Determining the adhesion / cohesion strength of plasma spray coatings using the Rockwell - c method

Abstract

The plasma spray coatings are subject to high influence of surface loads, corrosion, and temperatures which cause damage in the form of separation of the coating from the substrate or flacking of the coating from the substrate edges. Adhesion is the main factor that opposes the influence of the external loads, and defines the quality of the bond of the coating with the substrate. Each type of coating has a determined quality of adhesion as per appropriate standard in order to meet functional properties during operation. There is no universal coating test for all types of the coatings, the test is chosen depending on the technology used for the production of the coating, the type of material from which it was made and its thickness. One of the many tests that are used for assessment of adhesion / cohesion strength of plasma spray coatings is the scratch test. The aim of this paper was to evaluate the cohesive / adhesive strength of the plasma spray Ni22Cr10Al1Yalloycoating. The testing was conducted using the Rockwell C diamond indenter with a tip radius of 200 µm. The results showed that the scratch test is an efficient method for assessment of adhesion and cohesion of plasma spray coatings.