**1.3.2 The composition analysis of Ti-O film**

Figure 1-3 shows the SEM topography (at different amplifications) of a Ti-O film cathodically-electrodeposited. It can be seen from the figure that under this experimental parameter, the Ti-O film obtained was well-distributedly deposited on TiNi SMA surface. This Ti-O film is closely composed of a lot of tiny particles, the particle's size is in about dozens of nanometers. This close bonding of the particles in nanometer class is conducive to strengthen the TiNi SMA surface properties, and to prevent Ni release from substrate.

Figure 1-4 shows an EDS analysis of the Ti-O film after cathodic-electrodeposition. It can be seen from the figure that this film mainly contains Ti element, as well as a small of amount of Ni element, and the ratio of Ti and Ni reachs 3:1. It illustrates that there is a lot of Ti element in the film. Because EDS might possibly puncture the Ti-O film, thus reflecting the substrate's element, so it could be preliminarily verified that by cathodic-elcetrodeposition, a layer of film mainly including Ti element indeed has been deposited on the surface of TiNi SMA.

Ti-O Film Cathodically-Electrodeposited on

0.0

2.0x103 4.0x103 6.0x103 8.0x103 1.0x104 1.2x104 1.4x104 1.6x104 1.8x104 2.0x104 2.2x104

Intensity

**Ti3s**

Fig. 1-5. XPS survey spectra of sample cathodically-electrodeposited

5.0x10<sup>3</sup>

1.0x10<sup>4</sup>

1.5x10<sup>4</sup>

Intensity

2.0x10<sup>4</sup>

2.5x10<sup>4</sup>

3.0x10<sup>4</sup>

the Surface of TiNi SMA and Its Bioactivity and Blood Compatibility 9

Ti2p

**C1S**

0 200 400 600 800 1000 1200

Binding energy (eV)

2p3/2(Ti4+:458.8eV)

2p1/2(Ti4+:464.6eV)

445 450 455 460 465 470 475 480

Binding energy (eV)

Fig. 1-6. Ti2p XPS energy spectrum of sample cathodically-electrodeposited

**Ti(LMM)**

**<sup>O</sup> O(KLL) 1s**

Figure 1-5 shows an XPS (X-ray photoelectron spectroscope) analysis result of Ti-O film surface after cathodic-electrodeposition of TiNi SMA. It can be seen from the figure that Ti-O film mainly contains the elements of O and Ti, besides element C (an extraneous pollutant), no Ni element exists.

Figure 1-6 shows a high resolution XPS analysis result of Ti2p in Ti-O film. It can be seen from the figure that there are two peaks, at 458.8eV and 464.6eV respectively, both are Ti quadrivalentcations, corresponding with Ti-O bonding energy at the spin state of 2p3/2 and 2p1/2.

Figure 1-7 shows a high resolution XPS analysis result of Ni2p in Ti-O film. It can be seen from the figure that there are no clear peaks emerging, illustrating that no Ni element existing in the Ti-O film.

Figure 1-8 shows a high resolution XPS analysis result of O1s in Ti-O film. It can be seen from the figure that there are two peaks existing, one 530.2eV, this is O2-; another one 530.7eV, and this peak is an integrated OH-. So, the Ti-O film obtained by cathodicelectrodeposition should exist in the form of TiO2 or hydrate of Ti(OH)4.

Fig. 1-3. SEM result of Ti-O film

Fig. 1-4. EDS result of Ti and Ni in Ti-O film

Figure 1-5 shows an XPS (X-ray photoelectron spectroscope) analysis result of Ti-O film surface after cathodic-electrodeposition of TiNi SMA. It can be seen from the figure that Ti-O film mainly contains the elements of O and Ti, besides element C (an extraneous

Figure 1-6 shows a high resolution XPS analysis result of Ti2p in Ti-O film. It can be seen from the figure that there are two peaks, at 458.8eV and 464.6eV respectively, both are Ti quadrivalentcations, corresponding with Ti-O bonding energy at the spin state of 2p3/2 and

Figure 1-7 shows a high resolution XPS analysis result of Ni2p in Ti-O film. It can be seen from the figure that there are no clear peaks emerging, illustrating that no Ni element

Figure 1-8 shows a high resolution XPS analysis result of O1s in Ti-O film. It can be seen from the figure that there are two peaks existing, one 530.2eV, this is O2-; another one 530.7eV, and this peak is an integrated OH-. So, the Ti-O film obtained by cathodic-

electrodeposition should exist in the form of TiO2 or hydrate of Ti(OH)4.

pollutant), no Ni element exists.

existing in the Ti-O film.

Fig. 1-3. SEM result of Ti-O film

Fig. 1-4. EDS result of Ti and Ni in Ti-O film

2p1/2.

