Influence of different amount of Na2O additive on the structure, mechanical properties and degradability of bioactive wollastonite

Wollastonite (CaSiO3) ceramics with various Na2O contents (0, 5, 10, 15 and 20 mol%) were successfully prepared by sintering sol-gel derived precursors. The ceramics are composed of β-CaSiO3. With increasing Na2O content, Na2Ca2Si3O9, Na4Ca4Si6O18 and Na2CaSi3O8 are observed. The particle size distribution obeys the normal distribution. Na2O decreases the total pore volume of wollastonite powder, and increases the apparent porosity of wollastonite ceramic block. Na2O increases the bending strength of wollastonite, and the elastic moduli of all ceramics match that of cancellous bone of human body. The thermal expansion coefficients (TECs) of the ceramics are all close to that of titanium alloy (Ti6Al4V). The degradation rate is increased with increasing Na2O content. All samples show the ability of apatite induction in simulated body fluid (SBF) solution.