Chemical Stability of Tricalcium Phosphate–Iron Composite during Spark Plasma Sintering

Tricalcium phosphate (Ca3(PO4)2, TCP) is a ceramic widely used as a bone filler material due to its good osteoconductivity. Nevertheless, its poor mechanical properties do not allow its use for load-bearing applications. Therefore, the option of improving its strength and toughness by adding a biocompatible metallic component is a promising alternative to overcome this drawback, leading to the fabrication of improved bone implants. The present work is focused on defining the thermal stability of alpha-TCP (α-TCP) when it is sintered together with iron (Fe) by spark plasma sintering. The results showed the thermal stability of the composite with no degradation or oxidation in the ceramic or metal phase. A clear advantage from the TCP-Fe composites when compared with others, such as hydroxyapatite-titanium, is the complete retention of the TCP due to the less reactivity with iron respect to titanium. Furthermore, the allotropic phase transformation from alpha to beta-TCP polymorph was reduced by sintering at 900 °C. However, the densification of the material was also impaired at this temperature. It is expected that spark plasma sintering will allow the fabrication of TCP–Fe composites free of secondary phases that compromise the mechanical strength of the material