水基磁流变液的制备和性能

Preparation and Properties of an Aqueous Magnetorhological Fluid

采用共溶胶-凝胶法对微米羰基铁粉进行了包覆和接枝的改性处理,以制备具有高稳定性的水基磁流变液,用于硅酸盐玻璃的磁流变抛光。对复合羰基铁粉的显微特征、磁性能、在水性体系中的抗氧化性能和水基磁流变液的零场粘度、磁致剪切强度等进行了分析和研究。结果表明,获得的复合羰基铁粉具有核-壳复合结构和亲水性表面基团,其磁性能与改性前相比无明显变化,但复合羰基铁粉在水性体系中的抗氧化性能显著提高;制得的水基磁流变液在无磁场作用时为具有触变性和剪切稀化特征的非牛顿型流体,其剪切稀化指数n=0.144,在剪切率为10s-1时零场粘度约为250mPa.s,其磁致剪切强度在磁感应强度为0.5T时可达到40kPa以上。

Carbonyl iron powders with diameter of several microns were modified by coating and grafting with a conjunct sol-gel method to prepare an aqueous magnetorhological fluid with high stability for magnetorhological polishing of silicate glasses.The microstructure,magnetic properties and anti-oxidizing performance in an aqueous system of the modified carbonyl iron powders,the off-state viscosity and on-state shearing stress of the aqueous magnetorhological fluid were analyzed and studied.It was showed that the modified carbonyl iron powders have a core-shell composite microstructure with hydrophilic surface groups,and its magnetic properties are changed little by the modification while its anti-oxidizing property in the aqueous system is improved markedly.In the absence of magnetic field,the aqueous magnetorhological fluid was shown to be a non-Newtonian fluid with thixotropy and shear-thinning,and its shear-thinning index,n,was 0.144,and its off-state viscosity was about 250mPa.s at shearing rate of 10s-1.And its on-state shearing stress was above 40kPa under magnetic induction strength of 0.5T.