Abstract: A process for preparing fine aluminium nitride (AlN) powder is described using an inorganic flocculant based on polyaluminium chloride (PAC) having the following structural formula:Al.sub.n (OH).sub.m Cl.sub.3n-mwhere n and m are positive whole numbers and n is greater than m/3.

Abstract: Disclosed is a process for obtaining a metallurgical bond between a metal material, or a composite material having a metal matrix, and a metal casting, or a metal alloy casting, which comprises carrying out a surface treatment on said material by means of the deposition of a thin layer of a metal, generally different from the metals contained in the material and in the casting, which is capable of increasing the wettability between the metal of the casting and the material, as well as the heat transfer coefficient between said two partners; and a step of casting around the same material, positioned inside a mold, of the metal, or of the metal alloy the same casting is constituted by.