Microstructural aspects of the protective ceramic coatings applied on the surfaces of refractory alloys produced by additive manufacturing

Abstract

The possibility of depositing multi layers made of metals/alloys and high temperature ceramics by electron beam physical evaporation process under high vacuum (EB-PVD) on the surface of a parallelepiped sample made by selective laser melting (SLM) from a Ni base refractory super alloy was experimentally tested. The SEM-EDAX micro structural analysis revealed the morphology and thickness of the coatings consisting of a NiCrAlY base alloy as bonding layer and three successive YSZ, LZO and GZO ceramic layers on the Ni-based super alloy substrate obtained by additive manufacturing. The adhesion of the layer deposited was evaluated by the scratch test method. The analysis highlighted the importance of pre-preparing the surface of the additive manufactured substrates, in order to control the adhesion and uniformity of the deposited layers.

Keywords

• ni-base superalloys
• ceramic coatings
• slm
• eb-pvd
• scratch test