摘要:
An aqueous slurry of a magnetic iron oxide powder is mixed with a suspension prepared by neutralizing an aqueous ferrous salt solution with an alkali to form ferrous hydroxide and then adding an aqueous cobalt salt solution thereto, and the excess OH concentration of the mixed slurry is adjusted to 0.05 to 3 mol/l, thereby obtaining a cobalt-and ferrous iron-containing ferromagnetic iron oxide. The cobalt-and ferrous iron-containing ferromagnetic iron oxide is excellent in coercivity, distribution of coercivity and other magnetic properties, and the magnetic tape produced by using such iron oxide is also excellent in coercivity and switching field distribution.
摘要:
A cobalt-containing magnetic iron oxide powder is provided by first coating a magnetic iron oxide base powder with a ferrous compound and then coating it with a cobalt compound. The cobalt-containing magnetic iron oxide powder provided is improved in stability of coercivity under aging and various other magnetic properties, and the magnetic tape produced by using the powder is also appreciably improved in stability of coercivity under aging as well as in various magnetic properties such as squareness, orientability and switching field distribution.
摘要:
Cobalt-containing magnetic iron oxide particles extremely suitable for magnetic recording mediums, especially for image recording mediums and a process for producing the same from the precursor, .gamma.-FeOOH which is advantageous in industry are disclosed. Cobalt-containing magnetic iron oxide particles satisfying the following equations (1), (2) and (3):20.ltoreq.SSA.ltoreq.50 (1)-16.70.ltoreq.log [V].ltoreq.-3.05 log [SSA]-11.35 (2)0.10.ltoreq.Fe.sup.2+ /total Fe.ltoreq.0.30 (3)where SSA is a BET specific surface area (m.sup.2 /g), and V is a magnetic switching unit (cm.sup.3), can be produced by producing iron oxide particles having a concentration of Fe.sup.2+ of 0.10 to 0.36 as expressed by Fe.sup.2+ /total Fe from the precursor, .gamma.-FeOOH, and coating a cobalt compound or a combination of a cobalt compound and other metal compounds on the surfaces of the iron oxide particles.
摘要:
Ferromagnetic fine powder for magnetic recording, characterized by comprising platelet like ferrite crystal particles which have such a metallic element composition that the Ba/Fe molar ratio is 1/50 to 1/8 and that the total amount of Ni and Zn is less than 0.5 mole and not less than 0.07 mole per mole of Fe, a crystal phase of magnetoplumbite phase, spinel phase or composite phase thereof and a saturation magnetization of 60 emu/g or more; and a process for producing said ferromagnetic fine powder for magnetic record.
摘要:
A process for producing ferromagnetic fine particles for magnetic recording which comprises preparing a starting material solution containing Ba, Fe and Me (Me representing at least one element selected from the group consisting of Co, Ti, Ni, Mn, Zr, Zn, Ge, Nb and V, the amount of which is 0.2 mol or less per mol of Fe) selected such that the molar ratio of Ba/(Fe+Me) is (1+m)/12 (m being a number of 0.1 to 2), mixing this starting material solution with an alkaline solution to form a coprecipitate-containing alkaline suspension, collecting and using the coprecipitate as precursor, or subjecting the coprecipitate-containing alkaline suspension to a heat treatment at a temperature below 250.degree. C. to form a precursor, and calcining such precursor at 650.degree.-950.degree. C. to produce the hexagonal platelet Ba-ferrite particles. The process is further characterized in that a boron compound is contained in the precursor in an amount of (0.01 to 1) mmol (calculated as B.sub.2 O.sub.3) per 12 mols of Fe and Me combined.
摘要翻译:一种制备用于磁记录的铁磁细颗粒的方法,包括制备含有Ba,Fe和Me的原料溶液(Me代表选自Co,Ti,Ni,Mn,Zr,Zn,Ge, Nb / V的摩尔比为(1 + m)/ 12(m为0.1〜2)的摩尔比,选择Nb / 将该原料溶液与碱性溶液混合以形成含共沉淀物的碱性悬浮液,收集并使用共沉淀物作为前体,或在低于250℃的温度下对含共沉淀物的碱性悬浮液进行热处理,形成 前体,并在650-950℃下煅烧这种前体以产生六方晶系的Ba-铁素体颗粒。 该方法的特征还在于,前体中含有硼化合物的量为(0.01-1)mmol(以B 2 O 3计)/ 12摩尔Fe和Me组合。