Novel automatic electrochemical-mechanical polishing (ECMP) of metals for scanning electron microscopy

A low-stress automated polishing device was developed for preparing titanium and nickel alloys for scanning electron microscopy imaging. The system used pulsed electrochemical reactions within an alkaline electrolyte to generate a thin passivation layer on the surface of the sample, which was removed by the mechanical vibration of the system. The passivation layer development and removal were documented for Ti-6Al-4V and IN718 samples subjected to varying electrical potential cycles and polishing times. Results indicated that the applied cyclic potentials removed material faster than typical removal techniques. In addition, electron back scatter diffraction data showed a decrease in subsurface damage using the developed electrochemical-mechanical process compared to standard mechanical polishing techniques.