THEORETICAL RESEARCH AND PRACTICAL DEVELOPMENT OF THE ARC SPRAYING PROCESS WITH A PULSATING SPRAY AIR STREAM TO IMPROVE THE QUALITY OF COATINGS

Abstract

The subject of the study is intensive oxidation of metal, sprayed in the process of arc metallization, due to the oxygen in the air, which leads to a significant reduction in the content of alloying elements in the coating and, accordingly, deteriorates the quality of the sprayed layer. Other authors of scientific publications also paid attention to this issue, proposed the use of kerosene, propane and air mixture, inert gases as a transport gas, but these solutions led to a significant increase in the cost of the arc metallization process, and most often had no quantitative calculations of the impact on the quality of coatings or were approximate. The aim of the work was to scientifically substantiate the concept of quality of coatings by reducing the negative impact of air oxygen during arc metallization through the use of a pulsating spray airflow. In order to reduce the oxidative effect of air-spraying jet on the liquid metal of electrodes the method of pulsating air supply to the electrode melting zone by introducing an additional element - pulsator valve in the spray system of electroarc metallizer was proposed. The task of this article is to define and select the design of the device - pulsator valve for creating a controlled pulsating spray flow with certain impulses during arc metallization. The methods of theoretical approach, namely, mathematical analysis, were used to accomplish the task in this paper, as well as practical results – data on the presence of airflow pulsations recorded by an oscilloscope. Thus, the theoretical justification of the pulsator valve application is confirmed by practical results. Based on the presented analysis the results were obtained, which allowed to determine the optimal design, and allows minimizing the impact of the particles (namely oxygen in the air) transporting flow on the material of the electrodes that are sprayed. Conclusions: the use of a pulsating spray airflow during the application of coa tings by arc metallization method will reduce the burnout of alloying elements such as manganese, silicon, increase the carbon content in the applied coating, therefore improving the quality of the restored parts.