Physical Properties of Sintered Alumina Doped with Different Oxides

Authors

  • Suzana Filipović Institute of Technical Sciences, Serbian Academy of Sciences and Arts
  • Nina Obradović Institute of Technical Sciences, Serbian Academy of Sciences and Arts
  • Smilja Marković Institute of Technical Sciences, Serbian Academy of Sciences and Arts
  • Antonije Đorđević School of Electrical Engineering, University of Belgrade; Serbian Academy of Sciences and Arts
  • Igor Balać Faculty of Mechanical Engineering, University of Belgrade
  • Aleksandra Dapčević Department of General and Inorganic Chemistry, Faculty of Technology and Metallurgy, University of Belgrade
  • Jelena Rogan Department of General and Inorganic Chemistry, Faculty of Technology and Metallurgy, University of Belgrade
  • Vladimir B. Pavlović Institute of Technical Sciences, Serbian Academy of Sciences and Arts

Abstract

Corundum (α-alumina) is a suitable material for usage in various industry fields owing to its chemical stability, electrical and mechanical features. It is known that properties of ceramics could be modified by addition of different oxides, as well as by changing the consolidation parameters. In this respect, alumina was doped with 1 wt.% of Cr2O3, Mn2O3 and NiO, followed by 1 hour of mechanical activation in a high-energy planetary ball mill. A sensitive dilatometer was used for sintering of powder mixtures up to 1400 oC and recording the obtained dilatation. The final density varied between cca. 1.9 and 3.3 g/cm3. Microstructural changes were detected by SEM measurements. Changes in electrical permittivity and loss tangent were associated with the preparation conditions (types of additives, duration of mechanical activation). For a given mixture, the sintering increases the relative permittivity and decreases losses, exhibiting the optimal values of 8.32 and 0.027, respectively, for the sample activated 60 minutes and sintered, with the addition of MnO2. Mechanical measurements indicate significant differences in strength with the addition of different transition metal oxides. Samples with Mn and Ni, activated and sintered, with strength of 121 and 86 MPa, respectively, have a significantly higher tensile strength than the other tested samples, due to their more compact microstructures.

Downloads

Published

2018-06-13

Issue

Section

Articles