| 摘要 |
1498631 Magnetic pigments BASF AG 30 Dec 1974 [29 Dec 1973] 56001/74 Heading C7U A magnetic pigment comprises magnetic single domain particles which comprise Co and Ni with oxygen as the sole non-metallic element, consisting of a ferromagnetic phase Co 0À04-0À96 Ni 0À96-0À04 and an antiferromagnetic phase which is the oxidized form of this phase having a ratio remanence/ saturation induction greater than 0À2 and a coercive force greater than 16 KA/m measured in an applied field of 800KA/m, exhibiting exchange anisotropy and anisotropic remanence after saturation. The phases may contain Fe, Cr, Mn, Zn and/or Al in such amounts as not to interfere with the exchange reaction. The pigment may be made by superficial oxidation of the ferromagnetic particles and heating in an inert gas at 100-450‹C. The metallic particles may be made by reduction of mixed oxides (e.g. formed by heating precipitated mixed hydroxides). |
