低碳钢表面化学镀Ni-Zn-P合金镀层的沉积行为及沉积机理

目的通过研究低碳钢表面碱性化学镀Ni-Zn-P合金镀层的沉积行为及其沉积机理,对化学镀Ni-Zn-P有进一步认识。方法采用碱性化学镀方法,改变施镀时间在低碳钢表面化学镀Ni-Zn-P合金镀层。使用扫描电镜观察合金镀层的表面和断面形貌,用电子能谱仪分析镀层表面和断面成分。结果化学镀Ni-Zn-P合金镀层的形成过程是:固液界面形成原子团→原子团在能量较高的地方择优沉积→原子团累积生长→向周围延伸扩展→覆盖整个机体→形成完整镀层→均匀叠加生长。试样表面成分检测表明,施镀1~3 s内表面出现Ni元素,Ni质量分数在3 min时达到最大值75.93%,此后维持相对稳定;施镀1 min时表面出现P,P质量分数随施镀时间延长而逐渐增加,在30 min时达到最大值12.03%,此后维持相对稳定;施镀5 min时表面出现Zn,随着施镀时间的延长,Zn沉积量变化不大。表面和断面成分分析表明,化学镀Ni-Zn-P合金镀层的沉积过程不是Ni,Zn,P三种元素同时沉积,而是Ni优先沉积,然后Ni和P共沉积,最后Ni,Zn,P三种元素共同沉积。根据能斯特方程算得沉积电位E_(Ni~2+/Ni)=-0.337 V,E_(Zn~2+/Zn)=-0.906 V,两者的沉积电位相差较大,说明该化学镀条件下不能发生合金共沉积。结论推测化学镀Ni-Zn-P合金镀层是催化诱导还原反应沉积机理,即在镍还原诱导下引发的Zn共沉积。     

Zn-Ni合金镀层中添加第三种元素和纳米颗粒的研究新进展

介绍了在汽车、航空航天等行业中得到广泛应用的钢铁零件电镀Zn-Ni合金镀层,以及往碱性、氯化物等锌镍合金镀液中加入Fe、Co、Mn、Ce、P等第三种元素所获得的锌镍三元合金镀层,具有更优良的耐腐蚀性、催化性等性能的情况。介绍了往Zn-Ni合金镀液里加入氧化硅、氧化铈、氧化钛、氧化铝、碳化硅等纳米颗粒的进展情况,发现含有纳米颗粒的锌镍复合镀层具有耐腐蚀性、耐磨损性、热稳定性更好,硬度更高等优点。梳理了2016年以来在Zn-Ni合金电镀中添加第三种元素和纳米颗粒的多层镀层研究新进展。从Zn-Ni单一镀液中沉积Ni-P和Zn-Ni合金多层镀层时,在低电流密度下沉积出Ni-P层;在较高电流密度下,沉积出含3.2%P的Zn-Ni-P合金镀层,这种多层镀层可以大幅度提高钢铁零件的防腐蚀性能。介绍了在含12%Ni的Zn-Ni镀层上镀覆Ni-Co-SiC纳米复合镀层的情况,这种多层结构既可以提高镀层的结合力,又可提高其在3.5%NaCl溶液中的耐腐蚀性能。该复合镀层是一种硬度高、磨损量低的新型Zn-Ni合金复合镀层。     

镍对热镀锌耐蚀性的影响

对Q235和Q345两种材料表面热浸镀纯Zn和Zn－Ni合金，研究Ni对热镀锌耐蚀性的影响。采用中性盐雾试验对镀层耐蚀性测试，将纯Zn镀层和Zn-Ni合金镀层进行对比，并用电子天平称量试样重量变化。结果表明Zn－Ni合金镀层比纯Zn镀层更耐腐蚀。     

MLCC三层镀中甲基磺酸镀锡体系工艺条件对锡镀层性能影响的研究

研究了片式多层陶瓷电容器(MLCC)三层镀中甲基磺酸镀纯锡体系pH值、温度、电流密度等工艺条件及杂质金属离子对镀液稳定性、镀层结构和性能等方面的影响。从电流效率、沉积速度及锡镀层表面的扫描电镜等方面,对比了不同pH值、温度、电流密度以及锡镀液中掺杂Cu2+、Ni2+后对锡镀层结构和性能的影响。研究结果给出了电镀工艺中最佳的pH值为3.5±0.2、温度为(23±2)℃、电流密度可以有较宽的范围,当镀液中掺有镍、铜等杂离子会对镀层产生负面影响,在给出的工艺参数下电镀,可以确保镀出最佳的纯锡镀层。     

