| 초록 |
Hydrothermal deposition of hydroxyapatite coatings on two types of ZrO2 substrates (3 mol% Y2O3-doped and 13 mol% CeO2-doped tetragonal ZrO2s) was studied using aqueous solutions of Ca(NO3)2•4H2O and (NH4)2HPO4 containing EDTA (ethylene diamine tetra acetic acid) disodium salt as a chelating agent for Ca2+ ions. For the precipitation of the coatings, the EDTA-Ca2+ chelates were decomposed by oxidation with H2O2 at 90°C. The deposition behavior, morphology, and orientation of the coatings were investigated with varying the solution pH using scanning electron microscopy and X-ray diffractometry. For both the two substrates, sparse deposition of the coating was obtained at pH 5.5, whereas uniform deposition obtained at pH 7.1, 9.8, and 11.4 with denser microstructure with increasing the pH. The coating consisted of thin needle-like or plate-like crystals (1-2 μm length or diameter) at pH 7.1, while fine rod-like crystals (1-2 μm length, 0.1 μm diameter) at pH 9.8 and 11.4. The coatings were 1-3 μm thick and showed preferred orientation of the hydroxyapatite crystals with their c axis (i.e., the elongated direction) perpendicular to the substrate surface especially for pH 9.8 and 11.4. |
