US3083164A - Method of producing ferrite bodies - Google Patents

Method of producing ferrite bodies Download PDF

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Publication number
US3083164A
US3083164A US852097A US85209759A US3083164A US 3083164 A US3083164 A US 3083164A US 852097 A US852097 A US 852097A US 85209759 A US85209759 A US 85209759A US 3083164 A US3083164 A US 3083164A
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Prior art keywords
sintering
temperature
cores
mixture
indicated
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US852097A
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English (en)
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Edgar C Leaycraft
Jr George H Morris
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International Business Machines Corp
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International Business Machines Corp
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Priority to NL256989D priority Critical patent/NL256989A/xx
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Priority to US852097A priority patent/US3083164A/en
Priority to GB37934/60A priority patent/GB971208A/en
Priority to FR843295A priority patent/FR1273158A/fr
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    • 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
    • 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

  • This invention relates to ferrite magnetic materials of the spinel type generally referred to as ferrospinels, and relates particularly to an improved method for processing bodies of such materials so as to provide bodies having improved squareness of the hysteresis characteristic.
  • Ferrospinel bodies are employed as magnetic memory elements and as pulse transfer elements in computers and other data processing apparatus.
  • the squareness of the hysteresis characteristic is of particular importance.
  • the most usual application requiring a maximum of hysteresis squareness is the application involving the use of ferrospinel bodies for coincident current memory devices in which the bodies have a high degree of squareness making possible to switch the magnetic state of the bodies upon the occurance of two simultaneously existing current pulses, one of which alone is of insufiicient intensity to produce magnetic switching.
  • This type of memory device is well known in the art.
  • Ferrospinel bodies are produced by sintering bodies pressed from mixed powders of ferric oxide and one or more bivalent metal oxides. During the sintering operation, the constituents of the molded bodies arrange themselves to form a spinel type crystal structure. Processes and compositions for producing these ferrospinel structures are well known.
  • the primary object of the present invention is to improve the squareness characteristic obtained from these spinel type crystal structures and this improvement isbrought about by interrupting the sintering process by cooling the cores and, thereafter, reheating the cores and continuing the sintering process for the completion of the desired sintering time interval.
  • a square loop memory body desirably exhibits a maximum possible amount of squareness in order that its magnetic state will be substantially undisturbed by a pulse having one half the intensity of a pulse capable of changing the magnetic state of the body.
  • a pulse having one half the intensity of a pulse capable of changing the magnetic state of the body there is some degree of disturbance resulting from half select pulses being applied thereto. The result of this disturbance is to reduce, to some degree, the density of magnetization retained by the body.
  • the body is capable of retaining one of two opposite states of magnetization, one of these may be considered as being as 1 state and the other may be considered as being a state.
  • Vhen a body is driven from one of these states to the other by means of the application of a magnetic driving force, an output is produced which may be sensed on a suitable sense line and the amplitude of the output may be measured in milli-volts.
  • the hysteresis squareness of a body may be defined as the ratio of the output of switching from a disturbed 1 state to the 0 state, expressed as V divided by the output of switching from a disturbed 0 state to the 0 state, expressed as V It is a further object of the invention to improve the .V V ratio of magnetic ferrite cores.
  • FIGURE 1 shows a hysteresis loop and indicates diagrammatically full and half select pulses for switching a body represented by the loop from one magnetic state to another.
  • FEGURE 2 is a diagrammatic showing of a sintering cycle in accordance with the invention.
  • FiGURE 3 is a chart showing the effects on the V V ratio of cooling to various temperatures during the sintering cycle.
  • FIGURES 4a and 4b are charts showing respective V V ratios of cores produced by interrupted sintering cycles and cores produced by uninterrupting sintering cycles.
  • ferrospinel bodies employed as magnetic memory elements are desirably possessed of a square hysteresis characteristic.
  • FIGURE 1 there is indicated generally at 10, a hysteresis loop of such a body.
  • the loop is drawn on conventional B and H coordinates. If there is applied to the body a full select 1 driving force on the H axis as indicated by the pulse 12, the body will be driven to a +B state or a l state as indicated by the point 14 on the loop, and, when the driving force is relieved, the residual magnetism in the core will be at a value indicated by the point 16 on the B axis.
  • the magnetic state of the body will be switched to a B state or the 0 state as indicated by the point 29 on the loop, and, when the driving force is relieved, the body will retain a residual magnetism indicated by the point 22 on the B axis.
  • Theratio V V provides a highly satisfactory measure of squareness in that V is a relatively absolute value of disturbance resulting from lack of perfect squareness and ,.V accommodates for the fact that various materials will have hysteresis loops of various BH ratios. Thus, for a high value of B, a greater displacement between points 22 and 30 may be tolerated than for a low value of B. Accordingly, hereinafter, :squareness ratio will be merely referred to as the expression V V and the following discussion will consider only values of V and V in the considerations of this squareness ratio.
  • the usual techniques employed in the production of ferrospinel bodies involve the mixing of commercially pure fine particles of oxides of desired materials in desired proportions. Such mixing is accomplished, for example, by wet ball milling to form a slurry. The slurry is thereafter dried and the resulting dry cake is ground to a line powder. This powder is then placed in a suitable container and calcined in air at temperatures of approximately 600 C. to 1000 C. for time intervals ranging from 3.0 minutes to 180 minutes. The actual temperatures and times employed vary with the compositions involved.
  • the material is again milled and there is added to. the material suitable binder and lubricant materials to facilitate the subsequent molding operation.
