Fujihara Ichiro

Hardening of β-tricalcium phosphate (β-TCP) mixed with a 2.5wt% Na₂HPO₄ aqueous solution was investigated by a compressive strength test, XRD, SEM, and calorimetry. The β-TCP starting material was ground using a mortar grinder for 7, 24, and 72 h in an air atmosphere. Compressive strength for β-TCP cement ground for 24 h was stronger than that ground for 7 h and 72 h, and was 42.8±4.1 MPa after soaking in saline for 7 days. It was found that β-TCP requires rapid hydrolysis to harden β-TCP cement. The Na₂HPO₄ aqueous solution facilitates this hydrolysis reaction. The compressive strength of β-TCP cement depends on the length and the number of acicular apatite crystals deposited from β-TCP.

Hardening of β-tricalcium phosphate (β-TCP) mixed with a 2.5wt% Na₂HPO₄ aqueous solution was investigated by a compressive strength test, XRD, SEM, and calorimetry. The β-TCP starting material was ground using a mortar grinder for 7, 24, and 72 h in an air atmosphere. Compressive strength for β-TCP cement ground for 24 h was stronger than that ground for 7 h and 72 h, and was 42.8±4.1 MPa after soaking in saline for 7 days. It was found that β-TCP requires rapid hydrolysis to harden β-TCP cement. The Na₂HPO₄ aqueous solution facilitates this hydrolysis reaction. The compressive strength of β-TCP cement depends on the length and the number of acicular apatite crystals deposited from β-TCP.

beta-tricalcium bis(orthophosphate) [Ca-3(PO4)(2)] (beta-TCP) was mechanochemically treated with a mortar grinder in three different atmospheres of air, wet N-2, and wet CO2. H2O and CO32- were incorporated into ground beta-TCP, the amount of which depended on both the grinding time and the atmosphere. As the grinding time of beta-TCP increased, it hydrolyzed easily to Ca-deficient hydroxyapatite. The apatite-formation ratio for beta-TCP ground in Wet CO2 was remarkably lower than that for beta-TCP ground in air or wet N-2. The role of H2O and CO32- in the hydrolysis of ground beta-TCP was investigated by calorimetry together with spectroscopy. In calorimetry for each ground beta-TCP, a strong exothermic band was observed, which was followed by a broad exothermic band. It is considered that the first band corresponds to the process of adsorption of H2O in the solvent onto the fresh surface of ground beta-TCP and the second broad band corresponds to the apatite-formation process. With increasing amount of H2O incorporated into ground beta-TCP, both the heat evolution of the first exothermic band and the apatite-formation ratio increased linearly. The H2O incorporated into ground,beta-TCP promotes the dissolution of beta-TCP and apatite formation. In terms of the effect of the incorporated CO32- on hydrolysis, the incorporated CO32- prevents not only apatite formation but also the dissolution of beta-TCP. (C)2009 The Ceramic Society of Japan. All rights reserved.