Metals and Ceramics Division progress report for period ending December 31, 1992

Abstract

This report provides a brief overview of the activities and accomplishments of the Metals and Ceramics (M&C) Division during the period October 1991 through December 1992. The division is organized to provide technical support, primarily in the area of high-temperature materials, for the various technologies being developed by the U.S. Department of Energy (DOE). Activities span the range from basic research (through applied research and engineering development) to industrial interactions (through cooperative research and a strong technology transfer program). The division is organized in functional groups that encompass nearly ali of the disciplines needed to develop and to apply materials in high-temperature applications. Sections 1 through 5 describe the different functional groups; Sect. 6 provides an alternative view of the division in terms of the major programs, most of which cross group lines; and Sect. 7 summarizes external interactions including cooperative research and development programs, educational activities, and technology transfer functions. Appendices describe the organizational structure, note personnel changes, present honors and awards received by division members, and contain listings of publications completed and presentations made at technical meetings. instantaneousinformationregardingboth uniformand localizedcorrosionprocessesand does not require the use of a reference electrode. EN will initiallybe applied in the model boiler tests to be performed for the NPR-MHTGR in cooperation with ABB-Combustion Engineering inChattanooga, Tennessee.Tasks on the high-temperaturecorrosion of advanced aluminides and intermetallics were conductedfor the Fossil Energy Program as part of overall alloy development initiatives. Recent ORNL results had shown significant improvement in the roomtemperatureductilityof iron aluminideswhen aluminumconcentrationsare reduced to the 16 at. % level. Therefore,we initiateda studyto define the criticalconcentrationof this element for resistance in high-temperature oxidizing and oxidizing/sulfidizing environments.These have been determinedto be 18 and 20 at. % AI for H2S-H20-H2 and air environments,respectively. Adding 5% chromiumto the 16 at. % AI alloys significantlyimproved the equi,.alent of Fe3AI (28 at. % AI) in terms of air-oxidation resistance. We also initiated a cyclic oxidation experiment with iron aluminides containing16 to 28 at. % Ai and found beneficialeffect of small additionsof zirconium on ',._cal9 adherencefor Fe3AI alloys. Iron aluminideswith 16 at. % AI and additionsof chromium (5%) and zirconium (0,1%) were superior in scaling resistance to binary alloys of 16 and 20 at. % AI and exhibited weight changes comparable to the Zr-containing Fe3AI alloys.A relatedtask in suppo,'t of the FossilEnergyProgramentailedthe developmentof phase stability diagrams for silicon carbide in the presence of sodium contaminants as contained in typical coal gasifier and pressurized fluidized-bed combustion environments.These resultshaveprovidedguidanceto the developmen...