1. Growth mechanism of house-of-cards aggregates of alumina platelets containing Na2O–B2O3–SiO2 glass flux
- Author
-
Yusuke Daiko, Sawao Honda, Yuji Iwamoto, Shinobu Hashimoto, and Daimu Muto
- Subjects
010302 applied physics ,Materials science ,Process Chemistry and Technology ,Evaporation ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Boric acid ,chemistry.chemical_compound ,Compressive strength ,Flux (metallurgy) ,Thermal conductivity ,chemistry ,0103 physical sciences ,Materials Chemistry ,Ceramics and Composites ,Composite material ,0210 nano-technology ,Porosity ,Sodium carbonate ,Solid solution - Abstract
Porous alumina bodies, intended for use as heat-insulating refractory materials, were fabricated by a high-temperature evaporation method and characterized. A series of flux systems was used by adding a third component to Na2O–B2O3 glass in addition to boric acid and sodium carbonate. When SiO2 was added as the third component, the primary alumina particles grew anisotropically, forming a plate-like shape, and the house-of-cards structure was self-organized. The anisotropic growth of alumina platelets was promoted by the solid solution of Si4+ ions in the flux on the α-Al2O3 surface. Furthermore, the bonding between the alumina platelets was strengthened by the high-SiO2-concentration flux. Our typical alumina body had a porosity of 71.5%, a compressive strength of 3.7 MPa, a shrinkage rate of 2.6% when reheated at 1700 °C, and a thermal conductivity of 0.24 W m−1•K−1 at 1000 °C. Thus, the present alumina bodies are expected to find application as high-performance heat-insulating refractory materials. more...
- Published
- 2020
- Full Text
- View/download PDF