Electrolytic processing of NiTi shape memory alloys

Electrolytic procedures are of great interest to produce components made of NiTi-shape-memory alloys (NiTi-SMA). Products of medical technology and micro system technology as well as components with elaborately manufactured structures or outlines are of special importance. In literature you can hardly find any systematic investigations about the electrolytic processing of NiTi-SMA and the surface structurings achieved in the process. The paper at hand shows that it is possible to polish NiTi-SMA in austenitic and martensitic state and to achieve satisfactory results (smooth surfaces). In the process of polishing in austenitic state, however, a formation of waves due to segregation occurs after longer periods of polishing. In the course of electrolytic polishing in martensitic state the current density is more uniformly and the formation of waves is omitted. The surface polished in martensitic state shows a pseudo-martensite-relief after the conversion into austenite. This relief structure offers additional possibilities in the substrate preparation for coatings. Within this process electrolytic etching of NiTi-SMA is also appealing. It was possible to show that defined, finely structured surfaces can be manufactured.