Experimental investigations of mechanical and tribological behaviours for organic and inorganic coatings deposited on mild steel substrate

Abstract

ABSTRACT Surface treatment technologies are constantly evolving. Increasingly, surface functionalisation is of major concern to lighten structures, improve product performance and reduce costs. To fulfil its decorative and protective functions, it is essential that a coating adheres properly to its support. During the last few decades, many new deposition techniques have been developed and more and more tribological and corrosion resistant coatings have been made available. In this context, the present research has focused on two pneumatically sprayed epoxy/polyamide and inorganic silicate coatings which are deposited on the mild steel substrate. First, the main interest in this study is devoted to the analysis of the coating/substrate adhesion strength by using the squaring and pull-off tests. Second, the study has also focused on the analysis of friction and wear behaviours for the two systems of paint coatings under consideration by using a linear reciprocating tribometer under dry sliding condition. Experimental findings have shown that after appropriate surface preparation and degree of cleaning according to the standard ISO 8501-1, selected paint systems composed of organic or inorganic coatings effectively improve the service life of coated steel. Meanwhile, under the same sliding conditions, the wear results have revealed that the organic coatings have a higher anti-wear ability compared to the inorganic coatings. Thus, both organic and inorganic coatings play an important role in protecting the substrate against severe industrial environment. From the squaring and pull-off analyses, it has been deduced that scratch and pull-off behaviours of both coatings have been severely affected by the surface preparation, the number of protective layers and the thickness of coatings. In fact, the best adhesion, friction and wear properties are obtained for the paint system containing organic coatings where the third body is formed on the entire sliding strip in the test.