热浸纯Zn和Zn-0.05Ni合金镀层组织性能的对比

采用组织分析、硬度测试和腐蚀实验等方法对比研究了在Q235钢板表面分别热浸纯Zn和Zn-0.05Ni合金镀层的组织和性能.结果表明,在Zn浴中加入Ni后,可抑制Q235钢的硅反应性,消除圣德林效应带来的镀层表面发灰现象,获得外观质量较好的合金镀层.与纯Zn镀层相比,Zn-0.05Ni合金镀层流动性好,锌耗少;镀件表面光滑、平整、美观;镀层厚度薄,硬度高,耐蚀性好.     

烧结钕铁硼磁体表面Zn-Co合金镀层制备工艺与耐蚀性能

采用氯化物镀液体系在钕铁硼磁体表面制备Zn-Co合金镀层,优化了Zn-Co合金镀层制备过程中的电镀工艺参数(镀液pH值、镀液温度、电流密度以及添加剂浓度),通过中性盐雾试验(NSS)、扫描电子显微镜(SEM)和动电位极化曲线,系统研究了Zn-Co合金镀层的显微组织及耐蚀性能。结果表明:烧结钕铁硼电镀Zn-Co合金镀层的最佳电镀工艺参数为:添加剂浓度为15 mL/L,pH值为4,电镀温度为25℃,电流密度为1 A/dm~2。在最佳工艺条件下制备的Zn-Co合金镀层经钝化后其耐中性盐雾时间可达120 h。合金镀层结构致密,有效填补了钕铁硼磁体的固有缺陷,为后期钝化形成致密钝化膜提供了材料基底基础。钝化后的Zn-Co合金镀层表面平整光亮,动电位极化曲线测试表明,相比Zn镀层,钝化后的Zn-Co合金镀层的自腐蚀电流密度下降了一个数量级,表明Zn-Co合金镀层钝化后具有更加优异的耐腐蚀性能。     

化学沉积Ni-Zn-P合金制备和腐蚀性能研究

采用柠檬酸钠为络合剂 ,在氨性缓冲介质中化学镀Ni Zn P合金 .考察了工艺参数 (pH、ZnSO4·7H2 O浓度和温度 )对沉积速度和镀层组成的影响 .发现Zn离子在沉积过程中起阻碍作用 ,致使镀层中Zn含量不高 (最多含16 .0mass% ) .采用差示扫描量热 (DSC)和X射线衍射 (XRD)技术研究所得化学镀Ni Zn P合金 (Ni=78.7mass % ,Zn =11.7mass % )的晶化行为和结构 .结果表明 ,镀态Ni Zn P合金主要由非晶相和少量立方镍两相构成 .热处理至 384 .8℃时出现四方Ni3 P相 ,至 5 80 .7℃时出现Ni5Zn2 1相 .镀态及热处理后的Ni Zn P合金 (Ni=78.7mass% ,Zn =11.7mass% .)在 3.5 %NaCl中 (pH =7.0 )的腐蚀失重及阳极极化测量 .结果表明 ,该合金的耐腐蚀性能优良 ,特别是镀态Ni Zn P合金 .     

电沉积镍-碳钠米管复合镀层的工艺研究

利用电沉积方法制备了镍-碳纳米管复合镀层.分析了镀液中碳纳米管的悬浮量、镀液温度、pH值、阴极电流密度及搅拌速度对镀层中碳纳米管含量的影响.扫描电镜结果表明,碳纳米管能均匀地嵌镶于基体中,并且端头露出,覆盖于基体表面.     

高强度航空结构钢电镀Zn-Ni合金的氢脆性能

目前,对航空300M超高强度结构钢电镀Zn-Ni合金的氢脆性能研究鲜见报道。采用正交试验法研究了工艺参数对300M钢Zn-Ni合金镀层含Ni量和氢脆性能的影响规律;采用EDA能谱分析、SEM形貌观察、缺口拉伸试验和断口分析等方法,对Zn-Ni合金镀层的氢脆性能和断口特征进行了分析研究,探讨了其代替松孔镀镉层的可行性。结果表明:从工程应用安全性出发的氯化物-硫酸盐体系Zn-Ni合金电镀优化工艺条件为镀液Ni2+/Zn2+质量浓度比0.53、温度30℃、电流密度4 A/dm2,所得镀层的氢脆敏感性低,符合航空工业高强度钢氢脆性能要求,可以代替剧毒镀镉工艺用于航空结构钢的表面防护处理。     

