低温镀铁时电流密度对镀层性能的影响

研究了不同电流密度下所得低温镀铁层的沉积速率、显微硬度和腐蚀速率。结果表明,当电流密度为14A/dm2时镀层可获得最佳的综合性能。电流密度过低时,镀层沉积速率慢,硬度低;电流密度过高时,镀层表面出现针孔,厚度不均。     

黑瓷封装IC外引线镀锡后连锡短路的故障处理

分析了黑瓷封装IC外引线镀锡中出现的封装玻璃发白、表面粗糙、封装玻璃与外引线连锡造成引线极间短路的原因,提出了解决方法。     

硫酸盐溶液体系中三价铬镀厚铬工艺及镀层性能研究

采用硫酸盐溶液体系进行三价铬电镀,获得厚度超过30μm的铬镀层。分别探讨了ρ(Cr3 )、ρ(添加剂)、ρ(H3BO3)、φ(络合剂)和pH对镀液覆盖能力和镀速,电镀时间对镀速和镀层厚度的影响。研究了不同热处理温度下镀层的硬度和表面形貌。通过正交实验获得了最佳工艺条件:144g/LNa2SO4,50g/LK2SO4,60～80g/L硼酸,15g/LCr3 ,10～15mL/L络合剂,1.0～1.5g/L添加剂,适量润湿剂,pH=2.5～3.0,温度40°C,电流密度为10～20A/dm2。在此工艺下,获得了半光亮、银白色的铬镀层,硬度为706HV。通过200°C热处理后,铬镀层的硬度达到最大值,为1401HV。但热处理温度升高,铬镀层表面出现裂纹而影响镀层质量。     

镀锡前酸洗工艺对酸洗液中游离铅含量的影响

研究了甲基磺酸(MSA)电镀锡前处理的电解酸洗电流、温度、硫酸质量浓度、时间等工艺条件对阴、阳极区酸洗液游离铅含量的影响。结果表明,阴极区酸洗液的铅含量高于阳极区铅含量。随酸洗时间延长,阴、阳极区的铅含量均先升高后趋于平缓;随电流或温度升高,阴、阳极区酸洗液铅含量均增大;随硫酸质量浓度增大,阴极区铅含量略有增大,阳极区铅含量减小。     

紫铜箔碱性镀锡常见问题浅析

列举了紫铜箔碱性镀锡过程中出现的几种常见问题,如:阳极(锡板)表面金黄色钝化膜变淡(或消失)甚至变黑,镀层呈暗灰色海绵状等。分别对产生这些问题的原因进行了简要分析,并给出了相应的解决方法。     

镀锡扁铜线发展现状及微细扁线镀锡工艺初探

介绍了镀锡扁铜线的主要特点及加工难点,概述了国内外镀锡扁铜线的研究现状.评述了热镀、电镀、化学镀3种常用镀锡方法的优缺点.建议采用化学镀法对微细扁铜线进行镀锡.描述了3种化学镀锡方法(包括还原法、歧化法和浸镀法)的反应机理及特点.提出了一种化学浸镀锡工艺,其流程包括除油、活化、镀锡、烘干等,镀液配方为:SnCI2 25...     

稀土催化剂抗酸性镀锡液氧化变质的研究

酸性镀锡液稳定性差,易氧化变质。探讨了酸性镀锡液产生氧化变质的机理。在镀锡液中加入0．05－0．1g/L稀土催化剂,通过加速氧化试验和空气暴露试验研究镀锡液的稳定性。结果表明：镀液稳定性显著提高。     

焦磷酸盐镀铜液中正磷酸盐含量对镀层性能的影响

介绍了一种焦磷酸盐镀铜溶液中铜、总焦磷酸根、磷酸根、柠檬酸铵含量的分析方法和计算方法。分析了正磷酸根产生的原因及其危害,并给出了一种化学处理方法。对正磷酸根含量不同的镀液进行了分析,并测试了相应镀层的性能?采取了不同的措施对镀液进行改进,并对效果进行了讨论。结果表明,正磷酸根的存在是不可避免的,控制槽液温度和pH值、定期过滤溶液、补充新料等措施都可抑制正磷酸根含量的增长。     

Effect of low temperature plasma treatment on the electroless nickel plating of polyester fabric

The present study is performed with an objective to acquire a deeper understanding of the properties of nickel‐plated polyester fabric after conducing low temperature plasma (LTP) treatment. LTP treatment with oxygen and argon gases was employed to render a hydrophilic property of woven polyester fabrics and facilitate the absorption of a palladium catalyst to provide a catalytic surface for electroless nickel plating. The properties of LTP‐induced electroless nickel‐plated polyester fabrics were evaluated by various standard testing methods in terms of both physical and chemical performances. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

