Abstract
For the purpose of micromachining application, we have studied basic characteristics of electrochemical etching of NiTi Shape Memory Alloy (SMA) in new electrolytes of inorganic salt in alcohol for comparison with conventional H2SO4-methanol solution, especially from the viewpoint of the suppresion of the etching rate. In the case of conventional H2SO4-methanol solution, good etching with planarized etched surface and high etch rate could be carried out, however, the etch factor (etching depth/side etching width) and surface flatness became worse under low etch rate conditions. The electrochemical etching of SMA also could be carried out in new electrolyte solutions using NH4Cl, NaClO4 and LiCl solute. Especially in the case of LiCl-ethanol, good etching properties such as controllable low etch rate of 3.5μm/min, planarized etched surface and high etch factor of 1.5 were realized. Although the etching condition was not in the electrolytic polishing region, the etched surface was planarized because there were no influences of a reaction of passivation, which inhibits the surface planarization. In the case of LiCl-methanol, the etching rate was over 10μm/min, however, planarized etched surface and high etch factor were also realized.
