Reaction sintering of inactive alumina powders was investigated by usi
ng three groups of additives, depending on their chemical composition.
Most effective were those additives which, at lower temperatures and
in smaller amounts, brought about densification up to the elimination
of open pores. Hence the most effective among the additives used were
oxide mixtures without SiO2, followed by oxide mixtures with SiO2 and
finally mixtures of oxides and nitrides.