GB722175A - Improvements in or relating to the production of magnetisable material - Google Patents

Improvements in or relating to the production of magnetisable material

Info

Publication number
GB722175A
GB722175A GB2728349A GB2728349A GB722175A GB 722175 A GB722175 A GB 722175A GB 2728349 A GB2728349 A GB 2728349A GB 2728349 A GB2728349 A GB 2728349A GB 722175 A GB722175 A GB 722175A
Authority
GB
United Kingdom
Prior art keywords
pot
hydrogen
water
ferric oxide
heating
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
Application number
GB2728349A
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.)
Clevite Corp
Original Assignee
Clevite Corp
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 Clevite Corp filed Critical Clevite Corp
Priority to GB2728349A priority Critical patent/GB722175A/en
Publication of GB722175A publication Critical patent/GB722175A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
    • G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
    • G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
    • G11B5/70678—Ferrites
    • G11B5/70684—Ferro-ferrioxydes

Abstract

<PICT:0722175/III/1> Black ferroferric oxide having a coercive force of about 250-325 oersteds and a remanence of about 3,500 gaus or higher and suitable for making a magnetic sound recorder-reproducer tape, is prepared by heating finely divided yellow, hydrated ferric oxide to about 400-450 DEG C. for about 60-120 minutes and, whilst heating, applying or reducing gas such as hydrogen or carbon monoxide under pressure, e.g. at 25-35 lbs./sq. in. above atmospheric. The ferric oxide used may be obtained by precipitation or by heating ferrous sulphate heptahydrate at 600-700 DEG C. A suitable reduction furnace comprises a pot 20 mounted on rollers 11 and heated electrically by coil 12. The pot may be arranged to rotate. A valved pipe 35 extends through the non-heated portion of the pot, and a baffle wall 21. The furnace is first heated to 600-700 DEG C., and the pot with ferric oxide therein, bearing, say, a volume ratio of 1:50 with the void space, is then placed in position. Cover 30 is bolted on, and moisture escapes through valved pipe 25. Thereupon, the valve is closed and hydrogen under pressure admitted through pipe 35 for the prescribed period. Evolved steam condenses on the water-cooled end cover 30. Alternatively, water-absorbing material, such as silica gel or alumina, may be put into the pot. The pot when removed may be allowed to cool, or quenched in water. If the reduction process is carried too far, whereby a spontaneously-ignitable product is formed, it may be reversed by replacing the hydrogen by steam.
GB2728349A 1949-10-24 1949-10-24 Improvements in or relating to the production of magnetisable material Expired GB722175A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2728349A GB722175A (en) 1949-10-24 1949-10-24 Improvements in or relating to the production of magnetisable material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2728349A GB722175A (en) 1949-10-24 1949-10-24 Improvements in or relating to the production of magnetisable material

Publications (1)

Publication Number Publication Date
GB722175A true GB722175A (en) 1955-01-19

Family

ID=10257052

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2728349A Expired GB722175A (en) 1949-10-24 1949-10-24 Improvements in or relating to the production of magnetisable material

Country Status (1)

Country Link
GB (1) GB722175A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3036889A (en) * 1957-04-11 1962-05-29 Frey Friedrich Process of producing black oxide of iron

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3036889A (en) * 1957-04-11 1962-05-29 Frey Friedrich Process of producing black oxide of iron

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