Rheological characteristics of a water-based emulsion of polymethylsiloxane oil used for steel hardening
A. YU. RYAZANOVA1, V. V. STROKOVA1, P. S. BASKAKOV2
1Shukhov Belgorod State Technological University, Belgorod, Russia
2Melnikov Central Research and Design Institute of Steel Structures, Moscow, Russia
Keywords: viscosity, polyvinyl alcohol, polymethylsiloxane oil, aqueous emulsion, quenching medium
Abstract
The analysis of the rheological characteristics is presented, and the possibility and efficiency of using aqueous emulsions of polymethylsiloxane (PMS) oils as a quenching medium during the heat treatment of steel products is established. The emulsion is composed of the dispersed phase (polymethylsiloxane oil of grades PMS-100, PMS-200, and PMS-300), and the dispersive medium (an aqueous solution of SUNDY polyvinyl alcohol PVA 088-05). The aqueous dispersions of PMS oils were obtained by high-speed emulsification. The obtained rheological characteristics of emulsions under the conditions of temperature change (10, 25 and 40 °C) confirm the hypothesis concerning the relationship between the conformational state of the surfactant macromolecules (polyvinyl alcohol) and the aggregate stability of the aqueous emulsion of PMS oil. The results of the study revealed a strict correlation between the rheological characteristics of the emulsion system and its concentration in water, as well as the kinematic viscosity (100, 200, and 300 cSt) of PMS oil under temperature changes. These dependencies for aqueous emulsions based on PMS oil with different initial viscosities follow the Kraemer equation in the logarithmic form with a confidence level R2 > 0.95. It has been experimentally proven that temperature conditions and mechanical loads do not affect the structural state of stabilised emulsion droplets. The system demonstrates high stability, predictable rheological characteristics, and preservation of structural integrity over a wide range of PMS oil concentrations. The emulsifying capacity of polyvinyl alcohol is a constant value and does not correlate with the kinematic viscosity of PMS oil. These findings have practical significance for creating highly effective quenching media with desired thermophysical and technological properties.
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