In this paper, the structure of Al2O3 is modified with magnesium to synthesize MgAl2O4 as an oxygen carrier (OC) support. The surface properties and structural stability of the modified support are improved by the incorporation of magnesium in the structure of the support and additionally by narrowing the pore size distribution (about 2.3 nm). Then, iron oxide is impregnated on both an Al2O3 su...

low water-wettability and oxidation resistance of graphite have limited its application in carbon containing refractory castables. the aims of this study were improvement of water-wettability and the oxidation resistance of natural flaky graphite by applying an oxide coating on its surface. to develop the coating, magnesium aluminate spinel sol was formulated via a citrate-nitrate route and gra...

MgAl2O4 and x wt% ZrO2–MgAl2O4 (1 # x # 30) composite powders were prepared by the urea combustion route. The powders were further ground by either ball milling or attrition to refine the grain size. Zirconia was found solely in the tetragonal form. Dense materials were prepared by hot pressing. The spinel matrix grains were submicronic in size. The ZrO2 particles were homogeneously dispersed a...

OBJECTIVES Aim of the study was to analyze the mold filling capacity and the dimensional accuracy of a spinel-based investment for titanium castings. METHODS Expansion of the investment in dependence of the preheating temperature was measured in a dilatometer. The degree of transformation of MgO and Al2O3 to spinel (MgAl2O4) was evaluated by means of X-ray powder diffraction. Mold filling cap...

The electronic structure of zinc aluminate (ZnAl2O4) and that of zinc gallate (ZnGa2O4) were studied by the self-consistent tight-binding linearized muffin-tin orbital method with the atomic sphere approximation. The calculated results predict these zinc-based spinel oxides to be direct-gap materials. The direct gap at 0 is found to be 4.11 eV for ZnAl2O4 and 2.79 eV for ZnGa2O4. With reference...

An electron paramagnetic resonance (EPR) investigation on Ti-doped MgAl2O4 spinels has been made in order to study the Ti sites. The study we present here concerns the angular dependencies of the Ti EPR lines and the variations of the EPR spectra due to a modification of the TiO2 content or of the chemical composition from MgAl2O4 to MgAl4O7 and MgAl6O10. In all the studied samples except one, ...

Controlling microstructure and density of MgAl2O4 spinel is a crucial step in the elaboration industrial ceramics products. Understanding sintering characteristics key issue to optimize mechanical optical properties. In this paper, Olevsky's model used simulate trajectories spinel. The densification grain growth behaviors were identified via ramping interrupted isothermal cycles highlighting fi...

The subsolidus structure of the four-component system MgO – Al2O3 FeO TiO2 was studied in six temperature ranges. Geometric-topological characteristics phases under study have been determined, topological graphs relationship elementary tetrahedrons constructed, their volumes, degrees asymmetry for all ranges found. optimal regions compositions production spinel-containing materials predicted, w...