Abstract
Fibrous carbonate-containing hydroxyapatite (CO3HAp) which had long axes of about 50 pm was prepared by homogeneous precipitation method, using urea. The fibrous CO3HAp materials were compressed at a pressure between 50 and 200 MPa to form compacts. The compacts were fired at a temperature between 1100 and 1350°C for 5 h to form the porous hydroxyapatite ceramics. The results obtained are summarized as follows :
(1) Acidic-aqueous solutions (0.1 mol. dm-3 HNO3 1500 cm3) containing 0.167 mol·dm-3 Ca (NO3) 2, 0.1 mol·dm-3 (NH3) 2HPO4 (Ca/P =1.67) and 0.5 mol·dm-3 (NH2) 2CO were heated under two conditions : (i) 80°C for 24 h and then 90°C for 72 h or (ii) 80°C for 24 h and then 95°C for 46 h. The fibrous CO3 HAp with Ca/P =1.66 was prepared under both conditions.
(2) Porous hydroxyapatite ceramics which had the porosities of 43% to 10% were easily fabricated from firing the above compacts. The compressed strength of the ceramics with the porosity of 20% showed an average value of 45 MPa in 10 test pieces, ranging from 30 to 60 MPa.
(3) The pore-diameter distribution of ceramics with the total porosity of 39% showed a narrow normal-distribution histogram, ranging from 1 pm to 0.1 pm.
