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(2)O(3). 5SiO(2)) powder was prepared by a solution-polymerization route emplo ying a Pechini resin or a poly-(vinyl alcohol) (PVA) solution as the p olymeric carrier. After calcination at 800 degrees C for 1 h under atm ospheric conditions, the bulky precursor changed into a very soft and porous powder. A 30 nm size, amorphous-type cordierite powder was prep ared by attrition milling the calcined powder, which was made using a PVA precursor solution. The nano-size powder, which had a high specifi c 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 SiO2 phase and had a dense microstructure with a relative density of 99% and a thermal expansion coefficient of 2.1 x 10(-6)/degrees C.