提高硬铬镀层耐蚀性的双层镀铬工艺

以某型发动机的水泵轴为基体,在同一镀液和镀槽中电沉积制备乳白/光亮双层铬镀层。工艺流程为:前处理─装挂─入槽─镀乳白耐蚀铬─镀光亮耐磨铬─出槽─清洗─除氢─抛光─检验。镀液组成为:CrO3200~250g/L,H2SO42.2~2.6g/L,Cr3+离子2.0~3.5g/L。先在60~65℃、15~25A/dm2下施镀30min得到乳白铬镀层,随后在55~60℃、40~50A/dm2下施镀90min,即得乳白/光亮双层铬镀层。双层铬镀层的孔隙率比单层光亮铬镀层小,二者显微硬度相近,耐磨性优越。实际生产应用表明,双层铬镀层的耐蚀性优于单层光亮铬镀层。     

甲基磺酸锡光亮镀锡工艺研究

研究了甲基磺酸锡(MSAS)、甲基磺酸(MSA)、电流密度、温度以及添加剂等工艺参数对甲基磺酸锡镀锡沉积速率的影响,确定的最优工艺条件为:MSAS 90 g/L,MSA 140 g/L,添加剂A(含酚类抗氧化剂和主光亮剂)25 mL/L,添加剂B(含非离子表面活性剂和辅助光亮剂)6 mL/L,温度30 ℃,电流密度5A/dm2.甲基磺酸锡镀锡沉积速率快,镀液的电流效率高,分散能力好,覆盖能力优良,镀层的耐氧化性能强,焊接性能和耐腐蚀性能优异.     

碳纤维增强环氧树脂复合材料化学镀镍工艺的研究

采用正交实验的方法,研究了碳纤维增强环氧树脂复合材料化学镀Ni-P合金的工艺。通过对镀层结合力、金相组织、沉积速率、硬度等性能的比较,选出最优镀液配方,并对所得最优组镀件进行SEM和EDS分析及耐腐蚀性能测试。通过正交实验得出最佳镀液配方为:硫酸镍30g/L,次磷酸钠25g/L,乳酸20mL/L,乙酸钠15g/L。所得镀层中磷的质量分数为11.88%,是高磷镀层;经耐腐蚀性能检测,该镀层具有良好的耐蚀性。     

快速全光亮硫酸锌镀锌

介绍了一种硫酸锌镀锌工艺,其镀液组成包括硫酸锌140～200 g/L,硫酸钠60～80 g/L,氯化钾80～140 g/L,硼酸25～30g/L,Lx-600A光亮剂15～20mL/L.其操作条件为:温度5～60 ℃,pH 3～6,电流密度2～5A/dm2,阴极移动速率15～20次/min.描述了镀液的配制,讨论了镀液中各组分及工艺条件对镀液和镀层性能的影响.该工艺沉积速率高、分散能力好,所得镀层达到全光亮,有机物夹杂较氯化钾镀锌件少.     

硫酸盐溶液体系三价铬镀铬添加剂的研究

在由70 g/L Cr2(SO4)3、30 g/L HCOONa·2H2O、15 g/L NH2CH2COOH、80 g/L K2SO4、120 g/L Na2SO4、60 g/L H3BO3、和0.05 g/L C12H25NaSO4组成的基础镀液中,研究了含硫添加剂SN、WS、SH、TS和有机胺类添加剂TH对三价铬镀铬工艺和镀层性能的影响。结果表明,5种添加剂均可改善镀液分散能力和覆盖能力,拓宽允许的阴极电流密度范围,提高阴极电流效率。基础镀液中添加不同添加剂时,所得铬镀层的耐蚀性、表面形貌和色泽有差异。SN、SH、TS、TH可用作三价铬电镀白铬添加剂,WS则适用于三价铬电镀黑铬。     

低泡型氯化钾镀锌

介绍了SF-522型低泡型氯化钾镀锌(第三代氯化钾镀锌)工艺,与国外某低泡型氯化钾镀锌进行对比。探讨了镀液成分、工艺条件和不同杂质对镀锌层性能的影响,并说明了镀液维护要点。各项试验和生产应用的结果表明,SF-522氯化钾镀锌液低泡,可采用压缩空气搅拌,允许电流密度范围广(0.5～4.0A/dm2),添加剂消耗量低,生产效率高。镀锌层经三价铬钝化后,其耐中性盐雾腐蚀时间超过经六价铬钝化的氰化物镀锌层。     

一种新型无氰镀铜溶液

研制出一种新型的无氰镀铜溶液,其最佳配方为:CuSO4.5H2O 45g/L,ZGA350mL/L,ZGB150mL/L,添加剂6mL/L。该镀液稳定,电流效率和深镀能力均优于氰化物镀铜溶液的,分散能力接近甚至超过氰化物镀铜溶液的。所得镀层光亮、结合力良好,可以取代氰化物镀铜在钢铁等基材上直接预镀铜。     

