US3226327A - Ferrite compositions and method of manufacture - Google Patents

Ferrite compositions and method of manufacture Download PDF

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Publication number
US3226327A
US3226327A US213639A US21363962A US3226327A US 3226327 A US3226327 A US 3226327A US 213639 A US213639 A US 213639A US 21363962 A US21363962 A US 21363962A US 3226327 A US3226327 A US 3226327A
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Prior art keywords
calcium
percent
oxide
mol percent
ferrite
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US213639A
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English (en)
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Frank R Monforte
Frank J Schnettler
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to US213639A priority Critical patent/US3226327A/en
Priority to DEW34906A priority patent/DE1263575B/de
Priority to FR942428A priority patent/FR1364391A/fr
Priority to GB29439/63A priority patent/GB1048386A/en
Priority to NL63295921A priority patent/NL138885C/xx
Priority to NL295921D priority patent/NL295921A/xx
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Publication of US3226327A publication Critical patent/US3226327A/en
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
    • C04B35/2608—Compositions containing one or more ferrites of the group comprising manganese, zinc, nickel, copper or cobalt and one or more ferrites of the group comprising rare earth metals, alkali metals, alkaline earth metals or lead
    • C04B35/2625—Compositions containing one or more ferrites of the group comprising manganese, zinc, nickel, copper or cobalt and one or more ferrites of the group comprising rare earth metals, alkali metals, alkaline earth metals or lead containing magnesium

