Rheological and sealing properties study of carbon nanotube-modified high viscosity magnetic fluids

The preparation of magnetic fluids (MFs) with high viscosity, high saturation magnetization, and high stability has long been a critical challenge hindering the progress of related applications. In this study, we successfully prepared carbon nanotube-modified Poly-Alpha-Olefine20-based magnetic fluids (CNT-MF). The rotational rheometer was employed for rheological characterization under different conditions. Through a self-built magnetic fluids sealing test rig, the impact of their rheological properties in practical working environments was verified. The results revealed that the CNT-MF achieved a saturation magnetization of up to 36.2 KA/m, an apparent viscosity exceeding 2336 mPa s (at 0 T, 1000 1/s shear rate, and 25 °C). When applied to magnetic fluid sealing, CNT-MF showed more excellent sealing performance, especially in low-speed sealing and small seal clearance conditions. In the static sealing with a 0.6 mm sealing gap, the sealing capacity value of CNT-MF exceeds that of PAO3.5-MF by more than 19.28%, which effectively demonstrates the significant improvement effect of the rheological properties of MF on sealing performance.