Coated component

摘要

#CMT# #/CMT# In a component with a corrosion- and/or oxidation-resistant coating with a platinum (Pt)-aluminum (Al) substrate region (12), formed on a nickel (Ni)-based substrate surface (11) by depositing Pt and Al, the Pt-Al region has an outer zone (13) with a 2-phase or duplex structure of finely dispersed Pt-Al deposits in Ni-based mixed crystals; and an inner zone (14), between the substrate and outer zone, with a single-phase structure of Ni-based mixed crystals #CMT# : #/CMT# Independent claims are included for: (1) a coating as described above; and (2) the production of a corrosion- and/or oxidation-resistant coating, by depositing Pt on a substrate or component surface, so that the Pt diffuses into the surface then aluminizing, where aluminization is carried out by depositing Al thermochemically in a high-activity gas phase process and the Al diffuses into the surface to give a 2-phase or duplex structure as described above. #CMT#USE : #/CMT# The component with the coating is specifically a gas turbine component (claimed), e.g. a moving gas turbine vane of crystallized nickel-based alloy of the SC 2000 type. #CMT#ADVANTAGE : #/CMT# The Pt-Al region has good thermal-mechanical strength, and provides lasting protection against oxidation and corrosion, even at high temperatures and under mechanical stress. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The figure shows a schematic cross-section through a component of nickel-based material, with one form of the coating. 10 : Component 11 : Substrate surface 12 : Platinum-aluminum substrate region 13 : Outer zone 14 : Inner zone #CMT#METALLURGY : #/CMT# Preferred Composition: The 2-phase or duplex structure consists of finely dispersed, globulitic PtAl 2 deposits of size 0.1-3 (preferably 0.1-1.0) mu m in beta -AlNi mixed crystals, the content of this structure being 2.0-40.0 (preferably 2.0-20.0) vol. % and the Al content in the mixed crystals being more than 20.0 (preferably more than 25.0) vol. %. The inner zone is a diffusion zone, in which the Al content in the mixed crystals is at most 15.0 (preferably at most 10.0) wt. % and the Pt content is at most 8.0 wt. %. The outer and/or inner zone has a yttrium content of at most 1.5 wt. % and/or a hafnium content of at most 1.5 wt. %. A ceramic layer is optionally applied over the Pt-Al region, with a thin aluminum oxide (Al 2O 3) layer between the Pt-Al region and the ceramic layer. Specifically the Al 2O 3 layer contains at least 90.0 vol. % alpha -Al 2O 3 with a rhombohedral structure and at most 10.0 vol. % gamma -Al 2O 3 with a cubic structure; and the ceramic layer is a zirconium oxide layer containing at most 8.0 wt. % yttrium oxide. The substrate is of a directed solidified or single crystalline Ni-based composition containing 18.0-48.0 wt. % Ni and 1.0-8.0 wt. % Al. Preferred Process: The deposited Pt layer is 1.0-10.0 (preferably 2.0-4.0) mu m thick. Diffusion of the Pt is carried out at 960-1160 (preferably 1000-1100)[deg]C for 5-60 (preferably 5-15) minutes. Thermochemical deposition of Al is carried using an atmosphere containing Al halide (specifically at 15 vol. % of more) under a gauge pressure of 10-800 mbars. The Al is diffused in to give an Al activity of at least 50 atomic % (based on pure Ni), at a temperature at least 10[deg]C below the Pt annealing temperature, for 180-360 minutes. If the ceramic covering layer and Al 2O 3 intermediate layer are used, the intermediate layer is formed by cleaning the Pt-Al region, heating under a high vacuum and maintaining a low or partial vacuum under an atmosphere containing 25-60 vol. % oxygen and 75-40 vol. % argon or helium.