ODS Coating Development Using DED Additive Manufacturing for High Temperature Turbine Components

Abstract

New generation of turbine blade coating using additive manufacturing (AM) technique to coat a layer of oxide dispersion strengthening (ODS) alloy on superalloy substrate is presented. A novel combined mechanochemical bonding (MCB) plus ball milling process is utilized to produce near spherical and uniform alloyed ODS powders. AM-assisted ODS coating by direct energy deposition (DED) method on MAR-247 substrate, with laser powers of 100 W, 150 W and 200 W were carried out. The ODS coated samples were then subjected to cyclic thermal loadings for over 1280 cycles. Corresponding Young’s modulus measurements of ODS coating at various thermal loading cycles were conducted using a unique non-destructive micro-indentation testing method. Correlation of the measured Young’s modulus with evolution of the ODS microstructures are studied. In particular, the presence of secondary gamma prime phase in the ODS coating after thermal cycles is noted. Test results revealed a thin steady durable alpha alumina oxide layer on the 200 W ODS sample. After 1280 thermal cycles, strong bonding at ODS/substrate interface is maintained for the 200 W ODS coated sample. Test results also showed stable substrate microstructures due to the protective ODS coating.