Definitions

  • calcium oxide additions to these compositions over the restricted range of 0.5 to 5.0 percent by weight of composition act to further lower coercive force without significantly detracting from the rectangularity of the hysteresis loop. Additions of at least 0.5 percent are required to noticeably lower coercive force, while additions above 5.0 percent sufficiently detract from the rectangular hysteresis loop characteristic so as to preclude their use.
  • FIG. 1 is a graph on coordinates of coercive force in oersteds against weight percent calcium showing the coercive force of two identical ferrite compositions containing varying amounts of calcium, the calcium being added as a carbonate to the composition depicted by curve 1 and as a soluble salt to the composition depicted by curve 2;
  • FIG. 5 is a graph on coordinates of magnetic induction B in gauss against field strength H in oersteds, showing a reproduction of an actual picture of a hysteresis loop as traced on the screen of an oscilloscope of a MgO-MnO-ZnOFe O ferrite composition containing 0.2 percent by weight calcium added to the ferrite as a soluble salt, the ferrite being fired at a temperature of 1250 C. for 10 hours.
  • Curve 2 of FIG. 1 depicts the relationship between coercive force and calcium content of the same composition as curve 1.
  • calcium was added as a soluble salt, in this instance calcium acetate.
  • This curve is exemplary of other soluble calcium salts, such as calcium benzoate, having a solubility with respect to calcium of at least one gram of calcium per cc. of water.
  • Both ferrite compositions depicted by curves 1 and 2 of FIG. 1 have the same basic ferrite composition: 32.1 mol percent magnesium oxide, 25 mol percent manganese oxide, and 42.9 mol percent ferric oxide. Both compositions Were processed under identical conditions including a final firing at 1300 C. for 12.5 hours.
  • the data exemplified by curves 1 and 2 of FIG. 1 is exemplary of all magnesium-manganese ferrite compositions disclosed in United States Patents 2,715,109 and 2,981,689.
  • FIGS. 2 through 4 show the hysteresis loops associated with a 32.1 mol percent magnesium oxide, 25 mol per cent manganese oxide, and 42.9 mol percent ferric oxide ferrite composition containing 0, 0.1, and 0.25 percent by weight calcium, respectively, the calcium being added to the composition during processing as calcium acetate.
  • the 0.1 percent calcium-containing composition in common with the calcium-free compositions, exhibits good rectangul-arity and sharp corners.
  • the 0.25 percent calcium-containing composition while also exhibiting good rectangul-arity, has somewhat rounded corners. Although not shown in the figures, it has been found that the corners of the hysteresis loops of compositions containing an amount of calcium in excess of 0.30 percent are too rounded to satisfy the requirements of a rectangular loop ferrite.
  • a calcium content for the previously described ferrite compositions of 0.075 to 0.30 percent calcium by weight of the composition. Calcium inclusions greater than 0.30 percent adversely affect the rectangularity of the hysteresis loop, with inclusions less than 0.075 percent being too small to sufficiently minimize coercive force. Based on these considerations, a preferred calcium content range is 0.13 to 0.30 percent by weight, with an optimum range being 0.20 to 0.25 percent.
  • FIG. 5 shows the hysteresis loop associated with a 20 mol percent magnesium oxide, 23.1 mol percent manganese oxide, 39.5 mol percent ferric oxide, and 17.4 mol percent zinc oxide ferrite composition containing 0.2 percent by weight calcium.
  • the zinc-containing composition exhibits good rectangularity and the corners of the curve, while being somewhat rounded, are sufficiently sharp to satisfy the requirements of a rectangular hysteresis loop ferrite.
  • Zinc oxide additions in excess of 18 mol percent sufficiently detract from the rectangularity of the loop as to preclude their inclusion in the magnesium-manganese ferrite compositions disclosed in United States Patents 2,715,109 and 2,981,689.
  • the calcium-containing compositions of the invention permit the beneficial inclusion of zinc oxide in amounts up to 18 mol percent (14 percent by weight of composition).
  • United States Patent 2,981,689 precludes such additions in amounts greater than 8 percent by weight due to their adverse effect on the rectangularity of the loop.
  • the ferrite-forming process of the invention is otherwise conventional and, as such understood by the art.
  • processing includes forming a slurry of the desired components, the components being present as the oxides or other compounds which, with firing, will yield the oxides.
  • the slurry also contains calcium present as a soluble salt having a solubility with respect to calcium of at least one gram of calcium per 100 cc. of water. Since the amount of water necessary to form the slurry is sufficient to dissolve the salt, the salt may be introduced to the slurry mixture as either the salt per se or a solution of the salt in water.
  • an illustrative calcining example would comprise heating the mixture over an appropriate temperature range of 800 C. to 1100 C. for 2 to 16 hours.
  • agglomerations formed during calcining are broken up by ball milling, generally for a period of 5 to hours, in a carrier such as water, acetone, ethanol, or carbon tetrachloride.
  • a binder is added during ball milling to aid in properly binding the composition together.
  • conventional binders include polyvinyl alcohol or Opal Wax (hydrogenated castor oil) for a water carrier and parafiin or Hal-owax (chlorinated naphthalene) for organic carriers.
  • the ball-milled slurry is then dried and the resulting solids granulated into particles of nearly uniform size. Generally, a 10 or #20 United States standard mesh is used for this purpose.
  • the particles are then formed into the desired configuration under pressures in the order of 5,000 to 50,000 pounds per square inch.
  • Final firing of the shaped body completes formation of the ferrite com-position. Such firing involves heating at temperatures preferably in the order of 1200 C. to 1350 C. for several hours, for example 7 to 15 hours.
  • the firing is generally carried out in an oxygen-containing atmosphere, the fired product being then cooled to room temperature in an inert atmosphere such as nitrogen.
  • Example 1 54.7 grams magnesium carbonate, 58.0 grams manganese carbonate, 138.1 grams ferric oxide, and 0.79 gram calcium acetate were dry mixed. The mixed ingredients were funneled into an Eppenbach Homo-Mixer and enough distilled water was added thereto to form a slurry. The slurry was then dried in a heated planetary mixer. The dry filter cake thus obtained was then calcined in air at a temperature of 900 C. for 16 hours. After calcining, the mixture was ball-milled in carbon tetrachloride for 16 hours. A ten percent by weight addition of Halowax to serve as a binder was introduced during ball milling. After ball milling, the solvent was substantially removed by drying the mixture in a heated planetary mixer.
  • the material was then granulated by passing it through a #20 United States standard screen mesh and then further dried for six hours in a vacuum at a temperature of 45 C. to remove the last traces of the solvent.
  • the material was then shaped into a ring having the dimensions 0.50 inch OD. and 0.35 inch I.D. under a pressure of 50,000 pounds per square inch.
  • the ring was dewaxed by bringing it to a temperature of 400 C. over a period of six hours and maintaining the 400 C. temperature for another six hours.
  • the final firing of the ring was carried out in an oxygen atmosphere at a temperature of 1300 C. for 7.5 hours.
  • the ring was then allowed to cool to room temperature in a nitrogen atmosphere.
  • the formed ring had the composition of 32.1 mol percent magnesium oxide, 25 mol percent manganese oxide, 42.9 mol percent ferric oxide, and 0.1 percent calcium by weight of the composition.
  • the ring had the hysteresis loop depicted by FIG. 3 of the drawing and a coercive force of 0.67 oersted.
  • Example 2 54.7 grams magnesium carbonate, 58.0 grams manganese carbonate, and 138.1 grams ferric oxide were dry mixed. The mixed ingredients were funneled into an Eppenbach Homo-Mixer and enough distilled Water was added thereto to form a slurry. milliliters of calcium acetate solution containing 1.97 grams of calcium acetate was then added to the slurry, which then underwent the same processing steps described in conjunction with Example 1.
  • the formed ring had the composition: 32.1 mol percent magnesium oxide, 25 mol percent manganese oxide, 42.9 mol percent ferric oxide, and 0.25 percent by weight calcium.
  • the ring had the hysteresis loop depicted by Example 3 33.2 grams magnesium carbonate, 52.2 grams manganese carbonate, 124.1 grams ferric oxide, 27.9 grams zinc oxide, and 1.58 grams calcium acetate were dry mixed. The mixture then underwent the same processing steps described in conjunction with Example 1.
  • the formed ring had the composition: mol percent magnesium oxide, 23.1 mol percent manganese oxide, 39.5 mol percent ferric oxide, 17.4 mol percent zinc oxide, and 0.2 percent by Weight calcium.
  • the ring had the hysteresis loop depicted by FIG. 5 of the drawing and a coercive force of 0.13 oersted.
  • a method of making a rectangular hysteresis loop ferrite composition comprising the steps of slurrying with water, drying, and calcining a mixture comprising components equivalent to 5 to 60 mol percent manganese oxide, 8 to 50 mol perecnt magnesium oxide, to mol percent ferric oxide, and containing from 0.075 to 0.30 percent calcium by Weight of the mixture added as a soluble salt having a solubility with respect to calcium of at least one gram of calcium per 100 cc. of Water, shaping the resultant material under pressure into the desired configuration, and firing the shaped material at a temperature of from 1200 C. to 1350 C., the said soluble salt being of such nature as to yield calcium oxide during the said method.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Compounds Of Iron (AREA)
  • Magnetic Ceramics (AREA)
US213639A 1962-07-31 1962-07-31 Ferrite compositions and method of manufacture Expired - Lifetime US3226327A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US213639A US3226327A (en) 1962-07-31 1962-07-31 Ferrite compositions and method of manufacture
DEW34906A DE1263575B (de) 1962-07-31 1963-07-17 Ferritzusammensetzungen und Verfahren zu ihrer Herstellung
FR942428A FR1364391A (fr) 1962-07-31 1963-07-23 Compositions de ferrites et procédé pour leur fabrication
GB29439/63A GB1048386A (en) 1962-07-31 1963-07-25 Improvements in or relating to ferrite compositions
NL63295921A NL138885C (nl) 1962-07-31 1963-07-29 Werkwijze voor het bereiden van een ferrietsamenstelling en gevormd voorwerp van het aldus bereide ferriet.
NL295921D NL295921A (de) 1962-07-31 1963-07-29

