Effect of CaF₂ on densification and properties of hydroxyapatite-zirconia composites for biomedical applications

Hydroxyapatite (HA) composites with zirconia (ZrO₂) up to 40vol% were fabricated with the addition of CaF₂. The sinterability of the composites was found to be enhanced markedly by the addition of small amounts of CaF₂ (<5vol%). Decomposition of HA to β-TCP was suppressed due to the substitution of F^- for OH^-, consequently forming fluor-hydroxyapatite (FHA) solid solution. This suppression of decomposition allowed the production of a fully dense body, which retained both high flexural strength and fracture toughness. The osteoblast-like cell (MG63) response to these F^- ion-containing composites displayed comparable cell viability to pure-HA by in vitro proliferation test.