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Mullite-zirconia composites prepared from halloysite reaction sintered with boehmite and zirconia
AbstractIn this study, Algerian halloysite, a naturally occurring clay mineral, was used as low-cost precursor for the production of mullite-zirconia composites. The halloysite was reaction sintered with boehmite and zirconia in the temperature range 1250–1650°C for 2h. Differential thermal analysis (DTA), thermogravimetry (TG), dilatometry, high temperature X-ray diffraction (XRD), and scanning electron microscopy (SEM) complementary techniques were used to characterize the prepared materials. The influence of ZrO2 content on the microstructure, densification, hardness, and coefficient of linear thermal expansion of the composites was investigated. Algerian halloysite was found suitable material for the synthesis of low-cost mullite based composites. All prepared samples exhibited same phase transformations that ended at 1550°C with the formation of monolithic mullite in halloysite-boehmite mixture and mullite-zirconia composites in halloysite-boehmite-zirconia mixture. The composite materials showed higher values of hardness and coefficient of linear thermal expansion compared with monolithic mullite. The composite containing 10% ZrO2 possessed the highest hardness value of 13.5GPa. The composite containing 30% ZrO2 possessed the lowest value of linear coefficient of thermal expansion of 7.5725×10−6K−1 between 200 and 1500°C.
Graphical abstract
HighlightsUse of Algerian hallosyite for production of advanced ceramicsDevelopment of low-cost mullite-zirconia composites by reaction sinteringCharacterization of phase transformations and sintering behaviorEvaluation of hardness and coefficient of thermal expansion
Mullite-zirconia composites prepared from halloysite reaction sintered with boehmite and zirconia
AbstractIn this study, Algerian halloysite, a naturally occurring clay mineral, was used as low-cost precursor for the production of mullite-zirconia composites. The halloysite was reaction sintered with boehmite and zirconia in the temperature range 1250–1650°C for 2h. Differential thermal analysis (DTA), thermogravimetry (TG), dilatometry, high temperature X-ray diffraction (XRD), and scanning electron microscopy (SEM) complementary techniques were used to characterize the prepared materials. The influence of ZrO2 content on the microstructure, densification, hardness, and coefficient of linear thermal expansion of the composites was investigated. Algerian halloysite was found suitable material for the synthesis of low-cost mullite based composites. All prepared samples exhibited same phase transformations that ended at 1550°C with the formation of monolithic mullite in halloysite-boehmite mixture and mullite-zirconia composites in halloysite-boehmite-zirconia mixture. The composite materials showed higher values of hardness and coefficient of linear thermal expansion compared with monolithic mullite. The composite containing 10% ZrO2 possessed the highest hardness value of 13.5GPa. The composite containing 30% ZrO2 possessed the lowest value of linear coefficient of thermal expansion of 7.5725×10−6K−1 between 200 and 1500°C.
Graphical abstract
HighlightsUse of Algerian hallosyite for production of advanced ceramicsDevelopment of low-cost mullite-zirconia composites by reaction sinteringCharacterization of phase transformations and sintering behaviorEvaluation of hardness and coefficient of thermal expansion
Mullite-zirconia composites prepared from halloysite reaction sintered with boehmite and zirconia
Raghdi, A. (author) / Heraiz, M. (author) / Sahnoune, F. (author) / Saheb, N. (author)
Applied Clay Science ; 146 ; 70-80
2017-05-25
11 pages
Article (Journal)
Electronic Resource
English
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