Science and Technology of Energetic Materials

Vol.66, No.4 (2005)Special Issue for ISEM 2005


Underwater-shock compaction of hydroxyapatite-zirconia bio-composites powder
Akira Chiba, Yasuhiro Morizono, and Daisuke Michishita


Hydroxyapatite-zirconia (HAp-ZrO2) bio-composites were fabricated by our newly developed underwater-shock compaction technique. Hydroxyapatite [Hap; Ca10(PO4)(OH)2] is well known to be a bioactive ceramic having excellent biocompatibility with body environment. However, fracture strength and toughness of this bio-ceramic itself are low and its tensile strength does not withstand to practical use for implant materials.

Therefore, ZrO2 powder is added to HAp powder in order to obtain good mechanical properties of HAp without any degradation of biocompatibility.

Experimental assembly for underwater-shock compaction consists of three parts, i.e. explosive container, water tank and powder container from top to bottom. The water tank is shaped to be a circular cone, and so, the energy of shock wave was increased by the convergence of shock wave due to the reduction of cross section area of the water tank. Sound compacts of HAp-ZrO2 composites without any cracks and tears were fabricated. The relative densities of the composites were more than 80% as compared with 40% stacking density. The compacts were post-sintered at various temperatures. The structures were almost the same as the as-compacted state to 1373K sintering. Fracture toughness was obtained to be 3.04 MPa√m, which is equal to that of human bone. As a result, the addition of ZrO2 is confirmed to be effective for an improvement of low fracture strength of HAp.

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Shock compaction, Hydroxyapatite, Zirconia, Bio-composites, Powder compaction

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