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Wollastonite (CaSiO 3 ) ceramics with various Na 2 O contents (0, 5, 10, 15 and 20 mol%) were successfully prepared by sintering sol–gel derived precursors. The ceramics are composed of β-CaSiO 3 . With increasing Na 2 O content, Na 2 Ca 2 Si 3 O 9 , Na 4 Ca 4 Si 6 O 18 and Na 2 CaSi 3 O 8 are observed. The particle size distribution obeys the normal distribution. Na 2 O decreases the total pore volume of wollastonite powder, and increases the apparent porosity of wollastonite ceramic block. Na 2 O 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 Na 2 O content. All samples show the ability of apatite induction in simulated body fluid (SBF) solution. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Wollastonite CaSiO 3 (W-0) and CaSiO 3 doped with Na 2 O (W-Na) or MgO (W-Mg) were synthesized by sintering sol–gel derived powders and compacts. The effects of Na 2 O and MgO on structure, in vitro bioactivity, degradability and mechanical properties of wollastonite were studied. The main crystal phases of these ceramic powders were β-CaSiO 3 . In addition, Na 2 Ca 2 Si 3 O 9 appeared in sample W-Na and Ca 3 Mg(SiO 4 ) 2 appeared in W-Mg. For ceramic block W-Mg, CaMgSi 2 O 6 appeared. After soaking in simulated body fluid (SBF) for 7 days, the apatite layer was formed on the surface of these ceramics. The addition of Na 2 O increased the degradation rate of wollastonite and MgO decreased the degradation rate. Na 2 O and MgO improved the bending strength of wollastonite. The elastic moduli of ceramics accorded with that of dense bone of human body. [ABSTRACT FROM AUTHOR]

Highlights: [•] The crystallization and mechanical properties are greatly influenced by additives. [•] t-ZrO2 significantly improves the mechanical properties of glass-ceramics. [•] Nanometer apatite is formed on glass-ceramic surface in simulated body fluid. [•] The in vitro cytotoxicity test shows the glass-ceramic has no toxicity to cell. [•] The sedimentation mechanism and growth process of apatite on surface are discussed. [ABSTRACT FROM AUTHOR]

Abstract: HA/45S5 composite films were deposited by pulsed laser, the crystalline phases, microstructure and bonding configurations of the films were studied by XRD, SEM and FTIR respectively, and the film-to-substrate adhesion was investigated by micro-scratch testing. In addition, the in vitro and in vivo assays were carried out. The results showed that the crystallinity and the adhesive strength of the films increased with the increase of the substrate temperature. The film deposited with the substrate temperature of 200°C is amorphous, while crystalline HA and β-TCP were detected in the film deposited at 600°C. The in vitro test indicates that the amorphous film has faster dissolution rate and reprecipitation rate, which implies that this film has better bioactivity than the crystalline film. However, the in vivo test suggested that the 600°C film was more suitable to serve as clinical application than the 200°C film, because new bone tissue grew better onto the 600°C film surface than onto the 200°C film surface when they were implanted in the rabbit shin bones. [Copyright &y& Elsevier]