镍及其合金镀层的电磁屏蔽性能

为了提高硅钢的低频磁屏蔽效能,在硅钢上电镀了Ni、Ni-P、Ni-Fe合金镀层,用金相法检测了镀层的厚度,用X射线能谱分析了镀层的化学成分,用赫姆霍兹线圈方法测试了低频磁屏蔽效能.结果表明在硅钢上镀Ni,使屏蔽效能降低,镀Ni-P合金使屏蔽性能略有改善,镀Ni-Fe合金后经过热处理后能够显著改善低频磁屏蔽效能.     

电沉积工艺对锌镍合金镀层镍含量的影响

实验分析了锌镍合金电沉积过程中温度、导电盐、添加剂量和pH值等工艺参数对镀层镍含量的影响。着重考察了pH值与添加剂之间的相互作用及其匹配关系对镀层镍含量的影响。发现pH值在有无添加剂时对镀层镍含量的影响规律不同,并试用极化曲线分析其原因。     

Role of cadmium on corrosion resistance of Zn-Ni alloy coatings

Cadmium (Cd) catalyzed Zn-Ni alloy plating has been accomplished galvanostatically on mild steel (MS) using gelatin and glycerol as additives. The effect of addition of Cd into Zn-Ni bath has been examined in terms of nickel (Ni) content and corrosion resistance of Zn-Ni-Cd ternary alloy coatings. The process and product of electrolysis under different concentrations of additives and Cd have been investigated by cyclic voltammetry (CV). The effects of current density (c.d.) on Ni content of the alloy have been studied by spectrophotometric method, supported by EDX analysis. The deposition has been carried out under different concentrations of Cd ranging from 0.004 to 0.1 M. The corrosion rates (CR) of Zn-Ni alloy coatings have been found to decrease drastically with addition of Cd. It has been also revealed that the CR of binary Zn-Ni alloy coatings decreased with the increase of Cd concentration only up to a certain optimal concentration, i.e., up to 0.02 M, and then remained unchanged. An effort to change the anomalous type of codeposition into normal one by changing the molar ratios of the metal ions, i.e. [Cd²⁺]/[Ni²⁺] as 0.01, 0.05 and 0.25 has remained futile. CV study demonstrated an important role of Cd in mutual depositions of Zn²⁺ and Ni²⁺ ions by its preferential adsorption, thus leading to the increased Ni content of the alloy. The bath composition and operating parameters have been optimized for deposition of bright and uniform Zn-Ni-Cd alloy coatings. Changes in the surface morphology and phase structure of Zn-Ni alloy coatings due to addition of Cd has been confirmed by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) study respectively. Experimental investigations so as to identify the role of Cd in codeposition Zn-Ni alloy coatings have been carried out and the results are discussed.     

Dual Bath Electrodeposition of Alternate Multilayer Coatings of Zinc and Nickel Deposits

ZINC electroplating is well established as a sacrificialcoating for the protection of steel substrates.Nevertheless,such coatings deteriorate and areconsumed quickly in severely corrosive environments.Increasing the thickness of pure zinc coating orimproving the passivation methods after plating mayenhance the corrosion resistance,but there are stillproblems during forming and post-deposition weldingprocesses"'.Recently,a new class of coatingsconsisting of a large number of alternate layers h…     

Characterisations of low phosphorus electroless Ni and composite electroless Ni-P-SiC coatings on A356 aluminium alloy

A low phosphorus electroless nickel coating of Ni-2.5?wt-%P alloy and a composite coating of Ni-5?wt-%P-SiC were prepared on A356 aluminium alloy substrates using two types of electroless bath solutions, an alkaline bath for low phosphorus and acidic for composite plating. The coatings morphologies have been characterised using optical and scanning electron microscopy. In addition, X-ray diffraction, microhardness, reciprocating wear testing and adhesion tests have been conducted to characterise structure and mechanical properties of the resulting coatings. The results obtained revealed that a crack-free and homogeneous coating could be produced using an optimum bath formulation. The maximum thickness of the composite coatings was 50?µm, the thickness of coatings tested. The composite coating was more resistant to wear in comparison to the low phosphorus nickel one, but had lower adhesion.     

