| Hydroxyapatite Coating on Al2O3 by Hydrothermal Process |
| Jung-Soo Ha |
| School of Advanced Materials Engineering, Andong National University |
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| ABSTRACT |
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Hydrothermal deposition of hydroxyapatite coatings on $Al_2$O$_3$ substrates was studied using aqueous solutions of Ca(NO$_3$)$_2$ㆍ4$H_2O$ and (NH$_4$)$_2$HPO$_4$ containing EDTA disodium salt as a chelating agent for $Ca^{2+}$. For the precipitation of the coatings the EDTA-Ca$^{2+}$ chelates were dissociated thermally at 20$0^{circ}C$ or decomposed by oxidation with $H_2O$$_2$ at 9$0^{circ}C$. Scanning electron microscopy and X-ray diffraction were used to investigate the deposition behavior and the phase of the coatings. Hydroxyapatite coatings were not deposited with the thermal dissociation method, whereas uniform deposition of the coatings (about 0.7 $mutextrm{m}$ thickness) was obtained with the oxidative decomposition method. The coatings consisted of fine rod-like hydroxyapatite crystals (hexagonal structure) with 60-80 nm diameters, having some preferred orientation with their length (i.e., the c axis) perpendicular to the substrate.ate. |
| Key words:
Hydrothermal deposition, Hydroxyapatite coatings, $Al_2$$O_3$ substrates, EDTA-$Ca^{2+}$ chelates, Thermal dissociation, Oxidative decomposition, Preferred orientation |
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