Project No: FWP-FEAA070
Performer: ORNL - Oak Ridge National Laboratory
Richard A. Dennis Technology Manager, Turbines National Energy Technology Laboratory 3610 Collins Ferry Road P.O. Box 880 Morgantown, WV 26507-0880 304-285-4515 firstname.lastname@example.org Briggs White Project Manager National Energy Technology Laboratory 3610 Collins Ferry Road P.O. Box 880 Morgantown, WV 26507-0880 304-285-5437 email@example.com Bruce Pint Principal Investigator Oak Ridge National Laboratory (ORNL) 1 Bethel Valley Rd. Oak Ridge, TN 37831 865-576-2897 firstname.lastname@example.org
DOE Share: $3,483,000.00
Performer Share: $0.00
Total Award Value: $3,483,000.00
Performer website: ORNL - Oak Ridge National Laboratory - http://www.ornl.gov
For this project, Oak Ridge National Laboratory (ORNL) has three tasks. The first task is to study the effect of higher water vapor contents during thermal cycling. Results show the average thermal barrier coatings (TBCs) life-time data for three specimens of each coating type at 1,150 degrees Celsius (°C) in dry oxygen (O2) and air with 10, 50, and 90 percent by volume water vapor for two different types of diffusion bond coatings. Lifetime is being defined as the time to 20 percent spallation of the low thermal conductivity yttria-stabilized zirconia (YSZ) top coating of the TBC. The addition of water vapor had a dramatic effect on the platinum (Pt)-modified aluminide coating, especially with 10 percent water vapor, but no statistical effect on the average lifetime of Pt-diffusion coatings. The second ORNL task is to quantify the benefit of adding yttrium (Y) and lanthanum (La) dopants to nickel (Ni)-base superalloys on TBC lifetime. Superalloy coupons were coated with nickel-cobalt-chromium-aluminum-yttrium (NiCoCrAlY) and NiCoCrAlY-hafnium-silicon (NiCoCrAlYHfSi) bond coatings using a thermal spray high velocity oxygen fuel (HVOF) process. Ten percent water vapor had a negative effect on coating lifetime at 1100 °C, but similar lifetimes were observed for the substrates with and without Y and La. The third task is characterization of the microstructure and microchemistry of these TBC systems to assist in mechanistic understanding of the roles of dopants and water vapor on coating lifetime. The initial results have demonstrated that titanium (Ti) from the superalloy can diffuse through the NiCoCrAlYHfSi coating and become incorporated into the thermally-grown alumina (aluminum oxide) scale.
Average lifetimes (number of 1-hour cycles to failure) for EB-PVD (electron-beam, physical vapor deposition) yttria-stabilized zirconia (YSZ)-coated superalloy specimens with two different platinum-containing diffusion bond coatings exposed in 1-hour cycles at 1150 °C in several environments. Two different superalloy substrates were evaluated. The bars note the standard deviation for 3 specimens of each type.
Program Background and Project Benefits
Turbines convert heat energy to mechanical energy by expanding a hot, compressed working fluid through a series of airfoils. Combustion turbines compress air, mix and combust it with a fuel (natural gas, coal-derived synthesis gas [syngas], or hydrogen), and then expand the combustion gases through the airfoils. Expansion turbines expand a working fluid like steam or supercritical carbon dioxide (CO2) that has been heated in a heat exchanger by an external heat source. These two types of turbines are used in conjunction to form a combined cycle— with heat from the combustion gases used as the heat source for the working fluid— improving efficiency and reducing emissions. If oxygen is used for combustion in place of air, then the combustion gases consist mostly of carbon dioxide (CO2) and water, and the CO2 can be easily separated and sent to storage or used for Enhanced Oil Recovery (EOR). Alternatively, the CO2/steam combustion gases can be expanded directly in an oxy-fuel turbine. Turbines are the backbone of power generation in the US, and the diverse power cycles containing turbines provide a variety of electricity generation options for fossil derived fuels. The efficiency of combustion turbines has steadily increased as advanced technologies have provided manufacturers with the ability to produce highly advanced turbines that operate at very high temperatures. The Advanced Turbines program is developing technologies in four key areas that will accelerate turbine performance, efficiency, and cost effectiveness beyond current state-of-the-art and provide tangible benefits to the public in the form of lower cost of electricity (COE), reduced emissions of criteria pollutants, and carbon capture options. The Key Technology areas for the Advanced Hydrogen Turbines Program are: (1) Hydrogen Turbines, (2) Supercritical CO2 Power Cycles, (3) Oxy-Fueled Turbines, and (4) Advanced Steam Turbines. Hydrogen turbine technology research is being conducted with the goal of producing reliable, affordable, and environmentally friendly electric power in response to the Nation's increasing energy challenges. NETL is leading the research, development, and demonstration of technologies to achieve power production from high hydrogen content (HHC) fuels derived from coal that is clean, efficient, and cost-effective; minimize carbon dioxide (CO2) emissions; and help maintain the Nation's leadership in the export of gas turbine equipment. These goals are being met by developing the most advanced technology in the areas of materials, cooling, heat transfer, manufacturing, aerodynamics, and machine design. Success in these areas will allow machines to be designed that have higher efficiencies and power output with lower emissions and lower cost. Oak Ridge National Laboratory (ORNL) will perform three tasks that will help understand the role of water vapor and dopants on thermal barrier coatings (TBC) lifetime. The first task will study the effect of higher water vapor contents on TBC life during thermal cycling. The second task will quantify the benefit of adding yttrium (Y) and lanthanum (La) dopants to nickel (Ni)-base superalloys on TBC lifetime. The third task will characterize the microstructure and microchemistry of these TBC systems to assist in mechanistic understanding of the roles of dopants and water vapor on coating lifetime. Materials research conducted under the Advanced Turbine Program seeks to improve coating materials that will allow for higher temperature operation and increased durability. These improvements will improve turbine efficiency and reduce maintenance, leading to lower capital costs, reduced operating costs, and reduced costs of electricity for consumers.