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三价铬脉冲电沉积纳米晶Ni-Cr合金工艺 总被引:1,自引:0,他引:1
采用脉冲电沉积方法对三价铬电沉积Ni-Cr合金镀层工艺进行研究,确定并优化三价铬脉冲电沉积Ni-Cr合金的最佳镀液配方及工艺参数。研究镀液中各成分及工艺参数对三价铬脉冲电沉积Ni-Cr合金厚度及合金镀层中铬的影响,利用扫描电镜和电子能谱分析Ni-Cr合金镀层的形貌、微观结构和化学组成。结果表明,镀层厚度和Ni-Cr合金中铬含量在不同浓度的络合剂、稳定剂、乙酸钠及不同的电流密度、温度、pH值、占空比和脉冲频率下都存在极大值,且Ni-Cr合金厚度随合金中铬含量的增加而减少。当铬含量为24%时,镀层的厚度大于10μm,无裂纹,其晶粒为纳米球状晶粒。 相似文献
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甲酸盐三价铬电镀工艺的研究 总被引:1,自引:1,他引:0
目的解决现有氯化盐体系和硫酸盐体系三价铬电镀存在的问题。方法以甲酸铬为主盐,甲酸铵、尿素和苹果酸为络合剂,通过Hull槽试验和方槽试验,研究铬离子、甲酸铵、尿素、苹果酸的浓度以及镀液pH值、镀液温度、电镀时间等工艺参数对黄铜表面三价铬镀层形貌、沉积速率和光亮范围的影响。结果甲酸铵和尿素分别与Cr3+形成活性络合物,苹果酸具有pH值的缓冲作用。最佳的工艺条件为:Cr3+浓度0.4 mol/L,甲酸铵浓度0.5 mol/L,尿素浓度0.2 mol/L,苹果酸浓度0.05 mol/L,镀液pH值3.5,镀液温度25~30℃。结论该甲酸盐三价铬电镀工艺具有较宽的光亮范围,镀层孔隙率低,光亮致密,沉积速率较高,与铜基体结合良好,结构为混晶态。在室温、电流密度为15 A/dm2的条件下电镀5min,镀铬层厚度即可达到1.78μm,满足装饰性镀铬层的要求。 相似文献
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我厂在连续大批量镀铬生产中,由于镀件形状复杂,体形大,需要大量外加阳极,因而大量消耗镀铬槽溶液中三价铬的含量,以致使镀液中三价铬供不应求,而达不到工艺要求,造成沉积速度缓慢、镀层质量恶劣、溶液均镀性能降低等疵病。尤其当镀液中三价铬低于1.2克/升时,就难获得较好的镀络层。这对我们连续三班制生产的电镀单位来说,是一个急待解决的重要问题。过去,我们是停产的情况下采用1:5的阳极〈铅板〉和阴极〈薄钢板》在温度约50~60℃和阴极电流密度为5~10安/分米~2的条件下进行处理。以求得镀液中三价铬的增高。这样的处理效果缓慢,满足不了生产的需 相似文献
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次亚磷酸盐溶液电镀三价铬工艺的电化学 总被引:1,自引:0,他引:1
研究了次亚磷酸盐溶液电镀三价铬工艺的溶液化学性质,对镀液中三价铬离子与次亚磷酸根离子的配位化合物进行了探讨。用线性电势扫描法、循环伏安法研究了镀液的电化学特征及镀液中氟离子、次亚磷酸根离子、溶液pH值对阴极析氢反应的影响。讨论了获得最佳电流效率的条件 相似文献
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脉冲电沉积纳米晶镍-铁-铬合金(Ⅰ)--电沉积工艺 总被引:2,自引:0,他引:2
在恒电位脉冲的条件下,pH控制在0.8~1,阴极电流密度为12~20 A*dm-2,周期为25 ms,占空比为0.3,镀液温度维持在20~30 ℃,采用循环镀液的方法以避免二价铬离子的干扰,从含三价铬离子的镀液中电沉积出镍-铁-铬合金.X射线衍射结果表明沉积的镀层为晶体结构,存在较强的(111)织构.能谱和扫描电镜的结果显示电沉积出的镍-铁-铬合金镀层中含有少量的硫,其晶粒尺寸小于100 nm.通过这种方法可以获得厚镀层.电化学分析表明随着电流密度的增大,镀层的耐蚀性相应增强. 相似文献
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Yong Choi 《Metals and Materials International》2012,18(4):667-671
Inner crack behavior of electro-deposited trivalent chromium was analyzed in-situ by small angle neutron scattering to study the abrasive heating effect on neutral salt fog spray life. The trivalent chromium was prepared by different current wave forms, namely, direct and pulse current-plating with a modified chromium chloride bath. The trivalent chromium layer has columnar grains in which small chromium clusters and inner cracks are present. Pulse current plated trivalent chromium has a longer neutral salt fog spray life than direct current plated trivalent chromium. As surface temperature increases to 80 °C, inner cracks of the trivalent chromium layer formed by direct current plating tend to have a fractal shape by opening crack tips, whereas those of the chromium layer formed by pulse current plating are relatively stable. The inner crack with a fractal shape is related to an abrupt reduction of the neutral salt fog spray life of the trivalent chromium. 相似文献
