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 utility of a storage element in a magnetic memory is determined by its pulse characteristics or dynamic characteristics.
• a distinct difference between the maximum value uVl of the undisturbed l-signal and the maximum value dVz of the disturbed 0-signal is important (for a good storage element the value uV1 and the value rVl, i.e. the maximum value of the disturbed l-signal, differ only slightly from each other).
• a further object of our invention is to provide a magnetic core as a storage element having a very short switching time.
• a still further object of our invention is to provide a magnet core as a storage element which has a switching time not exceeding 0.25 ,usec.
• annular core having an outer diameter not exceeding 0.6 mm. and an inner diameter which is at least half that of the outer diameter and which is constituted of a fired reaction product of lithium oxide, nickel oxide, and ferric oxide in the proportions of about 14 to 15 mol percent of Li O, about to 7 mol percent of NiO and about 78 to 81 mol percent of Fe O has a switching time not exceeding 0.25 ,usec. and a value of the quotient uVl/a'Vz 3 with a disturbance ratio of 0.61.
• the magnet cores are obtained by sintering a presintered product of a mixture of oxides of lithium, nickel and iron, which oxides may be replaced individually and Wholly or partly by an equivalent quantity of one or more other compounds of the metal concerned, which can be converted during the sintering process into the respective oxides, and in which mixture the relative quantities of lithium (calculated on Li O), nickel (calculated on NiO) and iron (calculated on Fe O are:
• the compressed product is then heated within a period of 1 minute in air or in an air-oxygen mixture on a substratum of a high-melting-point metal or a high-meltingpoint metal alloy to a temperature lying between 1060 C. and 1180 C., which temperature is maintained for 1.5 to 10 minutes.
• the sintered product then is cooled at a rate of at least 5 C. per minute and at the most 20 C. per minute to a temperature which is at least C. below the sintering temperature, the product being finally quenched by contact with the air at room temperature.
• the cores have a rather high coercive force-at least 6 oerstedthis does not appear to be detrimental since they have small dimensions.
• the invention will be described with reference to the following illustrative example, which not only specifies the switching time of the magnet cores, but also the peaking time.
• peak time (T of a magnet core denotes herein the period of time lying between the instant when the control-current attains an intensity of 10% of its maximum value and the instant when the output voltage of the l-signal, produced by the control-current pulse concerned is at a maximum.
• the peaking time is, of course, dependent upon the rising time (T,) of the control-current pulse. With the experiments relating to the present invention, the said rising time was always 0.05 sec.
• Example A finely divided mixture of 14.52 mol percent of lithium carbonate Li CO 6.45 mol percent of NiO and 79.03 mol percent of iron oxide Fe O was presintered for 10 hours at a temperature of 625 C. and then cooled.
• the presintered product was ground to powder and 50 gms. of the powdery presintered product was mixed in a mortar with 25 cms. of a 6% solution of polyvinyl alcohol in water to obtain a Slurry. This slurry was inspissated at C. to a weight of 55 to 59 gms. Then the mass was sieved through ditferent sieves having a gradually smaller width of mesh, i.e.
• the outer diameter of the sintered bodies obtained was 0.540 mm., the inner diameter 0.355 mm.
• the pulse characteristics, measured with a control-current of 995 ma., a pulse duration of 0.450 ,usec. and a rising time of 0.050 ,usec, were as follows:
• sintering temperature and the cooling temperature i.e. instead of sintering at a temperature of 1160 C., sintering was at a temperature of 1080 C., and if the cooling temperature was 980 C. instead of 1040 C., annular cores having an outer diameter of 0.550 mm. and an inner diameter of 0.360 mm. were obtained.
• the pulse characteristics measured with a control-current of 1485 3 ma., a pulse duration of 0.350 used, and a rising time of 0.050 ,usec. were:
• a method of manufacturing magnet core having an outer diameter not exceeding 0.6 mm. :and an inner diameter which is at least half that of the outer diameter, a switching time not exceeding 0.25 ,usec. and a value of the quotient uV1/dVz 3 with a disturbance ratio of 0.61 comprising the steps, heating at about 625 C. a finelydivided mixture of about 14 to 15 mol percent of Li O, about 5 to 7 mol percent of NiO, and about 78 to 81 mol percent of Fe O to form a presintered material, finely dividing and forming said presintered material into a slurry, increasing the consistency of the slurry to a mass having a weight 1.1 to 1.2 times that of the initial slurry,

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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)
• Soft Magnetic Materials (AREA)
• Powder Metallurgy (AREA)
• Hard Magnetic Materials (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=19754283

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Cited By (2)

Citations (5)

• 1962
  • 1962-12-13 NL NL286715D patent/NL286715A/xx unknown
  • 1962-12-13 NL NL136206D patent/NL136206C/xx active
• 1963
  • 1963-12-06 US US328493A patent/US3293184A/en not_active Expired - Lifetime
  • 1963-12-07 DE DE19631471342 patent/DE1471342B2/de active Pending
  • 1963-12-10 DK DK575563AA patent/DK116226B/da unknown
  • 1963-12-10 CH CH1509263A patent/CH453515A/de unknown
  • 1963-12-10 GB GB48741/63A patent/GB1062047A/en not_active Expired
  • 1963-12-10 AT AT988363A patent/AT241864B/de active
  • 1963-12-11 BE BE641146D patent/BE641146A/xx unknown
  • 1963-12-11 ES ES0294385A patent/ES294385A1/es not_active Expired

Patent Citations (5)

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