Features of jet plasma electrolytic chemical-thermal treatment of low-carbon steel flat surface

Plasma electrolytic treatment technologies are mostly based on immersion of the workpiece into an electrolyte. This method creates obvious limitations for processing large-sized products, complex-shaped parts, and internal surfaces. The paper considers a variant of jet plasma electrolytic chemical-thermal treatment. Jet treatment was performed on a flat surface of a low-carbon steel plate in ammonium chloride-based electrolytes with the addition of saturating components. Research was conducted to study the thermophysical characteristics of local plasma electrolytic treatment with a jet feed of electrolyte onto the treated area of a flat plate surface. Critical voltages were determined at which the transition from the electrolysis mode to the stationary heating mode occurs, ensuring a stable state of the vapor-gas layer and chemical-thermal processing of the surface. Critical voltages for the transition from the stationary heating mode to the non-stationary heating mode, which resumes the contact of the electrolyte with the surface and plasma electrolytic polishing is performed, were also determined. Based on the proposed models for calculating the temperature distribution in a thin metal plate during local processing, a method for determining heat flows has been developed. The effect of processing conditions on the heating temperature and its distribution over the surface, as well as heat exchange in the near-electrode region, has been studied. The specifics of heat exchange between a low-temperature vapor-gas layer and a processed sample and an aqueous electrolyte have been described. Dependences of heat flows into the plate and electrolyte on processing conditions have been obtained. Structural and phase changes in the surface layer of steel have been studied both in the area of local heating and outside it. It has been shown that jet treatment can form structures similar to those produced by immersion processing. At the same time, a gradient of structural and phase changes has been revealed, which is determined by changes in temperature and diffusion intensity over the surface, as well as by the cooling rate during quenching. • The option of carrying out jet-PET is considered. • The electrophysical conditions have been determined. • the distribution of heat flows under various conditions has been determined. • The specifics of heat exchange have been described. • The gradient of structural changeshas been shown.