Authors: Cong Mao Hongfu Zou Xin Zhou Yong Huang Hangyu Gan Zhixiong Zhou
Publish Date: 2014/02/01
Volume: 71, Issue: 9-12, Pages: 2073-2081
Abstract
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 05 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 shorttime ultrasonic vibration condition and the nanofluid with good suspension stability can be obtained when the ultrasonic vibration time exceeds 05 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 05 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
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