Pulse electric current sintering and microstructure of industrial mullite in the presence of sintering aids

A commercially available mullite powder with stoichiometric composition was densified by the pulse electric current sintering (PECS) technique at 1500 °C with a holding time of 2 min to produce a fully dense microstructure. Transition metal oxides such as 0.5 wt.% of SrO and 0.2 wt.% MgO were added as sintering aids for mullite. The sintering aids greatly assisted for the modification of mullite grains in the sintered specimens. MgO added mullite exhibited equiaxed morphology, whereas SrO addition led to an equiaxed and anisotropic morphology of mullite grains.