Cryogenic Solidification and Rheological Properties of Magnetic Fluids with Different Base Liquids

Abstract

Background: In many practical applications, the rheological properties of magnetic fluids (MFs) are essential for ensuring system stability and reliability, while the viscosity, polarity, and thermal stability of the base fluid significantly influence their flow behavior and overall stability. Aims: This study investigated the low-temperature solidification behavior of magnetic fluids with different base liquids and evaluated the influence of freezing–thawing treatment on their rheological recovery behavior and engineering applicability. Research Design: Four magnetic fluids, including water-based, ester-based, kerosene-based, and engine oil-based systems, were comparatively studied using a custom low-temperature testing device and rotational rheological measurements. Methods: The freezing behavior and flow states of the samples were compared at different temperatures. Rheological tests were conducted under magnetic fields ranging from 0 to 400 mT after the samples recovered to room temperature following freezing–thawing treatment. In addition, a magnetic fluid damper was fabricated to evaluate vibration attenuation performance. Results: The results showed that the base liquid strongly affected the low-temperature flowability of magnetic fluids. Water-based magnetic fluid froze at approximately −15 °C, whereas engine oil-based magnetic fluid maintained acceptable flowability until approximately −55 °C. All samples exhibited magnetoviscous behavior under external magnetic fields. After freezing–thawing treatment, the rheological trends remained generally stable, indicating good structural recovery capability. The magnetic fluid damper also showed effective vibration attenuation performance. Conclusion: Engine oil-based magnetic fluid exhibited the best overall low-temperature adaptability and rheological recovery stability among the tested samples. These results provide experimental references for the application of magnetic fluids in low-temperature sealing and damping systems.