Microstructural characteristics, wear and corrosion behaviour of HVOF and HVAF sprayed cermet coatings

Abstract

The present thesis approaches an important domain of Materials Science and Engineering namely that of thermally sprayed WC and CrC cermet based coatings with high density, good adhesion to the substrate, reduced porosity and also a relatively reduced decarburisation level due to modern HVOF and HVAF thermal spraying techniques. This type of coatings have a wide range of application, especially in the past decade, in various industrial fields like aeronautics, automotive, petrochemical, cellulose, energetics, chemical industry, etc. The deposited coatings aim to increase the lifetime of various components subjected to severe working conditions and also to recondition worn parts. This work presents research studies conducted on cermet coatings like WC-10Co-4Cr, Cr3C2-25NiCr, Cr3C2-37WC-18M and WCFeCrAl in order to obtain protective coatings deposited using the HVAF spraying process comparable in terms of microstructure, wear and corrosion resistance with coatings deposited using the HVOF spraying process but having as advantage a relativelly lower manufacturing cost due to the use of air as combustion gas.