Experimental Evaluation on the Effect of Nanofluids Physical Properties With Different Concentrations on Grinding Temperature

9.1 Introduction

Grinding is the final procedure in machining to achieve high machining accuracy (Li, Wang, & Wu, 2008). Given that grinding requires an extremely high energy input, a large portion of energy will be converted in the grinding zone. Most is converted to heat, thereby increasing the temperature in the grinding zone (Barczak, Batako, & Morgan, 2010). Grinding temperature can significantly affect the surface quality of the workpiece and the cutting performance of abrasive particles of the grinding wheel (Shen, Shih, & Tung, 2009). Higher grinding temperature will change the superficial metallographic structure of parts, causing grinding burns (Rowe, 2014). Moreover, high temperature will decrease the hardness of abrasive particles considerably and cause bonding wear and diffusive wear between abrasive particles and the workpiece, inducing rapid passivation of abrasive particles (Miyashita, 1990). Therefore, grinding temperature is important toin machining accuracy and quality. Grinding temperature should be studied.

With the technological progress and proposed further higher requirements on processing technology, MQL grinding is widely accepted by researchers. Nanofluid MQL grinding was proposed based on the theory of solid heat transfer enhancement to overcome the poor heat transfer of MQL cooling. The addition of nanoparticles into the base fluid can significantly increase the thermal conductivity of the base fluid and enhance the heat transfer capacity of the grinding zone (Ozerinc, Kakac, & Yazicioglu, 2010). Vajjha and Das added Al₂O₃ nanoparticles into the base fluid and prepared a 6 vol.% nanofluid. The tandem tested the thermal conductivity of the nanofluid through experiments and found that the prepared 6 vol.% nanofluid achieved 22.4% higher thermal conductivity compared with the base fluid (Vajjha & Das, 2012). Choi et al. carried out an experimental study on the effective thermal conductivity of multi-walled carbon nanotube (MWCNT) nanofluid, and found that the thermal conductivity of MWCNT was markedly higher than the theoretical value. The measured thermal conductivity was 150% higher than that of the base fluid (Li, 2011) Hong et al. (2005) synthesized the Fe-–glycol nanofluid by chemical vapor condensation method and increased its dispersity by using ultrasonic and high-energy pulses. According to experimental results, thermal conductivity presents a linear positive correlation with the volume fraction of nanoparticles. The thermal conductivity of the nanofluid with 0.55 vol.% nanoparticles was 18% higher than that of the base fluid. Murshed et al. (2005) measured the thermal conductivity of rod-like and spherical TiO₂ water-based nanofluid by using a transient barretter mount and a new integral relational model. The experimental results reflected that thermal conductivity increases with the increase in volume fraction of nanoparticles. In addition, the shape and size of nanoparticles could affect thermal conductivity (Mintsa, Roy, Nguyen, & Doucet, 2009). When the volume concentration of nanofluids was fixed at 5%, the nanofluids with rod-like and spherical nanoparticles achieved 33% and 30% higher thermal conductivity than the base fluid.