碱性脉冲电镀Zn-纳米SiC复合镀层工艺条件的优化

采用由30 g/L氧化锌、180 g/L氢氧化钠、2.8 g/L香草醛、4 g/L硫脲、4 g/L三乙烯四胺、1 mL/L甲醛和0.15 g/L SiC(粒径约40 nm)组成的碱性镀液对Q235钢脉冲电镀Zn-纳米SiC复合镀层,通过优化得到较佳的工艺条件为:平均电流密度2.0 A/dm2,占空比30％,镀液温度20～30°C,脉冲频率125 Hz,搅拌速率250 r/min,电镀时间20～25 min.在该工艺下所得复合镀层结晶细腻,含碳化硅的质量分数为1.67％,耐蚀性比脉冲电镀纯锌镀层更好.     

化学镀镍-硼合金工艺和镀液稳定性

以铁片为基材进行化学镀Ni–B合金。研究了镀液中主盐、还原剂和配位剂用量及稳定剂种类对镀速、镀液稳定性，以及Ni–B合金镀层外观和显微硬度的影响，得到的较佳配方为：SF-815镍盐A 60 mL/L,SF-815配位剂B 200 mL/L,SF-815还原剂C 20 mL/L，含巯基化合物(用作稳定剂)5 mg/L。采用该体系镀液在pH 6.2～7.2、温度60～70℃的条件下化学镀1 h所得Ni–B合金镀层均匀，呈半光亮，结晶细致，B质量分数为1.62%～3.23%，显微硬度为683.0～753.1 HV。该体系镀液性能稳定，连续工作10个周期后镀液保持澄清，镀层外观和各项性能保持合格。     

烷基糖苷对硫酸盐无光镀锌的影响

采用烷基糖苷为主添加剂进行硫酸盐体系无光镀锌,表征了镀层的光泽度、结合力和耐中性盐雾腐蚀性能。基础镀液组成和工艺条件为:ZnSO_4·7H_2O 225g/L,Na_2SO_4 70g/L,Al_2(SO_4)_3 25g/L,温度(25±5)°C,电流密度2A/dm~2,时间25min(镀层厚度8~12μm)。对比研究了分别采用烷基糖苷和葡萄糖作添加剂时所得镀锌层的外观和微观形貌。结果表明,使用烷基糖苷作添加剂时所得锌镀层外观均一,结晶致密,具有良好的基体结合力和耐蚀性。     

The rate of zinc deposition at zinc Amalgam and zinc metal

The reduction of Zn²⁺ ions in KCl (pH 3.0) has been investigated at Hg, Zn(Hg) and solid Zn. A reaction scheme is suggested by analogy with Cu(su2+) reduction     

Comparative electrochemical studies of zinc chromate and zinc phosphate as corrosion inhibitors for zinc

The anticorrosive performance of two inhibitive pigments, zinc chromate and zinc phosphate, was compared using electrochemical impedance spectroscopy (EIS) and the scanning vibrating electrode technique (SVET) in pigment extracts in 0.1 M NaCl. It was observed that zinc was protected from corrosion in both extracts. In tests using hot dip galvanised steel painted with an epoxy primer incorporating the pigments, the SVET detected the anodic and cathodic distribution along the scribes, although no significant differences were observed among the various primers. On the contrary, EIS was able to distinguish processes occurring on the metal surface exposed by the scribe in different samples. For primers with anticorrosive pigment, a time constant at high frequencies was attributed to a layer of protective nature, probably formed by metal ions from the substrate and inhibitive ions leached from the anticorrosive pigments.     

用锌渣制备高纯氧化锌

介绍了利用锌渣为原料生产高纯氧化锌的方法。采用黄铁矾法除去大部分铁，通过控制ｐＨ值进一步除铁，用锌粉或锌屑还原除去重金属，用氨水为沉淀剂，最终可使氧化锌的含量达９９．８６％以上。     

电镀锌及锌合金发展现状

综述了近年来锌电镀、锌舍金电镀、锌基复合电镀、锌合金基复合电镀的研究与应用现状，并对纳米技术在锌及锌合金电镀中的应用提出了展望。     

锌灰制备碱式碳酸锌和超细氧化锌及表征

室温下采用氨浸出锌灰制得碱式碳酸锌,再经煅烧制得超细氧化锌。研究了在合成碱式碳酸锌过程中表面活性剂对碱式碳酸锌和氧化锌颗粒尺寸与形貌的影响。结果表明,聚乙二醇（PEG20000）和聚乙烯吡咯烷酮（PVP-K30）这两种表面活性剂对颗粒的分散效果最好,制得的碱式碳酸锌颗粒为无定形片状且分散均匀,平均粒径为1 μm,煅烧后的氧化锌颗粒为六方晶系纤锌矿结构,粒径约为0.7 μm。添加PVP-K30比添加PEG20000的碱式碳酸锌热分解温度高。添加PEG和PVP的碱式碳酸锌反应活化能分别为139.9 kJ/mol和146.8 kJ/mol。     

