Polyethylene Glycol Addition as Non-ionic Surfactant in Water-based Carbon Microfluid for Quench Medium in Heat Treatment Process

The mechanical properties of a material depend on the quenching process. In this process, there is a rapid cooling from elevated to room temperature in a short time by using a quench medium. Therefore, the phase transformation from austenite to martensite occurs. The common medium used in the quenching process is water, oil, polymer, and gas. Nanofluids are started to be used as a quench medium because they offer better thermal conductivity compared with the conventional medium. Selection of carbon-based nanofluids as a quenching process medium aims to obtain high thermal conductivity values and controllable cooling rates. Thereby, the expected microstructure of the material could be relatively easier to form. In this paper, carbon particles were obtained using a top-down method with a planetary ball mill for 15 hours at 500 rpm. Based on the electron microscope and spectroscopy results, the particle dimension was average at 15 μm after milling, and the carbon purity of the powder used in this research was 99%. Carbon particles at 0.1%, 0.3%, and 0.5% with variation of non-ionic surfactant Polyethylene Glycol of 1%, 2%, 3%, 4% and 5% respectively was used in this research. AISI 1045 or JIS S45C carbon steel was used as a steel sample, and austenized at 1000°C for 1 hour and then quenched in the microfluid. The hardness obtained was up to 811 HV for the sample quenched in 0.5% carbon and 1% Polyethylene Glycol. The improvement was more than 100 HV, compared with the sample quenched in distilled water, which had a hardness only 666 HV.