Fig. 1-5. XPS survey spectra of sample cathodically-electrodeposited

Fig. 1-6. Ti2p XPS energy spectrum of sample cathodically-electrodeposited

Ti-O Film Cathodically-Electrodeposited on

formation of TiO2 is as the reaction formula:

EDT 300 EDT 450

1. 2. 3. 4.

> 1. 2. 3. 4.

Fig. 1-9. XRD result of heat treated Ti-O film

TiNi SMA 300

EDT: electrodeposition TiO2

TiNi SMA 450

Intensity

the Surface of TiNi SMA and Its Bioactivity and Blood Compatibility 11

Figure 1-9 shows an XRD analysis result of TiNi SMA deposited after heat treatments at different temperatures. It can be seen from the figure that in the Ti-O film crystallized at 300C, no TiO2 existing was found besides the main peak reflecting the substrate. But after crystallized at 450C, there is the peak emerging of anatase TiO2 in the figure. Because the substrate also has Ti element existing, to investigate if the anatase TiO2 formed by substrate's thermo oxidation, the same parameters' XRD for the TiNi SMA blank sample before depositing was done. But in the result, no clear TiO2 peak merged after crystallized at 450C, this illustrates that the film obtained by cathodic-electrodeposition is truly an amorphous-state Ti-O film, its composition is mainly in the form of hydrate Ti(OH)4. The

Ti(OH)4 → TiO2 + 2H2O (1.4)

△

△ TiNi (B2)

(Anatase)

● TiO2

15 20 25 30 35 40 45 50 55 60 65 70

2 Theta.

**1.3.3 Corrosion potential test of the materials in simulated physical environment** 

Figure 1-10 shows a relation of corrosionpotential-time of the samples before and after depositing in Hank's solution (PH7.45). It can be seen from the figure that the corrosion potential of the deposited sample dipping in solution went down quickly, about 5 minutes after, the corrosion potential did basically not change any more, stabilizing at -0.4V. Furthermore the stable corrosion potential was more positive than the non-depositing sample's, at about -0.2V. This illustrates that the deposited sample has a higher thermodynamic stability than the non-depositing sample's one at PH7.45 in Hank's solution. Figure 1-11 shows a graphofarelation of corrosionpotential-time of the samples before and after depositing in Fusayama solution (PH6.13). It can be seen from the figure that the corrosion potential of the deposited sample dipping in solution went down quickly also, 7 minutes after, basically stabilizing, although somewhat undulating, the potential did not change on the whole, keeping at -0.12V. But the non-depositing sample's potential basically stabilized at -0.15V, which was more negative than the deposited one's. This illustrates that

● ● ●

Fig. 1-7. Ni2p XPS energy spectrum of sample surface cathodically-electrodeposited

Fig. 1-8. O1s XPS energy spectrum of sample cathodically-electrodeposited

835 840 845 850 855 860 865 870 875 880 885 890 895

Binding energy (eV)

1s(O2-:530.2eV) 1s(OH-

:530.7eV)

520 525 530 535 540 545

Binding energy (eV)

Fig. 1-8. O1s XPS energy spectrum of sample cathodically-electrodeposited

Fig. 1-7. Ni2p XPS energy spectrum of sample surface cathodically-electrodeposited

1.7x104 1.7x104 1.7x104 1.7x104 1.7x104 1.8x104 1.8x104 1.8x104 1.8x104 1.8x104

8.0x103 1.0x104 1.2x104 1.4x104 1.6x104 1.8x104 2.0x104 2.2x104 2.4x104 2.6x104 2.8x104 3.0x104

Intensity

Intensity

Figure 1-9 shows an XRD analysis result of TiNi SMA deposited after heat treatments at different temperatures. It can be seen from the figure that in the Ti-O film crystallized at 300C, no TiO2 existing was found besides the main peak reflecting the substrate. But after crystallized at 450C, there is the peak emerging of anatase TiO2 in the figure. Because the substrate also has Ti element existing, to investigate if the anatase TiO2 formed by substrate's thermo oxidation, the same parameters' XRD for the TiNi SMA blank sample before depositing was done. But in the result, no clear TiO2 peak merged after crystallized at 450C, this illustrates that the film obtained by cathodic-electrodeposition is truly an amorphous-state Ti-O film, its composition is mainly in the form of hydrate Ti(OH)4. The formation of TiO2 is as the reaction formula:

$$\text{Ti(OH)}\_{4} \rightarrow \text{TiO}\_{2} + 2\text{H}\_{2}\text{O} \tag{1.4}$$

Fig. 1-9. XRD result of heat treated Ti-O film
