Two different materials have been selected for the development of higher temperature thermal barrier coatings (TBCs): (1) Pyrochlore oxides (specifically, gadolinium zirconate; Gd2Zr2O7 [GZO]) and (2) Modified Std. yttria-stabilized zirconia (YSZ, six to eight weight percent) through chemistry changes (doping). The overall technical approach of this project is focused on the development and evaluation of novel, multilayered/ composite TBC design architectures consisting of GZO and doped YSZ for improved relevant characteristics (reduction in thermal conductivity, erosion rate and sintering rate). The Phase I technical approach involved fabrication, characterization, and performance evaluation of the multilayered and monolayered TBC architectures. Electron beam physical vapor deposition (EBPVD) was utilized to fabricate monolayered and multilayered TBCs of the selected materials. Phase II of the project involves optimization of microstructure and design of the multi-layered TBCs, as well as fabrication and evaluation of composite TBCs fabricated by EBPVD and cost effective atmospheric plasma spray (APS) techniques. Fabricated TBCs are characterized in terms of microstructure, thermal conductivity, erosion resistance, sintering resistance under thermal gradient condition and thermal cycling tests.
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.
UES will develop and evaluate novel, multilayered/ composite thermal barrier coating (TBC) design architectures consisting of GZO (gadolinium zirconate; Gd2Zr2O7) and doped YSZ (yttria-stabilized zirconia) for improved relevant characteristics (reduction in thermal conductivity, erosion rate and sintering rate). Phase II of the project involves optimization of microstructure and design of the multi-layered TBCs, as well as fabrication and evaluation of composite TBCs fabricated by electron beam physical vapor deposition (EBPVD) and cost effective atmospheric plasma spray (APS) techniques. Fabricated TBCs are characterized in terms of microstructure, thermal conductivity, erosion resistance, sintering resistance under thermal gradient condition and thermal cycling tests. 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.
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