Abstract: A hydroxy-functional polymeric dispersant which is substantially free of acid groups, amine groups, and ethylenic unsaturation, the dispersant being especially adapted for dispersing pigments therein and being compatible with a variety of film-forming polymers, said dispersant being the free radical addition polymerization reaction product of a mixture of monomers consisting essentially of:(a) 15-30% by weight styrene; and(b) 15-30% by weight of at least one alkyl methacrylate monomer having 1 to 16 carbon atoms in the alkyl group; and(c) 20-60% by weight of at least one alkyl acrylate monomer having 1 to 16 carbon atoms in the alkyl group; and(d) 7-25% by weight of at least one hydroxy-functional ethylenically unsaturated monomer copolymerizable with monomers (a) (b) and (c);wherein said polymeric dispersant has a weight average molecular weight of 18,000 to 24,000, a number average molecular weight of 4,500 to 7,400, and a polydispersity of 2.9 to 4.2.

Abstract: A process for the manufacture of high purity, ultra-fine aluminum nitride powder by the carbo-nitridization of alumina. Agglomerates uniform in both size, chemical composition and porosity are formed containing a stoichiometric mixture of alumina and carbon with the addition of a small amount of catalyst. The agglomerates are furnaced in a controlled manner in a well-mixed reaction vessel to achieve a uniform and consistent level of conversion. Milling of the as-reacted agglomerates under a controlled atmosphere will produce high purity, micron sized aluminum nitride powder.

Abstract: A process for the sintering of a body comprising silicon carbide and a boron-containing material, which comprises heating the body to an effective sintering temperature in the presence of nitrogen; removing the nitrogen by evacuation to a pressure of less than 10.sup.-2 mbar; and continuing the sintering under vacuum or in the presence of an inert gas other than nitrogen. The invention also describes a sintered body comprising silicon carbide and a boron-containing material, having a density of at least 96% of its theoretical maximum density, in which the body contains less than 0.7% w of free carbon, and has a mean silicon carbide grain size of less than 5 microns.