Growth of zinc dendrites in acidic zinc chloride solutions

The heights and widths of zinc dendrites were measured in pure zinc chloride solutions in the concentration and pH range prevailing in zinc-halogen load leveling batteries.At constant overpotential the height increases linearly with time, indicating a constant growth rate. The higher the concentration and the overpotential, the faster is the growth. The critical overpotential for initiation of dendrite growth is 14 mV independent on the concentration. The growth rate increases when the pH decreases. The influence of hydrogen gas evolved at low pH on the growth rate is discussed. Propagation rate is discussed in terms of an extended Barton-Bockris model. When the height of the dendrite is smaller than the diffusion layer thickness, mass transport to the tip is linear and the dendrite propagates in an exponential manner. When the height is larger than the diffusion layer, mass transport to the tip is spherical and the propagation is linear with time. At constant overpotential the widht is a linear function of the square root of the height, indicating that the dendrite has a shape which is preserved during the growth and the tip radius is maintained constant as predicted by the theory.     

Electrodeposition of zinc from high acid zinc chloride solutions

Electrowinning of zinc from zinc chloride solutions, acidified by HCl, was conducted in a cation exchange membrane cell. The current efficiency was correlated with the deposit morphology. The deposits having lesser surface defects, which act as active sites for hydrogen adsorption, exhibited higher current efficiency. The (1 1 0) preferred texture was observed on the deposits grown in high acid solution containing gelatin. High temperature (40 ºC) and high current density decreased the current efficiency and the preferred texture.     

The electrodeposition of zinc from acidified zinc sulphate solution

In the electrodeposition of zinc from acidified zinc sulphate solutions the loss in current efficiency (CE) due to evolution of hydrogen at the cathode has often been attributed to the presence of metal impurities, and it has been thought that in a pure solution the CE would be 100%. In this paper it is argued that, whatever the degree of purity achieved, hydrogen must always be produced simultaneously with zinc. At the start of electrolysis the CE is determined solely by the zinc/acid ratio, but when impurities are present the CE falls progressively as electrodeposition proceeds. Further, colloid silica which is always present in plant solutions is not responsible for the CE falling below 100%, nor are the lead anodes that are used in practice. Some effects of manganese, both at the anode and the cathode, are reported. The deleterious influences of cobalt and manganese together are also discussed.     

Relative yield and zinc uptake by rice from zinc sulphate and zinc oxide coatings onto urea

Zinc (Zn) deficiency is prevalent worldwide and is a barrier to achieving yield goals in crops. It is also now recognized as a leading risk factor for disease in humans in developing countries. In general, soil application of 5–17 kg of Zn ha⁻¹ year⁻¹ as zinc sulphate (ZnSO₄) or more is recommended. However, in developing rice growing countries of Asia, ZnSO₄ of desired quality is not readily available and is also quite expensive, so the farmers generally fail to apply Zn, resulting in rice crop yield loss. Availability of Zn-coated urea guarantees not only the availability of quality Zn but also ensures its application. Field experiments were therefore conducted during the rice seasons of 2005 and 2006 at the Indian Agricultural Research Institute, New Delhi, to evaluate the relative efficiency of 0.5, 1.0, 1.5 and 2.0% Zn as ZnSO₄- or zinc oxide (ZnO)-coated ureas for rice. Soil application of ZnSO₄ was also compared in 2006. Rice grain and straw yields, Zn concentrations in grain and straw, and Zn uptake by rice increased with the level of Zn coating onto urea. Crop response was the highest with 2.0% ZnSO₄-coated urea, and higher than with the same rate of ZnO-coated urea, possibly related to the higher water solubility of Zn in ZnSO₄. Crop response with ZnSO₄-coated urea was also higher than with the same rate of ZnSO₄ and urea applied separately to the soil. However, apparent recovery data suggest that 1.0% coating with ZnSO₄ may be a better choice from the point of view of the utilization of applied Zn. Increased Zn concentrations in rice grain due to application of Zn-coated urea is important from the point of view of Zn nutrition of humans, since rice is the staple food in developing countries of Asia. Also, increased Zn concentrations in rice straw is of importance as regards cattle nutrition since in developing countries of Asia rice straw is the major feed for farm cattle.     

电镀锌及锌合金的智能数字化生产

根据清洁生产的要求,从电镀设备、电镀工艺以及工厂管理等方面,阐述了如何实现电镀锌及锌合金的智能数字化生产.列出了各工序所需的辅助设备,说明了滚、挂镀锌自动生产线的布置(包括前处理及后处理),介绍了自动生产线日常管理的方法(包括对人员、设备、材料和槽液的管理).