| 摘要 |
1297503 Electro-depositing magnetizable particles INTERNATIONAL BUSINESS MACHINES CORP 6 Jan 1970 [14 Jan 1969] 576/70 Heading C7B Magnetizable particles having sizes in the range 0À06 to 0À6 micron are prepared by electrolyzing a bath wherein a salt of a magnetic metal is dissolved in a dialkyl sulphoxide. Specified metal salts are Fe, Ni and Co chloride, sulphate, nitrate, acetate and propionate. The dialkyl sulphoxide may be dimethyl-, diethyl-, dipropyl-, dibutyl-, diisobutyl-, methyl ethyl- or methyl isobutylsulphoxide. The dimethyl sulphoxide may be diluted with water or any other mixible solvent. The electrolysis may be by DC or AC and the electrodes may be of Pt or carbon or the same metal as that of the metal salt. Current densities below 100 amps/sq ft and voltages under 200 volts are used. The particles produced may be removed by washing the deposition electrodes or by subjecting them to an ultrasonic field. The particles are of metal and may have an oxide shell. The oxide may be removed by heating the particles in a reducing gas, such as H 2 or CO, at elevated temperature. The bath may contain additives such as sucrose, saccharin or bipheryl for modifying the shape of the particles produced. Where magnetic recording media or magnetic responsive fluids are to be prepared, heat stable organic polymer binders for metal are added to the bath during electrode position. These coat around the metal particles, prevent agglomeration and inhibit surface oxidation thereof. Specified polymers are copolymers of acrylonitrile and styrene, copolymers of acrylonitrile and butadiene polyarylamides, polyamides, polyesters, vinyl chloride polymers, cellulose esters and ethers, aromatic polycarbonates, acrylate and styrene copolymers, epoxy resins, silicone resins, fluorinated resins, vinyl chloride - vinyl acetate copolymer, polyacrylic esters and polyurethanes. The polymers maybe brought into solution in a dimethyl sulphoxide bath with a co-solvent such as acetone, dimethyl formamide, butyl acetate, toluene, methyl ethyl ketone, methyl isobutyl ketone, amyl acetate, cyclohexane or tetralin. The particles may be used in preparing magnetic tapes, magnetic cores, permanent magnets and in preparing magnetic or electro-restrictive fluid. |
