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
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/90—Magnetic feature

Definitions

• This invention relates to magnetic cores for use in inductance tuning coils, and it relates particularly to the composition and to the method for producing magnetic cores which operate efficiently in resonant circuits in the high frequency television and FM range of about 76.5 to 108 mc.
• the characteristics of a magnetic core are often measured by the frequency range, Q factor and the thermal drift of the core within the frequency of its intended use.
• compositions suitable for use in circuits in the radio frequency or broadcast range may not be equally suitable for use in circuits operating at higher frequencies, such as the ultra high frequency FM and the television ranges. afiected by the increased frequency is the Q value, which may fall to an unusable low value even as a result of a minor increase in frequency.
• Optimum conditions are achieved when the magnetic core has the following characteristics, Q in excess of 80, thermal drift which is less than 0.01 percent degree centigrade, and range of the desired magnitude in the frequency band for which it is intended.
• Another object is to provide a magnetic core that has the characteristics of high Q, low thermal drift and satisfactory range within the high frequency bands of 76 to 108 mc.
• a further object is to provide a new method for producing magnetic cores for use in circuits, operating in these very high frequency ranges, which method includes the combination of commercially available raw materials to produce stable magnetic compounds and the combination of these compounds in various proportions, with and without modifying substances to form the final product.
• a core formed by reaction in combination of iron oxide (FezOa), cobalt oxide (C0203), nickel oxide (NiaOs), zinc oxide (ZnO), vanadium oxide (V205), and magnesium zirconate (MgZrOz) does not have characteristics comparable to a magnetic core formed from the same materials having a molecular arrangement of the type secured by my invention.
• the final product is a magnetic core having a frequency range of 108 to 76.5 mc., a Q of which remains practically constant over the entire range, and an exceptionally low thermal drift of about 0.004 percent degree centigrade.
• An important feature of my invention resides in the formation of stable salts of the cobalt or nickel components by the separate reaction of the cobalt or nickel oxides in sufiicient amount to form whatis believed to be the corresponding cobalt or nickel ferrites.
• the amount of ma terial employed for carrying out the invention may most easily be designated in terms of molecular equivalents since two molecular weights of iron oxide appear to thermally react with one molecular weight of the cobalt or nickel oxides in the formation of the corresponding salts according to the following formulae:
• the oxide of iron in finely divided form is mixed with the oxide of cobalt or the oxide of nickel in finely divided form and the mass is fired for about two hours at 2200 F.
• the time of firing might be varied according to the temperature employed and the mass to be reacted. For example, proper firing may require 3 to 4 hours at 2000 F., while 1 hour or less may suflice when reaction is carried out at a temperature of 2500 F.
• the reaction product, when cooled to room temperature, is a hard friable mass having magnetic properties
• magnetic cores might be formed of the finely divided reaction products of nickel oxide with iron oxide, or of cobalt oxide with iron oxide, I prefer to combine the two reaction products in substantially equal proportions or with one in excess of the other up to about 25 percent.
• Core formation is effected by a molding operation followed by a heat treatment to a temperature of about 1800 to 2350 F. for about 1 or more hours. Best results are secured when the heat treated cores are gradually cooled to room temperature at a rate, for example, of about 100 F. per hour.
• My invention is not limited to the above described conditions since the time of heat treatment may vary according to the temperature used and the rate of cooling is influenced by the mass of material involved.
• Temporary cohesive strength is imparted to the molded product prior to heat treatment by the admixture of a small amount of resinous binder which may include the reaction products of phenol-aldehydes, urea-aldehydes, vinylpolymers and copolymers, poiyacrylates, polystyrene, and the like. Up to percent bindermay be used, however, 2 to 3 percent ordinarily is sufficient.
• the described binders are heat sensitive and are subject to thermal decomposition as the temperature of heat treatment exceeds 500 F., whereupon the greater portion of the bonding action secured thereby is lost and reliance is had upon the development of a bond by one or more of the metallic substances making up the core composition, which bond is usually developed at higher temperatures.
