Transactions of the INDIAN CERAMIC SOCIETY Vol. 60 2001
Densification and Mechanical Properties of Sol-Gel
Alumina : Effect of Sinter Additives
K. Vishista, D. Doni Jayaseelan* and F. D. Gnanam
Pages : 141-144
DOI : 10.1080/0371750X.2001.10799988
Abstract
Boehmite sol was prepared by hot water hydrolysis of aluminium
iso-propoxide using nitric acid as a catalyst. Hydrolysis was
carried out at 80°C, magnesium nitrate and silver nitrate were
added so that peptization was complete at 80°C for 1 h. The sol
was precipitated in ammonia, the precipitate was centrifuged at
9000 rpm for 20 min, dried at 120°C and calcined at 600°C for
three hours. The amount of magnesium oxide was kept constant
at 0.5 wt"k and that of silver oxide was varied from 0.5 to 10 wt%.
The powder was compacted into cylindrical pellets using uniaxial
press at 180 MPa and sintered at 1400°C for 3 h. 94% T.D. was
achieved for 1.0 wt% silver oxide content. Mechanical proper·
ties such as hardness, fracture toughness for compacts con·
taining various concentrations of silver oxide were studied. The
results showed that there was an increase in fracture toughness
of alumina ceramics with increasing silver oxide content.