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Publikācija: Development of Mullite and Cordierite Crystalline Phases in Ceramics from Mixed Compositions

Publication Type Article in a collection of scientific publications or a chapter in a monograph with ISBN or ISSN
Funding for basic activity Unknown
Defending: ,
Publication language English (en)
Title in original language Development of Mullite and Cordierite Crystalline Phases in Ceramics from Mixed Compositions
Field of research 2. Engineering and technology
Sub-field of research 2.5 Materials engineering
Authors Gaida Maruta Sedmale
Ingunda Šperberga
Aloizijs Patmalnieks
Andris Actins
Keywords Mullite, Cordierite, Ceramics, Mixed Compositions
Abstract Development of ceramics with the prevailing mullite or cordierite crystalline phases is greatly dependent on the raw materials used. The purpose of this research is to examine the process of mullite and cordierite development from mixed compositions formed from precursors of the natural raw materials (illite clay, dolomite) and synthetic additives - MgO, γAl2O3 , K2CO3 to ensure the stoichiometry of intended crystalline phases. It is shown that the addition of 8.7 wt.% of illite clay to the stoichiometric composition of γAl2O3 and amorphous SiO2 promotes the densification of samples at the temperature of 12800C and also the development of mullite as the only crystalline phase. The addition of 4.5 and 15 wt.% of illite clay leads to the development of the secondary phases – cristobalite and corundum. The dominant morphology of mullite crystals is prismatic (pillar), also mullite of prismatic shapes flattened in direction of the y-axis and crystals of corundum and cristobalite of the imperfect nature can be observed, particulary, when the illite clay additive is of 15 wt.%. For the development of the cordierite phase in starting compositions along with the synthetic compounds (MgO, K2CO3, Al2O3), the quartz sand and equivalent addition of illite clay and dolomite precursors of 4.5-18.4 wt.% were introduced. It is verified that the addition of 4.5-8.2 wt.% of illite clay and dolomite at the temperature of 13000C results in the development of perfect-shaped crystalline cordierite (or cordierite and spinels). If the additive of mineral raw materials, each of them in starting cordierite compositions, exceeds 14 wt.%, the development of the secondary phases - forsterite and anorthite- results.
Reference Sedmale, G., Šperberga, I., Patmalnieks, A., Actins, A. Development of Mullite and Cordierite Crystalline Phases in Ceramics from Mixed Compositions. In: Global Roadmap. Toronto: Amer. Ceram.Society, Wiley, 2006, pp.1-8.
ID 3979