Preparation and Phase Transformation of Mullite-Zirconia from Boehmite and Algerian Halloysite
A. Raghdi, M. Heraiz, F. Sahnoune, A. Ouali and D. Redaoui
Physics and Chemistry of Materials Lab, Department of Physics, University Mohamed Boudiaf of M'sila, 28000, M'sila, Algeria
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In this work, mullite-zirconia composite were fabricated by reaction sintering of Algerian halloysite Al2Si2O5(OH)4, boehmite Al(OOH), and zirconia (ZrO2) powder using conventional heating. The appropriate amount of the three raw powders was ball milled for 5 h and sintered between 1250 and 1650°C for 2 h. A scanning electron microscope was used to characterize the microstructure of sintered samples. A dilatometer and X-ray diffractometer were used to analyze the formation and transformation of phases. It is found that for the addition of zirconia up to 20wt.% the zirconia phase retains its tetragonal structure. The formation of primary mullite in all samples was complete at 1220°C. The cristobalite started to form: at 1350°C, and disappeared at 1500°C in the samples of mullite, and at 1450°C when ZrO2 was added. The zircon compound ZrSiO4 started to form at 1350°C and completely disappeared at 1550°C. The increase in ZrO2 ratio promoted the formation of grains with a spherical shape.

DOI: 10.12693/APhysPolA.131.136
PACS numbers: 81.05.Mh,, 07.85.Nc