Analysis of models for calculation of temperature of anode plasma electrolytic heating

Plasma electrolytic processes used for treatment of materials are based on their heating in a vapor–gaseous medium. This work is concerned with the thermal models for calculation of the steady-state temperature of anode heating, which are based on solution of the heat conduction equation in a continuous and stable vapor–gas envelope (VGE). These models provide the decreasing current–voltage (CVC) and the increasing temperature–voltage (TVC) characteristics of anode heating, which are qualitatively agreed with experimental data in the voltage region corresponding to stationary heating up to 400–1000 °C. The analysis of assumptions accepted in these models has shown that the agreement between calculated and experimental data can be improved by taking into account the temperature dependence of thermal conductivity coefficient of vapor. This agreement remains unchanged when taking into account the role of the space charge in the envelope. Mean estimates of a value of effective electrical conductivity of the vapor envelope (2.13 × 10−3 S/m) and the mobility of ions in the envelope (1.6 × 10−4 m2/(Vs)) with the experimental data for aqueous solutions of ammonium nitrate in the concentration ranging from 1 to 3 mol/l have been obtained.