High temperature process for making fine magnetic particles
    4.
    发明授权
    High temperature process for making fine magnetic particles 失效
    制造精细磁性颗粒的高温工艺

    公开(公告)号:US4777031A

    公开(公告)日:1988-10-11

    申请号:US885345

    申请日:1986-07-14

    摘要: The present invention is a method of producing single, unaggregated magnetic iron oxide particles. An iron or iron and divalent metal halide feed solution is kinetically atomized into a high velocity flame. The feed solution is vaporized and held in a reactor at a temperature and partial pressure of an oxidizing phase sufficient to form either ferrous oxide or magnetite particles. The iron or iron and divalent metal halide vapor reacts with the oxidizing phase vapor and converts to either ferrous oxide vapor or magnetite vapor. Since the vapor phase is beyond equilibrium concentration ferrous oxide or magnetite particles precipitate from the vapor phase. Quenching of the magnetite particles at an enhanced rate to less than 500.degree. C. in a reducing atmosphere renders magnetite and in a oxidizing atmosphere renders maghemite. Quenching of the ferrous oxide particles in a non-oxidizing atmosphere produces magnetite particles.

    摘要翻译: 本发明是一种生产单一的未聚集的磁性氧化铁颗粒的方法。 铁或铁和二价金属卤化物进料溶液被动力雾化成高速火焰。 将进料溶液蒸发并在足以形成氧化亚铁或磁铁矿颗粒的氧化阶段的温度和分压下保持在反应器中。 铁或铁和二价金属卤化物蒸气与氧化相蒸汽反应并转化成氧化亚铁蒸气或磁铁矿蒸汽。 由于气相超过平衡浓度,氧化亚铁或磁铁矿颗粒从气相中沉淀出来。 在还原气氛中以增强的速率将磁铁矿颗粒淬火至低于500℃,使磁铁矿在氧化气氛中呈现磁赤铁矿。 非氧化性气氛中的氧化亚铁颗粒的淬火产生磁铁矿颗粒。

    High temperature process for producing fine magnetic particles of
M-phase structure
    6.
    发明授权
    High temperature process for producing fine magnetic particles of M-phase structure 失效
    用于生产M相结构精细磁性颗粒的高温工艺

    公开(公告)号:US4765920A

    公开(公告)日:1988-08-23

    申请号:US885346

    申请日:1986-07-14

    摘要: A method for producing fine magnetic particles having the barium or strotium ferrite M-phase crystal structure. An iron and alkaline earth metal halide feed solution is vaporized to form a precursor and oxidizing vapor phase. The precursor and hydrolyzing or oxidizing vapor phases are held in a reactor at a temperature sufficient to effect vaporization of the feed solution yet which is below the melting point of the desired M-phase crystal structure. Small iron oxide particles precipitate from the vapor phase and alkaline earth oxides thereafter. The alkaline earth oxide particles diffuse into the iron oxide particles to form the desired M-phase structure. When the desired width and thickness of the M-phase crystal platelets is achieved, the M-phase particles are cooled by quenching. Composition of the feed solution may be modified by substituting divalent metal halides for the alkaline earth metal halide or by substituting trivalent halides or a combination of a divalent metal halide and either a penta or quatravalent metal halide for the ferric halide.

    摘要翻译: 一种具有钡或碲酸铁氧体M相晶体结构的精细磁性颗粒的方法。 铁和碱土金属卤化物进料溶液蒸发以形成前体和氧化气相。 前体和水解或氧化气相保持在反应器中,其温度足以使进料溶液蒸发,但低于所需M相晶体结构的熔点。 此后,小的氧化铁颗粒从气相和碱土氧化物中沉淀出来。 碱土金属氧化物颗粒扩散到氧化铁颗粒中以形成所需的M相结构。 当达到期望的M相晶体血小板的宽度和厚度时,M相颗粒通过淬火冷却。 可以通过用二价金属卤化物代替碱土金属卤化物或用三价卤化物或二价金属卤化物和五价或四价金属卤化物的组合替代卤化铁来改变进料溶液的组成。