Effect of surfactant addition on TiO2 nanofluid as quench medium in heat treatment process of S45C medium carbon steel

Quenching is a rapid cooling process to obtain specific desirable material properties after soaking of a metal at a high temperature, above the recrystallization phase. The quench medium’s choice depends on the hardenability of the metal alloy, the thickness of the component, the geometry of the component, and the hardness needed for the application. As a quench medium, nanofluid has been studied using several different fluids as the base. Furthermore, a surfactant is added to stabilize the suspended particle in the nanofluid. In this research, a laboratory-grade TiO2 powder was used as a nanoparticle with three different types of surfactants. Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray (EDX) measurements were carried out to determine the particle morphology and purity. Observation by FESEM and EDX confirmed that the particle size was around 20nm and free from metal impurities. TiO2 nanoparticle content in nanofluid quench mediums used for this research was 0.5% of the nanofluid’s total volume. The amount surfactant added on each medium was 1% - 5% for each type of surfactant, i.e., Sodium Dodecyl Benzene Sulfonate (SDBS), Cetyl Trimethyl Ammonium Bromide (CTAB), and Poly Ethylene Glycol (PEG). These mediums were used to quench JIS S45C or AISI 1045 carbon steel samples, which annealed at 1000°C for 1 hour. The maximum hardness was reached at a 2% surfactant. The addition of 2% SDBS increased the hardness up to 59.6 HRC, while 2% of CTAB and PEG increased up to 58.9 HRC and 58.6 HRC, respectively.