Preparation of Porous LiAl5O8 by Reaction bonded sintering

Yaowapa Saengpayab, yotin kallayalert, Chumphol Busabok

Abstract


The porous LiAl5O8 was fabricated by the reaction bonded sintering process. Powders of Al2O3 (0.3mm) and Li2O (1.0 mm) were used as starting materials. They were mixed with ratios of Al2O3 and Li2O in 5:1, 7:3 and 5:5 by mole in the water for 6 hours and were dried at 100oC for 10 hours. The mixed powder was pressed to form a 10 mm diameter disk specimen. The disk specimens were then sintered at temperatures of 1300oC for 2 hours. Specimens sintered at 1300oC for two hours formed two kinds of lithium aluminates, namely LiAlO2, and the LiAl5O8 in the mixture with the ratios of 7:3 and 5:5. The mixture with the ratio of 5:1 formed only the LiAl5O8 phase. The specimen mixed by 5:1 molar ratio had a homogeneous grain size and a pore size distribution. The Li2O reacted completely with the Al2O3 even below the evaporation temperature of the Li2O. In the specimen mixed by 5:5 ratio, the pore of specimens was larger and longer which would be resulted from the evaporation of Li2O during the sintering process. The thermal expansion coefficient of the specimen mixed by 5:1 molar ratio was lower than that of the specimen with other mixing ration. 


Keywords


Porous ceramics, Reaction bonded Sintering, Lithium aluminates, Pore size distribution

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