Ultra-High Temperature Thermal Barrier Coatings

State of the art yttria stabilized zirconia (YSZ) based thermal barrier coatings (TBCs) are typically limited to maximum use temperatures of 1200-1300C. A thermal barrier coating (TBC) with a 1500C temperature capability would be a major gas turbine materials breakthrough. New coatings with a 200C temperature advantage can be used by the gas turbine industry to significantly increase turbine efficiency and reduce fuel consumption, but have proven to be difficult to realize in practice until now. HiFunda and UConn have demonstrated the feasibility of an advanced TBC with a new chemistry of yttrium aluminum garnet (YAG) that offers the potential of lower thermal conductivity, higher use temperature, greater erosion resistance, and improved sintering resistance compared with state of the art APS YSZ TBCs. These coatings are made possible through desirable strain-tolerant microstructures produced by a novel solution precursor plasma spray (SPPS) process. Through the Phase I and Phase II programs, HiFunda/UConn have successfully demonstrated that SPPS YAG TBCs have 1500C temperature capability based on sintering, phase stability and calcium magnesium aluminosilicate (CMAS) resistance tests. In addition, excellent durability was demonstrated using thermal cycling and particulate erosion tests. High-temperature thermal conductivity was shown to be lower than that of baseline APS YSZ TBCs. Based on these promising results, nine major industrial partners are testing SPPS YAG TBCs and evaluating the SPPS process in production facilities. In the proposed Phase IIA program, the HiFunda/UConn team will address specific technology improvements, such as further lowering TBC thermal conductivity, further improvement in CMAS resistance and increasing deposition rate/efficiency that will further enhance the commercialization potential of SPPS YAG TBCs. These modified SPPS YAG TBCs will be evaluated in thermal cycling, erosion and CMAS resistance tests by HiFunda/UConn, as well as several major gas turbine manufacturers and TBC coating service providers through significant cost-shared support. Commercial Applications and Other Benefits: These novel TBCs can enable highly durable and efficient next generation gas turbines and high-efficiency upgrades to existing turbines. The partnerships planned in this project with major gas turbine equipment manufacturers are expected to accelerate market adoption of the new technology with the result of reducing energy costs and reducing greenhouse gas emissions.