Abstract
Metallic alloy bond coats are used as an interlayer to promote adhesion of ceramic Thermal Barrier Coatings (TBCs) to the superalloy substrates. These bond coats can be applied through a variety of processing means such as Air Plasma Spray (APS), High-Velocity Oxy Fuel spray (HVOF), and Vacuum Plasma Spray (VPS). While widely adopted in the industry, some uncertainties remain as to the specific microstructural attributes which are influenced by the processing routes and their implications on durability. This paper seeks to elucidate these subtleties between bond coat deposition processing routes through an integrated study of processing to connect to furnace cycle durability on a single bond coat chemistry of NiCoCrAlYHfSi. A standard porous APS TBC top coating based on yttria stabilized zirconia (7YSZ) was consistently applied on these distinct bond coats and tested for durability in cyclic furnace testing at 1100 °C. The results point to substantial differences in durability which are not readily explained only by the variances in coating roughness. Detailed assessment of deposited bond coat properties (modulus, thermal expansion, chemistry) provided some explanation relative to durability. The results suggest a complex interplay among roughness, compliance, aluminum diffusion pathway, and thermal expansion mismatch. Photo-stimulated luminescence piezospectroscopy (PLPS) provided additional insights enabling a comprehensive assessment of processing-performance linkages.
| Original language | English |
|---|---|
| Pages (from-to) | 782-792 |
| Number of pages | 11 |
| Journal | Surface and Coatings Technology |
| Volume | 375 |
| DOIs | |
| State | Published - Oct 15 2019 |
Funding
The study was supported by the U.S. Department of Energy 's National Energy Technology Laboratory University Turbine Systems Research program award DE-FE000471 and by the Office of Fossil Energy , Advanced Turbine Program, (R. Dennis program manager and P. Burke project manager). The authors are extremely grateful to Dr. Anand Kulkarni (Siemens Energy Inc.) for providing superalloy substrates, Mitch Dorfmann (Oerlikon Metco) for providing the Amdry powder as well the compositional analysis of the sprayed coatings, Andrew Hague (Mitsubishi Hitachi Powder Systems America) for VPS deposition of coatings, Howard Wallar (Saint Gobain) for providing the YSZ powder and S. Dryepondt at ORNL for reviewing the manuscript. Financial support through the Industrial Consortium for Thermal Spray Technology is acknowledged. The study was supported by the U.S. Department of Energy's National Energy Technology Laboratory University Turbine Systems Research program award DE-FE000471 and by the Office of Fossil Energy, Advanced Turbine Program, (R. Dennis program manager and P. Burke project manager). The authors are extremely grateful to Dr. Anand Kulkarni (Siemens Energy Inc.) for providing superalloy substrates, Mitch Dorfmann (Oerlikon Metco) for providing the Amdry powder as well the compositional analysis of the sprayed coatings, Andrew Hague (Mitsubishi Hitachi Powder Systems America) for VPS deposition of coatings, Howard Wallar (Saint Gobain) for providing the YSZ powder and S. Dryepondt at ORNL for reviewing the manuscript. Financial support through the Industrial Consortium for Thermal Spray Technology is acknowledged.
| Funders | Funder number |
|---|---|
| Mitsubishi Hitachi Powder Systems America | |
| National Energy Technology Laboratory | DE-FE000471 |
| Siemens Energy Inc. | |
| U.S. Department of Energy | |
| Office of Fossil Energy | |
| Oak Ridge National Laboratory |
Keywords
- APS
- Bond coat
- HVOF
- PLPS
- VPS
- YSZ TBC