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39 条记录 (耗时 0.027 秒)

    Document authentication by means of exchange-anisotropic magnetic material
    7.
    发明授权
    Document authentication by means of exchange-anisotropic magnetic material 失效
    通过交换各向异性磁性材料进行文件认证

    公开(公告)号：US4396886A

    公开(公告)日：1983-08-02

    申请号：US212616

    申请日：1980-12-03

    申请人： Eberhard Koester ,  Joachim Hack ,  Manfred Steuerwald

    发明人： Eberhard Koester ,  Joachim Hack ,  Manfred Steuerwald

    IPC分类号： G06K19/10 ,  G06K7/08 ,  G06K19/12 ,  G07D7/04 ,  G11B5/00 ,  G11B23/30 ,  G01R33/12 ,  G06K9/00

    CPC分类号： G07D7/04 ,  G06K19/12

    摘要： A process for authenticating recording media which are to be safeguarded against falsification and which possess discrete regions of an exchange-anisotropic magnetic material, by comparison of the polarity of a residual magnetization which is left over, because of the exchange anisotropy of the magnetic material, from a predetermined initial magnetization after exposure of the material to a specific temperature cycle and, subsequently, to a magnetic AC field which decreases to zero, with the polarity of a residual magnetization formed in the same way from an opposite initial magnetization, and an apparatus for carrying out the said process.

    摘要翻译： 由于磁性材料的交换各向异性，通过比较留下的剩余磁化的极性，进行认证记录介质的处理，以防止伪造并具有互换各向异性磁性材料的离散区域， 从材料暴露于特定温度循环之后的预定初始磁化，以及随后以相反的方式从相反的初始磁化形成的剩余磁化的极性降低到零的磁性AC场，以及装置 用于执行所述过程。

    Manufacture of acicular cobalt-modified magnetic iron oxide
    9.
    发明授权
    Manufacture of acicular cobalt-modified magnetic iron oxide 失效
    针状钴改性磁性氧化铁的制造

    公开(公告)号：US4188302A

    公开(公告)日：1980-02-12

    申请号：US872262

    申请日：1978-01-25

    申请人： Hans-Juergen Becker ,  Christof Jaeckh ,  Eberhard Koester ,  Werner Loeser ,  Manfred Ohlinger ,  Werner Steck

    发明人： Hans-Juergen Becker ,  Christof Jaeckh ,  Eberhard Koester ,  Werner Loeser ,  Manfred Ohlinger ,  Werner Steck

    IPC分类号： C01G49/02 ,  C01G49/00 ,  C01G49/06 ,  G11B5/706 ,  H01F1/11

    CPC分类号： C01G49/06 ,  G11B5/70663 ,  G11B5/70673 ,  G11B5/70694 ,  C01P2002/54 ,  C01P2004/10 ,  C01P2006/10 ,  C01P2006/42

    摘要： A process for the manufacture of an acicular magnetic iron oxide containing from 0.5 to 10 percent by weight of cobalt and up to 24 percent by weight of divalent iron, each based on the amount of iron(III) oxide, wherein an aqueous suspension of gamma-iron(III) oxide, containing cobalt(II) and iron(II) ions, the suspension having a hydroxyl ion concentration of more than 3.6.times.10.sup.-6 moles/liter, is heated at from 50.degree. to 100.degree. C. for at least 15 minutes, and the resulting precipitate is filtered off, washed until neutral, dried at below 100.degree. C. and thereafter heated at from 100.degree. to 200.degree. C.The products thus obtained give, even when their cobalt content is low, a very high coercive force, while the effect of temperature on the coercive force and residual induction is very slight.

    摘要翻译： 一种用于制造针状磁性氧化铁的方法，其含有0.5至10重量％的钴和至多24重量％的二价铁，每个基于氧化铁（III）的量，其中γ 氧化铁（III），含有钴（II）和铁（II）离子，羟基离子浓度大于3.6×10 -6摩尔/升的悬浮液在50℃至100℃下加热至 至少15分钟，滤出所得沉淀物，洗涤至中性，在100℃以下干燥，然后在100〜200℃下加热。由此得到的产物即使在钴含量低的情况下也能得到 矫顽力非常高，而温度对矫顽力和残余感应的影响非常小。