Effect of Rare-Earth Oxides on Reaction Sintered
Non-Stoichiometric Magnesium Aluminate Spinel |
Biswajit Baruah,* Sidhanta Kumar Parija and Ritwik Sarkar
Pages : 115-121
DOI : 10.1080/0371750X.2023.2186953 |
Abstract |
Non-stoichiometric spinel compositions with molar ratio of MgO:Al2O3
= 1:2 and 2:1,
were prepared via single-stage reaction sintering technique at 1550o
-1600oC using
commercial grade oxide reactants. The effect of different rare-earth oxides, viz. CeO2
,
La2O3
and Y2O3
at 2 wt% level on the properties of different spinel batches was studied.
Y2O3
was found to favour densification in both the spinel batches while CeO2
and
La2O3
were found to favour densification only in the MgO-rich spinel compositions.
Phase analysis revealed that Y2O3
containing Al2O3
-rich spinel has a secondary phase
with similar crystal structure to spinel (both cubic) and improved densification, while
in the MgO-rich condition, Y2O3
remained as secondary phase and assisted in
densification. CeO2
and La2O3
in Al2O3
-rich samples formed secondary phases with
different crystal structures and resulted in reduced densification. While in MgO-rich
condition, CeO2
(cubic) did not react with Al2O3
and La2O3
formed a secondary phase
with similar crystal structure as that of spinel and therefore assisted in densification.
Addition of rare-earth oxides led to improvement in strength of MgO-rich spinels and
maximum improvement in strength was observed with the addition of yttria.
[Keywords: Non-stoichiometric spinel, |
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