电镀污水中有机污染物去除工艺初探

电镀废水中的有机污染物来源主要有3个方面:镀前处理、电镀过程和镀后处理。介绍了污水中有机污染物的3种去除方法:生化法、微波化学法和物化法。通过对3种处理方法的效果比较得出,微波化学法效果最好,物化法次之,生化法最差。但就成本而言,物化法最低。     

温度对微波器件镀层结构的影响

现代移动通信所使用的微波器件,基于微波的传导特性而对器件的表面特性有很高的要求,如表面光亮度和表面金属组织结构。通常都是采用电镀来获得这种表面结构,致密细小的结晶有利于微波的传导。微观观测表明,温度对镀层的结晶大小有明显影响。例如镀银,只有当温度在30℃以下时,才能获得细致的镀层。这也是微波器件镀银工艺需要采用低温控制系统的原因。     

钾盐镀锌溶液中铁杂质的影响及消除

详细介绍了钾盐镀锌溶液中铁杂质对镀锌的有害影响。分析了铁杂质的来源并提出了几种去除铁杂质的方法。     

水合肼体系化学镀镍时间对钕铁硼电镀/化学镀镍层耐蚀性的影响

以钕铁硼永磁体为基体,先采用瓦特体系镀液电镀镍,再采用以水合肼为还原剂的镀液化学镀镍,总施镀时间为4 h。分别采用金相显微镜、扫描电镜、能谱仪、中性盐雾试验和电化学测试研究了化学镀镍时间对镀镍层厚度、微观形貌、元素组成和耐蚀性的影响。结果表明,随化学镀镍时间延长,镀镍层的厚度维持在10μm左右,致密性、均匀性和耐蚀性都有改善。     

Effect of process conditions on particle growth for spouted bed coating of urea

The aim of this work was to analyze the influences of operational variables on particle growth for urea coating in a conventional spouted bed (CSB). An aqueous polymeric suspension was the coating liquid sprayed on the spouted particles. The effects of inlet air temperature, coating suspension flow rate and atomizing air pressure on particle growth were analyzed by a central composite rotatable design (CCRD) of experiments. The results showed particle growth in the range of 1.1–2.6%, therefore, some results below the expected for a film coating (2–8%). A second-order polynomial model was obtained for estimating particle growth as a function of the statistically significant variables: air temperature, suspension flow rate and atomizing air pressure, with percentage of explained variation R² = 90.72%. The urea growth kinetics during coating was analyzed for the optimal operating condition and a linear growth coefficient of 1.13 × 10⁻³ min⁻¹ was obtained. The volatilization analyses showed that the polymer film coating provided a decrease of the nitrogen loss in the range of 3–57%. And, SEM analyses demonstrated a total, uniform and homogeneous covering of the urea particles surface.     

Effect of amine degradation products on the membrane gas absorption process

The effect of the presence of monoethanolamine (MEA) degradation products on membrane hollow fibers was investigated using untreated polypropylene (PP) as a model material. Common amine oxidative degradation products were added to MEA to simulate a degraded solution. The effect of these degradation products on the membrane gas absorption process using PP hollow fiber membrane was quantified. When PP membrane which has been exposed to amine degradation products is used in a membrane gas absorption contactor, the mass transfer rate of CO₂ is reduced relative to the use of unexposed PP. It was found that the presence of oxalic acid reduced the mass transfer rate of CO₂ in MEA most significantly followed by formic acid and then acetic acid. These acids are believed to adsorb into the PP, altering the surface properties and reducing the hydrophobicity of the membrane. This in turn increases the degree of wetting of the membrane pores. The membrane was characterized before and after use in a membrane gas absorption contactor containing degraded MEA solvent and studies showed that membrane pore wetting increased by 22-31% after 69 h of use. SEM images and XPS spectra of exposed PP membrane indicate that wetting may be due to both morphological and chemical changes in the membrane due to contact with the solvent. This study highlights the need to consider reductions in the mass transfer rate of membrane gas absorption processes associated with inevitable changes in the solvent composition that comes with prolonged use.     

