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    • 4. 发明授权
    • Particles containing iron carbide
    • 含有碳化铁的颗粒
    • US5437805A
    • 1995-08-01
    • US134873
    • 1993-10-12
    • Takuya AraseYoshiyuki ShibuyaShigeo Daimon
    • Takuya AraseYoshiyuki ShibuyaShigeo Daimon
    • B01J27/22C01B31/30G11B5/706
    • B01J27/22C01B31/301G11B5/70615G11B5/70626G11B5/70642C01P2002/72C01P2002/77C01P2004/10C01P2004/54C01P2004/61C01P2004/62C01P2006/42C01P2006/80
    • The present invention provides acicular particles (A) containing an iron carbide, which have (a) a free carbon content of at most 20 wt. %, and (b) and Fe.sub.5 C.sub.2 ratio(x) of at least 70% and a coercive force of 3.times.+300 to 7.times.+270 Oe, the ratio(x) being expressed by ##EQU1## where S1 is the X-ray diffraction strength of Fe.sub.5 C.sub.2, and S2 is the X-ray diffraction strength of Fe.sub.3 O.sub.4.The invention further provides particles (B) containing nickel and an iron carbide.The invention further provides acicular particles containing an iron carbide which are obtained by heating an aqueous dispersion of ferric hydroxide in an alkaline system in the presence of a water-soluble compound capable of coordinating to iron to obtain acicular .alpha.-ferric oxide and contacting the product with a carbon-containing reducing-and-carburizing agent or with a mixture of the agent and a carbon-free reducing agent, with or without contacting the product with the carbon-free reducing agent.These particles (A) and (C) are controllable in coercive force and usable for magnetic record media of various standards.
    • 本发明提供了含有碳化铁的针状粒子(A),其具有(a)游离碳含量至多为20重量% %,(b)和Fe5C2比(x)至少为70%,矫顽力为3x + 300〜7×270ee,比例(x)由表示,其中S1为X射线衍射 Fe5C2的强度,S2是Fe3O4的X射线衍射强度。 本发明还提供含有镍和碳化铁的颗粒(B)。 本发明还提供了含有碳化铁的针状颗粒,其通过在碱性体系中在能够与铁配位的水溶性化合物的存在下加热氢氧化铁的水分散体而获得,得到针状的α-氧化铁并与产物接触 与含碳还原和渗碳剂或与该试剂和不含碳的还原剂的混合物,与或不使该产物与无碳还原剂接触。 这些颗粒(A)和(C)在矫顽力方面是可控的,可用于各种标准的磁记录介质。