Effect of calcinations of starting powder on mechanical properties of hydroxyapatite-alumina bioceramic composite.

The effect of calcinations of starting powder on the mechanical properties of hydroxyapatite (HA)-based bioceramic composite was investigated. The calcinations of HA powder in air at 900 degrees C increased the crystallinity as well as the size of the powder. Ball milling after the calcinations was effective in eliminating large agglomerates in the powder. When the powder was mixed with reinforcing Al(2)O(3) powder, the mixture became fine and homogeneous. The flexural strength of HA-Al(2)O(3) composite was increased by the calcinations processes at all the Al(2)O(3) concentration. However, the fracture toughness was not much influenced by the calcinations. These results lead to the conclusion that the calcinations process effectively reduced the critical flaw size in the body by removing the agglomerates in the HA powder.