| 摘要 |
1,175,890. Casting processes; making metal spheres. OLIN MATHIESON CHEMICAL CORP. 4 Sept., 1967 [8 Sept., 1966], No. 40280/67. Headings B3A and B3F. [Also in Divisions C7 and E1] A process for obtaining spherical metal particles comprises providing powdered metal preferably having a particle size below 100 mesh, providing less than 10% by weight of a binder which volatilizes above 150‹ and 200‹ F. below the melting point of said metal powder, admixing said metal powder and binder in the presence of from 5 to 35% by weight of moisture to form agglomerated masses of metal powder and binder, coating said masses with a weld preventing material, heating said coated masses in a protective atmosphere to a temperature above the volatilization temperature of said binder, and heating further in a protective atmosphere above the melting point of said metal powder to form a plurality of coherent metal spheres. The spherical particles may contain metallic additives which do not alloy and also non-metallic additives. The metal may be copper or copper alloy, aluminium or aluminium alloy, ferrous materials, noble metals, precious metals, titanium, magnesium, zinc, nickel, beryllium, solders &c. The binder may be a brazing flux, polyethylene glycol, metal stearates, stearic acid, organic binders, gum &c. The moisture may be provided by water, alcohols, acetone, toluene, benzene, naptha, carbon tetrachloride, trichlorethylene &c. The weld preventing material may be talc, lime, graphite, alumina, titanium dioxide, zirconium oxide, flour, non-reducible oxides, and mixtures thereof. The protective atmosphere may be provided by hydrogen, carbon monoxide, dissociated ammonia, nitrogen, argon, helium and may be a neutral or a reducing gas.
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