Fatigue behavior of a Hi-Nicalon™/SiC–B4C composite at 1200°C in air and in steam

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 534; pp. 119 - 128
• Main Authors: Ruggles-Wrenn, M.B., Delapasse, J., Chamberlain, A.L., Lane, J.E., Cook, T.S.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.02.2012; Elsevier
• Subjects: Applied sciences; Ceramic–matrix composites (CMCs); Corrosion; Corrosion mechanisms; Crack propagation; Elasticity. Plasticity; Exact sciences and technology; Fatigue; Fatigue (materials); Fatigue failure; Fatigue tests; Fibers; Fibres; Fractography; High-temperature properties; Mechanical properties; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Production techniques; Surface treatment; Tensile properties; Mechanical properties; Fatigue; Ceramic–matrix composites (CMCs); High-temperature properties; Fractography; High temperature; Coatings; Composite material; Non oxide ceramics; Boron; Fatigue test; Chemical vapor infiltration; Stress effects; Ceramic-matrix composites (CMCs); Oxidation; Damaging; Carbon fiber; Multilayer; Stress strain relation; Multiple layer; Tensile property; Water vapor; Carbon; Tension test; Tensile strength; Tensile stress; Lifetime; Pyrocarbon; Silicon carbide; Microstructure; Fracture mode
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2011.11.049

► Hi-Nicalon™/SiC–B4C ceramic composite with a self-healing matrix exhibits good fatigue performance at 1200°C in air. ► The loading frequency has minimal effect on the fatigue performance of Hi-Nicalon™/SiC–B4C at 1200°C in air. ► At 1200°C, the presence of steam has little influence on the fatigue performance of the composite at 1.0Hz, but noticeably degrades fatigue lifetimes at 0.1Hz. ► Fiber degradation during fatigue is not caused by oxidation, but is due to an intrinsic creep-controlled flaw growth mechanism. ► The fatigue performance of the Hi-N/SiC–B4C composite is controlled by the creep resistance of the Hi-Nicalon™ fibers. Effects of steam environment on fatigue behavior of a non-oxide ceramic composite with a multilayered matrix were investigated at 1200°C. The composite was produced via chemical vapor infiltration (CVI). The composite had an oxidation inhibited matrix, which consisted of alternating layers of silicon carbide and boron carbide and was reinforced with laminated woven Hi-Nicalon™ fibers. Fiber preforms had pyrolytic carbon fiber coating with boron carbon overlay applied. Tensile stress–strain behavior and tensile properties were evaluated at 1200°C. Tension-tension fatigue tests were conducted at 0.1Hz and at 1.0Hz for fatigue stresses ranging from 100 to 140MPa in air and in steam. Fatigue run-out was defined as 105 cycles at 0.1Hz and as 2×105 cycles at 1.0Hz. Presence of steam had little influence on fatigue performance at 1.0Hz, but noticeably degraded the fatigue lifetimes at 0.1Hz. Specimens that achieved run-out were subjected to tensile tests to failure to characterize the retained tensile properties. Prior fatigue in air and in steam caused significant reduction in tensile strength and modulus. Composite microstructure, as well as damage and failure mechanisms were investigated.