Formation of Si3Al3O3N5 oxonitride from mixtures of xerogels and silicon and aluminum nitrides in the nitrogen atmosphere

Abstract

To obtain silicon and aluminium oxonitrides, the transformations of xerogels and nitrides during firing in a nitrogen atmosphere were studied by thermal and x-ray phase analysis. It was established that the interaction between nitrides and xerogels in a nitrogen atmosphere with the formation of oxonitrides is due to reduction-nitriding reactions. The CO and hydrogen which are formed during the pyrolysis of adsorbed and chemisorbed alcohols (which are the products of the hydrolytic decomposition of silicon and aluminium alkoxides in xerogels) is a reducing agent for the finely dispersed oxides. The effect of the composition of the initial mixtures on the phase composition of the final product (SiAlON) and the morphological features of the powders obtained in one stage of firing in a nitrogen atmosphere is shown.