Ultrasonic Intensification of Low-Temperature Plasma Synthesis of Ceramic-Like Coatings of Valve Metals

Abstract

The authors have presented a method of ultrasonic intensification of anode–cathode interactions during the formation, in water–alkali electrolytes, of ceramic-like coatings on the surface of valve metals in the process of low-temperature plasma synthesis. An algorithm of directional influence of high-energy fields on the distinctive features and rate of chemical reactions at the electrolyte–metal–coating interface through changing the solution’s state by ultrasonic pulses in the process of anodic microarc oxidation has been developed. The authors have elucidated the mechanism and have determined the character and level of effect of the proposed intensification on the dynamics of growth of a coating under low-temperature-plasma conditions of a liquid medium. It has been shown that mechanical (ultrasonic) activation of the electrolyte is responsible for the intensification of the process of transfer of charge carriers, which are primarily electrolyte ions. Procedures and equipment have been described using which the values of an ultrasonic signal formed under various conditions were recorded. The nature of more intense buildup in the thickness of a ceramic-like coating with reduced energy expenditure to form it has been elucidated. This is explained by the appearance in the electrolyte, during its ultrasonic activation, of the great number of high-frequency damped oscillations of irregular waveform with a high amplitude as far as the current is concerned (5 A or higher), which is attributable to the occurrence of a synergetic effect.