  • the binder may be polyvinyl alcohol added in the amount of approximately 3% by weight and the lubricant may be a dibutyl phthalate added in the amount of approximately 1% by weight.
  • the resulting mixture is then molded into the for-m of a desired body which may be of toroidal or of other desired shape.
  • a desired body which may be of toroidal or of other desired shape.
  • the body in this condition is termed a green body.
  • the green body may be heated to approximately 600 C. and the binder and lubricant which are organic compounds, are driven therefrom.
  • the green molding is placed in a furnace and sintered at temperatures ranging from approximately 110i) C. to 1500 C. for time intervals ranging from approximately to 30 minutes depending upon its composition and the characteristics desired.
  • the sintered body is removed from the furnace and either left to cool in air or, in some instances, furnace cooled to an intermediate temperature of approximately 960 C. and then cooled in air to room temperature.
  • FIGURE 2 shows a plot of sintering temperature versus timein which t indicates the time required for cores introduced into a furnace to come up to furnace temperature.
  • the actual sintering temperature employed will be determined by the core composition involved and the characteristics desired in the finished product. however, in any event, after the cores have been positioned in the furnace for a time interval 13, they will have arrived at furnace temperature and this temperature condition will prevail for a time interval 1
  • the time interval t is preferably extended to at least half the total sintering time, however, under some conditions of composition and desired final characteristics, this limitation is not critical. The essential consideration is that the cores remain in the furnace sufficiently long to insure their having been soaked throughout to the sintering temperature.
  • the cores are removed from the furnace and cooled in air.
  • the cores are handled in small flat containers in which the cores may be spread over the surface of the container. to permit rapid and uniform heating and cooling of the core and to permit access by the atmosphere to the core surfaces.
  • this container is withdrawn from the furnace and placed on a metal plate at room temperature, a quenching effect will occur and the temperature of the cores will drop to the quench temperature along a curve as is indicated during time i in FIGURE 2.
  • the duration of this interval is not critical, the essential consideration being that the cores be reasonably uniformly cooled, thus 1 may be of the order of minutes or days.
  • the cores are re-admitted to the furnace wherein, during time interval t they will be reheated to the sintering temperature. Thereafter, the cores are held at sintering temperature for a time interval r
  • the total time of t and I is equal to the optimum time interval for sintering the particular core composition involved to achieve the particular characteristics desired. In other words, the total time the cores are retained at sintering temperature in the present process is substantially identical to the total time which would be employed with an uninterrupted or conventional sintering process.
  • the cores are removed from the furnace and handled in any conventional manner. Some cores are immediately quenched to room temperature and some cores are first quenched to an intermediate temperature, however, any of the conventional sintering techniques may be employed following the sintering cycle as indicated by time intervals to shown in FIGURE 2.
  • Chart 1 there are set forth four compositions, each comprising a manganeseferrite ferrospinel.
  • FIGURE 3 is a chartshowing the relation between the V V ratio and the tempenature to which the cores are cooled in the quenching cycle, i.e., the temperature of the cores during time t; of FIGURE 2.
  • the data for the charts of FIGURE 3 was obtained from K-107 material processed to have a coercivity H of 1.8 oersteds.
  • the chart shows interrupted firing quench temperatures of 25 C., 100 C., 150 C., 250 C., and 500 C., and also shows a continuous firing, i.e., uninterrupted firing. Plotted against these values are values ,V V and V V
  • the plots are numbered 42, 44, and 46, respectively. From plot 46, it will be evident that a substantial increase in the V V ratio takes place when the interrupted firing quenching temperature is carried downwardly below 250 C. and maximum benefit is obtained when the quenching is carried to 100 C. or below.
  • FIGURE 40 there are shown in four columns indicated generally at 62, 64, 65, and 68, short lines indicating the relationships between various core characteristics obtained by continuous firing and interrupted firing.
  • the columns are headed M8, K-107, NCM, and CM, respectively, indicating the compositions of the respective materials and all of the materials in FIGURE 4a were processed to produce cores having approximately 1.1 oersteds coercivity.
  • the lines indicated V ,V and V connect data points and indicate the changes in these characteristics between continuously fired and interrupted fired cores for each of the compositions shown.
  • the lines V V indicate the changes in squareness ratio resulting from the improved firing process. It will be noted that in each example, the squareness ratio improves substantially.
  • Switching time T is measured in microseconds and represents the time between the rise and fall of the core response to a full select drive current measured at a predetermined milli-volt level approximately equal to of the voltage output of V It will be observed that in each instance, the improved firing produces either substantially the same or an improved switching speed.
  • FIGURE 4b contains three columns of data indicated generally at 72, 74 and 76 for materials K107, NCM and CM, respectively when processed to produce cores of 1.5 oersteds coercivity.
  • FIGURE 4 shows V and V data points and resulting V l V ratio data points for each of the materials listed. It will be observed that in each of these examples the interrupted firing technique provides an improved squareness.
  • sintering said molded body comprising the sequential steps of heating said molded body to a temperature in a range between 1100 to 1500 C. for a first sintering period of about 15 to 30 minutes, cooling said heated body in air to a temperature below 250 C. and reheating said cooled body to a temperature in said range for a second sintering period, Where said second sintering period is at least equal to one half the total sintering time.
  • sintering said molded body comprising the sequential steps of heating said molded body to a temperature in a range between 1100 to 1500 C. for a first sintering period of about 15 to 30 minutes, cooling said heated body in air to a tempera ture below C. and reheating said cooled body to a temperature in said range for a second sintering period, where said first sintering period is at least equal to one half the total sintering time.

