镁合金基体上镍磷镀层的阳极退除

采用阳极退除方法退除镁合金上化学镀镍磷镀层,研究了退除液成分对镀层退除的作用,对常用的镁合金化学镀镍层的退除工艺（HF＋NaNO3）进行了改进。退镀液中含有一定浓度的F^-,可保护基体不受腐蚀;溶液中的NaNO3对保护膜起破坏作用;生成的保护膜主要为MgF2。     

铜基不合格镀层的退除方法

前言无论是印制电路板生产过程中,还是其它铜基电镀金属或合金制造过程中,都存在不合格镀层需要退除处理的问题.特别是一些贵重金属、稀有金属镀层更需要及时回收、综合利用.近几年来,许多研究单位、公司、企业注重镀层退除方法的研究,一些操作简便、价格便宜、效果明显的退镀溶液不断问世,一些探索机制的论文和披露配方的专著也相继发表.作者多年来注意这一领域的发展成果,先后撰写不少退镀方面的文章.本文主要介绍一些行之有效的铜基不合格镀层退除方法,着重配方、操作条件及其工艺参数的研究,对此感兴趣的单位可根据自己实际情况选择使用.     

不合格镀层的退除和补镀

1　前言　　镀铬过程中因各种原因会造成产品铬层不合格 ,如局部不上铬层、铬烧等 ,或者防腐能力差 ,外观轻微生锈。如果这些不合格产品直接报废 ,会大幅度增加生产成本。为节约成本 ,我厂对现有自动生产线进行合理改造 ,以实现不合格铬层产品的退除与补镀。2　自动生产线的工艺改造2 1　原工艺流程　第一阳极除油水洗超声波除油水洗 (2次 )阳极电解酸蚀水洗 (2次 )第二阳极除油水洗 (2次 )活化镍 (镍铁 )电镀回收水洗 (2次 )镀铬回收水洗 (2次 )2 2　改造后的工艺流程阳极除油、除铬水洗超声波除油水洗…     

从铁基体上退除金属镀层的方法

前言研究从铁基体上退除各种金属镀层,是一件非常有意义的工作.选择合适的退镀溶液,制定既经济又简捷的退镀工艺,是广大电镀工作者经常遇到的实际问题.而保证退除速度和退除质量,则是问题的关键.作者近几年来一直关注这类问题,先后撰写有关退除铜、金、银、锡、铬及铅锡等镀层的文章,引起一些同行的关心.本文介绍从铁基体上退除金属镀层的有关配方,供有关单位选用.     

镁合金基体上镍磷镀层的退除

提出了一种采用HF与HNO3退除镁合金上化学镀镍磷镀层的方法。测试了不同HF与HNO3组合的退镀液的性能,并分别测定了不同HF与HNO3含量对退镀效果的影响。结果表明,退镀液中含有一定含量的F^-,可保护基体不受腐蚀,其生成的保护膜主要为MgF2。当退镀液中ω(HF)：ω(HNO3)：ω(H2O)为4：3：3时,效果最好。由于HF有剧毒,因此操作过程应采取相应的防护措施。     

镁合金化学镀镍工艺研究进展

镁合金以其质量轻、比强度高、成型性好等优点备受人们关注.但是镁的电极电位比较低,容易被腐蚀,因此,使其应用受到限制.在镁合金表面进行化学镀镍,生成一层光滑、平整、致密的镍镀层,能有效地提高镁合金的耐蚀性能.     

退除铜及黄铜工件上镍镀层的“退镍粉”

介绍了一种退除铜及黄铜工件上镍镀层的退镍粉配方(以配制l kg为例):六水合硫酸镍30 g,硫酸钠435 g,硫氰酸铵30 g,苯并三氮唑5 g,防染盐S(间硝基苯磺酸钠)500 g.退镀液的组成及操作条件为:退镀粉120g/L,浓硫酸60 mL/L,温度25～ 75℃,机械搅拌.退镀流程主要包括化学除油、退铬、退镍和除黑膜.介绍了退镀液的配制及维护方法.     

