Abstract: Provided is an aluminum nitride powder useful as a raw material when an aluminum nitride sintered body excellent as an insulating high thermal conductive member is manufactured, particularly, by press molding. An aluminum nitride powder includes particles having a sphericity of 0.8 or more, in which a median size D50 obtained by a laser diffraction method is 0.5 to 1.5 ?m, a ratio D90/D50 of a particle size D90 corresponding to a cumulative undersize distribution of 90% to the D50 is 2.2 or less, a BET specific surface area is 2 to 4 m2/g, and a total oxygen concentration is 0.6 to 1.2% by mass.

Abstract: Provided is a cationic polymer-modified silica dispersion which comprises silica fine particles having an average particle diameter of less than 200 nm and a cationic polymer and which does not bring about coagulation of the silica particles. The above dispersion which is diluted to a solid concentration of 1.5% by weight is characterized by having a light scattering index (n value) of 2.0 or more. The above dispersion can be produced by oppositely-colliding a mixed solution obtained by mixing silica with a cationic polymer in a polar solvent at a treating pressure of 300 kgf/cm2 or more or passing it through an orifice under a condition that a pressure difference between the inlet side and the outlet side of the orifice is 300 kgf cm2 or more.