Crystallization and densification of nano-size amorphous cordierite powder prepared by a PVA solution-polymerization route

A homogeneous and stable amorphous-type cordierite (2MgO·2Al ₂O ₃·5SiO ₂) powder was prepared by a solution-polymerization route employing a Pechini resin or a poly-(vinyl alcohol) (PVA) solution as the polymeric carrier. After calcination at 800°C for 1 h under atmospheric conditions, the bulky precursor changed into a very soft and porous powder. A 30 nm size, amorphous-type cordierite powder was prepared by attrition milling the calcined powder, which was made using a PVA precursor solution. The nano-size powder, which had a high specific surface area of 181 m ²/g, was obtained after milling for <1 h. The sintered cordierite grains did not show the presence of any amorphous SiO ₂ phase and had a dense microstructure with a relative density of 99% and a thermal expansion coefficient of 2.1 × 10 ^-6/°C.