Mg-Si-AI-O-N Glasses Prepared By Nitriding Cordierite Powders Derived from Polymer Precursors

We have previously reported the synthesis of cordierite polymer precursors directly from MgO, SiO2 and alumina.1 Removal of organics at 400°C in air and/or in oxygen gave amorphous, atomically mixed, oxide powders with surface areas of 250-400 m2/g. It is possible to convert these high surface area oxide powders to Mg-Si-Al-O-N powders by heating in a flowing NH3 atmosphere. The effects of selected processing conditions on nitrogen incorporation, in a set of well defined oxide powders, were examined. The powders are nitrided in flowing NH3, at temperatures of 700-1200°C, to obtain N contents of up to 5 atomic percent.