镁合金化学镀镍工艺的研究

采用浸锌法在镁合金表面化学镀镍,并研究了硫酸镍、次磷酸钠、温度对化学镀镍层的影响。采用金相显微镜、XRD衍射仪及电化学测试对最优条件下得到的化学镀镍层进行性能表征。结果表明:化学镀镍层呈现胞状结构,表面光滑,结构均匀致密;化学镀镍层的耐蚀性明显提高,其自腐蚀电流密度相比镁合金基体的自腐蚀电流密度降低了两个数量级。     

Corrosion protection of magnesium alloy ZM21 by polyaniline-blended coatings

Phosphate-doped polyaniline pigment was prepared by a chemical oxidation method using ammonium persulfate in phosphoric acid media. Fourier transform infrared studies were done to characterize the pigment. The magnesium alloy ZM 21 was coated with polyaniline-pigmented paint, based on an epoxy binder, and the corrosion performance of the coating was studied by potential measurements and electrochemical impedance spectroscopy in 0.1% and 0.5% NaCl solutions. The results were compared with strontium chromate and filler material-pigmented coatings. It was found that the coating containing polyaniline provided similar protection for the magnesium alloy as that offered by chromate-pigmented paint.     

镁合金固相反应复相陶瓷涂层性能对比

采用固相反应法分别在MB2镁合金基体上制备Al2O3基和SiO2基复相陶瓷涂层,确定了陶瓷涂层的较佳配方如下:SiO2基陶瓷涂层为m(SiO2):m(Al2O3):m(MgO):m(钠长石)=66.8:13.2:12:8,Al2O3基陶瓷涂层为m(Al2O3):m(SiO2):m(MgO):m(ZnO)=66:12:12:10,陶瓷料浆与粘接剂质量比为0.5:1。对所制备的涂层结构,封孔前后涂层的致密性、耐酸性、耐盐水性以及耐磨性进行了测试。结果表明,SiO2基复相陶瓷涂层因在热固化过程中产生大量新相,而提高了涂层的致密性。与镁合金基体相比,封孔后涂层的耐酸性和耐盐水性分别提高了21倍和17倍,相对耐磨性增强了1.94倍,均优于封孔后Al2O3基复相陶瓷涂层的相关性能。     

镁合金表面微弧氧化陶瓷膜的形成过程研究进展

归纳了镁合金表面微弧氧化过程中电解液组成及工艺条件对陶瓷膜层表面形貌、截面形貌和相组成等的影响.结合成膜过程中电压及膜层厚度的变化规律,综述了镁合金微弧氧化陶瓷膜的形成机理.     

化学镀非晶镍-磷合金分形分析

在由NiSO4·6H2O、NaH2PO2·H2O、Na3C6H5O7、CH3COONa和KIO3组成的化学镀镍液中,改变配位剂柠檬酸钠的浓度制备了4种不同含磷量的Ni–P合金镀层,用投影覆盖法计算了其表面分形维数,并考察了分形维数与柠檬酸钠浓度及镀层耐硝酸性能的关系。结果表明,镀层的表面分形维数介于2.3298~2.6586之间,与柠檬酸钠浓度具有良好的线性正比关系,而与镀层在硝酸中的腐蚀失重量呈良好的线性负相关。因此,表面分形维数可用于定量表征镀层的耐蚀性。     

Comparison of corrosion performance of various conversion coatings on magnesium alloy using electrochemical techniques

Comparative studies on some of the important chemical conversion coatings, namely, phosphate–permanganate, galvanic black anodizing, dichromate treatment, and micro arc oxidized and modified acid fluoride anodizing on magnesium alloy AZ31B have been conducted. The surface morphology and composition of the coatings were examined through SEM and EDX techniques. Corrosion resistances of these coatings were compared using electrochemical impedance spectroscopy (EIS) and linear polarization studies. The corrosion resistances of the coatings investigated were found to be according to the order as follows: modified acid fluoride > micro arc oxidized phosphate > micro arc oxidized silicate > dichromate > galvanic black anodizing > phosphate-permanganate > bare magnesium.     

