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
  • C04B35/2616—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 lithium

Definitions

• the peak time (T of a magnetic core is understood to mean the lapse of time between the point of time at which the control current reaches a strength of 16% of its maximum value and the point of time at which the output voltage of the one signal, which is produced by a control current pulse, has become a maximum.
• the peak time naturally depends upon the rise time (T of the control current pulse.
• the rise time should always be about 0.15 micro-second.
• Another object of our invention is to provide a ferromagnetic ferrite body suitable for use as a memory Patented Dec. 28, 1965 element which has a peak rise time substantially independent of temperature over a wide range of temperatures.
• ferromagnetic bodies having a substantially rectangular hysteresis loop and which have peak rise times substantially independent of temperature over a wide range of temperatures when used as memory cores can be manufactured by mixing lithium oxide, nickel oxide, and ferric oxide in the proportions of about 2 to 20 mol percent of Li -O, about 0.5 to 45 mol percent NiO, and about 50 to mol percent Fe O and after compacting the mixture to form a body, heating the mixture at a temperature of about 1200" to 1400 C. in an atmosphere containing at least as much oxygen as air.
• the mixture may also include up to 3 mol percent of ZnO, and up to 8 mol percent C110.
• compounds which are converted by heating into oxides may be used. In order to insure a more homogeneous product, it may be desirable to reduce the heated product, after cooling, to a powder and reheating. The product may be reduced to powder several times and heated several times.
• the mixture is heated at a temperature of about 1200 to 1400 C. after which it is first cooled at a rate of not more than 30 C. per minute to a temperature which is to 600 C. below the heating temperature and is then quenched or, if the mixture which is heated at a temperature of about 1200 to 1400" C. is cooled at a rate of more than 30 C. per minute to a temperature which is 100 to 600 C. below the heating temperature, is maintained at this lower temperature for at least five minutes and then quenched.
• the preferred composition of the cores for which optirum properties may be realized is in a range of compositions in which the oxides of lithium, nickel and iron correspond to 14-15 mol percent Li O, 5--7 mol percent NiO, and 7880 mol percent F5203.
• lithium-nickel ferrite cores having a substantially rectangular hysteresis loop which are manufactured by heating at a temperature of from 1100 to 1200" C.
• they are less suitable as memory elements than those manufactured accordin to the present invention. More particularly, when used as memory cores, the difference between the output voltage of the zero signal and that of the one signal is significantly smaller. It was believed heretofore that the volatility of the lithium oxide handicapped the use of heating temperatures higher than 1200 C. It has appeared, however, that this is not the case provided that it is ensured that the sintering takes place in a gas atmosphere which contains very little, if any, water vapour.
• a method of manufacturing a ferromagnetic body having a substantially rectangular hysteresis loop comprising the steps, forming a finely-divided mixture of about 2 to 20 mol percent of LL 0, about 0.5 to 45 mol percent one signal (rVl), as well as the peak time (T at a rise 5 N10, about 50 to 85 mol percent Fe O up to 3 mol pertime (TI) of the control current pulse of 0.15 micro-seccent of ZnO, and up to 8 mol percent of CuO, compacting end are speclfied for all compositions.
• a method of manufacturing a ferromagnetic body having a substantially rectangular hysteresis loop comprising the steps, forming a finely-divided mixture of about 2 to 20 mol percent of Li O, about 0.5 to mol percent NiO, about 50 to 85 mol percent Fe O up to 3 mol percent of ZnO, and up to 8 mol percent of CuO, compacting said mixture into a body, heating said body to a temperature of about 1200 to 1400 C. in an atmosphere substantially free of water-vapor containing at least as much oxygen by volume as air, cooling said body from said heating temperature to a temperature of about 100 to 600 C. below the heating temperature at a rate of not more than 30 C. per minute, and quenching said body fromthe temperature to which it was cooled.
• heating temperature to a temperature which is 100 to 600 C. lower than said heating temperature at a'rate which is greater than 30 C. per minute maintaining said body at said latter temperature for at least five minutes, and quenching said body from said latter temperature.
• a method of manufacturing a ferromagnetic body having a substantially rectangular hysteresis loop comprising the steps, forming a finely-divided mixture of about 14 to 15 mol percent of M 0, about 5 to 7 mol percent NiO, about 78 to 80 mol percent Fe O compacting said mixture int-o a body, heating said body to a temperature of about 1200 to 1400 C. in an atmosphere substantially free of water-vapor and containing at least as much oxygen by volume as air, cooling said body from said heating temperature to a temperature about to 600 C. below said heating temperature at a rate of not more than 30 C. per minute, and quenching said body from said latter temperature.

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

Applications Claiming Priority (1)

Publications (1)

Family

ID=19753515

Family Applications (1)

Country Status (11)

Cited By (4)

Citations (3)

Family Cites Families (4)

• 0
  • NL NL273242D patent/NL273242A/xx unknown
• 1962
  • 1962-12-29 DE DEN22554A patent/DE1265024B/de active Pending
• 1963
  • 1963-01-02 GB GB26063A patent/GB959643A/en not_active Expired
  • 1963-01-02 DK DK863AA patent/DK116073B/da unknown
  • 1963-01-03 CH CH4763A patent/CH437558A/de unknown
  • 1963-01-03 ES ES283884A patent/ES283884A1/es not_active Expired
  • 1963-01-04 FR FR920446A patent/FR1344662A/fr not_active Expired
  • 1963-01-04 US US249339A patent/US3226328A/en not_active Expired - Lifetime
  • 1963-01-04 AT AT7563A patent/AT238957B/de active
  • 1963-01-04 BE BE626825D patent/BE626825A/xx unknown
• 1964
  • 1964-12-12 OA OA50840A patent/OA00771A/xx unknown

Patent Citations (3)

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