Effect of Titanium Dioxide Particle Size in Water-based Micro/Nanofluid as Quench Medium in Heat Treatment Process

Abstract

Recently, nanofluid is used to improve the thermal conductivity of the quench medium in the heat treatment industry. In this research, ball-milled micro-sized TiO2 powder and nano-sized TiO2 particle were used and compared for their cooling characteristic in a micro/nanofluid. The micro/nanofluids were produced by mixing 0.1%, 0.3%, and 0.5% volume of both micro- and nano-sized particle into 100 ml of distilled water. The planetary ball mill was used at 500 rpm for 15 hours to reduce the dimension of micron-sized TiO2. Composition characterization by Energy Dispersive Spectroscopy (EDS) showed that the powder used were free from impurities. Nanofluids were then used to quench S45C carbon steel samples, which heated at 1000°C for 1 hour. The hardness test result showed that the sample quenched with 0.5%addition of the nano-sized particle in nanofluid had the highest number up to 691 HV, almost 100HV increment from a water-quenched sample where the hardness was 598 HV, showing that the cooling rate in the nanofluid was much higher. The addition of micro-size particle in fluid generally had a lower cooling rate than the addition of nano-size particle.