Effect of sintering temperature on the phase, microstructural, physical, mechanical, and in vitro biomineralisation properties of porous wollastonite ceramics fabricated using the gel casting method

Porous wollastonite ceramic was successfully prepared via a wet milling method using calcium oxide (CaO) and silicon dioxide (SiO2) as the raw materials, and a gel casting method using potato starch as the pore-forming agent. X-ray diffraction results demonstrated that a single phase of beta-wollastonite was obtained at 1050 and 1150 degrees C. Meanwhile, a single phase of pseudo-wollastonite was obtained at 1250 degrees C. The increasing sintering temperature has significantly affected the phase, microstructure, linear shrinkage, density, porosity, and compressive strength of the porous wollastonite ceramics. When the sintering temperature was increased, the density and compressive strength of wollastonite ceramics were increased. However, its pore size was decreased with increasing sintering temperature, i.e., the pore size of the sample sintered at 850 degrees C was 400-500 mu m, which was reduced to 300-400 mu m after the sample was sintered at 1250 degrees C. The surface of all porous ceramic samples exhibited apatite formation within a day. Thus, single-phase porous wollastonite ceramics, with good porosity and strength, were successfully fabricated using the gel casting method.