| 摘要 |
906,718. Magnetic compositions. GENERAL ELECTRIC CO. Nov. 21, 1958 [Dec. 16, 1957], No. 37526/58. Class 38 (2). Magnetic particles formed by electrodeposition of iron or iron-cobalt alloy in mercury as disclosed in Specification 815,919 are coated with antimony to prevent spheroidization and magnetic degradation at the temperatures (above 250‹ C.) necessary for the removal of the mercury. In one method, antimony is alloyed with lead or other mercury-soluble metals and added to the magnetic-particle mercury slurry so that as the lead dissolves it carries the antimony into intimate contact with the magnetic particles. In a second method, the antimony is electro.deposited in mercury and this is mixed with the mercury magneticparticle slurry. In either case the mixture is reacted to 200-300‹ C. for 10 minutes to form an antimonide coating on the particles. The final magnetic structure may be formed by distilling off the mercury and using an organic binding matrix such as cottonwood oil, tung oil or linseed oil, and this binder is added in a vacuum or an inert atmosphere. Alternatively, a lead or lead-antimony alloy matrix may be provided as disclosed in Specification 906,717. This is added to the slurry before heating, and after heating the material is compressed under 10,000 p.s.i. in a magnetic field of 4000 gauss. The mercury is then removed by distillation at a pressure of 1 mm. of Hg. for 1 hour at 350‹ C. The remaining material is ground, and compressed under 50,000 p.s.i. in a field of 4000 gauss. Alternatively, the material after distillation may be compressed hot under 3000- 50,000 p.s.i. at 350‹ C. in a field of 4000 gauss. Reference has been directed by the Comptroller to Specification 815,919. |
