Addition of ultradispersed oxides in nano alumina to promote sintering at low temperatures

Reference Presenter Authors
(Institution)
Abstract
12-020 Larissa Bezerra Silva Silva, L.B.(Universidade Federal do Rio Grande do Norte); Peres, A.P.(Universidade Federal do Rio Grande do Norte); Costa, A.C.(Federal University of Rio Grande do Norte); Acchar, W.(Federal University of Rio Grande do Norte); New ceramic-glass systems based on ? ? Al2O3 with 95 vol.% S iO2 ? B203 ? K2O, S iO2 ? B2O3 ? Na2O, S iO2 ? B2O3 ? Na2O ? K2O, Li2O ? ZrO2 ? S iO2, S iO2 ? ZnO ? MgO ? B2O3, 5 vol.%) were prepared and the effect of the addition of the oxides in improving the sinterability of nano alumina were investigated. Samples were sintered at 1200?C 67 for 60 minutes. The thermal proprieties were investigated by dilatometry and DSC measurements, apparent density of the sintered bodies were executed, the hardness surface of the samples was determined. The structural properties of sintered and powders samples were verified by X-ray diffraction (XRD). The effects of various alumina-filled oxides composites in order to ensure the formation of vitreous phase for improve the sinteribility were investigated by scanning electron microscope (SEM). The composites showed good densification kinetics at 1200 ?C. The combination of oxides SiO2, B2O3 and Na2O were suitable for the reduction of the sintering temperature of nano alumina. The addition of the alkali oxide K2O into the Al2O3-SiO2-B2O3 system can decrease the densification and thereafter hardness values at the temperature studied. The same happens in the ZnO-SiO-Al2O3-MgO-B2O3sytem. While, the addition of Na2O and B2O3 together with SiO2, can increase the densification and decrease the sintering temperature of the alumina. Also a content of LiO2 and ZrO2 can act as modifiers in the Al2O3 network and promotes densification at 1200 °C.
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