Control of Magnetic Particle Size in Ferrofluid and Its Effect on Rheological Properties

Abstract Rheological properties are the theoretical basis and key to common problems in ferrofluid applications, therefore they expected be adjustable satisfy different technical requirements through altering microstructure of during process preparation. In this paper, Four samples with magnetic particle size were prepared by controlling concentration precursor solution co-precipitation rheological these investigated. These exhibited field-controlled properties. Eternal field would enhance formation microstructures, resulting an increase viscosity. While shear rate, microstructures tended destroyed, causing viscosity decrease. There two opposing mechanisms influence concentration. On one hand, reduction produce primary particles smaller size. But on other surfactant became insufficient completely coat because increased specific surface area, aggregate form secondary clustering structures which strongly enhanced magnetoviscous effect weakened viscoelastic effect.