Nanofabricated multilayer coatings of Zn-Ni alloy for better corrosion protection

As an effort to increase the corrosion resistance of conventional monolayer Zn-Ni alloy coating, the multilayer Zn-Ni alloy coating have been done electrolytically on mild steel (MS), using gelatin and glycerol as additives. Multilayered, or more correctly composition modulated multilayer alloy (CMMA) coatings have been developed using square current pulse. Successive layers of alloys, in nanometric scale having alternately changing composition were fabricated by making the cathode current to cycle between two values, called cyclic cathode current densities (CCCD’s). The coatings having different configuration, in terms of composition and thicknesses of individual layers were developed and their corrosion performances were evaluated by electrochemical methods. The corrosion rate (CR)’s were found to decrease drastically with progressive increase in number of layers (up to 300 layers), and then increased. The coating configurations have been optimized for best protection against corrosion. The CMMA Zn-Ni coating having 300 layers was found to be about 37 times more corrosion resistant than corresponding monolayer alloy, developed from same bath for same time. High protection efficacy of the coatings were attributed to alternate layers of alloys having different surface structure and composition, supported by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) study, respectively. Optimization procedure has been explained, and results are discussed.     

装饰性Zn-Ni/Ni-P镀层的研究

为进一步提高镀层的耐蚀性、降低脆性,在含有缩合物添加剂的镀液中制备了结晶为14～33nm的Zn-Ni合金镀层.采用SEM、XRD对镀层的微观形貌及相组成进行了研究.将此Zn-Ni合金镀层作为底层,制备了双层Zn-Ni/Ni-P镀层,结果表明:双层镀层的耐蚀性比装饰铬组合镀层提高1倍以上,而且镀层的氢脆大大降低,尤其适合于高强度零件的电镀.     

Development of nano-structured cyclic multilayer Zn-Ni alloy coatings using triangular current pulses

Cyclic multilayer alloy (CMA) deposits of Zn-Ni were developed on mild steel from sulphate bath having thiamine hydrochloride (THC) and citric acid (CA) as additives. CMA coatings were developed galvanostatically using triangular current pulses, under different conditions of cyclic cathode current density (CCCD’s) and number of layers. The corrosion behaviors of the coatings were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy methods, and were compared with that of monolayer Zn-Ni alloy of same thickness. At optimal configuration, CMA coating represented as, (Zn-Ni)_2.0/5.0/300 was found to exhibit ∼40 times better corrosion resistance compared to monolayer alloy, (Zn-Ni)_3.0. Cyclic voltammetry study demonstrated that THC and CA have improved the appearance of the deposit by complexation with metal ions. The corrosion protection efficacy of CMA coatings was attributed to the difference in phase structure of the alloy in successive layers, evidenced by XRD analysis. The formation of multilayer and corrosion mechanism was analyzed by Scanning Electron Microscopy (SEM) study.     

铝合金表面化学镀 Ni-Co-P / SiC 复合镀层的组织与性能研究

通过化学镀的方法,在铝合金表面成功地制备了Ni-Co-P/SiC复合镀层。对复合镀层的表面形貌、化学成分、晶态结构、硬度进行了表征分析,通过电化学测试对其耐腐蚀性进行了研究。结果表明:SiC纳米微粒起到了提高Ni-Co-P合金镀层硬度的作用,向镀液中加入12 g/L SiC纳米微粒时,复合镀层的硬度达到最大值524HV;Ni-Co-P/SiC复合镀层能增强铝合金材料的耐蚀性能,镀液中SiC微粒的质量浓度为9 g/L时,复合镀层的耐腐蚀性相对最好。     

6063铝合金碱性化学镀镍耐腐蚀性能研究

针对6063铝合金不耐碱腐蚀的问题,对其表面进行了碱性化学镀镍处理以提高其在碱性溶液中的耐腐蚀性能.采用扫描电镜(SEM)、能谱分析仪(EDS)和X射线衍射仪(XRD)分别分析了镀镍层的表面微观形貌、成分和物相结构;采用电化学和全浸蚀腐蚀试验方法测试了铝合金化学镀镍前后在w(NaOH)=4%的NaOH溶液阳极极化曲线和腐蚀失重.研究结果表明,铝合金化学镀镍处理后其表面获得了致密的非晶态高磷镀镍层,化学镀镍后的铝合金阳极极化电位达到析氧过电位时,镀层依然没有破坏,并且该镀层在w(NaOH)=4%的NaOH溶液中基本不发生腐蚀.