Improvements in or relating to a method of producing non-metallic magnetic cores having substantially rectangular hysteresis loops

摘要

759,246. Magnetic compositions. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Dec. 20, 1954 [Dec. 21, 1953], No. 36756/54. Drawings to Specification. Class 38 (2). A magnetic core is made of a material with a substantially rectangular hysteresis loop and low value of coercivity and having the formula Ni x Mg (1-x) Fe 2 O 4 , where x is in the range 0.2-0.8, which material is made by heating a mixture of compounds of nickel, magnesium and iron in an atmosphere containing more than 50 per cent by volume of oxygen at 1375- 1475‹ C. If desired, to reduce the coercivity, Zn may be added so that the formula becomes Ni x Mg (1-x-y) Zn y Fe 2 O 4' where x=0.6-0.8, y= 0.1-0.3 and x+y=0.7-0.9. Magnesium and nickel carbonates, ferric oxide and, if desired, zinc oxide, are ground in alcohol or benzene, preheated at 900‹ C., reground after cooling and sintered at 1450‹ C. in oxygen.