不同形貌纳米Fe_3O_4颗粒磁流体的传动性能

Transmission properties of magnetic fluids containing nano-particles of Fe_3O_4 with different morphologies

选用无规则、正八面体和六方片状形貌的纳米Fe3O4磁性颗粒制备的磁流体,通过设计、组装磁流体传动性能测试仪,探讨了磁流体传动性能与传动盘间距、传动盘之间的转速差的关系,并研究了磁流体中纳米磁性颗粒的形貌对磁流体传动性能的影响。结果表明,在传动盘间隙一定时,磁流体传递扭矩的大小在磁性粒子未达到其饱和磁化强度时,传递扭矩大小随感应磁场强度增大而迅速增大,但随着磁感应强度的进一步加大,磁性粒子逐步达到其饱和磁化强度,磁流体传递扭矩大小的增长减缓,最后几乎不再增大;传动盘之间的间隙对磁流体传递扭矩的大小影响很大,间隙越大,传递的扭矩越小;传动盘之间的转速差对磁流体传递扭矩的大小影响较小,在低转速差下传递的扭矩随转速差的增加而有所增加,但超过一定的转速差后,由于磁流体的剪切稀化效应,传递的扭矩将有所减小。另外,磁流体中磁性粒子的形貌对磁流体传递扭矩的大小有一定的影响,正八面体形貌的磁性粒子相对于无规则和六方片状形貌的磁性粒子,其磁流体能够传递更大的扭矩。

This paper selected nanoparticles of Fe304 with irregular, octahedron and sixparty flake morpholo gies as solid phase material used in magnetic fluids. A test device for the magnetic fluid transmission was de signed. The relationships among the transmission torque and the disk space, rotation difference and particle morphology of the as prepared magnetic fluids were investigated. The results showed that the transfer torque was correlated to the magnetic induction in a certain gap between the drive plates when the magnetization of magnetic particles does not reach a saturation value. The transmission torque increased with increasing the mag netic induction. However, the magnetic particles gradually reached the saturation magnetization when the mag netic induction was further increased, leading to a constant transmission torque. The gap between the drive disks had an impact on the transmission torque. A greater gap could give a smaller transmission torque. The ro tation difference between the transmission disks had a slight effect on the transmission torque at a lower rota tion. The transmission torque increased with increasing the rotation difference. However, the transferred torque would decrease when the rotation difference exceeded a certain limit due to the shearthinning effect of the magnetic fluid. The morphology of the magnetic particles in the magnetic fluid could affect the transfer torque. The nanoparticles of Fe3 04 with octahedral morphology could transfer a greater torque rather than the nanoparticles with irregular or sixparty flakelike morphologies.