Correlating crystallinity and reactivity in an α-tricalcium phosphate

In this study, the effect of how variant milling time affects material characteristics of alpha phase tricalcium phosphate powder (α-TCP) was studied. Two α-TCP batches were separated in small lots and milled for various times for up to 4 h. The resulting milled lots were characterized by measuring their crystallinity, particle size, specific surface area, thermal stability, and heat released during hydration. Mechanical treatment was seen to greatly increase the α-TCP X-ray amorphous fraction and heat release during hydration, almost independently of α-TCP particle size and specific surface area. Therefore, the results suggest that the formation and presence of an X-ray amorphous phase in the α-TCP powder greatly contribute to its reactivity. The exotherm of the powders increases from 103 to 238 kJ/mol after milling.