During this project, researchers will improve the design of high-efficiency gas atomization nozzles in order to maximize powder yields in special size classes most suitable for thermal-sprayed coatings. Sizes will include ultrafine powders, with particle diameters of less than 10 microns (µm), and mid-range powders, with particle diameters ranging between 10 and 44 µm. Powder production tests will be performed in laboratory atomization systems to demonstrate steady-state operation and controls systems suitable for industrial use. Researchers will perform a detailed analysis of atomization process responses to alloy and parameter modifications to verify the effect of process innovations. Initial work will involve pure metals and simple model alloys for each target area of process or alloy development.
The U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) sponsors the development of innovative, cost-effective technologies for improving the efficiency and environmental performance of advanced power systems. These emerging technologies require development of high-performance materials that can withstand demanding high-temperature, high-pressure, and often corrosive environments. Power system components made with materials that perform well in high temperatures may be coated by thermal spraying with high-melting point alloys that withstand oxidation and corrosion. The manufacturing process that is most suitable for the complex, high-melting-point alloys for these emerging technologies is gas atomization, especially with the use of a close-coupled nozzle.
These nozzles have potential for improvements in efficiency and process control; however, most industrial gas atomization practitioners have not pursued the develop-ments needed to reliably produce specific class sizes of metal powders. Rather, sieves and pneumatic separators are used to separate and collect powder with the desired particle size range and the rest is recycled or inventoried, if possible, or scraped. This conventional practice is process and energy intensive, wasteful of materials, and quite costly, thus making it unacceptable for complex alloy compositions without additional markets. NETL is partnering with Ames Laboratory to develop a close-coupled atomization nozzle and control system that can be calibrated to generate liquid droplets in the atomization spray, which then solidify to the specified size range of particles in powders for specific applications.
This project will extend the benefits of powder metallurgy within and beyond the fossil energy field. The ability to harvest high yields of specific sizes of powder particles will significantly lower the costs of specialty metal powders. This will enable their use in such high-performance materials as ODS alloys and open the way to more effective alloy production processes for industries serving the fossil energy market. The resulting alloys will be used in applications including coal gasifier heat exchangers and gas turbine blades. Further development of other metals may be used to fabricate components such as hydrogen separation membranes. These developments will enable more efficient power plants operating with reduced emissions and adaptability to carbon sequestration or capture.
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