Effects of steam environment on creep behavior of Nextel™720/alumina–mullite ceramic composite at elevated temperature

• Published in: Composites. Part A, Applied science and manufacturing Applied science and manufacturing, 2010-12, Vol.41 (12), p.1807-1816
• Main Authors: Ruggles-Wrenn, M.B., Kutsal, T.
• Format: Article
• Language: English
• Subjects: A. Ceramic–matrix composites (CMCs); B. Creep; B. High-temperature properties; Ceramics; Continuous fibers; Creep (materials); Creep rate; Cross-disciplinary physics: materials science; rheology; D. Fractography; Degradation; Exact sciences and technology; Fibers; Materials science; Other materials; Physics; Specific materials; Stress-strain relationships; Tensile creep; Tensile properties
• ISSN: 1359-835X; 1878-5840
• DOI: 10.1016/j.compositesa.2010.09.006

The tensile creep behavior of an oxide–oxide continuous fiber ceramic composite was investigated at 1000 and 1100 °C in laboratory air and in steam. The composite consists of a porous alumina–mullite matrix reinforced with laminated, woven mullite/alumina (Nextel™720) fibers, has no interface between the fiber and matrix, and relies on the porous matrix for flaw tolerance. The tensile stress–strain behavior was investigated and the tensile properties measured. Tensile creep behavior was examined for creep stresses in the 70–140 MPa range. The presence of steam accelerated creep rates and dramatically reduced creep lifetimes. The degrading effects of steam become more pronounced with increasing temperature. At 1000 °C, creep run-out (set to 100 h) was achieved in all tests. At 1100 °C, creep run-out was achieved in all tests in air and only in the 87.5 MPa test in steam. Composite microstructure, as well as damage and failure mechanisms were investigated.