Microwave sintering of mullite–cordierite precursors prepared from solution combustion synthesis

Sintering and final properties of kaolinite‐magnesite tapes for the manufacture of cordierite‐mullite ceramics

“…Therefore, this could justify the delay observed for the crystallization of cordierite (1200°C) in our samples, and thus related to the diffusion of magnesium. The latter also applied for contributing to the flowing of the amorphous phase though viscous flow sintering mechanisms already investigated in kaolinitic materials 13,21,32,35 . Along with these, when the sintering temperature increased to 1200°C, the stress to rupture increased significantly and the corresponding apparent porosity decreased from 56.5% to 31% for the sample with 6 mass% of MgCO 3 .…”

“…Therefore, pure cordierite with high resistivity ( ρ > 10 12 Ωcm), high density (2.53 g/cm 3 at 1470°C), low thermal conductivity ( λ = 1.5‐2.5W.m −1 .K −1 at room temperature), 12 low coefficient of thermal expansion ( α = 1‐2 * 10 −6 C −1 ), and low dielectric constant ( ε = 5‐6) of stoichiometric composition, 2MgO.2Al 2 O 3 .SiO 2 , is difficult to obtain. This is related to the fact that the annealing product of commonly used raw materials shows a complex phase composition consisting of cordierite—in one of its polymorph varieties—several crystalline byproducts (mullite, corundum, spinel, forsterite, clinoenstatite, and cristobalite) and even a vitreous phase 13 …”