Features of structural-phase states of Co-Cr-Al-Y composite coatings after heat treatment

Abstract

One of the urgent problems in the field of mechanical engineering is the development of technology for improving the strength and performance properties of coating materials for critical parts of power plants [1]. Of great importance is the development of new methods of influencing the structure and properties of coatings, and the complex use of existing developments, the optimal combination of which can create new opportunities for directed influence on the structure and properties of the resulting coatings [2, 3]. At the same time, the structural-phase state has a significant impact on the physical, mechanical and operational properties of coatings. This article describes the results of studying the structural-phase state of composite Co-Cr-Al-Y coatings in the initial state and after thermal treatment, obtained because of using the developed magnetron method for applying multilayer coatings with a controlled concentration of constituent elements. According to the results of SEM measurements, it was revealed that unannealed coatings form dense coatings with a columnar structure. The results of transmission electron microscopy confirm the SEM and EDS measurements, and there are clear layer boundaries in the structure for each type of multilayer coating. A distinctive feature of the synthesized layers is the almost complete absence of a crystalline structure for all types of Co-Cr-Al-Y multilayer coatings, which is apparently due to the amorphous properties of cobalt and its tendency to form metallic glasses. The main process occurring during the heat treatment of the studied multilayer coatings is the formation of a spinel-type phase. The obtained results of experimental studies give new, deeper ideas about the processes of formation of structural-phase states of composite coatings obtained by magnetron sputtering.