2003 Volume 54 Issue 10 Pages 693-697
This paper describes the effects of pulse voltage application on the basic characteristics of electrochemical etching of NiTi shape memory alloy in LiCl-ethanol solution. The influence of dissolves products on etching characteristics has been also considered. The etched surface tended to be rough in the case of pulse etching under a low pulse duty ratio, under low applied voltage and with a wide etching pattern. The etch rate was about 4μm/min in the case of DC etching ; on the other hand, the etch rate could be suppressed below 0.5μm/min in the case of pulse etching with linear dependence on the duty ratio. Etch factor (etched depth/side etching width) increased above 2.0 with a wide pattern in the case of pulse etching because the dissolved products can be diffused out from the etched groove in the OFF-time of the pulse. However, there was little drastic effect of pulse etching on the etch factor when the pattern was narrower than 60μm because of the difficulty of the diffusion. It has become apparent that the dissolved products are necessary to obtain a uniform etched surface ; however, the dissolved products inhibit the high etch factor. Suitable etching conditions should be selected according to the application.
