Análise da resistência à erosão de revestimentos WC10Co4Cr aspergidos pelos processos HVOF e HVAF

Abstract

Processes and materials used in modern engineering are in a constant process of improvement in order to increase efficiency, reducing losses in our activities. With regard to industrial applications of turbines and components subject to the flow of some fluid, erosion is one of the main phenomena to be mitigated, since its occurrence characterizes a reduction in the efficiency and work life of system components. Currently, among processes of protection or extension of the work life of this equipment is the HVOF and HVAF thermal spray. In the later, the propellant fluid of the particles that will coat the eroding component is a mixture of air and fuel propelled at high speed against a surface, in the former, the fuel is mixed with pure oxygen, producing coatings of greater density and cohesion, as a result of higher temperatures of process. The determination of the component alloys of this coating can be evaluated in relation to the type of environment to which the mechanical components will be subject to in operation. In erosion by slurry, the need for hard coatings, capable of withstanding the impact of solid particles of high hardness, such as silica, for example, is evident. Thus, it was decided to analyze the coating produced with WCCrCo alloy. The coated samples were subjected to erosion test by Slurry using equipment and specific technical standards for this test at two different angles, 60° and 90°. The characterization of the coatings was carried out with the aid of a Scanning Electron Microscope and subsequent surface analysis of the samples. It was found that tungsten carbide coatings deposited by the VAF process have greater resistance to erosion than HVOF, while the erosion angle variation did not show significant differences.