Open AccessMaterials support for HITAF. Final report for Phase 1
Author(s) -
Kristin Breder,
V.J. Tennery
Publication year - 1995
Language(s) - English
Resource type - Reports
DOI - 10.2172/93420
Subject(s) - materials science , ceramic , silicon carbide , composite material , coal , carbide , scanning electron microscope , heat exchanger , boiler (water heating) , metallurgy , mechanical engineering , waste management , engineering
Improvements in coal-fired systems will require a change from steam turbines to gas turbines using air as working fluid; pressurized ceramic heat exchangers operating up to 1600 C will be needed. Leading candidate materials are SiC-based ceramics. Mechanical properties of 3 materials are compared in this work: NT230 Si/SiC from Saint Gobain Norton, {beta}-SiC from Coors Ceramics Co., and Lanxide DIMOX SiCp/Al{sub 2}O{sub 3} from Du Pont Lanxide Composites Inc. The first material is siliconized Si carbide, the second is sintered. They all were tested in 4-point flexure at RT and 1100 and 1400 C. Fast-fracture tests were carried out. Slow crack growth was investigated. Failure modes were studied using optical microscopy and SEM. Four materials were exposed to two coal ashes at two different temperatures. In the comparison, Coors {beta}-SiC stands out from a strength and reliability standpoint when exposed to air at high temperatures. Lanxide DIMOX withstood coal ash exposure well