• magnetic cores can be produced solely from the reaction products of the oxides of cobalt and nickel with iron oxides
• zinc oxide may be added to extend the frequency range which is obtained by means of the cores, especially when used in amounts corresponding to less than percent by weight of the final prodnot.
• sufiicient additional iron oxide should be incorporated in the mix to neutralize the zinc oxide.
• the addition of zinc oxide and corresponding amounts of iron oxide to the described reaction products might be made during the core forming process, but in many instances, best results are secured when the added substances are first reacted at firing temperature corresponding to those previously described to efiect the formation of a neutral salt, believed to be zinc ferrite.
• Zinc oxide and iron oxide combine in substantially equi-molecular proportions and, therefore, it is expedient to designate the amounts that may be added in such terms, it being understood that variations of about 10 percent from theoretically calculated amounts are permissible. Although it is undesirable to disturb the neutral salts of cobalt and nickel, a small amount of displacement by zinc may be unavoidable under the conditions employed in the heat treatment.
• Vanadium oxide functions chiefly to expand the frequency range obtained with the core and for this purpose, amounts up to 5 percent by weight of the core composition have been successfully used.
• the improvement secured by further additions does not warrant the added cost of vanadium oxide and, therefore, I prefer to limit my use to less than 10 percent,
• magnesium zirconate in the core compositions previously described. Importance is directed to the addition of magnesium zirconate because it has the novel and very desirable characteristic of substantially reducing the thermal drift while supporting the Q values of the compounded materials.
• Magnesium zirconate is effective when used in amounts up to 12 percent by weight of the composition, and best use is made when used in amounts ranging from 4 to 8 percent. The same effect on thermal drift cannot be secured by the addition of other commonly used materials, such as zirconium oxide, magnesium titanite, strontium titanite, or calcium stannite. When used in designated amounts, magnesium titanite can be substituted in part with about 25 percent by weight lead titanite.
• the materials set forth may be formulated together within the weight limitations prescribed to secure magnetic cores having excellent characteristics with respect to range, Q, and thermal drift, in television or FM circuits. It will be understood that these same compositions might also be used in lower frequency circuits such as radio frequencies and the like.
• the additive materials may be compounded with the separate thermal reaction products formed of cobalt and nickel and zinc oxides with iron oxide, and with zinc oxide, unless previously separately reacted with iron oxide, and then molded to core formation followed by'heat treatment under the conditions previously described. With these materials in the desired arrangement, inequalities in density which normally follow molding under high pressure, are compensated by unequal shrinkage during heat treatment to the extent that a magnetic core is secured having substantially equal permeability throughout.
• EXAIVIPLEI Materials 56 percent iron oxide (FeaOa) 10 percent cobalt oxide (C0203) 8 percent nickel oxide (NizOa) 13 percent zinc oxide (ZnO) 5 percent vanadium oxide (V205) 8 percent magnesium zirconate (MgZrOa) Cobalt oxide and nickel oxide are separatelywith the other ingredients, and compounded with about 2 to percent "A" stage phenol formaldehyde resin dissolved in alcohol medium.
• the composite mass is molded to core shape under about 2000 pounds per square inch pressure and then heat treated for about two hours at 2000 F.
• the heat treated core is cooled to room temperature by decrements of 100 per hour.
• the product has the following characteristics:
• Example 2 The amount of material employed is the same as that in Example 1 above.
• the cobalt oxide, nickel oxide and zinc oxide are separately mixed with the required molecular equivalents of iron oxide and fired at a temperature of about 2200 F. for about 1 /2 hours.
• the reaction products When cooled to room temperature, the reaction products are subdivided to powdery form and mixed with the vanadium oxide, magnesium zirconate and the remaining iron oxide.
• To this mixture about 2.5 percent by weight-phenol formaldehyde resinous binder are added and then it is molded to core formation.
• the molded product is subjected to heat treatment in the manner previously described in Example l, except that the heat treatment is carried out at 2000 F. for 1 hours.
