Implementation of the Method of Fundamental Solutions for the correction of parameters of the thermal HM spraying process

Abstract

The innovative technology of thermal spraying with micro-jet cooling is one of the important modifications of classical ultrasonic spraying methods, which allows to shortening time of the spray coating process during the protection of machines structures used in the production and transport of energy. Using micro-stream with gases such as argon or nitrogen allows the cooling of the coating immediately after spraying, and thereby reducing the time of transition during the injection of each layer. As a result of the process, the fine dispersive structure of coatings is obtained in a shorter amount of time when compared with the classical high-velocity oxygen fuel (HVOF) process. The parameters of the process and the type of stream equipment determine the quality of the obtained structure and thermal stress in the coating. The relationship between the selected parameters of the HM method and the properties of coatings are presented. The parameters were confirmed by the Fundamental Methods of Solutions. The presented technology should be adapted to the actual production of the protective coating for machines and construction working in condition of wear. A computer simulation, made by using MFS, has been performed for heat transfer in layers of coatings. During the numerical experiment it was found the distance between micro-jet device and the sprayed surface for the HM spraying method allowing to obtain the 0.4 s time of cooling process. The experimental investigation showed that, the cooling faster than 0.2 s could provoke the cracks in the obtained structure and the time above 0.5 sec is not effective enough.