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  • 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)
US852097A 1959-11-10 1959-11-10 Method of producing ferrite bodies Expired - Lifetime US3083164A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL256989D NL256989A (en, 2012) 1959-11-10
US852097A US3083164A (en) 1959-11-10 1959-11-10 Method of producing ferrite bodies
GB37934/60A GB971208A (en) 1959-11-10 1960-11-04 Improvements in and relating to methods of producing ferrite bodies
FR843295A FR1273158A (fr) 1959-11-10 1960-11-08 Méthode de fabrication de ferrites

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US852097A US3083164A (en) 1959-11-10 1959-11-10 Method of producing ferrite bodies

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FR (1) FR1273158A (en, 2012)
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NL (1) NL256989A (en, 2012)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1278921B (de) * 1963-09-06 1968-09-26 Siemens Ag Verfahren zur Verbesserung der zeitlichen Permeabilitaetskonstanz von Mangan-Zink-Ferritkernen

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE532384A (en, 2012) * 1953-10-07 1955-04-07
FR1121088A (fr) * 1955-02-03 1956-07-20 Lignes Telegraph Telephon Matériaux ferromagnétiques à cycle d'hystérésis rectangulaire
FR1125577A (fr) * 1955-05-03 1956-11-02 Lignes Telegraph Telephon Matériaux ferromagnétiques à cycle d'hystérésis rectangulaire
US2818387A (en) * 1954-10-28 1957-12-31 Philips Corp Square loop ferromagnetic material
GB797168A (en) * 1955-06-16 1958-06-25 Philips Electrical Ind Ltd Improvements in or relating to ferrite material for use at microwave frequencies andto methods of manufacturing such material
AT204795B (de) * 1955-06-30 1959-08-10 Siemens Ag Verfahren zur Herstellung magnetisierbarer Kerne
US2905641A (en) * 1953-12-22 1959-09-22 Philips Corp Method of manufacturing a magnet core having an approximately rectangular hysteresis loop
US2988508A (en) * 1956-09-17 1961-06-13 Philips Corp Copper containing ferrite cores

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE532384A (en, 2012) * 1953-10-07 1955-04-07
US2905641A (en) * 1953-12-22 1959-09-22 Philips Corp Method of manufacturing a magnet core having an approximately rectangular hysteresis loop
US2818387A (en) * 1954-10-28 1957-12-31 Philips Corp Square loop ferromagnetic material
FR1121088A (fr) * 1955-02-03 1956-07-20 Lignes Telegraph Telephon Matériaux ferromagnétiques à cycle d'hystérésis rectangulaire
FR67809E (fr) * 1955-02-03 1958-03-24 Lignes Telegraph Telephon Matériaux ferromagnétiques à cycle d'hystérésis rectangulaire
FR1125577A (fr) * 1955-05-03 1956-11-02 Lignes Telegraph Telephon Matériaux ferromagnétiques à cycle d'hystérésis rectangulaire
GB797168A (en) * 1955-06-16 1958-06-25 Philips Electrical Ind Ltd Improvements in or relating to ferrite material for use at microwave frequencies andto methods of manufacturing such material
AT204795B (de) * 1955-06-30 1959-08-10 Siemens Ag Verfahren zur Herstellung magnetisierbarer Kerne
US2988508A (en) * 1956-09-17 1961-06-13 Philips Corp Copper containing ferrite cores

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GB971208A (en) 1964-09-30
FR1273158A (fr) 1961-10-06
NL256989A (en, 2012)

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