镁合金表面羟基磷灰石/介孔SiO_2自修复耐蚀涂层的研究

通过旋涂法,在AZ31镁合金表面制备了聚多巴胺/羟基磷灰石复合涂层,并将负载有缓蚀剂2-巯基苯并咪唑(MBI)的介孔SiO_2纳米颗粒掺杂到复合涂层中,以改善镁合金的耐腐蚀性能。使用SEM、TEM、XRD和BET等手段表征介孔SiO_2纳米颗粒的形貌、结构及缓蚀剂的负载情况;通过傅里叶红外光谱(FTIR)和扫描电子显微镜(SEM)对涂层的成分和形貌进行表征;使用电化学阻抗谱(EIS)研究了不同涂层的耐蚀性能和自修复性能。结果表明,制备的二氧化硅为介孔纳米颗粒,可负载缓蚀剂。将负载有缓蚀剂MBI的介孔SiO_2纳米颗粒掺杂到聚多巴胺/羟基磷灰石复合涂层中,能够改善涂层的耐蚀性能,使涂层具有自修复性能。     

Thermal study of selectively plated nickel sulfamate coatings

Nickel sulfamate solution was applied to mild steel substrates by the process of selective plating. The coated samples were heated to temperatures in the range of 50–1000 °C. Thermal analysis, X-ray diffraction and microscopy techniques were used to investigate the effect of secondary heating on the microstructure, mechanical properties and the composition of the surface coatings.     

机械镀锌-铝复合镀层的结构分析

采用金相显微镜、扫描电镜、能谱仪分析了混粉法机械镀锌-铝复合镀层的结构、形貌和化学成分分布。结果表明，机械镀锌-铝镀层主要是由尺寸不等的锌粉颗粒相互参杂、填充，形成致密结构体；锌粉颗粒之间的间隙填充着更小尺寸的锌粉和夹杂物，镀层中部分锌粉颗粒发生变形；片状铝粉在镀层中不均匀分布，铝粉和锌粉没有明显的包裹、缠绕；镀层中Fe，Sn，Zn的含量分布正常，且Al的含量比施镀前混粉中Al的含量低得多。     

Corrosion behaviors of Zn/Al-Mn alloy composite coatings deposited on magnesium alloy AZ31B (Mg-Al-Zn)

After being pre-plated a zinc layer, an amorphous Al-Mn alloy coating was applied onto the surface of AZ31B magnesium alloy with a bath of molten salts. Then the corrosion performance of the coated magnesium alloy was examined in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the single Zn layer was active in the test solution with a high corrosion rate while the Al-Mn alloy coating could effectively protect AZ31B magnesium alloy from corrosion in the solution. The high corrosion resistance of Al-Mn alloy coating was ascribed to an intact and stable passive film formed on the coating. The performances of the passive film on Al-Mn alloy were further investigated by Mott-Schottky curve and X-ray photoelectron spectroscopy (XPS) analysis. It was confirmed that the passive film exhibited n-type semiconducting behavior in 3.5% NaCl solution with a carrier density two orders of magnitude less than that formed on pure aluminum electrode. The XPS analysis indicated that the passive film was mainly composed of AlO(OH) after immersion for long time and the content of Mn was negligible in the outer part of the passive film. Based on the EIS measurement, electronic structure and composition analysis of the passive film, a double-layer structure, with a compact inner oxide and a porous outer layer, of the film was proposed for understanding the corrosion process of passive film, with which the experimental observations might be satisfactorily interpreted.     

镀银件返修及防变色处理

１　前言　　本厂库存一批组合电子器件,分别为铝制波导、铜质电缆及端板,镀银连接件及接插件,还有部分镀锌件。入库前分别按设计要求严格进行了表面处理。经过１０多年库存积压,大部分工件仍可使用,只是镀银件已严重变色,表面产生一层牢固黑膜。厂里新开发了一种电子整机产品,正好需要这种组合器件,由于重新制造不仅需要资金,且加工周期太长,因此决定启用这批已变色的镀银组合件。变色的镀银层表面接触电阻增大,影响整机性能,因此必须设法去除。２　镀银件表面产生黑膜的原因由于银具有优良的导电、导热及焊接性能,因此,镀银…