US3420777A - Procedure for producing a ferrite,especially adequate for use in pulse relay cores - Google Patents

Procedure for producing a ferrite,especially adequate for use in pulse relay cores Download PDF

Info

Publication number
US3420777A
US3420777A US510816A US51081665A US3420777A US 3420777 A US3420777 A US 3420777A US 510816 A US510816 A US 510816A US 51081665 A US51081665 A US 51081665A US 3420777 A US3420777 A US 3420777A
Authority
US
United States
Prior art keywords
ferrite
temperature
cores
magnetostatic
magnetization
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US510816A
Other languages
English (en)
Inventor
Karl Hans Polasek
Sven Jan Einar Rudestedt
Elmar Johannes Umblia
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telefonaktiebolaget LM Ericsson AB
Original Assignee
Telefonaktiebolaget LM Ericsson AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget LM Ericsson AB filed Critical Telefonaktiebolaget LM Ericsson AB
Application granted granted Critical
Publication of US3420777A publication Critical patent/US3420777A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • C04B35/265—Compositions containing one or more ferrites of the group comprising manganese or zinc and one or more ferrites of the group comprising nickel, copper or cobalt

Definitions

  • a mould lubricant is added thereto and subsequently the mixture is moulded to desired form, for instance cores.
  • the cores are subjected to a final sintering process by heating to a constant sintering temperature during a predetermined holding time, the sintering temperature also this time being below the melting point of the oxides.
  • the ferrite material to be adequate for pulse relay cores ought to have a high volume resistivity, a relatively high coercive force, a high remanent magnetization, and the hysteresis loop should be of substantially square form.
  • dynamic magnetization i.e. at pulse magnetization where maximum field force is applied within a few microseconds, the energy losses caused by the magnetic relaxation distortion should be small.
  • the known ferrites are principally of two different kinds, soft-magnetic and hard-magnetic, but neither of them fulfils all the mentioned requirements.
  • the soft-magnetic ferrite often has a square hysteresis loop, but its coercive force is very low (0.15Hc530). This material, therefore, is not adequate as a source of magnetic force or for the control of a sufficiently strong permanent magnetic field eventually used as a power source for a pulse relay.
  • the hard-magnetic material has a very high coercive force (HczlOOO) and cannot be used for pulse magnetization, because it requires too high amount of energy for magnetization.
  • the cobalt ferrite is a hard-magnetic ferrite, the coe'rcive force of which may be lowered by the addition of certain non-magnetic materials, but this ferrite has a relatively low volume resistivity l0,000 ohm cm.), which is a great disadvantage.
  • the pulse relays are so arranged that their electric contacts form an integrating part of the magnetic circuit. Therefore, said magnetic circuit may not form a closed electric circuit.
  • an insulating separator has to be introduced in the magnetic circuit, which means an extra air gap that highly reduces the elfectivity of the magnetic circuit.
  • FIG. 1 shows hysteresis loops for a ferrite material at magnetostatic magnetization'as well as at dynamic magnetization
  • FIG. 2 shows the coercive force He as a function of the maximum magnetization field Hm.
  • magnetostatic magnetization is meant a magnetization at which the magnetization current is raised from O-value to maximum value so slowly, that the least possible energy losses occur
  • dynamic magnetization is meant a magnetization with an instant raising of the current to maximum value.
  • Hc(d) is the coercive force at dynamic magnetization
  • Hc(st) the coercive force at magnetostatic magnetization
  • Hm(k) the value of the magnetizing field at 'which an increase gives only an insignificant increase of the magnetic energy of the ferrite.
  • the magnetostatic remanence ratio is defined as the ratio between the magnetostatic remanence Br and the magnetization Bm'.
  • the magnetostatic coercive force ratio is defined as the ratio between the value of the magnetizing field force Hm(k) and the corresponding coercive force Hc(k).
  • the energy loss ratio finally is defined as the ratio between the coercive force at dynamic magnetizing Hc(d) and the coercive force at magnetostatic magnetizing Hc(st) and constitutes a good approximation for the ratio between required energy in the two magnetization cases.
  • the amount of energy is represented by the size of the surface enclosed within the respective hysteresis loop (FIG. 1). The difference between the sizes of these surfaces represents the energy loss caused by the magnetic relaxation distortion at pulsing.
  • the oxide mixture being composed substantially according to the molecular formula Co Zn Fe O in which formula 0.01x0.04, gg- Example 1 Cobalt zinc ferrite according to fhe mo
  • the bodies are thereafter sintered in a final sintering oven, the heating up being performed with a speed of 100 C. per hour to a temperature of 1150f C. After a four hour holding time at 1150 C. the sintering temperature is rapidly raised to 1250 C. whereafter the form bodies immediately are rapidly cooled off in air to a temperature below 200 C.
  • the ferrite material thus obtained has the following properties.
  • Cobalt zinc ferrite according to the molecular formula
  • Manganese carbonate (MnCO 79 is sintered preliminarily by heating in air to 1000 C. with a holding time of 1 hour at this temperature. After cooling the sintering product is finely pulverized and dried. The dry ferrite powder is mixed with a convenient mould lubricant, granulated and pressed to cores.
  • the cores are heated up at a heating speed of 100 C. per hour to a temperature of 1350 C., whereafter the cores are immediately cooled down to 1250" C. After a holding time of 3 hours at 1250 C. the cores are cooled in the oven to 950 C. at which temperature the oven is held during 18 hours. Thereafter the cores are rapidly cooled down to room temperature.
  • the cores thus obtained have the following properties:
  • the cores are exposed to a temperature shot of about 100 C. above the high final sintering temperature and is because of practical reasons performed at the beginning or the end of the holding time. With respect to the effects of this temperature shot it is, however, of no importance at which time it is effectuated.
  • the final cooling off at the last sintering process should generally be rapid as this gives a square hysteresis loop. It is often of advantage to carry out the cooling off in two stages by interrupting the cooling off at a temperature in the inverval between 750 C.1050 C. and maintaining the cores at this temperature during a time of 12-18 hours. By this procedure it is assured that the individual cores have, as far as possible, equal properties.
  • the final sintering process is carried out in air, whereby the oxygen of the air sustain the oxidation of the metals.
  • the oxygen of the air sustain the oxidation of the metals.

