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把针状γ-Fe_2O_3、Fe_3O_4、包钴γ-Fe_2O_3和掺钴γ-Fe_2O_3等粒子的试样磨碎并进行机化反应,测定其磁特性、形状、结晶构造、比表面积、相变、耐热性以及空洞孔径的变化等,并据此分别进行研究对比。另外,还研究了研磨环境对反应的影响。形状的变化是因针状粒予被剪断而引起的,全部试样都达到了大体一定的针状比。γ-Fe2_O_3和Fe3_O_4的矫顽力和矩形比,在研磨初期有过下降,而后又上升了。磁通密度在α-Fe_2O_3生成的同时减少了。γ-FeOOH经加热脱水得到的γ-Fe_2O_3,最容易发生向α-Fe_2O_3的相变,其次是经过还原氧化的钴γ-Fe_2O_3、Fe_3O_4、掺钴γ-Fe_2O_3。包钴γ-Fe_2O_3几乎不发生相变。这是因为包钴层可靠地防止了机械化学变化。在研磨环境里,空气中的水份对相变有抑制作用,而空气中氧气则促进相变,温度对相变没影响。一般来说,比表面积越大,研磨效果就越显著。并且,根据包钴效果、研磨气氛的效果等判明,样品表面的状态是机化反应的重要因素,机化相变是从表面发生的。
The samples of acicular γ-Fe_2O_3, Fe_3O_4, cobalt-doped γ-Fe_2O_3 and cobalt-doped γ-Fe_2O_3 were ground and subjected to mechanochemical reaction to measure their magnetic properties, shape, crystal structure, specific surface area, phase transformation, Heat and the change of the void diameter, etc., and accordingly study and contrast. In addition, the effect of grinding environment on the reaction was also studied. Shape changes are caused by needle-shaped particles to be cut, all the samples have reached a generally fixed acicular ratio. The coercivity and squareness ratio of γ-Fe2_O_3 and Fe3_O_4 decreased slightly in the initial stage of grinding and then rose again. The magnetic flux density is reduced while α-Fe 2 O 3 is generated. γ-FeOOH obtained by heating the dehydration of γ-Fe_2O_3, the most likely to happen to α-Fe_2O_3 phase transition, followed by reduced oxidation of cobalt γ-Fe_2O_3, Fe_3O_4, cobalt-doped γ-Fe_2O_3. Cobalt-containing γ-Fe_2O_3 hardly undergoes phase transition. This is because the cobalt-coated layer reliably prevents mechanochemical changes. In the grinding environment, the moisture in the air has an inhibitory effect on the phase transition, while the oxygen in the air promotes the phase transition, and the temperature has no effect on the phase transition. In general, the greater the specific surface area, the more significant the grinding effect. And, according to cobalt effect, the effect of the grinding atmosphere and other identified, the state of the sample surface is an important factor in the mechanochemical reaction, the mechanical phase transition occurs from the surface.