Preparation of betaTCP/HAP biphasic ceramics with natural bone structure by heating bovine cancellous bone with the addition of (NH(4))(2)HPO(4).

In this study, the calcined bovine bone (CBB)-removing the organic substance by a burning process-with addition of different quantities of ammonium phosphate [(NH(4))(2)HPO(4)] (AP) was heated to a high temperature to transform its crystalline phase constitution from hydroxyapatite (HAP) into a tricalcium phosphate (TCP)/HAP biphasic structure. Results revealed that the CBB without AP appeared to be mainly composed of an HAP type pattern when heated to 1300 degrees C. After adding doped AP to CBB, the HPO(4)(2-) ions of AP condensed into P(2)O(7)(4-) ions at temperatures of 400-600 degrees C. P(2)O(7)(4-) ions reacted with the OH(-) ions of HAP to form betaTCP at temperatures up to 600 degrees C. The conversion reaction of HAP to betaTCP finished at around 900 degrees C. With increasing AP in the CBB, HAP gradually converted into different phase compositions of TCP/HAP or TCP at high temperature. Mechanical testing results showed that there was no significant difference in sintered CBB with different quantities of AP. By heating calcined bovine cancellous bone with different quantities of AP, we obtained different crystalline phase compositions of bioceramics with a natural porous structure. Copyright 2000 John Wiley & Sons, Inc.