The polishing mechanism of electrochemical mechanical polishing technology

In this paper, the polishing mechanism of the electrochemical mechanical polishing (ECMP) technology for tooling steel SKD11 was investigated. Suitable electrochemical process parameters were evaluated. The electrochemical characteristics of a material such as active, passive and trans-passive (dissolution) can be revealed from its I–V curve. The characteristics of passive and trans-passive have great effects on the ECMP polishing mechanism. Experimental procedures included qualitative, quantitative and surface quality analyses. Qualitative analyses utilized potentiostat to study the I–V curves of a specific specimen in various electrolytes and electrolytic concentrations, and to find out the voltages at each electrochemical state. In quantitative analyses, the electrochemical polishing processes of the ECMP technology were conducted. From the measured and theoretical weight losses, each process state can be verified whether or not it followed the Faraday’s law. Finally, the surface roughness was measured by a surface profiler. The scanning electron microscopy (SEM) was used to observe the surface profile. The energy dispersive spectroscopy (EDS) analysis was employed to analyze the metallurgical compositions of the surface. In summary, the proposed mechanism and analyses were a good methodology in finding suitable electrochemical process parameters for ECMP technology.