Influence of Ruthenium on the Oxidation Behavior of Platinum-Rich gamma-gamma' Bond Coats and Their Performance in Thermal Barrier Coatings Deposited on a Nickel-Base Superalloy

摘要

We show that a gamma-gamma' bond coat synthesized by diffusing 5 mu m layer of Pt and 5 mu m layer of Ru into a Ni-base superalloy has oxidation resistance and thermal barrier coating performance approaching those provided by the conventional bond coat synthesized by 8 mu m layer of Pt. However, this is found to be dependent upon the deposition sequence of the Pt and Ru layers due to the corresponding significant effect on bond coat microstructure. Deposition of Pt followed by Ru results in a microstructure similar to that of the conventional bond coat. Reversing the deposition sequence results in a surface layer of Cr-rich sigma phase, which precludes the formation of protective layer of Al2O3. It is concluded that it is possible to substitute some of the Pt consumption with the less expensive Ru while still maintaining adequate properties.