基于中空钴微米颗粒的磁流变液性能研究

Properties of magneto-rheological fluids based on hollow cobalt micro-particles

采用水热法制备钴微米颗粒，通过X射线衍射仪、扫描电镜和振动样品磁强计对颗粒的相结构、形貌及磁性能进行表征。结果表明，颗粒为密排六方结构的单质钴，粒径3～5μm，内部呈中空结构，饱和磁化强度为161A·m^2／kg。以中空钴微米颗粒为悬浮相，以硅油为基液，制备颗粒体积分数为12％的磁流变液。测试结果表明，基于中空钴微米颗粒的磁流变液的磁致剪切屈服强度在250kA／m磁场下达到37kPa，剪切应力的时间稳定性、长期静置的沉降稳定性等均优于同体积浓度的羰基铁粉磁流变液。

Cobalt particles were prepared by hydrothermal method. Their composition, morphology, and magnetic property were analyzed by X-ray diffractometer, scanning electron microscope and vibrating sample magnetometer, respectively. The results indicated the composition of the particles was pure cobalt with closepacked hexagonal structure. The particles presented hollow structure with particle size distributed in the range of 3 to 5 micrometers. The saturation magnetization of the particles was 161A·m^2/kg, which was close to that of carbonyl iron particle （CIP）. Magnetorheological （MR） fluids were prepared with the hollow cobalt particle （HCP）, the volume fraction of which was 12%, and silicone oil. Their properties were tested, the results of which indicated that the MR fluids presented a field-induced yield stress of 37 kPa. Their shear stress stability with time at constant shear rate, and sedimentation stability during long time standing was better than that of the MR fluids based on carbonyl iron particles with the same volume fraction.