Powders Mixtures Based on Ammonium Pyrophosphate and Calcium Carbonate for Preparation of Biocompatible Porous Ceramic in the CaO–P2O5 System

Resumo

Powder mixtures are considered containing ammonium hydrophosphate and calcium carbonate intended for preparing biocompatible porous ceramic in the CaO–P₂O₅ system. Pore formation on heating in workpieces based on the powder mixtures in question occurs due to occurrence of gas liberation in the presence of melt in the NH₃–H₂O–CO₂–CaO–P₂O₅ or CO₂–CaO–P₂O₅ systems. Gas phase formation is due to liberation of gaseous water and ammonia, thermal hydrolysis of calcium polyphosphate, decomposition of calcium carbonate, and oxidation of carbonized organic compounds remaining within a powder mixture in the form of associated calcium carbonate synthesis reaction product.