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机械镀锌镀层钝化与耐蚀性能研究 总被引:1,自引:0,他引:1
对机械镀锌层分别用三价铬、稀土和六价铬进行了钝化处理,利用盐雾试验和电化学测试对不同钝化膜的耐蚀性与电化学行为进行了比较研究.盐雾试验结果表明,稀土与三价铬钝化处理的效果均已超过传统的六价铬钝化,比六价铬钝化膜的耐蚀性提高了一倍以上;稀土钝化膜的耐蚀性最好,三价铬钝化膜的耐蚀性仅次于稀土钝化膜的.电化学测试表明,三价铬、稀土和六价铬钝化膜都能够不同程度地抑制腐蚀的阴极电极反应,抑制阴极反应程度最大的是稀土钝化膜,其次是三价铬钝化膜,最小的是六价铬钝化膜.三价铬与稀土钝化工艺的环保和良好的防腐效果使其具有良好的应用前景. 相似文献
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硫酸铈对三价铬钝化膜耐腐蚀性的影响研究 总被引:2,自引:2,他引:0
目的研究硫酸铈对三价铬钝化膜耐蚀性能的影响。方法通过在三价铬镀铬盐溶液中分别添加0.3、0.5、0.8、1.0、1.5 g/L的硫酸铈,然后通过极化曲线测试,对比不同硫酸铈添加量的钝化膜的腐蚀电流密度,确定硫酸铈在三价铬镀铬盐溶液中的最佳添加量,然后分别制备未添加硫酸铈和添加最佳添加量硫酸铈的三价铬钝化膜,通过电化学工作站CHI660E测量Tafel极化曲线和电化学阻抗谱。分析钝化膜的电化学性能,研究不同钝化膜的耐腐蚀性。观察试样表面的微观形貌,对比添加硫酸铈和未添加硫酸铈的钝化膜的微观形貌。结果通过极化曲线测试发现,当硫酸铈的添加量为1.0 g/L时,钝化膜的腐蚀电流密度小于其余添加量的钝化膜,添加硫酸铈和未添加硫酸铈的钝化膜的耐蚀性能不同,添加硫酸铈后的钝化膜性能得到改善,且钝化膜膜层的微观形貌发生改变。结论添加硫酸铈后,三价铬钝化膜的耐腐蚀性能增强。当硫酸铈的添加量为1.0 g/L时,腐蚀电流密度最小,为3.835×10~(-6) A/cm~2,耐腐蚀性能优于其余钝化膜。 相似文献
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分析了铝合金三价铬钝化液的钝化机制,研究了复合盐钝化剂用量、钝化处理时间和温度对钝化膜质量的影响。结果表明,经铝合金三价铬钝化液钝化后的试样,其抗腐蚀性能优于铬酸钝化液,可在常温下进行处理,且处理时间较短,有利于减轻铬酸钝化液中六价铬离子对环境的影响。 相似文献
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分析了一种高效、环保压铸锌合金用三价铬钝化液的主要成分及其操作工艺条件,优化了钝化液工作的参数,包括钝化液pH值、钝化温度和钝化时间的影响.研究结果表明,经三价铬钝化液处理后的锌合金,其钝化膜层均匀,色泽白亮、略显淡蓝色,耐中性盐雾腐蚀时间超过96h;该三价铬钝化液不仅有利于减轻原六价铬钝化液中六价铬对环境的污染,而且价格便宜、操作工艺简单. 相似文献
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Yong Choi 《Metals and Materials International》2010,16(5):755-760
Thick trivalent chromium layers were prepared in a modified chromium sulfate bath by pulse plating to replace hexavalent hard
chromium coating in industrial fields; layer microstructure development was systematically studied by using electron microscopy
and small angle neutron scattering (SANS) to give a model for nucleation and growth behaviors during the pulse plating. Finer
columnar grain was formed by pulse plating due to its high nucleation rate at the same current density. Average deposition
rate of the trivalent chromium layers is in the range of 32.4 μm/h to 49.7 μm/h. The deposition rate increases as the diameter
of cylindrical shape of chromium cluster in a columnar grain is reduced. The highest deposition rate in this study was observed
under the conditions of direct current density of 0.4 Acm−2, combined with a rectangular shape pulse current density of 1.5 Acm−2 with a 10/2 on-off time ratio. Most of the inner-cracks of the trivalent chromium layers have dimensions in the range of
about 39 nm. Ultrasonic agitation during pulse plating resulted in an increase of neutral salt fog spray life, which is related
to smaller crack size and broader size distribution in the trivalent chromium. 相似文献
