**1.2.2.1 Cathodic-electrodeposition of Ti-O film**

A standard trielectrode system was used in the experiment. The device sketch is as shown in figure 1-1. The power supply was DJS-292 type of potentiostat; the reference electrode was saturated calomel electrode (SCE); a TiNi SMA sample was connected with copper wire, its working area was 10mm×10mm, and the non-working area was coated with silica gel; the electrolyte was the self-prepared Ti(SO4)2 solution.

Before cathodic-depositing the PH value of the Ti(SO4)2 solution was modified to PH1.2 with 300g/l of KOH solution, adding to 20g/l KNO3. Under this circumstance of that let sample be cathode, at a constant current density of 5mA/cm2 for 4 min of electrodepositing, a layer of Ti-O film was formed on the surface of TiNi SMA. After finished deposition, the samples were exposed to air for drying naturally, then put them in drying oven for 1h at 120 C, and then awaited for use.

Fig. 1-1. Schematic plan of the trielectrode system
