Depending on the calcium:phosphorus molar ratio of the initial precipitates determined by precipitation conditions (calcium:phosphorus molar ratio of reactants and pH of reaction environment), after sintering at 1250°C, monophase, biphase, or triphase ceramics consisting of hydroxyapatite, β‐tricalcium phosphate, α‐tricalcium phosphate, and calcium oxide were obtained. The phase composition and properties—i.e., density, shrinkage, hardness, bending strength, and roughness—of the fractured surfaces of the isostatically re‐pressed sinters were determined.

1997 mechanical properties, thermal properties mechanical properties, thermal properties D 3000 -002Calcium Phosphate Materials Prepared from Precipitates with Various Calcium:Phosphorus Molar Ratios. -Six calcium phosphate samples with Ca:P molar ratios ranging from 1.50 to 1.73 are prepared by the wet chemical method and sintering at 1250 . degree.C. The phase composition and the properties such as density, shrinkage, hardness, bending strength and toughness of the sintered materials depend on the Ca:P ratio in the precipitates. The composition of the latter is determined by the reactant composition and the reaction parameters, i.e. pH and temperature. -(SLOSARCZYK, A.; STOBIERSKA, E.; PASZKIEWICZ, Z.; GAWLICKI, M.; J.

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Double yttrium-aluminium oxide with perovskite structure (YAP) doped with chromium(III) ions seems to be a promising material for red pigments for new ceramic bodies and glazes. The aim of the present paper was to examine the influence of the precursors morphology on colour properties of the YAP pigments. Two kinds of aluminium hydroxide powders were used, fine- and coarse-grained. The fine Al(OH)3 powder was amorphous with D50=4.58 µm and the coarse one was crystalline gibbsite with D50=42.4 µm. It was stated that using of aluminium hydroxide powders of different morphology led to substantial differences in phase composition of the final materials. Using coarse-grained aluminium hydroxide powder caused formation of over 95 wt% of YAP phase whereas the pigments prepared with amorphous aluminium hydroxide contain significant amounts of other phases in the Y2O3-Al2O3 system. The differences in phase compositions resulted in differences in colour properties of the pigments.