镀银层高温烘烤发黄原因分析

从皮膜保护剂、镀银层厚度、中间层、基材、镀镍工艺等5个方面进行试验,分析了镀银层高温烘烤发黄的原因。给出了2种解决方法:一是增加镀银层的厚度,二是在银镀层下加镀一层镍。     

氧化对铜基件镀银产品电气性能的影响及其预防和解决方法

从镀银工艺和环境两方面探讨了铜基镀银产品氧化的原因,分析了氧化后镀银产品的电气性能,提出了镀银层防变色的措施、氧化后处理方式和镀银层替代方案。     

无氰电刷镀银镀层性能研究

分别采用以丁二酰亚胺和亚氨基二磺酸铵为主配位剂的两种无氰镀银液,通过电刷镀工艺成功在紫铜基体表面制备出了镀银层.通过X射线光谱法、SEM、EDS、显微硬度及摩擦磨损实验等分析方法,对镀银层外观、厚度、微观形貌、硬度以及摩擦磨损性能等方面进行了分析及比较.结果表明:两种体系制备出的镀银层外观均平整光亮,厚度及硬度均满足Q...     

酸洗工艺对铝合金镀银质量的影响

铝合金基体镀银层容易存在气泡和起皮现象,主要是前级加工引起的成分偏析、有机物的渗入和残余应力没有得到很好的释放等原因。采用无挥发的新型酸洗工艺,在酸洗存在偏析的铝合金表面镀银,获得良好的镀银层,对镀银层测试,结合力良好。经过批量试验,零部件镀银层合格率大幅提高。     

铝及其合金高附着力镀银工艺探讨

通过对原浸锌工艺的改进及增加表调工序,采用多元合金化的浸锌工艺,提高了锻铝、高硅铸铝表面镀银层的附着力,解决了铝合金镀银质量不稳定的难题。描述了铝基材上电镀存在的问题及原因分析,针对锻铝和高硅铸铝两种材质采用了不同工艺镀银,分别进行了热震、磨削和拉力试验,验证了新工艺提高了镀银层的附着力。     

装饰镀银新工艺

提出了一种氰化光亮冲击镀银工艺,分析了电流密度、温度、时间对镀银层性能的影响,并对镀银层进行抗变色处理。     

无氰镀银新工艺的研究

介绍了一种可以产业化应用的无氰镀银新工艺。采用多种测试及表征方法,对镀液稳定性、分散能力及深镀能力等性能进行了测定;对无氰银镀层的外观质量、微观形貌、结合力、可焊性、抗变色性能及导电性等性能与氰化镀银层进行了对比分析。结果表明,无氰镀银新工艺的镀液与镀层性能接近或优于氰化镀银层。     

镁合金镀银工艺

本文对镁合金AZ41材料镀银进行了大量工艺试验,确定了镁合金镀银较优工艺配方和参数。所得镀银层光亮、均匀、细致;镀银层热震结合力试验合格,镀层无起泡、脱落;热震后的镀银试片进行划格试验,镀银层无起皮、脱落。对试验样件进行可焊性和抗硫性试验,均符合HB5051-93《镀银层质量检验》标准要求。     

实用氰化镀银工艺

介绍了各种氰化镀银工艺(包括半光亮、光亮镀银,镀硬银,装饰性冲击镀银等)的镀液组成及其操作条件,对镀银前化学除油、去氧化皮、酸洗、预镀银以及镀银后防变色处理等工序进行了详细叙述,说明了一些添加剂的制作,归纳了不良镀层产生的原因及解决排法,给出了退镀以及银层变色后的处理方法,总结了氰化镀银生产中常用的数据。介绍了如何从废镀银液中回收金属银,银料头的再利用,以及老化液的再生。     

无铬耐指纹热镀铝锌钢板黑斑缺陷研究

采用ZEISS Merlin Compact场发射扫描电镜、OXFORD X-max N型能谱仪、激光共聚焦显微镜等分析技术对无铬耐指纹热镀铝锌钢板黑斑缺陷进行了原因分析并提出了改进措施。结果表明：黑斑缺陷主要是由于镀层厚度凹凸不平致使钝化膜分布不均匀,镀层薄的部位钝化膜厚,镀层厚的部位钝化膜薄,钢卷在运输过程中钢板层与层之间相互摩擦致使钝化膜破损甚至脱落,导致钢板表面反射率不同,从而产生黑斑缺陷。     

PET表面金属银涂层的制备与性能

以聚对苯二甲酸乙二酯(PET)为基体,基于化学刻蚀和敏化处理的表面改性,采用双组分喷涂法在改性基体表面制备了高性能的银涂层.改变喷涂过程中银氨溶液和还原溶液的浓度以及喷涂次数,研究它们对银涂层的微观形貌、宏观形貌、沉积量和光学常数的影响,考察了最佳喷涂条件下所得银涂层的成分和性能.结果表明:化学刻蚀后表面产生大量凹坑,...     

