A Method and Apparatus for Measuring the Magnetization Relaxation Times of Ferrofluids
A Method and Apparatus for Measuring the Magnetization Relaxation Times of Ferrofluids
复制标题
一种测量铁磁流体磁化弛豫时间的方法和装置
DOI：
10.1109/tim.2022.3166782
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发表时间：
2022
影响因子：
5.6
通讯作者：
Boshi Fang
中科院分区：
文献类型：
--
作者：
Wenming Yang;Yue Jin;Boshi Fang
铁磁流体的磁化弛豫时间的确定值对于检查其在磁场存在下的流动现象非常重要。本文提出了一种测量磁化弛豫时间的方法，该方法是通过测量垂直于刚性旋转铁磁流体中施加的磁场的场分量来实现的。为了建立填充在两个旋转圆柱体之间的间隙中的铁磁流体中的弛豫时间、流动涡量和场分量之间的关系，分析推导了该结构中的流速、磁场和磁化场的分布。建立了实现所提出的方法的装置。使用一种铁磁流体进行校准后，在设备上测量另外两种铁磁流体的磁化弛豫时间以测试其可行性。结果表明，与动态光散射技术相比，相对误差分别为2.1%和6.1%。相比之下，本方法不需要确定铁磁流体中颗粒的尺寸分布，而只需要预先确定初始磁化率和校准系数。相应的设备坚固耐用并且结果可以轻松读出。
A definite value of the magnetization relaxation time for a ferrofluid is important to scrutinize its flow phenomenon in the presence of magnetic fields. A method for measuring the magnetization relaxation time is present in this article, which is achieved via the measurement of the field component perpendicular to the applied magnetic field in rigidly rotational ferrofluids. In order to establish the relationship among the relaxation time, the flow vorticity and the field component in a ferrofluid filled in the gap between two rotating cylinders, the distributions of flow velocity, magnetic field, and magnetization field in this configuration are derived analytically. An apparatus to implement the proposed method is set up. After calibration using one ferrofluid, the magnetization relaxation times of the other two ferrofluids are measured on the apparatus to test its feasibility. The results show that the relative errors are 2.1% and 6.1%, respectively, in comparison with that obtained by the dynamic light scatting technique. In contrast, the present method does not need to determine the size distribution of particles in ferrofluids, while only the initial magnetic susceptibility and a calibrated coefficient are required in advance. The corresponding apparatus is robust and the results can be read out easily.