Classifications

• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S100/00—Presses
  • Y10S100/917—Magnetic

Definitions

• This invention relates to magnetic cores for use in inductance tuning coils and transformers or other elements in electrical circuits and particularly for use in high frequency circuits in the television or FM range of about 76.5 to 108 me, an in excess of 200 me.
• Another object is to produce a magnetic core having desirable operating characteristics and to provide a method for expediently and economically producing the same from commercially available raw materials combined in a novel manner to provide a molecular arrangement that imparts the desired characteristics.
• a further object is to provide a new compound for the manufacture of magnetic cores which includes the combination of certain new complex compounds with various additives that beneficially alter the characteristics of the core to meet predetermined specifications.
• a magnetic core formulated of cobalt oxide, nickel oxide, iron oxide, zinc oxide, vanadium oxide, and magnesium zirconate, mixed in proportion to produce a stable composition has a Q of 90 at frequencies of 108 to 76.5 me. when the first two metal oxides are separately reacted with the necessary molecular equivalents of iron oxide to form substantially stable salts. When measured at 200 me. however, the Q value dropped to between and 40, depending on the proportion of materials in the final product.
• NizOa 203 N10 F9204 0! FGOI'I'O NiO The metal oxides may be designated as being present in amounts corresponding to the equal molecular equivalents, but, for all practical purposes, variations of 10 percent from theory are permissible. It will be understood that the reaction of cobalt oxide and nickel oxide together with iron oxide will not result in the complete conversion to the complex indicated in Equation 2, but some of the complexes in Equations 1 and 3 will be formed in minor amounts.
• the metal oxides in finely divided form are intimately mixed together and subjected to firing at 2,000 to 2,500 F. for one to five hours, depending on the temperature used.
• the reaction product is a hard friable mass which can be finely divided to form a raw material for magnetic core formation, the reaction product having exceptionally good magnetic properties.
• magnetic cores might be formed of the reaction product of cobalt oxide with iron oxide in amounts to produce the complex compound or by the reaction of nickel oxide with iron oxide in the desired amounts, cobalt and nickel oxides are not considered to be full equivalents because the characteristics of each in high frequency circuits are in variance in the range of 100' to 200 mc.
• a complex compound formed of the two in various proportions gives improved results and a compound formed of the two in substantially equal proportions gives very excellent results through the entire range.
• the complex indicated by Equation 3 when compounded into a core, has a range between 108 to 88.5 mc. and a Q of 18, while the corresponding complex produced by the reaction of Equation 1 gives a range of 108 to 104 me. with a Q of 171. Since the Q value of the cobalt complex is in excess of that normally required, the range can be expanded at higher frequencies until the corresponding drop in Q is at a limiting value. Thus, with this composition, a magnetic core having acceptable properties may be produced for use in frequency ranges over 200 mc., and probably over 500 me.
• Compounding for magnetic core formation may be carried out by admixing the finely divided reaction products with a small amount of binder and molding the mixture under relatively high pressure to core shape.
• binder use may be made of the organic resinous materials, such as the phenol-aldehyde resins, urea-aldehyde resins, vinyl polymers and copolymers, polystyrenes, polyacrylates, elastomers, and the like. These materials are generally heat sensitive but serve to impart cohesive strength to the molded product until well beyond their thermal decomposition temperature of about 400 to 500 F. When organo silicons or silicates are used as the adhesive component, it is conceivable that some cohesion may remain after heat treatment. In any event, binder content in amounts ranging from about 2 to percent may be used depending on the type of binder and the characteristics of the core materials, but ordinarily 2 to 3 percent is sufiicient.
• the molded composition is heat treated by subjecting the mass to a temperature in the range of 1,800 to 2,350 F. for one-half to two hours, depending on the amount of material being handled.
• one or more of the constituent materials may function as an agent to bond the particles to mold form.
• Inequalities in density and permeability following molding are compensated during heat treatment by resulting shrinkage ultimately to produce a product having the very desirable property of equal permeability throughout. Best results are secured when the rate of cooling from heat treating temperature is controlled to secure an annealing effect, such as by the reduction of temperature in 100 F. per hour decrements.
• Zinc oxide may be used with these complex compounds to extend the range without causing excessive harm to the Q values.
• iron oxide in substantially equal molecular amounts to convert the greater portion of the zinc oxide to a stable salt, such as zinc ferrite.
• further iron oxide should be added in an amount sufficient to neutralize the base and to minimize the disturbing effect it might other- Wise have on the complex compound.
• the addition of zinc oxide to a nickel-cobalt-iron complex may be illustrated by the following examples:
