Characterization of nanostructured ceramic and cermet coatings deposited by plasma spraying

Abstract

Industry has a growing need of advanced coatings for a variety of applications (aerospace, special machinery, medicine ...). Nanostructured coatings have the potential of providing novel materials with enhanced properties. This paper describes the results of recent research on wear resistant nanostructured coatings. Cermet (WC- Co) and ceramic (Al2O3-TiO2) coatings were obtained by atmospheric plasma spraying. Coating microstructure and phase composition were characterized using SEM, EDX and XRD techniques. Vickers microhardness (HV) of the coatings was also measured. The microstructure and properties of the developed nanostructured coating was compared with those of their conventional counterparts. The influence of the substrate on both microstructure end properties was investigated, as the coatings were deposited on two different steels. In the WC-Co coatings, significant decomposition of the WC particles occurred during spraying which is prejudicial to wear resistance. Nanostructured Al2O3-TiO2 coatings exhibited a bimodal microstructure that retained the initial nanostructure of the powder. The presence of these areas leads to better tribological properties.