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)
  • Compounds Of Iron (AREA)
US510816A 1964-12-16 1965-12-01 Procedure for producing a ferrite,especially adequate for use in pulse relay cores Expired - Lifetime US3420777A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE1520764 1964-12-16

Publications (1)

Publication Number Publication Date
US3420777A true US3420777A (en) 1969-01-07

Family

ID=20300311

Family Applications (1)

Application Number Title Priority Date Filing Date
US510816A Expired - Lifetime US3420777A (en) 1964-12-16 1965-12-01 Procedure for producing a ferrite,especially adequate for use in pulse relay cores

Country Status (5)

Country Link
US (1) US3420777A (enrdf_load_stackoverflow)
DE (1) DE1671152A1 (enrdf_load_stackoverflow)
FR (1) FR1460258A (enrdf_load_stackoverflow)
GB (1) GB1074178A (enrdf_load_stackoverflow)
NL (1) NL6516418A (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1074178A (en) * 1964-12-16 1967-06-28 Ericsson Telefon Ab L M Procedure for producing a ferrite, especially adequate for use in pulse relay cores

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2994522A (en) * 1960-06-02 1961-08-01 Indiana General Corp Process and apparatus for firing ceramic ferrites
GB954775A (en) * 1962-03-26 1964-04-08 Philips Electrical Ind Ltd Improvements in methods of manufacturing sintered ferrite bodies
FR1460258A (fr) * 1964-12-16 1966-11-25 Ericsson Telefon Ab L M Procédé de fabrication d'un ferrite pour des noyaux de relais à impulsions

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2994522A (en) * 1960-06-02 1961-08-01 Indiana General Corp Process and apparatus for firing ceramic ferrites
GB954775A (en) * 1962-03-26 1964-04-08 Philips Electrical Ind Ltd Improvements in methods of manufacturing sintered ferrite bodies
FR1460258A (fr) * 1964-12-16 1966-11-25 Ericsson Telefon Ab L M Procédé de fabrication d'un ferrite pour des noyaux de relais à impulsions

Also Published As

Publication number Publication date
NL6516418A (enrdf_load_stackoverflow) 1966-06-17
GB1074178A (en) 1967-06-28
DE1671152A1 (de) 1971-09-09
FR1460258A (fr) 1966-11-25

Similar Documents

Publication Publication Date Title
Cochardt Recent ferrite magnet developments
US4081297A (en) RE-Co-Fe-transition metal permanent magnet and method of making it
US3502584A (en) Magnetic composite materials
US4076561A (en) Method of making a laminated rare earth metal-cobalt permanent magnet body
JPS54124822A (en) Permanent magnet material
GB820959A (en) Improvements in or relating to ferromagnetic materials of the ferrite type and methods of manufacturing same
Wallace et al. High energy magnets from PrCo 5
US3420777A (en) Procedure for producing a ferrite,especially adequate for use in pulse relay cores
US3002930A (en) Process of making a ferromagnetic body
KR900015187A (ko) 고성능 스트론튬 페라이트 자석의 제조방법
JPS56109827A (en) Manufacture of iron compound particle for magnetic recording medium
EP0069362B1 (en) Permanent magnet
JP2848533B2 (ja) 永久磁石の製造方法
US3032503A (en) Composition of magnetic core material and method of producing same
GB820853A (en) Improvements in or relating to methods of manufacturing non-metallic ferromagnetic materials
GB803625A (en) Improvements in or relating to magnetisable cores made of sintered oxides and methods of manufacturing such cores
JPS56150153A (en) Permanent magnet alloy
US3072576A (en) Ferrites having rectangular hysteresis loops and method for manufacture of same
US2960472A (en) Mixed ferrites of manganese, magnesium and zinc and their methods of preparation
US3024196A (en) Ferrite with constricted magnetic hysteresis loop
US3297576A (en) Method of making memory core
US3042619A (en) Ferrite composition for bistable magnetic circuits
US3376227A (en) Lithium nickel ferrite magnetic switching element
GB883291A (en) Improvements in or relating to ferromagnetic ferrite cores
JP2633700B2 (ja) 希土類永久磁石の製造方法