Development in novel electroless plating of compositionally graded coating with high deposition rate

复合化学镀或电镀是一种典型的表面涂层工艺。将电解液射流应用于氧化铝或碳化硅颗粒/镍体系的复合电镀。电解液射流不仅可以提高极限电流密度，加快沉积速度，而且可以通过改变射流速度来控制颗粒的体积分数。本研究提出了一种新的化学镀工艺，即利用压力容器来形成高沉积速度的SiC/Ni-P复合镀层。除了提高沉积速率外，本研究旨在通过改变镀覆温度和搅拌速度来控制磷含量、SiC颗粒体积分数和颗粒平均直径。作为SiC颗粒体积分数和粒径控制的典型应用， ...更多信息 以纯铜（99.94%）为基体，研究了Ni-P合金镀层的成分梯度与镀层中颗粒体积分数和颗粒平均直径的关系。本研究所采用的化学镀系统包括压力控制系统、搅拌槽和镀液时间控制系统。采用扫描电镜对化学沉积镍基复合材料进行了表征。在363 K下，压力提高了化学镀中电解液的沸点，使沉积速率比常规化学镀快约10倍;随着镀液温度的升高，磷含量增加，在不改变电解液中次膦酸浓度的情况下，通过改变温度来控制，搅拌速度和电解液温度决定了SiC颗粒的体积分数在5至17体积%的范围内而不改变电解质中的颗粒浓度。在不改变电解液中SiC颗粒粒径的情况下，确定了沉积物中SiC颗粒的平均粒径。因此，这种新的高压下的化学镀实现了SiC颗粒/Ni-P沉积物，其具有关于颗粒体积分数和颗粒平均直径的组成梯度，并且具有高沉积速率。少

Composite electroless or electro plating containing ceramic reinforcements or selflubricant particles is typical surfacecoating process. The authors applied an electrolyte jet to the composite electroplating of aluminum oxide or silicon carbide particle/nickel system. The electrolyte jet enable not only a fast deposition rate because of a rise in the limiting current density, but also makes possible volume fraction control of particles by changing the jet velocityThis research presents a new electroless plating process that uses a pressure vessel for the formation of electroless deposited SiC/Ni-P composite coating with high deposition rate. In addition to an improvement in deposition rate, this research is aimed at making control of the phosphorus content, the SiC particle volume fraction and the particle average diameter possible by changing the plating temperature and agitation speed. As a typical application of the volume fraction of SiC particles and the particle diameter controls … More , we discuss the compositional gradient Ni-P deposits in relation to the particle volume fraction and the particle average diameter, which increases in the thickness direction.A piece of pure copper (99.94%) was employed as a substrate. The electroless plating system which consists of vessel pressure control system, a stirring bath to disperse the particles into the electrolyte and the plating time control system is used in the present study. Scanning electron microscopy observation was performed to characterize the electroless deposited nickel alloy matrix composites. The abrasion test was carried out in the plated specimen.The pressure increases the boiling point of electrolyte in electroless plating, so that the deposition rate will be approximately 10 times faster than conventional electroless plating at 363K.And phosphorus content increases with the plating temperature increase, it is also controlled by change the temperature without changing the phosphinic acid concentration in electrolytes.The agitation speed and temperature of electrolyte determine the volume fraction of SiC particles in the range from 5 to 17 vol.% without changing the particle concentration in electrolyte. And they determine the SiC particles average diameter in deposits without changing the particle diameter in electrolyte. Hence, this novel electroless plating under the high pressure realizes SiC particle/Ni-P deposits with compositional gradient regarding the particle volume fraction and the particle average diameter with high deposition rate. Less