Metalurgia & Materiais Síntese e caracterização de mulita utilizando sílica obtida da casca de arroz

Abstract Mullite, composed of 1,4Al 2 O 3 .SiO 2 was synthesized using commercial α -alumina (Alpha Cesar Company) and silica obtained from the calcinations ofrice husk. This silica exhibits a high specific surface area, high purity and smallaverage particle diameter. Silica (26.2 wt.%) and α -alumina powders (71.8 wt.%) were mixed and homogenized using an alumina orbital disc mill before andafter the calcinations at 1100oC for 4 h in an air atmosphere. Then, the powderswere pressed uniaxially at a pressure of 1200 MPa. The green compacts weresintered at 1650oC, for 4 h, in air . The density of compacted sintering samples wasdetermined using the hydrostatic method. The chemical and structural propertieswere observed using ICP (Inductively Coupled Plasma), XRD (X-ray diffraction)and 29 Si MAS (Magic Angle Spinning) NMR (Nuclear Magnetic Resonance) andthe microstructural characterization performed using SEM (Scanning ElectronMicrography). The results show that it is possible to synthesize mullite ceramic ofhigh-purity and with little glassy phase from the