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Amorphous α‐Tricalcium Phosphate: Preparation and Aqueous Setting Reaction
Author(s) -
Gbureck Uwe,
Barralet Jake E.,
Radu Lavinia,
Klinger Hans G.,
Thull Roger
Publication year - 2004
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2004.01126.x
Subject(s) - crystallinity , amorphous calcium phosphate , materials science , cement , amorphous solid , chemical engineering , grinding , porosity , aqueous solution , phosphate , ball mill , apatite , compressive strength , solubility , calcium , mineralogy , composite material , chemistry , metallurgy , organic chemistry , engineering
The mechanical and setting properties of calcium phosphate cements are considerably determined by the pretreatment of the constituents. In this report we show for the first time that prolonged high‐energy ball milling of α‐tricalcium phosphate (α‐TCP) led to mechanically induced phase transformation from the crystalline to the amorphous state. The amorphous material demonstrated a high reactivity such that the time for substantially complete conversion of α‐TCP to calcium‐deficient hydroxyapatite in 2.5% Na 2 HPO 4 solution decreased from about 20 h (1 h of grinding in ethanol, 85% relative crystallinity) to 4–6 h for a material with a crystallinity of 8% (24 h of grinding). This reactivity could be attributed to an increased thermodynamic and kinetic solubility of the ground materials. Mechanically activated α‐TCP cements were produced with compressive strengths of up to 80 MPa and setting times of 5–16 min. The effect of reactant preparation and cement mixing parameters on the physical and chemical properties of mechanically activated α‐TCP cement was investigated. By comparing cements of similar porosity and degree of conversion it was demonstrated that apatite specific surface area has a strong influence on cement mechanical performance, which highlights the importance of this previously overlooked parameter in improving strength.