PREPARATION OF HYDROXYAPATITE AND CALCIUM PHOSPHATE BIOCERAMIC MATERIALS FROM THE AQUEOUS SOLUTION AT ROOM TEMPERATURE

摘要

A chemical reaction method was used to study the formation mechanism of hydroxyapatite on the surfaces of Ca{sub}3 (PO{sub}4){sub}3, Ca{sub}3 (PO{sub}4){sub}3/Al{sub}2O{sub}3, and Ca{sub}3 (PO{sub}4){sub}3/ZrO{sub}2 ceramic substrates, when these ceramic substrates were chemically reacted with Ca{sup}(2+), (PO{sub}4){sup}(3-) and OH{sup}- ions in the different aqueous solutions. With a dipping coating or soaking technique, brushite (dicalcium phosphate dihydrate, CaHPO{sub}4·2H{sub}2O) was formed on the surface of ceramic substrate in the phosphate acid solution at pH = 2.5. After a subsequent solution treatment in a 2.5M of NaOH aqueous solution at 80℃ for 1h, brushite coating was converted into hydroxyapatite (HA). Except for the phase change, the morphologies of surface coatings were also progressively changed from the plate-like structure to the network structure as the pH value increased. In the Ca{sub}3 (PO{sub}4){sub}3/Al{sub}2O{sub}3 and Ga{sub}3 (PO{sub}4){sub}3/ZrO{sub}2 ceramic substrates, HA was much easier to form on these substrate surfaces after an alkaline solution treatment, if the volume ratio of Ca{sub}3 (PO{sub}4){sub}3/Al{sub}2O{sub}3 or Ca{sub}3 (PO{sub}4){sub}2/ZrO{sub}2 in the ceramic substrate was 7/3. As to the effect of basicity, HA was much easier to form on the ceramic substrates at pH = 12-14 after a subsequent NaOH-containing solution treatment.