Three-dimensional morphology of field-induced chain-like aggregates of superparamagnetic microparticles

We develop a study concerning the three-dimensional morphology of chain-like aggregates formed by 1 μ m-sized super-paramagnetic particles suspended in water under the action of a constant uniaxial magnetic field. This kind of fluids are known as magneto-rheological fluids (MRF) and are present in many industrial and technological applications. In order to characterize the morphology of the aggregates, the fractal dimension, D f , is obtained by a simple implementation of the small angle light scattering (SALS) technique with a CCD Camera. In the experiments, the values of the magnetic field amplitude and particle concentration are changed, finding that the fractal dimension depends on the ratio of two characteristic lengths, R 1 / R 0 . Besides, we also discuss the relation between 3D (obtained by light scattering) and 2D (obtained by image analysis) fractal dimensions for the case of these anisotropic aggregates.