Papers by Keyword: Strontium Oxide

Abstract: Thermodynamic modeling of phase equilibria with the subsequent construction of the phase diagram of the SrO–Al₂O₃ system has been carried out. To calculate the activities of the oxide melt in the course of this work, we used the approximation of the theory of subregular ionic solutions, with the most optimal values of the energy parameters Q₁₁₁₂ = –104 349: Q₁₁₂₂ = –217 689; Q₁₂₂₂ = –104 436 J/mole. The results obtained for the liquidus line in this work are in good agreement with the literature experimental data. In the course of the calculation, the values of the equilibrium constants for the formation of strontium aluminates from the components of the oxide melt were estimated.

Abstract: The bioactive glasses of SiO₂-CaO-P₂O₅-SrO system have been prepared by a quick alkali mediated sol-gel method. The prepared bioactive glass of 1, 3, 5 wt% of SrO (coded: SR1, SR3, SR5, respectively) were characterized by SEM, XRD and FTIR. XRD pattern of all glasses calcined at 700°C in air confirmed that the calcined bioactive glass generally existed in amorphous state. The samples were immersed in simulated body fluid (SBF) to investigate the presence of hydroxyapatite (HA). All bioactive glass samples can induce the formation of hydroxyapatite (HA) as verified by SEM and XRD.

Abstract: The most common method to produce biodiesel is the transesterification of oils in the presence of methanol and a catalyst. Catalysts may be either homogeneous or heterogeneous, whereas the heterogeneous consume fewer resources, energy and are reusable, being considered an environmentally attractive approach. This research presents the production of a heterogeneous catalysis system for biodiesel synthesis, consisting of alumina foam with a thin coating of SrO. The support, obtained by direct foaming of suspensions, presented approximately 90% vol. of highly connected pores. The SrO film was obtained by soaking the ceramic foam into either a Pechini resin with SrO precursors or an aqueous solution of strontium nitrate, followed by heating to 1400°C for 2 hours. The density and permeability of samples were evaluated and microstructure was characterized by EDS and SEM. The results show that the use of ceramic foams as catalyst support is feasible using the proposed route.

Abstract: The synthesis conditions and mechanical performance of alite-rich cement clinker were investigated by the orthogonal test method. Sintering temperature, sintering time and contents of strontium oxide or strontium sulfate were taken as the influencing factors for the orthogonal test. The experimental results show that the optimal sintering temperature and sintering time are 1450 °C and 60 min, and the best strontium oxide or strontium sulfate content in the clinker is 1.5% and 0.5%, respectively. The doping of strontium oxide or strontium sulfate can promote the formation of alite mineral. That is beneficial to the increase of cement strength. The early strength of cement can be improved by addition of strontium oxide, and the long strength of cement can be increased through adding a little of strontium sulfate.

Abstract: Composites of calcinated bovine bone derived hydroxyapatite (HA) with 5 and 10 wt % SrCO3 were prepared by sintering. The production of HA from natural sources is preferred due to money and time saving reasons. In this study scanning electron microscopy (SEM) investigations and together with measurements of microhardness, density, and compression strength were performed. The experimental results indicated that compression strength and microhardness values of HA-Sr-oxide composites decrease when the content of SrCO3 and sintering temperature increase. The best compression strength values were achieved after sintering at 1000°C. It was seen that at higher temperatures the compression strength and the microhardness values decrease due to the pore formation. The pore formation is very important for scaffold formation for tissue engineering purposes.