• the nickel oxide and cobalt oxide are fired at 2200 F. for three hours with the necessary equimolecular equivalents of iron oxide.
• the reaction product is cooled at room temperature and reduced to finely divided form.
• the reaction product is intimately mixed with the zinc oxide and the remaining iron oxide and compounded with about 2 percent phenolformaldehyde A- stage resin.
• the mixture is molded to core formation at about 2,000 pounds per square inch pressure and then subjected to a heat treatment for one hour at 2200 F.
• the heat treated product is cooled to room temperature in increments of F. per hour and then ground down to a finished product.
• the characteristics of the core produced by the above are as follows:
• Example II To 60 parts of a complex compound manufactured of nickel oxide with iron oxide in equimolecular proportions under the conditions set forth in Example 1, 40 parts of the thermal reactions products of zinc oxide with iron oxide in equal molecular portions are added. The materials are mixed with about 2 percent organic binder and molded to core formation, and annealing of a desirable character is secured by subjecting the molded product to 2,100 F. for one hour and then cooling to room temperature in 100 F. per hour increments. The product of this reaction has:
• Range 108 to 81 mc., Q '72 This is to be compared with the range of 108 to 104 me. and Q of 171 secured by the complex compound along without the zinc ferrite addition.
• the efiect of zinc oxide to extend the range but with a permissible lowering of the Q value.
• Vanadium oxide carries the range still further when used in amounts up to 5 percent. Although increased amounts may be used, the extension of range does not warrant the increased cost and, therefore, I prefer to use less than 5 percent, although as much as 10 percent by weight has been successfully employed.
• additional iron oxides are added in sufficient amount for neutralization purposes. It is believed that the possible reaction product in this instance may be ferro-vanadanite.
• magnesium zirconate to lower the thermal drift of the core, particularly when made of the compositions described.
• Magnesium zirconate is unlike other elements or compounds heretofore used for reducing thermal drift in corresponding systems because it apparently is able at the same time to support the Q values at their desirable level.
• the desired effect is secured when at least 4 percent of magnesium ,zirconaute is employed, but best results are se cured when the magnesium zirconate is present in amounts ranging from 6 to 12 percent by weight.
• magnesium zirconate may be substituted by lead titanite. Substitution, however, seldom exceeds 25 percent.
• Example III The cobalt oxide, nickel oxide, and equi-molecular equivalents of iron oxide are fired at 2,400 F. for one hour to form the complex compound. Upon cooling to room temperature, the thermal reaction products are ground to powdery form. Admixture is made with the zinc oxide, vanadium oxide, magnesium zirconate, the remaining iron oxide, and 4 percent phenolformaldehyde binder. Molding to core formation is effected by a suitable press operating under about 2,000 pounds per square inch pressure. The molded product is heat'treated at a temperature in the range of 2100 to 2350 F. for one and one-half hours, and then it is cooled down slowly under room conditions. The characteristics of the resulting core areas follows:
• a magnetic core containing a complex compound comprising the product of the reaction of a metal oxide selected from the group consisting of Ni203, C0203 and mixtures'thereof with FezOa in substantially equal molecular proportions at 7 about 2000-2500 F. for 1-4 hours, zinc ferrite, vanadium ferrite and magnesium zirconate in which the materials when calculated on the basis of their oxides are present in amounts ranging from 5-20 parts by weight cobalt oxide, 10-25 parts by weight nickel oxide, 40-60 parts by weight iron oxide, a small amount up to about 15 parts by weight zinc oxide, a small amount up of the magnesium zirconate.
• the method of manufacturing magnetic cores comprising reacting NizOs and C0203 in about equal proportions with about a molecular equivalent of F6203 at 2000-2500 F. for 1-4 hours to form a complex having magnetic properties, mixing the complex with a small amount up to about 15 percentzinc oxide, a small amount up to about 10 percent vanadium oxide, a small amount up to about 12 percent magnesium zirconate and suiiicient additional iron oxide to react with the zinc and vanadium oxides to form the corresponding ferrites, mixing a binder with the material in amounts ranging up to 10 percent by weight, molding the compound to core shape, and heating the treated molded product at a temperature between 2100-2350 F; for at least one hour and then slowly cooling the heated product to room conditions.

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• Engineering & Computer Science (AREA)
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• Ceramic Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Soft Magnetic Materials (AREA)
• Magnetic Ceramics (AREA)

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Citations (2)

• 1949
  • 1949-01-03 US US69044A patent/US2656319A/en not_active Expired - Lifetime
  • 1949-12-29 GB GB33267/49A patent/GB673720A/en not_active Expired
  • 1949-12-30 FR FR1007498D patent/FR1007498A/fr not_active Expired
• 1950
  • 1950-01-02 BE BE493081D patent/BE493081A/xx unknown
  • 1950-01-03 NL NL82929D patent/NL82929C/xx active

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