This study investigates the influence of electrolytic cell parameters on the electrolyte boiling rate during electrolytic plasma processing, a critical stage for plasma formation and subsequent surface modification. Focusing on a coaxial cell configuration with a conical anode and cylindrical cathode, this research employs analytical calculations based on the solution of the Laplace equation in spherical coordinates, validated by numerical simulations using the finite element method (Elcut 6.6), to predict electrolyte boiling times. These results are compared with experimental data, demonstrating good agreement, particularly at higher voltages (−200 V). The analysis reveals that while a simplified model provides a reasonable first approximation, it deviates at lower voltages (−50 V) due to the increasing importance of heat removal, neglected in the model construction. This discrepancy underscores the need for more sophisticated models accounting for non-uniform current distribution and heat transfer effects in complex cell geometries. The findings contribute to a deeper understanding of cathodic electrolytic plasma processing (EPP) dynamics and provide a foundation for optimizing cell design and process parameters for industrial applications such as diffusion saturation of steel components.

This study investigates the thermal response and surface modification of low-carbon manganese-alloyed 20GL steel during electrolytic plasma hardening. The objective was to evaluate the feasibility of surface hardening 20GL steel—traditionally considered difficult to quench—by combining high-rate surface heating with rapid cooling in an electrolyte medium. To achieve this, a transient two-dimensional heat conduction model was developed to simulate temperature evolution in the steel sample under three voltage regimes. The model accounted for dynamic thermal properties and non-linear boundary conditions, focusing on temperature gradients across the thickness. Experimental temperature measurements were obtained using a K-type thermocouple embedded at a depth of 2 mm, with corrections for sensor inertia based on exponential response behavior. A comparison between simulation and experiment was conducted, focusing on peak temperatures, heating and cooling rates, and the effective thermal penetration depth. Microhardness profiling and metallographic examination confirmed surface strengthening and structural refinement, which intensified with increasing voltage. Importantly, the study identified a critical cooling rate threshold of approximately 50 °C/s required to initiate martensitic transformation in 20GL steel. These findings provide a foundation for future optimization of quenching strategies for low-carbon steels by offering insight into the interplay between thermal fluxes, surface kinetics, and process parameters.

The study investigates the spectral, structural, and phase changes occurring in austenitic steel 12Kh18N10T during cathodic electrolytic plasma nitriding (EPN) in a Na₂CO₃–CO(NH₂)₂–NH₄Cl electrolyte at 550 °C for 10 min. Emission spectroscopy revealed active plasma components: N₂⁺, N I, Hα, and O I. The electron density, calculated from the Hα line broadening, was approximately 8.5 × 10¹⁸ cm⁻³. X-ray phase analysis revealed the formation of CrN, Fe₃N phases, and a solid solution of nitrogen in γ-Fe. SEM analysis revealed a three-layer structure of the nitrided layer: a nitride zone, a transition region, and the austenitic matrix. The EDS profile confirmed a decrease in nitrogen concentration, accompanied by a reduction in microhardness from a maximum of 480 HV at the surface, both gradually decreasing with depth. The friction coefficient decreased from ~0.8 (in the initial state) to ~0.6 after EPN. The results confirm the effectiveness of EPN in strengthening and improving the wear resistance of stainless steel.

This study investigates the effect of electrolytic-plasma hardening (EPH) on the structure, phase composition, and tribological properties of the low-alloy steels 20Cr2Ni4A and 37Cr4 (1.7034) (EN). Hardening was carried out at a voltage of 320 V for 7 s in an aqueous solution containing 20% soda ash and 10% carbamide. Using scanning electron microscopy, the formation of a zonal structure with a hardened surface layer characterized by a needle-like martensitic morphology was revealed. X-ray diffraction analysis revealed the presence of Fe, Fe₃C, Fe₂C, and FeO phases. Microhardness measurements confirmed a significant increase in the hardness of the hardened layer. Tribological tests showed a reduction in the coefficient of friction to 0.574 for 20Cr2Ni4A steel and to 0.424 for 37Cr4 (1.7034) (EN) steel, indicating an improvement in wear resistance after EPH.

This study investigated the electrolytic-plasma hardening (EPH) of cast 20GL steel, used for railway spring beams. The main objective was to analyze the spectral characteristics of the cathodic discharge and establish correlations between the plasma parameters, processing regimes, and resulting surface properties. Optical emission spectroscopy revealed that the plasma at 260 V exhibited a high-energy state with an electron density of ~5.3 × 10¹⁶ cm⁻³ and an electron temperature of 10,031 K. Using these parameters, the heat flux from the plasma to the steel surface was estimated at ~1.5 × 10⁷ W/m², confirming that the discharge provides sufficient energy for surface austenitization. Microstructural analysis demonstrated that the electrolyte flow rate, which determines the cooling rate, is the key parameter controlling phase transformations. At low flow rates, ferrite–pearlite and bainitic structures formed, while a fully martensitic structure and maximum hardness (1046 HV) were achieved at 10 L/min. Tribological tests confirmed the superior wear resistance of the martensitic layers, showing a friction coefficient of 0.454 and a wear volume 3.4 times lower than in the as-cast state. These findings verify that EPH offers an energy-efficient, low-cost method for improving the surface performance and service life of 20GL steel components in heavy-duty railway applications.

: In this paper, we investigate the improvement of the operational and mechanical properties of 45 steel used in agricultural machinery by electrolytic plasma quenching (EPH). The experiments were carried out under three treatment modes: 320 V voltage, 50 A current and exposure time of 9 seconds. Microstructure analysis showed the formation of a martensitic layer with a thickness of 500-550 microns, which led to an increase in the microhardness of steel from 200 HV to 683 HV, that is, 3.4 times. The zonal structure of the material is revealed: a reinforced (martensitic) layer with a thickness of 500 microns, a thermal impact zone of 200-250 microns and a basic matrix. The results of the study confirmed the high efficiency and reliability of EPC as a method of hardening highly loaded working bodies of agricultural machinery. The introduction of this technology makes it possible to reduce the cost of replacing parts by 30-35%, increase the efficiency of equipment and contribute to the development of domestic agricultural machinery. The use of a 20% sodium carbonate solution, which does not pollute the environment, during the EPH ensured an even distribution of electric current in the cell and contributed to achieving an optimal cooling rate of the sample.