Abstract
The vibration damping implant (VDI) is an endosseous implant system,which is designed to absorb input dynamic force by using the intrinsic function of internal friction of TiNi alloy. The intermetallic compound TiNi alloy shows a thermoelastic type of martensite phase (M-phase) transformation from a regularly atomic arranged crystal structure (P-phase:a body-centered crystal structure for TiNi alloy) at a specified temperature, and the transformation temperature and the internal friction property substantially depends on its constitution of titan (Ti) and nickel (Ni). Thus it is important to know the material properties of the actual TiNi alloy that is clinically used.
In this study, material properties of internal friction and elastic moduli (i.e.,Young's modulus and Poisson's ratio) are presented for the following three materials:
1) 56(weight)% Ni-44% Ti alloy (M-phase): the objective specimen,
2) 54.8% Ni-44% Ti-1.2% Co alloy (P-phase): the comparative specimen,
3) pure Ti: the comparative specimen.
Here a P-phase alloy (the second one) is used as a comparative specimen in order to confirm that the vibration damping performance of the NiTi alloy is intrinsically changed across the transformation temperature. A bending vibration method was used, and the testing equipment was the ”MS Fyne” manufactured by Nippon Mechatron Co.
