Application of Electrolyte Jet to Rapid Composite Electroplating
Application of Electrolyte Jet to Rapid Composite Electroplating
复制标题
电解液喷射在快速复合电镀中的应用
DOI：
10.1179/026708404225010568
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发表时间：
2004
影响因子：
2.8
通讯作者：
M. Okumiya
中科院分区：
文献类型：
--
作者：
Hiromitsu Takeuchi;S. Tamura;Y. Tsunekawa;M. Okumiya
本文介绍了一种利用含陶瓷颗粒的电解液射流在铝合金基体上快速电镀Ni-P基复合镀层的工艺。电解液射流不仅使Ni-P基体的沉积速度极快，而且通过改变射流速度控制沉积物中颗粒的体积分数和磷含量。高沉积速率是由于电解液射流强制提供镍离子而使阴极表面附近的扩散层变薄而引起的。极限电流密度随射流速度的平方根线性增加。然而，随着射流速度的增加，在由析氢电压确定的电流密度下达到饱和。随着喷射速度的增加，沉积层中SiC颗粒的体积分数逐渐减小到零。这是因为当喷射速度加速时，吸附在阴极表面上的颗粒在解吸时受到更高的剪切力。相比之下，吸附的颗粒受到较低的剪切力时，射流减慢，虽然颗粒吸附力增加，由于阴极电位。基体中的磷含量随射流速度的增大而增大，随电流密度的减小而减小。由于吸附的磷原子抑制了镍晶体的生长速率，基体晶粒尺寸变细。因此，通过改变喷射速度和电流密度，喷射电镀工艺以高沉积速率实现颗粒体积分数和/或磷含量的组成分级共沉积。
This paper presents a rapid electroplating process which uses an electrolyte jet containing ceramic particles for the formation of Ni-P matrix composite coatings on an aluminium alloy substrate. The electrolyte jet not only makes the deposition rate of Ni-P matrix extremely fast, but also controls the volume fraction of the particles and phosphorus contents in the deposits by changing the jet velocity. The high deposition rate is caused by a thinned diffusion layer adjacent to the cathode surface as a result of nickel ions forcibly supplied by the electrolyte jet. The limiting current density increases linearly with the square root of jet velocity. As the jet velocity increases, however, it reaches saturation at the current density determined by the hydrogen evolution voltage. The volume fraction of SiC particles in deposits decreases to zero with increasing jet velocity. This is because the particles adsorbed on the cathode surface are subjected to a higher shearing force on desorption when the jet velocity accelerates. In contrast, the adsorbed particles are subjected to a lower shearing force when the jet slows, although the particle adsorbing force increases owing to the cathodic potential. The phosphorus content in matrices increases with the increase in jet velocity and with decrease in the current density. The matrix grain size becomes finer owing to a restraint on the growth rate of nickel crystals by adsorbed phosphorus atoms. Therefore, through a change in both the jet velocity and current density, the jet electroplating process achieves compositionally graded codeposits of the particle volume fraction and/or the phosphorus content with a high deposition rate.