Low temperature synthesis of alpha alumina platelets and acicular mullite in MgO-Al2O3-SiO2 system

Abstract

The refractory materials are more reliable and less expensive, this research is based on materials like alumina and mullite because it offers a very high refractoriness. In the present study an acicular mullite and a-alumina platelets were synthesized by using a synthesis of chemicals related to raw materials SiO2 45 wt%-Al2O3 45 wt% – MgO 10 wt%. The a-alumina platelets and acicular mullite were obtained in a reduced processing time and temperature, compare to conventional methods, such as sol-gel method, microwave sintering, chemical synthesis, combustion synthesis and lip casting and sintered. The composition, thermal analysis and micro structure evolution were followed by X-ray diffraction, differential thermal analysis and scanning electron microscopy (SEM). The synthesis of chemicals method based on Pechini process was successfully to synthesize a-alumina platelets and acicular mullite. All the precursor powders used have an amorphous structure with submicron particle size. The effect of MgO in the formation of a-alumina platelets and acicular mullite at low temperature was found. Thea-alumina platelets and acicular mullite was detected after heating at 800 °C and the dissolution a-alumina platelets for the formation of secondary mullite is around 1000 °C. It was observed that at 1400 °C it’s crystallized type III of secondary mullite. The behavior of the evolution of the phases and compact solid samples from oxides was made.