Sintering behaviour of porous ceramic kaolin–corundum composites: Phase evolution and densification

[Display omitted] ► We set out to design controlled mullite–corundum matrixes with appropriate physicochemical properties. ► Corundum from calcined bauxite, constituted by hard particle inclusions acts in the matrix composites as second-phase. ► Main features: the increasing of softening point, the absence of vitrification in the temperature range of refractory composites in service and the achievement of a good thermal stability. ► Into the refractory matrix, the such reinforcing second-phase strongly improve the final mechanical properties by deflecting the cracks at the grain boundaries. Kaolinite–corundum (derived from bauxite) associations were assessed as candidate matrices in the field of porous ceramics composites. Particles of corundum were expected to behave as non reactive second phase, deflecting the matrix cracks and increasing the toughness. Porosity and densification were monitored by developing coarse grains (67 wt.% of grains 56 wt.%), the secondary expansion (