Analysis of suspension stability for nanofluid applied in minimum quantity lubricant grinding

作者：Mao, Cong^*; Zou, Hongfu; Zhou, Xin; Huang, Yong; Gan, Hangyu; Zhou, Zhixiong

来源：International Journal of Advanced Manufacturing Technology, 2014, 71(9-12): 2073-2081.

DOI：10.1007/s00170-014-5642-9

• Nanofluid
• Suspension stability
• Minimum quantity lubrication
• Grinding

The nanofluid is usually applied in minimum quantity lubricant (MQL) grinding to decrease grinding temperature and to improve surface integrity of workpiece. However, a large challenge in the application process of nanofluid is the sedimentation of the nanoparticles due to their poor suspension stability in the base fluid. Then, the lubrication and heat conduction characteristics of nanofluid will be deteriorated, and the nanofluid cannot be atomized as expected during grinding. Therefore, the heat transfer performance of nanofluid during MQL grinding severely decreased. In this study, the force state of nanoparticle in base fluid was analyzed and the effect of dispersant on the force state of nanoparticle was researched. The suspension stability of Al2O3 (0.5 wt.%) nanofluid was investigated under different ultrasonic vibration times, pH values, and dispersant concentrations (sodium dodecyl benzene sulfonate, SDBS). It is found that the suspension stability of nanofluid is quite poor under short-time ultrasonic vibration condition, and the nanofluid with good suspension stability can be obtained when the ultrasonic vibration time exceeds 0.5 h. A higher concentration of SDBS will lead to a better suspension stability of nanofluid when the concentration of SDBS is quite low. However, if the concentration of SDBS exceeds 0.5 wt.%, there is oversaturated adsorption on the nanoparticles surface which results in the deterioration of suspension stability of nanofluid with the increase of the SDBS concentration. As pH value is below 7, the suspension stability of nanofluid is significantly improved with the increase of pH value. The sedimentation clearly appeared in the disperse system when pH value is higher than 7. The dispersion morphology of the Al2O3 nanoparticles in disperse system is analyzed by using a scanning electron microscope. It is found that some large aggregates appeared when no dispersant was applied in the disperse system, and the Al2O3 nanoparticles are uniformly dispersed in disperse system with the application of the dispersant.

• 出版日期2014-4
• 单位湖南大学