HOMOGENEOUS COATING OF HYDROXYAPATITE ON MULTI-WALL CARBON NANOTUBE IMMERSED IN CALCIUM PHOSPHATESOLUTION BY MICROWAVE HEATING

: The conditions for the homogeneous coating of hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ; HAp) on the multi-wall carbon nanotubes (MWCNTs) were examined via the processes of (i) the acid treatment of conc . nitric and sulfuric acids at 50  C for 24 h or the citric acid at 300 and 350°C for 0.5 h in Ar atmosphere in order to form carboxyl group, and (ii) the microwave heating (100  C, 5 min) of acid-treated MWCNTs in the “apatite-dissolved solution” prepared by bubbling CO 2 gas into the commercial HAp-dispersed water. The microwave heating of surface-modified MWCNTs (the citric acid treatment at 300°C for 0.5 h) in the apatite-dissolved solution was effective in the homogeneous coating of calcium-deficient HAp (Ca/P ratio =1.57), compared to the case of surface modification by conc . nitric and