Effect of Polymer Concentration on Wetting and Cooling Performance During Immersion Quenching

Abstract

The effect of varying concentrations (0 to 100 vol pct) of glycol polymer solution on wetting kinetics, kinematics, and cooling performance during immersion quenching was studied by using goniometry, online video imaging, and cooling curve analysis techniques. An increase in concentration of the polymer solution resulted in improved wettability and accelerated spreading kinetics of the quench medium. The quench medium showed medium-fast-nonuniform, fast-uniform, slow-uniform, explosive/rapid, repeated, and slow-nonuniform rewetting phenomena depending on the concentration of the polymer solution. The collapse of the vapor film was by an instantaneous rupture process in the quench medium containing more water and by nucleation of bubbles caused by the selective rupture process in the quench medium enriched with polymer. The quench medium consisting of an equal amount of water and polymer showed an explosive collapse of the vapor film on the quench probe surface. The nature of the wetting front was uniform with polymer quench media except at 100 vol pct concentration of polymer quenchant. There was enhancement in the cooling performance of the quench medium, which was enhanced for a lower volume concentration of the polymer solution. However, an increase in the concentration of the polymer resulted in a decreased cooling performance. The cooling of the probe was more uniform with polymer quenchants (5 to 25 vol pct), which exhibited fast and uniform rewetting. Polymer quenchants (75 to 100 vol pct) that exhibited repeated and slow-nonuniform rewetting showed large variation in heat transfer over the quench probe surface. © 2015, The Minerals, Metals & Materials Society and ASM International.