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

Under trielectrode system, in mixing well the self-prepared Ti(SO4)2 solution electrolyte, catodic-electrodeposition was carried out at a constant current density of 5mA/cm2 for 4min. Because NO3- and H2O on the surface of cathode sample obtained electrons to be reduced, making sample surface PH value get high, moreover Ti (IV) could be easily hydrolyzed, so that a layer of amorphousstate Ti-O film was deposited on the surface of TiNi SMA. Its producing process is as following:

$$2\text{H}\_2\text{O} + 2\text{e} \rightarrow \text{H}\_2 + 2\text{OH} \cdot \text{} \tag{1.1}$$

$$\mathrm{NO}\_{3}^{\cdot} + \mathrm{6H}\_{2}\mathrm{O} + 8\mathrm{e} \rightarrow \mathrm{NH}\_{3} + \mathrm{9OH} \cdot \tag{1.2}$$

$$\text{Ti}^{4+} + \text{4OH} \cdot \text{I} \rightarrow \text{Ti(OH)} \tag{1.3}$$

The Ti(SO4)2 gel reactively produced was deposited on the surface of the sample.
