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The aim of this study was to improve the mechanical properties of porous corundum ceramics by adding various types of SiO2 source (SiO2, SiC and Si3N4), but at the same time retaining high porosity (at least 55%). Ceramics were fabricated by slip casting. Pores were formed using aluminium's reaction with water. It was found that the bending strength of the material can be improved and relatively high porosity retained by producing corundum–mullite composites. Addition of 3.7 equivalent wt% of SiO2 source increased the bending strength by up to 250% in comparison with unmodified corundum ceramics. The apparent porosity decreased by up to ca. 8%. If the amount of SiO2 source was increased from 3.7 equivalent wt% to 7.3 equivalent wt%, the bending strength decreased. The best mechanical properties were achieved with samples that were modified with SiC and Si3N4 nanopowders. This is due to better dispersion in Al2O3 matrix. 相似文献
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Ludmila Mahnicka-Goremikina Ruta Svinka Visvaldis Svinka 《Ceramics International》2018,44(14):16873-16879
Porous mullite-corundum refractory ceramics were produced by a patented slurry slip casting method from compositions based on commercially available α-Al2O3 and γ-Al2O3, fused SiO2 and kaolin. Pores were formed as a result of a chemical reaction of aluminium with water. The influence of usage of raw materials and doping additives such as micro-size ZrO2 and WO3 on the sintering temperature, formation of crystalline phases, linear thermal expansion, thermal conductivity and thermal shock resistance of mullite-corundum ceramic was studied. The best thermal shock resistance and, simultaneously, lower thermal conductivity was achieved for the samples doped with WO3. This was due to the influence of micro-sized WO3 on the change in γ-Al2O3 modification to α-Al2O3 and on the structure of mullite ceramics. 相似文献
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