Wear Resistance of TiO2 Thin Films to Prosthetic Heart Valve

MIGUEL A. ALTERACH; PABLO C. FAVILLA; MARIO R. ROSENBERGER; ALICIA E. ARES; CARLOS E. SCHVEZOV; OSVALDO AMERIO

Santa Fé. Argentina.

Workshop; PRIMER TALLER DE ÓRGANOS ARTIFICIALES, BIOMATERIALES E INGENIERÍA DE TEJIDOS ? BIOOMAT 2009; 2009

Sociedad Latinoamericana de Biomateriales, Ingeniería de Tejidos y Órganos Artificiales (SLABO)

Titanium dioxide (TiO2) thin films have good haemocompatibility, which is required for covering mechanical heart valve prosthesis. In addition the films must have good wear resistance and adherence. In the present investigation the wear of TiO2 thin films made by a sol-gel dip coating technique is studied. A rotating ball-on-flat machine was used in order to reproduce the movement of a pivot of a mechanical heart valve. Ethylenglycol was used as lubricant; and a 6 mm  in diameter glass ball was used as counterface. A constant velocity of 7 rpm and a load of 1 N were chosen to perform the tests. Electronic microscopy and X-ray diffraction were used to characterize the coating and measures the anatase-to-rutile ratio, respectively. The influence of the following dip-coating process parameters was analyzed: the withdrawing velocity, the aging time and the temperature of the heat treatment and the number of oxide layers. The thickness of the films obtained ranged from 25 to 200 nm. The withdrawing velocity and aging time had an influence on the film thickness. On the other hand, the temperature of the heat treatment and the numbers of layers had more influence on the wear resistance than the withdrawing velocity and the aging time of the sol. Higher process temperature and more layers increased the wear resistance. The temperature has an influence on the crystal structures of the titanium dioxide; three different cases were observed: only anatase or rutile, and a mixture of both.