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为提高圆筒状工件内壁电镀铬的沉积速度,采用自行研制的离心高速电镀铬装置。研究了电流密度与沉积速度、晶粒尺寸及镀层硬度的关系。结果表明,离心高速电镀铬的极限电流密度及沉积速度、镀层硬度均增大,镀层晶粒更细致。 相似文献
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脉冲电镀镍及其性能的研究 总被引:3,自引:0,他引:3
采用瓦特镀镍液,研究了脉冲占空比、平均电流密度、温度对电沉积速率,镀层光亮度和镀层在w=3.5%的NaCl溶液中耐蚀性的影响.用扫描电镜研究了直流和脉冲镍镀层的表面形貌.结果表明:电沉积速率随脉冲占空比、平均电流密度及温度的增大而加快;镀层耐蚀性,光亮度随脉冲占空比增大而变差,随温度、平均电流密度的增大先变好后变差.较佳脉冲电镀条件为:平均电流密度0.75 A/dm~2,脉冲占空比5%,温度45~50 ℃,pH 2.5~3.0.X射线衍射分析结果表明,与直流镀镍相比,脉冲镍镀层在(111)晶面存在择优取向,镀层更致密,性能更好. 相似文献
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采用氨基磺酸盐镀液电沉积镍层,通过WLI,SEM,XRD和MHT对镀层的三维形貌、微观织构及硬度进行分析。结果表明:在镀液中不含添加剂的情况下,随着阴极电流密度的增加,镀层晶粒细化,但镀层致密性变差且硬度呈近似线性关系降低;镀液中加入适量添加剂后,镀层衍射谱特征和各晶面的择优取向度无明显改变,但在相同阴极电流密度下所得镀层的晶粒更加细小且硬度有所提高。 相似文献
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采用电沉积方法制备Cu-SiO2复合镀层,并研究了搅拌速率、电流密度和电流施加方式对其形貌与硬度的影响。结果显示:随着搅拌速率的提高,复合镀层的形貌先趋好后变差,硬度先升高后降低;而随着电流密度的增加,复合镀层的形貌呈现逐渐变差的趋势,硬度近似线性降低;在同等条件下,电流以脉冲形式施加有利于改善复合镀层的形貌,密实组织结构,提高硬度。 相似文献
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Ping Wang Ying-liang Cheng Zhao Zhang 《Journal of Coatings Technology and Research》2011,8(3):409-417
Ni–SiC nanocomposite coatings were prepared on a brass substrate by electrocodeposition. The electrodeposition was carried
out by adding the SiC nanoparticles to a nickel-containing bath. Nickel deposition processes were analyzed by cathodic polarization
curves, and the plating parameters were determined preliminarily by analyzing the effects of different technological parameters
on the deposition process. Then, electrocodeposition processes were carried out with different concentrations of SiC nanoparticles
in the bath. The effects of current density, stirring rate, and SiC nanoparticle’s concentration in the plating bath on the
hardness of coatings were investigated by microhardness tests. Besides the microhardness tests, wearing tests and corrosion
tests were also applied to the coatings with the highest hardness and coatings of pure nickel. The structures and surface
morphologies of the coatings were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The
experimental results show that the microhardness of the codeposited coating increases with increasing current density and
attains a maximum at the SiC concentration of 6 g/L. The decrease in the microhardness at higher SiC concentrations may be
due to agglomeration of nanosized particles in the plating bath. Increasing the stirring speed did not give a better quality
deposition as coatings produced at low stirring rates always had higher microhardness values than did those at high stirring
rates. Furthermore, the Ni–SiC nanocomposite coatings have lower friction coefficient and better corrosion resistance than
those of pure nickel coatings. 相似文献
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