镀银层表面变色机理的电子能谱研究 (Ⅱ)光照和Na_2S处理致变色的机理

本文用电子能谱(XPS和AES)研究了不同波长光照射后,镀银层表面膜的组成和状态的变化,结果表明:(1)光波的致变色能力按以下顺序递降2537(?)>3650(?)>日光;(2)同一波长光照射时间越长,变色愈甚;(3)应用俄歇参数方法进行表面元素价态分析,发现2537(?)照射18小时表面约有43%的银为Ag_2O,照射24小时后表面约有18%的银为AgO;(4)XPS测定表明.银层在大气中照射时,表面银先被氧化和氯化,随后氯化物可能转化为Ag_2O,最后Ag_2O被光转化为黑色的超细颗粒的银粒子和AgO.镀银层浸在Na_2S溶液中,然后将一半面积提出液面.让其露在大气中,结果浸在Na_2S液中的部分不变色,露在大气中的部分却变为蓝色.通过Ag(3d)、S(2P)结合能以及M_4VV、M_5VV俄歇峰的测定.证明未变色银表面仍为银,蓝色层则是Ag_2S.因此,镀银层浸入Na_2S溶液后在大气中的变色反应可表示为4Ag+O_2+ZH_2O+2Na_2S→2Ag_2S+4NaOH     

The influence of basecoat pigmentation on chemical structure and surface topology of automotive clearcoats during weathering

The present study aims at elucidating the effect of basecoat pigmentation on the chemical structure and surface topology of its attached clearcoat during weathering exposure. Two extremes of differently behaviored basecoat pigmentations (i.e. silver and black) were chosen. Different analyses such as FTIR, ATR, surface energy measurements and AFM were carried out on such coatings after they were subjected to accelerated weathering conditions. It was found that the black basecoat procured more post-curing reactions to the attached clearcoat at initial weathering times, while the silver basecoat induced higher degrees of photodegradations during the whole time of weathering. Such inductions were attributed to the inherent absorptive or reflective behavior of the black or the silver basecoats toward incident radiation.     

Effect of sulphuric acid and copper sulphate concentrations on the morphology of silver deposit in the cementation process

The silver ion cementation on copper was investigated in the presence or absence of oxygen in solutions containing 1.85 × 10⁻⁴ M Ag⁺ at 25 °C. The influence of sulphuric acid and copper sulphate concentration (0.005-0.5 M) on the silver cement morphology was studied in details and results were linked with the previously determined kinetics data of the process. The morphology of silver deposit was found to be independent of the presence of oxygen in the system as well as the sulphuric acid concentration. Contrary, the concentration of copper sulphate strongly influenced the morphology of silver deposit. At the beginning of the cementation process silver covers uniformly the copper surface. Afterwards, a growth of dendrites is initiated on preferential parts of the surface. The growing dendrite behaves as cathodic sites, with relatively huge surface area and promotes the creation of anodic sites in a close neighbourhood. Finally, the anodic site encloses the dendrite island and develops its area inward the copper material. Copper ions at low concentration modified slightly silver dendrites but the increase in concentration up to 0.5 M Cu²⁺ leads to completely disappearance of dendrites from the surface. The lack of dendrites on the surface is a result of the competitive process that consumes additional silver ions, occurring in the bulk of the solution. The morphology of silver deposit cemented in the deoxygenated solution containing 0.5 M H₂SO₄ + 0.5 M CuSO₄ depends strongly on the mechanism of the process.     

Studies on tack of pressure-sensitive adhesive tapes: On the relationship between pressure-sensitive adhesion and surface energy of adherends

The relationship between wetting and pressure-sensitive adhesion was studied using an adhesive composed of poly(butyl acrylate) and various adherends of different surface tension. The amount of adhesive deposit was determined quantitatively by tracer technique although the unbonding process was apparently observed as interface failure. The adhesive force and amount of deposit were both dependent on the critical surface tension of the adherends. Maximum tack value and contamination were observed with adherends whose critical surface tension was close to that but a little higher than that of the adhesive. The adhesive force obtained was lower than cohesive strength of adhesive. From this evidence, a mechanism for pressure-sensitive adhesion was discussed: the bond breaks in the addesive mass around the very minute spots where interaction is at work between adhesive and adherend. Inasmuch as the density of the minute spots per unit area depends on the surface tension, the adhesive force also depends on the surface tension.     