Effect of vermicomposting on the transformation of some trace elements in fly ash

One major constraint of the agricultural uses of fly ash (FA) is the low availability of different plant nutrients despite their high occurrence in the total amount. However, degrading FA through increased microbial activity can improve the availability of these nutrients substantially. It has been found that intestines of epigeic earthworms contain a high concentration of different microorganisms. Therefore, in the present study we addressed the effects of vermicomposting technology on the solubility of some micronutrient cations (Fe, Mn, Cu, and Zn) and some heavy metals (Pb, Cd, and Cr) in different combinations of fly ash and organic matter, applied in the form of cow dung (CD). Various combinations of FA and CD were treated with and without an epigeic earthworm (Eisenia fetida) and the solubility of different trace elements in the treatments were estimated periodically. The results revealed that the inclusion of epigeic earthworm Eisenia fetida in different combinations of fly ash and cow dung converted a considerable amount of the micronutrients into bio-available forms. On the other hand, the solubility of heavy metals tended to be reduced by the microorganisms, presumably by formation of some organo-metallic complex. Application of these vermicomposted FA and CD combinations to a red lateritic soil was found to improve the soluble Fe, Mn, Cu, and Zn status of the soil. Furthermore, the use of vermicomposted FA and CD (1:1) in potato cultivation demonstrated that use of this mixture at 10 ton per hectare (t ha⁻¹; fresh weight) was able to compensate 80% of the recommended NPK fertiliser, along with farm yard manure application, without compromising the crop yield.     

汽车用钢板纳米晶镀锌层在氯化钠溶液中的腐蚀机理

将汽车用钢板置于碱性镀锌液中电镀,制备了纳米晶镀锌层.采用场发射扫描电子显微镜(FE-SEM)观察镀锌层在3.5%NaCl溶液中腐蚀前后的表面形貌,以能谱仪(EDS)研究腐蚀产物组成,运用塔菲尔(Tafel)曲线和电化学阻抗谱(EIS)考察纳米晶镀锌层的电化学腐蚀行为.结果表明,镀锌层由直径为80～100 nm的针状结...     

Effect of plating mode, thiourea and chloride on the morphology of copper deposits produced in acidic sulphate solutions

The influence of plating mode, chloride and thiourea (TU) on morphology of copper deposits has been studied. All experiments were conducted on disc electrodes rotating at 500 rpm and an average current density of 4 A dm⁻² to produce 10 μm thick deposits. In additive-free solutions, the use of pulsed current (PC) improved deposit morphology and brightness over DC plating. In the presence of thiourea (no Cl⁻), the deposits obtained by DC and PC plating were similar under most plating conditions. The presence of thiourea generally improved deposit quality over that obtained in additive-free solutions, but caused the formation of microscopic nodules and the deposits to appear slightly cloudy, resulting in lower reflectances than that of a polished uncoated copper surface. The addition of Cl⁻ to thiourea-containing solutions strongly influenced deposit morphology at both microscopic and macroscopic scales depending on chloride concentration and pulse conditions. It prevented nodule formation and created microscopically bright and reflective deposits, but caused extreme macroscopic roughness. Nevertheless, PC plating at 50 Hz in solutions containing appropriate amounts of thiourea and Cl⁻ was found to yield macroscopically and microscopically smooth deposits with reflectance similar to that of a polished uncoated copper substrate.     

N,N−二甲基−二硫代甲酰胺丙磺酸钠对THPED体系化学镀铜的影响

研究了N,N?二甲基?二硫代甲酰胺丙磺酸钠(DPS)作为添加剂对以四羟丙基乙二胺(THPED)为单一配位剂的化学镀铜体系的沉积速率、镀层形貌和晶体结构的影响。结果发现,当DPS的质量浓度从0 mg/L增大到1.0 mg/L时,沉积速率从2.91μm/h提高到6.73μm/h,所得镀层结晶均匀、细致。线性扫描伏安测量结果表明,DPS是通过促进甲醛的阳极氧化来加速化学镀过程。本体系的Cu镀层主要呈面心立方多晶取向,DPS的添加会令晶面取向从(220)转变为(111)。     

Effect of air velocity in dehumidification drying environment on one-component waterborne wood top coating drying process

In this study, the effect of air velocity in dehumidification drying environment on one-component waterborne wood top coating drying process is analyzed by drying time and moisture content and surface temperature of coating, in which air temperature is 35°C and relative humidity is 50%, and the air velocity is the only change parameter, varying from 0.2 to 1.2?m/s. It is found that drying time of top coating shortens and moisture content of top coating decreases with increasing air velocity. Surface drying time is about 15?min, hard drying time 21?min, and sanded drying time 37?min. To accelerate the drying speed, the air velocity is increased to more than 0.4?m/s. Moisture content of top coating is 58.2% during surface drying, 31.4% during hard drying, and 21.9% during sanded drying time. An infrared thermometer is used to measure the surface temperature of coating. Surface temperature of top coating is 30.0°C when it is dried to the surface drying degree, 33.5°C when the top coating is dried to the hard drying degree, and 34.6°C when the top coating is dried to the sanded drying degree. The drying degree of coating can be judged from the drying time and surface temperature and moisture content of coating. The drying degree of top coating is better when surface temperature is higher and the moisture content is lower.