HYDROXYAPATITE COATING ON ALUMINA SUBSTRATE BY SOL-GEL TECHNIQUE

The purpose of the present work was to investigate synthetic condition of viscous coating sol by sol-gel technique in reaction of Ca(NO3)2-(C2H5O)3PO-C2H5OH system, burning temperature after dip-coating the viscous sol onto alumina substrate and thick control of porous hydroxyapatite (HAp, Ca10(PO4)6(OH)2) coating on the substrate as bone substitute. The products on the substrate were characterized by using X-ray diffraction, scanning electron microscopy, infrared spectroscopy and chemical analysis. The formation of viscous sol as precursor of amorphous calcium phosphate (ACP) was remarkably affected by synthetic conditions such as aging time, Ca/P atomic ratio and pH in an initial mixed solution. In order to stabilize porous HAp coating onto alumina substrate, it was more effective to burn at 1000 °C after dip-coating onto the substrate with viscous sol which formed by aging for 8 days under conditions of Ca/P atomic ratio 1.5 and pH 8 in an initial mixed solution. Also the thickness of HAp layer on the substrate was continuously increased by repeating dip-coating processes 2 to 3 times and developed to about 20μm after repeating 3 times. Consequently, the production of the new artificial biomaterials which joined strongly to the thin layer of HAp on surface of alumina substrate was expected.