High purity, finely dispersed aluminium nitride powder prodn. - by mixing aluminium salt soln. with sodium carboxymethyl:cellulose soln. calcining the easily filtered prod., nitriding and igniting

摘要

The prodn. involved the reaction of a homogeneous mixt. of Al203 powder and C (II) in a N2-contg. atmos., followed by pyrolysis to remove excess C. The reaction mixt. is prepd. by mixing aq. Al salt soln. with aq. Na carboxymethylcellulose (Na-CMC) soln. at pH 3-8, filtering off the sparingly soluble ppte. of Al cellulose-glycolate, washing, drying and calcining at 200-350 deg.C. then nitriding and igniting by known methods. Pref., the pH is adjusted by addn. of ammonia. USE/ADVANTAGE - (I) is useful for the prodn. of sintered polycrystalline ceramics with high thermal conductivity, for use as dielectrical insulators, high temp. dielectrics and substrates for high performance electronic circuits, etc.. The invention provides a simplified process for the prodn. of mixt. (II) in the form of very pure, highly reactive powder which is more suitable for nitriding than prior art mixts. (which require long mixing times and subsequent grinding operations)