锌槽中间加隔板将其分成两个滚镀锌槽。第一镀槽中的亚铁杂质视作镀液的有效成分,将镀锌改为镀锌铁合金。第二镀槽切断了亚铁杂质的主要来源,用于制备高质量的镀锌层。钢铁件在第一镀槽中镀锌铁合金制备底镀层,然后在第二镀槽中镀锌得到面镀层,从而消除了铁杂质对氯化钾镀锌的不良影响,克服了传统工艺镀层出现滚桶眼子印和钝化困难等技术缺陷。本工艺无需处理氯化钾镀锌槽中的铁杂质,解决了用双氧水氧化处理法导致镀液性能下降的问题。结果表明:所制备的镀锌铁合金与镀锌组合镀层的耐蚀性高于传统的镀锌层。本工艺镀液维护简单,镀液和镀层性能优于传统工艺,具有良好的应用前景。

碳钢表面电镀锌镍/有机富铝复合涂层的制备与性能

为提高碳钢表面电镀锌镍的防护性能和应用限制,采用电镀锌镍层作为底层,有机富铝涂层作为顶层,设计出一种复合涂层防护体系。采用扫描电镜(SEM)、能谱(EDS)、中性盐雾试验、电化学测试等手段对电镀锌镍/有机富铝复合涂层的表面/截面形貌及耐蚀性进行表征与分析。结果表明:电镀锌镍/有机富铝复合涂层表面光滑平整,无明显缺陷,复合涂层体系界面结合良好,无分层现象,经1500 h中性盐雾试验后复合涂层无红锈。复合涂层较单独的电镀锌镍合金层腐蚀电流密度降低了2个数量级,表现出受控的牺牲阳级作用,并实现了在海洋防护领域的应用。复合涂层有效提升了电镀锌镍层的耐腐蚀性能,拓宽了电镀锌镍层在腐蚀防护领域的应用范围。

十六烷基三甲基溴化铵对电镀铜-镍合金耐蚀性的影响

[目的]研究Cu-Ni合金电镀液中添加不同质量浓度的十六烷基三甲基溴化铵(CTAB)对Cu-Ni合金镀层耐蚀性的影响。[方法]通过浸泡腐蚀试验、塔菲尔极化曲线测试和电化学阻抗谱(EIS)考察了Cu-Ni合金镀层的耐蚀性。通过扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析了Cu-Ni合金镀层的表面形貌、成分和晶相结构。采用傅里叶变换红外光谱仪(FTIR)分析了CTAB在Cu-Ni合金镀层中的夹杂情况,并通过接触角测量研究了Cu-Ni合金镀层的疏水性。此外,根据阴极极化曲线测试结果,研究了CTAB质量浓度对Cu、Ni及Cu-Ni合金电沉积行为的影响。[结果]随着镀液中CTAB质量浓度增大,Cu-Ni合金镀层的耐蚀性先变好后变差。CTAB质量浓度为80mg/L时所得Cu-Ni合金镀层表面呈花椰菜状的空间立体形貌,镀层中Cu、Ni质量分数分别为50.25%和40.86%,对腐蚀液的接触角达到129.49°,耐蚀性最佳。[结论]镀液中添加适量CTAB能够显著提高Cu-Ni合金镀层的耐蚀性。

焦磷酸盐电镀Cu-Sn合金添加剂研究

焦磷酸盐电镀Cu-Sn合金是替代氰化物镀Cu-Sn合金的最重要电镀工艺,但是它的最大缺点是电沉积速度慢、镀层耐腐蚀性差。本工作采用电化学方法和失重腐蚀试验,研究了添加剂对焦磷酸盐电镀Cu-Sn合金的电沉积速度、失重腐蚀速度、腐蚀电流密度等的影响。结果表明,焦磷酸盐电镀Cu-Sn合金的最佳添加剂是光亮剂乙二胺(EDA,0.5g/L)、辅助光亮剂甲醛(HCHO,0.5g/L)与表面张力处理剂(SDBS,0.5g/L)三者的复合。