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US213639A US3226327A (en) 1962-07-31 1962-07-31 Ferrite compositions and method of manufacture

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US3226327A true US3226327A (en) 1965-12-28

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US (1) US3226327A (de)
DE (1) DE1263575B (de)
FR (1) FR1364391A (de)
GB (1) GB1048386A (de)
NL (2) NL295921A (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1174680A (fr) * 1957-05-09 1959-03-13 Csf Perfectionnements aux procédés de fabrication de ferrites ternaires au manganèse et au zinc
US2903429A (en) * 1954-07-13 1959-09-08 Centre Nat Rech Scient Modified ferrites
US2981689A (en) * 1953-02-03 1961-04-25 Steatite Res Corp Square loop ferrites

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2715109A (en) * 1954-06-14 1955-08-09 Steatite Res Corp Ferromagnetic ceramic materials with hysteresis loops of rectangular shape
FR1121088A (fr) * 1955-02-03 1956-07-20 Lignes Telegraph Telephon Matériaux ferromagnétiques à cycle d'hystérésis rectangulaire

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2981689A (en) * 1953-02-03 1961-04-25 Steatite Res Corp Square loop ferrites
US2903429A (en) * 1954-07-13 1959-09-08 Centre Nat Rech Scient Modified ferrites
FR1174680A (fr) * 1957-05-09 1959-03-13 Csf Perfectionnements aux procédés de fabrication de ferrites ternaires au manganèse et au zinc

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NL295921A (de) 1965-05-10
FR1364391A (fr) 1964-06-19
NL138885C (nl) 1973-10-15
GB1048386A (en) 1966-11-16
DE1263575B (de) 1968-03-14

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