Effect of zinc oxide and zirconia on structure, degradability and in vitro bioactivity of wollastonite

Abstract The partial substitution of ZnO or ZrO 2 for CaO in CaO–SiO 2 system was performed by sintering sol–gel derived precursor. The effects of ZnO and ZrO 2 on structure, mechanical properties, in vitro bioactivity and degradability of the CaO–SiO 2 ceramic were studied. Their pore size distribution was analyzed by the Barrett Joyner Halenda (BJH) method using Surface Area Analyzer (SAA). The bending strength and elastic modulus were determined by the three-point bending method. The degradability was evaluated in tris-(hydroxymethyl)-aminomethane and hydrochloric acid (Tris–HCl) buffer solution and the bioactivity by in vitro assays in simulated body fluid (SBF). Results indicate the main crystal phase to be wollastonite beta-CaSiO 3 . A new Ca 2 ZnSi 2 O 7 phase appears in the sample doped with ZnO, and t-ZrO 2 appears in the sample doped with ZrO 2 . The addition of ZnO or ZrO 2 decreases the total pore volume of wollastonite, improves the bending strength of wollastonite. The elastic moduli of all produced ceramics match that of human body bone. After soaking in Tris–HCl solution, the samples doped with ZnO or ZrO 2 present a lower weight loss. All samples have shown the ability of apatite induction in SBF solution.