Development of multiphase bioceramics from a filler-containing preceramic polymer

Multiphase bioceramics based on wollastonite and wollastonite/hydroxylapatite (W/HAp) have been successfully prepared by the heat treatment of a filler-containing preceramic polymer. CaO-bearing precursors (Ca-carbonate, Ca-acetate, and CaO nano-particles) were dispersed in a solution of silicone resin, subsequently dried and pyrolysed in nitrogen. The reaction between silica, deriving from the oxycarbide (SiOC) residue of the silicone resin, and CaO “active filler” led to the formation of several calcium silicates, mainly consisting of wollastonite (CaSiO3), in both low and high temperature forms. The phase assemblage of the final ceramic varied with the pyrolysis temperature (varying from 1000 to 1200 °C). HAp was additionally inserted, as “passive filler” (i.e. not reacting with SiOC), for the preparation of bioceramics based on W/HAp mixtures. The use of a filler-containing preceramic polymer to obtain bioceramics is favourable, besides for the simplicity of the procedure, for the possibility of achieving complex shapes. In fact, we demonstrated the possibility of fabricating an open-celled microcellular foam, prepared by mixing the filler-containing preceramic polymer with sacrificial PMMA microbeads. The proposed approach, due to the well-known bioactivity of wollastonite, W/HAp composites, and secondary calcium silicates, could be profitable for manufacturing various ceramic components for medical use.