镀银碳纤维布的制备及其毫米波RCS特性

采用化学镀方法在碳纤维布表面沉积了金属银层.测量了利用优化工艺制得的镀银碳纤维布的表面电阻,并采用冷热循环法对镀层结合强度进行了测试,应用雷达散射截面(RCS)测试系统对同样尺寸的镀银碳纤维布及未改性碳纤维布的毫米波波段RCS值进行了测试.结果表明:得到的镀银碳纤维布镀覆均匀、金属光泽强,有较强的导电性能.镀银碳纤维布在毫米波波段的RCS值较未改性碳纤维布有很大增幅,且与理论值相近.     

镀银层表面变色机理的电子能谱研究——(Ⅰ)镀银层的表面元素组成和化学态

用电子能谱(XPS和AES)研究了不同处理与历程的镀银层表面膜的元素组成和化学态,结果表明:(1)于干燥器内存放5天后的新鲜镀层(U_O)由元素银、氧、硫、氯和基底金属铜和沾污元素碳、钾和氮组成,随着存放时间增加,一系列未变色镀层(U_O与U_1)的元素银含量有规律地减少而氧几乎线性增加;(2)用NaCl溶液处理的镀层(U_1)的元素银、氧的分布在AES线扫描中一致,而用 Na_2S处理的镀层(U_2)的元素银、硫共存区部分取代了银、氧共存区,硫银原子比按下列顺序递减,即:室内干燥器内500天后的镀层(U_3)及室内干燥器内含1%H_2S的大气中24小时后的镀层(T_s)大于暴露室外大气中日光下24小时后的镀层(T_1);(3)由两维俄歇参数图发现在T_1已上面有19%的银为Ag_2O,而U_o上面仅有少量;(4)新鲜镀层用某些还原剂或络合剂处理后的防变色能力明显增加. 依据上述结果讨论了变色机理和防银变色原则.     

表面改性技术在连铸结晶器上的应用进展

表面处理是提高结晶器耐磨性和高温耐腐蚀性的有效手段,通过对镀层的改进可以达到提高连铸坯质量、延长结晶器寿命、提高铸坯的表面质量和降低生产成本的目的。综述了国内外最新的涂、镀层在结晶器上的应用情况及其特点。主要有热喷涂Ni-Cr镀层、超厚Ni-Fe镀层、Ni-Co合金、Ni-Fe-W-Co镀层、Ni-P复合镀层、陶瓷涂层、Hipercoat和Hiper H3镀层、纳米复合镀层等。同时指出采用稀土和纳米复合镀层等一些新型复合镀层是今后结晶器镀层的发展方向。     

Preparation and characterization of electromagnetic interference shielding polyimide foam

This article focused on the preparation and characterization of ultralight and high‐temperature resistant polyimide foam (PIF) for electromagnetic interference shielding. PIF was first prepared based on a one‐pot process by the primary reactions of derivatives of pyromellitic dianhydride and polyaryl polymethylene isocyanate. Then, PIFs with silver (0) coating were then prepared by spraying silver (0) on the surfaces of PIF through physical spraying method. The surface density of silver coating was 0.18 kg/m², and the densities of silver‐coated PIFs were less than 23 kg/m³. The scanning electron microscopy coupled with an energy‐dispersive X‐ray spectrometer (EDX) measurement were carried out to investigate the morphological and chemical properties of uncoated and coated PIFs. For coated PIFs, the EDX spectrums indicated increasing higher silver proportions from interior to exterior surface, together with increasing higher carbon proportions from exterior surface to interior. Thermogravimetry/Fourier transform infrared instrument that combined thermogravimetric analysis with pyrolysis product analysis by Fourier transform infrared spectroscopy were applied to investigate the thermal stability and pyrolysis products of uncoated and coated PIFs. The results indicated that the thermal properties of silver‐coated PIFs were improved obviously with the 5% weight loss temperature higher than 400°C and the residual weight retentions at 800°C ～ 80%. In the frequency range 200–7000 MHz, the EMI shielding efficiency with one surface and two surfaces coated with silver were in the range of 36.4–60.7 dB and 61.6–95.6 dB, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Silver nanoparticle deposition on hydrophilic multilayer film surface and its effect on antimicrobial activity

Silver nanoparticles were deposited on the surface of the external polyamide 6 (PA6) layer of a multilayer film, by spraying and ultrasound‐assisted methods. The effect of silver nanoparticles content and deposition method on the mechanical and optical properties of the multilayered films as well as the efficiency of silver ion release and their fungicidal characteristics were evaluated. Itaconic (IA) and Maleic anhydride (MA) were used as adhesion promoter agents for preventing the agglomeration of the silver nanoparticles and for improving the adhesion to the PA6 polymer surface. With IA, a homogeneous distribution of silver nanoparticles on the PA6 surface was achieved. The silver ion release and biocide effect of the multilayered films was found to be dependent on the anhydride type and on the deposition method used. The multilayer films with a layer of PA6‐silver nanocomposite demonstrated good fungicidal activity, specifically against fungus Aspergillius niger. The observed results could be applied in the design of industrial films for packaging. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012