Influence of crystal growth on sputtered films of hydroxyapatite onto titanium

摘要

This report demonstrates the poling effecs on the crystal growth of the sputtered hydroxyapatite (HAp) films using the simulated body fluid as in vitro testing medium. HAp thin films with 2 mu m thickness were prepared onto titanium plate from the CaHPO)4 powder target by r.f. magnetron sputtering, followed by the annealing at 200deg C for 24 hr under a high water vapor pressure using an autoclave. The specimens were polarized in a dc field of 25 kV/cm at 300 deg C for 1 hr, and then soaked in the SBF for the prescribed time. SEM observation showed that, compared with nonpolarized HAp specimens, polarized HAp accelerated or decelerated crystal growth, depending on the polarity; while the negatively charged surface was accelerated, the positively surface was decelerated. The HAp coatings polarized in negatively charged surface could be more useful in the fields of dental and medical application.