Papers by Author: Francisco Guitián

Abstract: Thermal treatment of ceramics composed of two or more oxides under controlled reducing conditions selectively volatilizes the less stable components, leaving microstructured surfaces consisting of the most stable of the original oxides. Volatility diagrams showing equilibrium partial pressures allow interpretation of this process and the calculation of equilibrium conditions for the different reactions involved. In this communication we present results for ceramics composed of mullite (3Al2O3·2SiO2), zircon (SiO2·ZrO2) and cordierite (2Al2O3·2MgO·5SiO2).

Abstract: The progression of the setting reaction of a tetracalcium phosphate (TTCP) –dicalcium phosphate dihydrate (DCPD) rapid setting cement was investigated as a function of time. Compressive strength and extent of conversion to hydroxyapatite (HA) were obtained at different incubation times. The results indicated a rapid development of both strength and HA conversion in the early stages of the reaction, which slowed down after 4 h, presumably as a result of HA formation on the surface of the reactants. This hypothesis was supported by scanning electron microscopy examination of cement fracture surfaces.