DoE Funding Opportunity - Experimental Studies for the Development of High Temperature Structural Materials

The implementation of high-efficiency coal-fired power systems requires materials with high-temperature creep properties and high-temperature oxidation and corrosion resistance. For example, ultra-supercritical fossil fuel power plants will require new materials for use at temperatures of 700 ºC and above. Superheater and reheater tubes are likely to experience the most severe service conditions with respect to fire-side corrosion, steam-side oxidation and creep. A material for this application must not only be: (i) creep resistant, (ii) oxidation resistant, and (iii) corrosion resistant at elevated temperatures; but also be, (iv) easily fabricated, (v) easily joined, and (vi) economical. Materials with improved mechanical properties need to be developed to allow the operation of power generation plants using supercritical steam cycles with steam conditions approaching 700◦ C and 325 bar, and cycle efficiencies of about 48%. In the case of steam turbines, in addition to mechanical properties, oxidation studies to determine the temperature dependence of material loss and tendency for scale exfoliation need to be evaluated. A variety of modern tools, such as micro-structural modeling, segregation behavior modeling and plastic deformation simulation could be used to optimize the process of engineering adapted materials and microstructures. Additionally, coatings need to be developed for corrosion resistance in oxidizing, sulfidizing, carburizing and water-containing environments. They are of particular interest for improving the corrosion resistance of alloys to achieve higher operating temperatures in fossil energy systems where sulfur and water vapor can cause severe oxidation problems. One of the factors that inhibit their application is a lack of sufficient data about their potential benefits in terms of lifetime and applicable environments. Model coatings need to be fabricated for corrosion testing and diffusion studies in order to develop a comprehensive lifetime evaluation approach. The objective is to explore routes for the development of materials with temperature/strength capabilities beyond those currently available. The issues being addressed arise from the fact that (a) alloys with melting temperatures higher than current alloys have inherent mechanical property and environmental resistance deficiencies, (b) the potential of these materials can be exploited by application of mechanistic and thermochemical approaches, (c) exploitation requires compromises among, e.g., ability to fabricate components, mechanical properties, and environmental sensitivity, (d) ceramics and ceramic composites have exceptional potential, but lack of understanding or databases of composition-structure-property relationships leads to need for extensive development, and (e) ceramics and refractories suffer rapid environmental degradation in some applications, which requires new approaches to develop increased corrosion resistance with good mechanical properties. The laboratory research could be accompanied by testing of the materials in actual or simulated power plant conditions. Read more