非晶質リン酸カルシウムを原料とするβ型リン酸三カルシウムの水熱合成

概要

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β-tricalcium phosphate (β-TCP) is usually prepared by burning a mixture of dicalcium hydrogenphosphate anhydride (DCPA) and calcium carbonate (CaCO_3) above 1100℃. However, hydrothermal synthesis may be a more effective process for energy-saving. In addition, amorphous calcium phosphate (ACP) is very useful as a raw material for the morphological control of crystalline calcium phosphates. The present work investigated about the hydrothermal synthesis of β-TCP from ACP. ACP (Ca/P atomic ratio of 1.25-1.55) as starting material was obtained by a hydrolysis reaction of a calcium dihydrogenphosphate monohydrate (MCP) solution. Hydrothermal synthesis of β-TCP occurred under the following conditions: liquid/solid weight ratio, 30; carboxylic acid (formic acid, acetic acid, propionic acid, butyric acid and valeric acid) concentration, 0-1.5 mol.dm^<-3'>; temperature, 160-260℃; time, 0-72 h. ACP crystallized into DCPA in hydrothermal conditions at 160℃, and was transformed into two phases, β-TCP and DCPA, above 200℃. Single-phase β-TCP formed at 220℃. Hydrothermal synthesis of β-TCP occurred under the following optimum conditions: formic acid solution, 1.0 mol. dm^<-3>; temperature, 220℃; time, 3h. Ca/P atomic ratio of the hydrothermal synthesized β-TCP was 1.48±0.01 and the product was quantified as Ca_<2.98> (HPO_4)_<0.04> (PO_4)_<1.96>.
社団法人日本セラミックス協会の論文
2002-08-01