化工进展 ›› 2023, Vol. 42 ›› Issue (10): 5101-5110.DOI: 10.16085/j.issn.1000-6613.2022-2073

• 化工过程与装备 • 上一篇    下一篇

低温下硅油基纳米磁流体沉降稳定性与黏度特性

朱启晨(), 吴张永(), 王志强, 蒋佳骏, 李翔   

  1. 昆明理工大学机电工程学院,云南 昆明 650550
  • 收稿日期:2022-11-07 修回日期:2022-12-09 出版日期:2023-10-15 发布日期:2023-11-11
  • 通讯作者: 吴张永
  • 作者简介:朱启晨(1992—),男,博士研究生,研究方向为流体传动与控制。E-mail:337032553@qq.com
  • 基金资助:
    国家自然科学基金(51165012);云南省教育厅科学研究基金(2015Y080);昆明理工大学分析测试基金(2021P20191103001)

Sedimentation stability and viscosity properties of silicone oil-based magnetic nanofluid at low temperature

ZHU Qichen(), WU Zhangyong(), WANG Zhiqiang, JIANG Jiajun, LI Xiang   

  1. College of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650550, Yunnan, China
  • Received:2022-11-07 Revised:2022-12-09 Online:2023-10-15 Published:2023-11-11
  • Contact: WU Zhangyong

摘要:

传统纳米磁流体存在低温稳定性差、低温黏度高等问题。硅油具有优良的低温性能和黏温特性,是低温纳米磁流体合适的基载液。以硅烷偶联剂KH-550、月桂酸和油酸为分散剂,利用两步法制备了硅油基Ni0.5Zn0.5Fe2O4纳米磁流体。通过扫描电镜(SEM)、X射线衍射仪(XRD)、红外光谱和振动样品磁强计对颗粒形貌、微观结构和磁性能进行了表征,并从多因素对低温下纳米磁流体沉降稳定性与黏度特性进行了研究。结果表明:分散剂形成的空间位阻和载液溶解度共同影响着低温下的稳定包覆,相较于羧酸类分散剂,硅烷偶联剂KH-550表面改性包覆制备的纳米磁流体具有更好的低温沉降稳定性,且凝固后的再分散性最佳;由于偶极间相互作用、范德华力的增强以及流体布朗运动的减弱,磁场会降低纳米磁流体低温沉降稳定性;温度的降低会导致无磁场下纳米磁流体向非牛顿流体类型的转变,并影响磁场下磁场强度、剪切速率与黏度间的平衡关系。制备的硅油基纳米磁流体具有较好的低温性能,可应用于低温工况,有助于今后硅油基纳米磁流体制备技术与性能调控的进一步发展。

关键词: 纳米磁流体, 低温, 分散剂, 沉降稳定性, 黏度特性, 磁场, 剪切致稀

Abstract:

Conventional magnetic nanofluids suffer from poor stability and high viscosity at low temperatures. Silicone oil is a suitable base carrier fluid for low-temperature magnetic nanofluids due to its excellent low-temperature properties and viscosity-temperature characteristics. In this paper, silicone oil-based Ni0.5Zn0.5Fe2O4 magnetic nanofluids were prepared by a two-step method using silane coupling agent KH-550, lauric acid or oleic acid as dispersants. The particle morphology, microstructure and magnetic properties were characterized by scanning electron microscope, X-ray diffactometer, infrared spectrum spectroscopy and vibrating sample magnetometer, and the sedimentation stability and viscosity properties of the magnetic nanofluids at low temperatures were investigated from multiple factors. The results show that the spatial site resistance effect and the solubility of the dispersant in the carrier solution jointly affect the stable coating at low temperature. Compared with carboxylic acid dispersants, the nanomagnetic fluids prepared by surface-modified coating with silane coupling agent KH-550 have better low-temperature sedimentation stability and the best redispersibility after solidification. The magnetic field reduces the low-temperature sedimentation stability of magnetic nanofluids due to enhanced dipole interactions and van der Waals forces as well as weakened Brownian motion of the fluid. The decrease in temperature leads to the transition from magnetic nanofluid to non-Newtonian fluid type without magnetic field and affects the equilibrium relationship between magnetic field strength, shear rate and viscosity under magnetic field. The silicone oil-based magnetic nanofluid prepared in this paper has good low-temperature performance and can be applied to low-temperature working conditions. This study contributes to the further development of the preparation technology and performance regulation of silicone oil-based magnetic nanofluid in the future.

Key words: magnetic nanofluid, low temperature, dispersing agents, sedimentation stability, viscosity properties, magnetic field, shear-thinning

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