Highly sinterable β-tricalcium phosphate synthesized from eggshells

Highly sinterable β-tricalcium phosphate (β-TCP) powders were fabricated by using recycled eggshells in addition with polyethylene glycol (PEG). A raw eggshell was easily turned to CaO by the calcining process and the calcined eggshell was mixed with phosphoric acid by the wet, ball-milling method. The observed phases of the heated mixtures were dependent on the mixing ratio (wt.%) of the calcined eggshell and phosphoric acid. A polyethylene glycol was added to the solution mixtures for making highly sinterable powders. In the process using the polymer, the final synthesized β-TCP powders showed smaller particle sizes and better sinterability in comparison with the synthesized β-TCP powders prepared without PEG. The ball-milled β-TCP powders employing PEG, were fully densified at the low temperature of 1150 °C without any transformation to α-TCP.In this study, the crystalline developments and Ca/P molar ratios of the synthesized calcium phosphate powders were studied by X-ray diffractometry and chemical analysis using ICP AES. In addition, the microstructures of the β-TCP powders and densified β-TCPs were examined using a scanning electron microscope.