Method for the preparation of metal matrix composite materials

A method for preparing deagglomerated fibres and/or particles and for providing said fibres and/or particles with a substantially uniform coating, said fibres and/or particles being of a material selected from the group consisting of carbides, oxides, nitrides, silicides, borides, metals and graphite, including SiC, TiC, ZrC, WC, NbC, AlN, TiN, BN, Si.sub.3 N.sub.4, MgO, Al.sub.2 O.sub.3, SiO.sub.2, ZrO.sub.2, Fe.sub.2 O.sub.3, Y.sub.2 O.sub.3, steel, tungsten, molybdenum and carbon, the method comprising

• (a) preparing an inorganic colloid sol by acidifying water or an aqueous solution to a pH in the range of 1-4, after which 0.5-10% by weight of an inorganic colloid-forming powder is added to the acidified water or aqueous solution while stirring, the sol being subsequently stirred for a period of 1-10 hours and subjected to gentle boiling for a period of 2-10 hours, the pH being maintained in the range of 1-4 during stirring and boiling, to result in a sol with a colloid concentration of 1-25% by weight, and
• (b) mixing the fibres and/or particles with the inorganic colloid sol to produce a dispersion in which the fibres and/or particles are deagglomerated and substantially homogeneously distributed.