Effect of Silicon Dioxide Nanoparticles on the Sintering Properties of Beta-Tricalcium Phosphate Composites

Composite sintered bodies comprising silicon dioxide (SiO₂) nanoparticles dispersed in β-tricalcium phosphate (β-TCP) were prepared. The addition of nano-sized colloidal SiO₂ to the β-TCP produced well-dispersed secondary phase nanoparticles that promoted densification by suppressing grain growth and increasing linear shrinkage of the sintered bodies. The SiO₂ was found not to react with the β-TCP at 1120 °C and the substitution of silicon for phosphorous to produce a solid solution did not occur. This lack of a reaction is ascribed to the absence of available calcium ions to compensate for the increase in charge associated with this substitution. The SiO₂ nanoparticles were found to be present near the intersections of grain boundaries in the β-TCP. β-TCP composite sintered body containing 2.0 and 4.0 wt% SiO₂ exhibited a bending strength comparable to that of cortical bone and hence could potentially be used as a bone filling material.