Characterization of thermophysical properties of dry ice-based ethanol/ester oil and its influence on surface hardening of machined Ti-6Al-4V alloy

Abstract

Recent pandemics played a cardinal role indevelopinghealth-conscious behavior and pushed the industries to seek eco-benign cutting fluids to improve machinability. Therefore, a sustainable hybrid lubri-coolant is proposed by mixing ethanol-biodegradable ester oilin varying proportions (1:0.25,1:0.5,and 1:1). In this work, dry ice (solid CO2)has been added (−76 °C) to improve the cooling capabilities bysublimation. The thermophysical properties along with the surface hardening of machined Ti-6Al-4V alloy was investigated experimentally and the results were compared to without dry ice. Experimental findings showeda reduction in specific heat, density, and viscosity while an enhancement in thermal conductivity by mixingdry ice. After dry ice was added, the specific heat of ethanol dropped by 40%. When ester oil was combined with dry ice, its specific heat also decreased by 50.4%. Therefore it is worthy to mention that the hybrid lubri coolant based on dry ice-based ethanol/ester oil could be an alternative to achieve high-speed machining parameters in machining hard to cut materials for aerospace Industry.