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热镀锌板三价铬钝化剂的制备及其钝化膜耐蚀性能 总被引:4,自引:2,他引:2
目的制备钝化膜耐蚀性良好的热镀锌板三价铬钝化剂。方法以铬酸酐、酒石酸盐、无机混酸、纳米硅溶胶为原料,制备三价铬钝化剂。采用该钝化剂对热镀锌板进行钝化处理,通过中性盐雾试验、Tafel极化曲线和交流阻抗谱分析钝化膜的耐蚀性能,并表征钝化膜的表面形貌和元素组成。结果钝化镀锌板经120 h中性盐雾试验后,腐蚀面积仅为5%。与未钝化镀锌板相比,钝化试样的自腐蚀电位有所正移,自腐蚀电流密度降低了约2个数量级。钝化膜表面较为平整,有少量白色颗粒沉积,膜中主要含有C,O,Si,Cr,Zn等元素,且Cr主要以三价和六价存在,Zn以二价存在。结论该三价铬钝化剂可提高镀锌板的耐蚀性能,具有较好的工业使用推广价值。 相似文献
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高耐蚀性三价铬蓝白色钝化膜获得方法 总被引:1,自引:0,他引:1
镀锌层蓝白色钝化膜耐腐蚀性差是电镀行业一个长期得不到解决的难题,六价铬盐蓝白色钝化膜是如此,三价铬盐蓝白色钝化膜也是如此;这是由于蓝白色钝化膜层太薄的缘故.为此,在增加蓝白色钝化膜的厚度方面进行了努力,终于研制成功了一种能获得较厚、具有高耐蚀性钝化膜的WX-3TC三价铬蓝白色钝化剂及其钝化工艺,盐雾试验出现白锈的时间可达240h以上,从而解决了蓝白色钝化膜耐腐蚀性差的难题. 相似文献
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C. M. Whittington 《金属精饰学会汇刊》2018,96(2):63-70
‘Nickel Allergy’ sometimes occurs when nickel-containing articles are in direct and prolonged contact with the skin, leading to corrosion of elemental nickel by sweat, liberating sufficient nickel ions to be absorbed through the skin and initiate an allergenic effect. EU ‘Nickel Restrictions’ impose limits on the amount of nickel released from articles intended for use in this application but permits a non-nickel surface coating that can ensure the rate of nickel release does not exceed 0.5?μg?cm?2?week?1 after 2 years of normal use. The official tests for coated items are simulated wear and corrosion under EN 12472 followed by determination of nickel release under EN 1811, and articles shall not be placed on the market unless they pass these tests. A paper published in Transactions during 2015 reported bright nickel coatings with top coats that would prevent nickel release and pass these tests. Regular chromium deposited from a hexavalent electrolyte was the benchmark, with microporous chromium and supplementary organic coatings evaluated for improved performance. All prevented nickel release, but the best low-cost commercial coating was regular (conventional) chromium deposited from a hexavalent electrolyte. Further tests reported here were conducted to evaluate bright nickel deposits with top coats of tin–cobalt alloy, and of hexavalent chromium with supplementary coatings of coloured physical vapour deposition and electrophoretic coatings. Tests with trivalent chromium top coats deposited from proprietary chloride and sulphate electrolytes showed that regular (conventional) chromium over bright nickel failed the nickel release test. But microporous trivalent chromium deposits passed the tests satisfactorily. 相似文献
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电沉积非晶态Cr—Fe—C合金镀层结构与性能研究 总被引:2,自引:0,他引:2
采用以三价铬为主盐的铬合金电镀工艺,对获得的Cr-Fe-C合金镀层的化学成分、结构、性能及其成因进行研究,结果表明,这种含铁量为20%,含碳为5%左右的镀层为非晶态结构,含有大量微裂纹,微观上镀层表面呈结瘤状,热处理后可出现极明显的硬化现象,并伴随镀层逐渐向晶态转化。 相似文献