The Effect of Sodium Dodecyl Benzene Sulphonate Addition in Carbon Nanotube-Based Nanofluid Quenchant for Carbon Steel Heat Treatment

Nanofluid is widely researched as it has a superior thermal characteristics. It is synthesized by adding a nano-sized particle with high thermal conductivity in the base fluid. The particle addition would increase the overall thermal conductivity of the fluid. Because of its thermally enhanced characteristics, nanofluid is commonly utilized for thermal transfer applications. However, agglomeration could hinder the dispersion of the particle in the fluid. To improve the nanoparticle dispersion, surfactant is commonly added. In heat treatment, nanofluid can be used as a quench medium. This research used a Multiwalled Carbon nanotube (MWCNT) as the nanoparticle, ranging from 0.1, 0.3, and 0.5% w/v. Sodium Dodecyl Benzene Sulphonate (SDBS) was added as the surfactant with a 0 – 30% w/v concentration. Higher concentrations of SDBS create better stability, as shown in Zeta Potential at -71.2 mV. The thermal conductivity was increased to 0.68 W/mK by adding 0.5% MWCNT and 3% SDBS. S45C medium carbon steel was quenched in the nanofluid and achieved a maximum hardness of 40 HRC at the addition of 0.3% MWCNT and 5% SBDS. Excessive addition of SDBS surfactant could decrease the thermal conductivity and steel hardness, even though the stability was better.