B. R. Marple, R. S. Lima, S. Kruger, National Research Council of Canada, Boucherville, QC, Canada; C. Moreau, National Research Council Canada (CNRC-NRC), Boucherville,, QC, Canada; L. Xie, M. Dorfman, Sulzer Metco (US) Inc., Westbury, NY
Thermal barrier coatings (TBCs) represent one of the major areas of application in the thermal spray field. These double-layer surfaces, comprised of a metallic bond coat and a ceramic top coat, are playing an increasingly important role in protecting and extending the life of various components exposed to high temperature combustion environments in the aerospace and industrial gas turbine fields. The thermal spray process commonly employed for depositing the yttria-stabilized zirconia top coat is air plasma spray (APS), frequently using a plasma gas mixture comprised of argon and hydrogen as primary and secondary gases, respectively. The present work investigated the challenges and potential advantages of replacing argon by nitrogen as the primary plasma gas. A systematic study was performed using a combination of in-flight particle diagnostics, microstructural characterization and property evaluation. Various parameter setting combinations were employed in order to sample a range of values in temperature-velocity space. In addition to the microstructure, the elastic, thermal and mechanical properties of coatings produced using N2/H2 were studied and compared to those deposited using Ar/H2. The results will be analyzed and discussed in terms of some of the potential advantages of employing nitrogen to replace argon as the primary plasma gas.
Summary: Thermal barrier coatings (TBCs) represent one of the major areas of application in the thermal spray field. These double-layer surfaces, comprised of a metallic bond coat and a ceramic top coat, are playing an increasingly important role in protecting and extending the life of various components exposed to high temperature combustion environments in the aerospace and industrial gas turbine fields. The thermal spray process commonly employed for depositing the yttria-stabilized zirconia top coat is air plasma spray (APS), frequently using a plasma gas mixture comprised of argon and hydrogen as primary and secondary gases, respectively. The present work investigated the challenges and potential advantages of replacing argon by nitrogen as the primary plasma gas. A systematic study was performed using a combination of in-flight particle diagnostics, microstructural characterization and property evaluation. Various parameter setting combinations were employed in order to sample a range of values in temperature-velocity space. In addition to the microstructure, the elastic, thermal and mechanical properties of coatings produced using N2/H2 were studied and compared to those deposited using Ar/H2. The results will be analyzed and discussed in terms of some of the potential advantages of employing nitrogen to replace argon as the primary plasma gas.
