摘要:
A magnetic iron oxide having a large coercive force and an improved squareness ratio prepared by coating the surface of needle-like particles of magnetic iron oxide with a cobalt compound, placing the coated iron oxide particles in a unidirectionally oriented magnetic field thereby orienting the particles in the direction of the magnetic field, and heat-treating the needle-like particles in this state with the application of an external magnetic field, or heat-treating the needle-like particles in a magnetized state.
摘要:
A process for stabilizing a ferromagnetic material comprising heat-treating a needle-like ferromagnetic material represented by the formula MO.sub.x wherein M is a ferromagnetic metal ion or a ferromagnetic non-metal ion and another metal ion, and x is the degree of oxidation which ranges from 1.36 to 1.47, and containing at least 0.5 atom % Co, at a temperature of at least about 40.degree. C, and a process for stabilizing a magnetic recording member comprising heat-treating a magnetic recording member produced by providing a ferromagnetic recording layer comprising (a) a ferromagnetic material represented by the formula MO.sub.x wherein M and x are the same as defined above, and containing at least 0.5 atom % Co, and (b) a binder, on a support, at a temperature of at least about 40.degree. C.
摘要翻译:一种用于稳定铁磁材料的方法,包括热处理由式MOx表示的针状铁磁材料,其中M是铁磁金属离子或铁磁性非金属离子和另一种金属离子,x是氧化程度 1.36至1.47,并且在至少约40℃的温度下含有至少0.5原子%的Co,以及用于稳定磁性记录元件的方法,该方法包括热处理通过提供铁磁性记录层产生的磁性记录元件,所述磁性记录元件包括 (a)由式MOx表示的铁磁材料,其中M和x与上述定义相同,并且在载体上至少包含至少约40的温度下含有至少0.5原子%的Co和(b)粘合剂 DEG C.
摘要:
A process for producing a cobalt-containing ferromagnetic iron oxide powder suitable for magnetic recording which comprises(a) mixing cobalt ion, ferrous ion and an alkali with an aqueous dispersion of acicular ferromagnetic iron oxide nuclei under non-oxidizing conditions at a temperature of about 50.degree. C. or less;(b) heating the dispersion to a temperature of at least about 60.degree. C. but below the boiling point of the dispersion under non-oxidizing conditions to cause a reaction; and(c) treating the dispersion at a temperature of at least about 60.degree. C. but below the boiling point of the dispersion under the following conditions:(1) initially treating the dispersion under non-oxidizing conditions for about 5 minutes or more;(2) subsequentially treating the dispersion under oxidizing conditions for about 5 minutes or more prior to the termination of the reaction; and(3) a total treating time under non-oxidizing conditions and oxidizing conditions of at least about 30 minutes.
摘要:
A Co- and Fe-containing ferromagnetic iron oxide powder having a high coercive force and improved stability to heat and pressure is produced by adding an aqueous alkali solution, an aqueous solution containing Co.sup.+2 ions, and an aqueous solution containing not more than 1 equivalent, based on the Co.sup.+2 ions, of Fe ions to a suspension of ferromagnetic iron oxide, and heating the mixture at a temperature of at least 80.degree. C in the presence of an oxidizing agent. The ferromagnetic iron oxide powder is especially suitable for producing magnetic recording media.
摘要:
In a process for producing ferromagnetic powder which comprises adding an aqueous solution containing Co.sup.+2 ions, with or without another cation or cations, and an alkali solution to a suspension of ferromagnetic iron oxide, and heating the mixture to produce ferromagnetic iron oxide containing the metal provided by such an ion (s), the improvement wherein the heating is carried out in the presence of an oxidizing agent.
摘要:
Co- and Fe-containing ferromagnetic iron oxide powder having a high coercive force and improved stability to heat and pressure is produced by adding an aqueous alkali solution, an aqueous solution containing Co.sup.+2 ions, and an aqueous solution containing not more than 1 equivalent, based on the Co.sup.+2 ions, of Fe.sup.+3 ions to a suspension of a ferromagnetic iron oxide, and heating the mixture at a temperature of at least about 80.degree. C, preferably 90.degree. to 105.degree. C. The ferromagnetic iron oxide powder is especially suitable for producing magnetic recording media.
摘要:
In a process for producing a ferromagnetic powder having a high coercive force which comprises adding an aqueous solution containing Co.sup.+2 ions, or both Co.sup.+2 ions and another cation(s), and an alkali solution to a suspension of a ferromagnetic iron oxide containing the metal(s) given by these ion(s), the improvement wherein said ferromagnetic iron oxide is treated with a reducing agent prior to the preparation of the suspension.
摘要:
A method for magnetic recording and reproduction comprising the steps of: (1) magnetically multiple-recording signals on a magnetic recording medium comprising a support having thereon an upper magnetic recording layer comprising barium ferrite having an increased coercive force at 60.degree. C. or more and a lower magnetic recording layer comprising at least one of chromium dioxide and Co-modified iron oxide, having a decreased coercive force at 60.degree. C. or more, disposed between said upper magnetic recording layer and said support; (2) heating said magnetic recording layers prior to reproduction due to a reproducing head; and (3) reproducing said magnetically recorded signal from said heated magnetic recording medium which is multiple-recorded.
摘要:
A magnetic Fe oxide containing Co, and optionally, a divalent metal, in which the oxidation degree indicated by the following formula ranges from about 30% to 80%; ##EQU1## wherein y is the amount of the Co, plus the divalent metal if present, in atomic % contained in the magnetic Fe oxide, and R is the ratio of the divalent Fe ion to the total Fe ions;and a process for producing a magnetic Fe oxide containing Co, and optionally, a divalent metal, and having an oxidizing degree of about 30 to 80%, which comprises dehydrating and reducing goethite containing Co, and optionally, the divalent metal, to obtain magnetic containing Co, and optionally, a divalent metal, and oxidizing gradually the magnetite at a relatively low temperature of lower than about 100.degree. C.
摘要:
A magnetic recording material which comprises a support having thereon a magnetic recording layer comprising a ferromagnetic substance and a binder, wherein the ferromagnetic substance comprises a mixture of (1) a Berthollide iron oxide having a particle size of about 0.5 .mu. or larger and a degree of oxidation represented by the value of x in FeO.sub.x of 1.33