| 摘要 |
<p>1,210,332. Cobalt-rare earth compounds. GENERAL ELECTRIC CO. 3 Jan., 1969 [31 Jan., 1968], No. 579/69. Heading C1A. [Also in Divisions C7 and H1] Particles of cobalt-rare earth intermetallic compound Co 5 R (where R is a rare earth metal, e.g. Y, Sm or Ce-rich mischmetal) made by grinding a bulk body of the compound, are chemically polished by contact with an acid solution. The coercive force of the magnetic material is thereby increased. Specified acid solutions contain (1) nitric, sulphuric, orthophosphoric and glacial acetic acids; (2) chromic oxide, nitric acid, sodium sulphate and water. Contact time may be 1 or 2 seconds to 30 minutes. In an example, Co 5 Y particles (about 44-60 microns) are contacted at 25‹ C. for 30 seconds with acid solution (1), rinsed in water and acetone and dried. The coercive force of the product, measured on a sample cooled in molten paraffin wax in an aligning magnetic field, is 3340 oersteds.</p> |
