Electropolishing of a Nickel-Titanium-Copper Shape Memory Alloy in Methanolic Sulfuric Acid

摘要

Electropolishing of NiTiCu shape memory alloy was performed in methanolic sulfuric acid as a surface processing method. The current investigation, using a rotating disk electrode, aims at identifying appropriate electropolishing conditions for this alloy based on understanding the underlying mechanism. The influence of temperature, rotation rate, and sulfuric acid concentration (3 or 5 M H2SO4) was quantified. Electropolishing in methanolic 5 M H2SO4 is solely mass-transport-controlled, while a mixed control is found for the methanolic 3 M H2SO4. This behavior is different from that of the binary NiTi alloy. From the electrochemical perspective, a methanolic 5 M H2SO4 solution is more suitable for electropolishing NiTiCu. The activation energy for electrodissolution is 21.5 kJ mol(-1).