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

Hydroxyapatite (HA) composites with zirconia (ZrO2) up to 40 vol% 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 (<5 vol%). 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.