Structure of MCrAlY Laser Cladding Coatings Deposited on Single Crystal Alloy Turbine Blades

摘要

Despite the improvements brought by the introduction of new alloys and the use of single crystalline material for turbine blades and vanes, it is impossible to find chemical compositions that allow the required mechanical and corrosion properties to be simultaneously achieve. As a result, turbine blades are usually coated with materials with outstanding oxidation and corrosion resistance such as the MCrAlY-type alloys. The protective action of these alloys depends of an adherent, slow growing and spalling resistant oxide layer. The possibility of eliminating high diffusivity paths like grain boundaries from coatings may constitute a major improvement in the oxidation resistance of these materials due to the reduction of the growth rate of the oxide scale. The deposition of single crystalline MCrAlY coatings on single crystalline turbine blade materials is demonstrated in this paper by the authors. This article reports the properties of single crystal the laser cladded coatings. Microstructural characterization and X-ray diffraction experiments were performed in order to establish relations between the substrate material and the deposited coating. Experimental evidences shows that the coating grows epitaxially from the substrate and inherit the crystal orientation of the substrate.