Development of the Multipuiose Thermal Spraying System

Abstract

Many components and structures require protection against corrosion, oxidization, excessive heat and wear. This is achieved by applying various types of coatings on the component base material, hence providing the necessary protection and improving performance of aircraft systems. For example, the application of the thermal barrier coatings (TBC), in the last decade, on the aircraft turbine blades, vanes and combustors brought up a substantial increase in the aircraft engine efficiency and reduction of NOx. Coatings are produced using various deposition techniques of which, thermal spraying technologies play a significant role. This paper presents a thermal spraying system developed on the principles of the High Velocity Air Flame (HVAF) process, as well as the results of thermal spraying of various materials, such as Zn-Al alloys, 316L stainless steel and WC-Co carbide powders. The anticorrosion Zn-Al coatings sprayed with the HVAF system showed considerably higher bond strength than coatings obtained by the conventional methods, indicating the advantage of this method in areas where the adhesion strength is critically important. The highly dense structure of the coating obtained with HVAF eliminates a need for a top paint coat for anticorrosion protection, which is typically applied on metal sprayed coatings to extend service life. The developed HVAF system produced high quality coatings of 316L stainless steel and WC-Co carbides as shown by the coating analysis and test results. In addition, the developed HVAF thermal spray system provides competitive spray rates, high deposition efficiency, and the process can be easily performed on-site. Lower operating costs of the HVAF process, in comparison with other high velocity systems, make this technology viable for anticorrosion protection and wear resistance.