A Comparative Study on Commercial Grade and Laboratory Grade of TiO₂ particle in Nanofluid for Quench Medium in Rapid Quenching Process

Heat treatment of material particularly quenching requires a high thermal conductivity quench medium. Hardenability of material, dimension, and geometry of the component are considerate on choosing quench medium. The cooling rate of quenching affects the properties and microstructures by creating specific phase transformation to occur. Enhancing the quench medium by accelerating the cooling rate can be attained by the addition of nanoparticle which has higher thermal conductivity. This nanoparticle-added medium is commonly termed as nanofluid. Commercial and laboratory grade of TiO₂ was used as the nanoparticle to distilled water as the nanofluid base to acquired higher conductivity on the heat treatment process. In this experiment, a top-down method was done to obtain TiO₂ particles by grounding using a planetary ball mill for 15 hours at 500 rpm. Nanofluid quench medium was mixed with TiO₂ in various concentration of 1%, 5% and 10% with a volume of 100 ml each. Samples of AISI 1045 or JIS S45C carbon steel were used to obtain different cooling rate on a different type of TiO₂ particles. Samples were heat treated by austenizing at 1000°C for 1 hour, followed by rapid quenching in nanofluid quench medium with the addition of agitation as quenching variable. Observation of particle morphology and size, material composition, and the change of surface ere measured by Field-Emission Scanning Electron Microscope (FE-SEM), and Energy Dispersive X-Ray Spectroscopy (EDX). Initial characterization showed that the TiO₂ particle size was at 150 nm range, and roughly free from any impurities. Martensite microstructures have the most significant area and the amount at laboratory-grade TiO₂ in 0.2 wt% composition, followed by commercial-grade at 0.3 wt% composition.