Study of the flexural behaviour and bonding strength of WC-Co metal matrix composite coatings produced by Laser Directed Energy Deposition

Abstract

Surface coatings enable more durable and sustainable solutions to face the degradation of the functional surfaces of high-added-value components. Particularly, metal matrix composites (MMC) are known to mitigate friction efficiently. However, the bonding strength of MMCs severely limits their durability. Hence, it is not sufficient to focus on wear performance. In this work, the flexural strength and interfacial bonding of Stellite 6/WC MMCs produced by Laser Directed Energy Deposition were investigated. The manufactured coatings exhibited a strong bond to the substrate regardless of the WC content, as no delamination was observed. Additionally, all MMC coatings produced under different processing conditions and with the same composition showed similar elastoplastic behaviour, while specimens containing a higher WC% failed prematurely. This was ascribed to the local embrittlement of the reaction layer surrounding the WC particles, which were found to be crack initiation sites.