• the characteristics of the resulting magnetic core correspond substantially with those secured by the use of the same elements in Example 1.
• the method of manufacturing magnetic cores comprising the steps of separately reacting NizOs, C0203 and ZnO with F6203 in the ratio of one equivalent weight of the nickel and cobalt oxides to about two equivalent weight of iron oxide and one molecular weight of zinc oxide to one molecular equivalent iron oxide at a temperature within the range of 2000-2500" F. for from 1-4 hours, compounding the reaction products in finely divided form with vanadium oxide and magnesium zirconate and a binder in amounts ranging up to 8 percent of the mix, molding the mix to mold shape, heat treating the molded mass at a temperature within the range of 1800- 2200 F.
• the material being incorporated in amounts ranging from 8-12 parts cobalt oxide, 6-12 parts nickel oxide, 5-15 parts zinc oxide, 1-10 parts vanadium oxide, 4-12 parts magnesium zirconate, and 40-65 parts iron oxide.
• reaction products for 1-4 hours, mixing the reaction products in finely divided form with the amount of the reaction product of zinc oxide and vanadium oxide being based upon a small amount up to about 15 percent zinc oxide and a small amount up to about 10 percent vanadium oxide based upon the mixture, molding the reaction product to core shape with less than 10 percent by weight of a temporary organic binder, and then heating the molded mass to a temperature between 1800-2350 F. for 1-2 hours.
• reaction products for l-4 hours, mixing the reaction products in proportions ranging from equal parts by weightto an excess of 25 percent 'by weight of the reaction product of nickel and cobalt oxide with iron oxide and a small amount up to about 15 percent by weight of zinc oxide as its reaction product and a small amount up to about 10 percent by weight of vanadium oxide as its reaction product with the reaction products in finely divided form and combined with up to 10 percent by weight of a temporary organic binder and 4-12 percent by weight of magnesium zirconate,
• reaction products in finely divided form with a small amount up to about percent by weight of a temporary organic 'binder, a small amount up to about 12 percent by weight of magnesium zirconate, a small amount up to about 15 percent by weight zinc oxide and a small amount up to about 10 percent by weight vanadium oxide with sufllcient iron oxide to react with the zinc and vanadium oxides to form the corresponding ferrite, molding the mass to core shape and then heating the molded mass to a temperature between 1800-2350 F. for at least /2 hour.
• the method of manufacturing magnetic cores comprising the steps of mixing nickel ferrite and cobalt ferrite as major ingredients in the ratio of equal parts by weight to an excess of 25 percent by weight of one over the other with zinc ferrite in amounts less than 15 percent by weight calculated on the basis of zinc oxide, the thermal reaction product of vanadium and iron oxide present in amounts less than 10 percent by weight calculated on the basis of vanadium oxide, and less than 10 percent by weight of a temporary organic binder, molding the mixture to core shape and then heating the molded mass to a temperature within the range of 1800-2350 F. for about -2 hours.
• the method of manufacturing magnetic cores comprising the steps of mixing nickel ferrite and cobalt ferrite as major ingredients present in the ratio of equal parts by weight to an excess or 25 percent by weight or one over the other with zinc ferrite in amounts ranging up to 15 percent by weight calculated on the basis of zinc oxide, the thermal reaction product of vanadium and iron oxide in amounts ranging up to 10 percent by weight calculated on the basis of vanadium oxide, 4-12 percent by weight of magnesium zirconate and up to 10 percent by weight of a temporary organic binder, molding the mass to core shape and then heating the molded mass to a temperature within the range of 1800-2350 F. for about -2 hours.
• a magnetic core as claimed in claim 8 in which magnesium zirconate may be substituted in amounts up to 25 percent by weight thereof by lead titanite.

Landscapes

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

Priority Applications (6)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22086355

Family Applications (1)

Country Status (6)

Cited By (16)

Families Citing this family (9)

Citations (2)

Family Cites Families (4)

• 1949
  • 1949-01-03 US US69043A patent/US2659698A/en not_active Expired - Lifetime
  • 1949-12-29 GB GB33266/49A patent/GB673719A/en not_active Expired
  • 1949-12-30 FR FR1007497D patent/FR1007497A/fr not_active Expired
• 1950
  • 1950-01-02 BE BE493080D patent/BE493080A/xx unknown
  • 1950-01-03 DE DEA584A patent/DE880723C/de not_active Expired
  • 1950-01-03 NL NL81385D patent/NL81385C/xx active

Patent Citations (2)

Also Published As

Similar Documents