Kinetics of Passive Oxidation of Hi-Nicalon-S SiC Fibers in Wet Air: Relationships between Si02 Scale Thickness, Crystallization, and Fiber Strength (Preprint)

Understanding the strength degradation of glass and carbon fibers due to exposure to liquids over time is important for structural applications. A model has been developed for glass fibers that links the strength reduction in water to the increase of the Griffith flaw size of the fibers. The speed of the increase is determined by regular chemical dissolution kinetics of glass in water. Crack growth and strength reduction can be predicted for several water temperatures and pH, based on the corresponding dissolution constants. Agreement with experimental results for the case of water at 60 °C with a pH of 5.8 is reasonably good. Carbon fibers in water and toluene and glass fibers in toluene do not chemically react with the liquid. Subsequently no strength degradation is expected and will be confirmed experimentally. All fiber strength measurements are carried out on bundles. The glass fibers are R-glass.

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Corrosion Behavior and Mechanism of Heat-Resistant Steel T91 in High-Temperature Carbon Dioxide Environment

Materials Science Forum ◽

10.4028/www.scientific.net/msf.944.398 ◽

2019 ◽

Vol 944 ◽

pp. 398-403

Author(s):

Yong Gui ◽

Zhi Yuan Liang ◽

Miao Yu ◽

Qin Xin Zhao

Keyword(s):

Carbon Dioxide ◽

High Temperature ◽

Corrosion Behavior ◽

Optical Emission ◽

Emission Spectrometry ◽

X Ray Diffraction ◽

Heat Resistant Steel ◽

Scale Thickness ◽

Corrosion Scale ◽

Kinetics Of

Corrosion behavior of martensitic heat resisting steel T91 in high-temperature carbon dioxide environment at 500-700 °C was investigated. X-ray diffraction, scanning electron microscopy and glow-discharge optical emission spectrometry were employed to characterize the corrosion products. The results showed that the corrosion kinetics of T91 followed a parabolic law with experimental time. The oxide scale thickness of T91 followed an exponential growth law from 500 °C to 700 °C. Internal carburization was detected underneath the corrosion scale. What’s more, the carburization depth was larger than the corrosion scale. The variations of Cr and C elements distribution were discussed.

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Passive-Oxidation Kinetics of High-Purity Silicon Carbide from 800o to 1100oC

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.1996.tb08724.x ◽

1996 ◽

Vol 79 (11) ◽

pp. 2897-2911 ◽

Cited By ~ 94

Author(s):

C. Eric Ramberg ◽

Gary Cruciani ◽

Karl E. Spear ◽

Richard E. Tressler ◽

Charles F. Ramberg

Keyword(s):

Silicon Carbide ◽

High Purity ◽

Oxidation Kinetics ◽

Passive Oxidation ◽

High Purity Silicon ◽

Kinetics Of

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Microstructural Investigation of Strength Degradation in A Developmental Cvd Sic Fiber At 2000° C

Microscopy and Microanalysis ◽

10.1017/s1431927600010606 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 743-744

Author(s):

A. Garg ◽

D. R. Hull ◽

R. T. Bhatt

Keyword(s):

Fiber Strength ◽

Chemical Vapor ◽

High Strength ◽

Pyrolytic Carbon ◽

Microstructural Investigation ◽

Sic Fibers ◽

Sic Fiber ◽

Heat Treated ◽

Carbon Coated ◽

Increasing Demand

SiC fibers fabricated by chemical vapor deposition (CVD) methods are being used as reinforcement for metal and ceramic matrix materials because of their high modulus, high strength and good corrosion resistance. These fibers have a complex composite microstructure consisting of a pyrolytic-carbon coated graphite core and a SiC sheath which is often protected by a single or a double layer of carbon-rich coating. Commercially available SCS-6 SiC fibers with a diameter of ˜ 140 μm have been most widely in use for composite fabrication. However, with an ever increasing demand for thinner and stronger fibers, an experimental SiC fiber with a diameter of ˜ 50 μm and having a C-rich SiC sheath was developed by Textron Specialty Materials. The as-fabricated tensile strength of this fiber was found to be ˜ 6 GPa, which is ˜ 50 % higher than that of the SCS-6 fiber.While the room temperature tensile strengths of these fibers heat treated for 1 h in Ar to temperatures ≤ 1600° C were better than those of the SCS-6 fiber, strength of the 2000° C heated fibers decreased to < 1 GPa.

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Interfacial reaction kinetics of coated SiC fibers with various titanium alloys

Scripta Metallurgica et Materialia ◽

10.1016/0956-716x(91)90207-h ◽

1991 ◽

Vol 25 (2) ◽

pp. 437-441 ◽

Cited By ~ 73

Author(s):

D.B. Gundel ◽

F.E. Wawner

Keyword(s):

Titanium Alloys ◽

Reaction Kinetics ◽

Interfacial Reaction ◽

Sic Fibers ◽

Kinetics Of

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Examining oxidation in β-NiAl and β-NiAl+Hf alloys by stochastic cellular automata simulations

npj Materials Degradation ◽

10.1038/s41529-021-00202-4 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Indranil Roy ◽

Pratik K. Ray ◽

Ganesh Balasubramanian

Keyword(s):

Cellular Automata ◽

Grain Boundaries ◽

Oxide Scale ◽

Oxidation Kinetics ◽

Basic Principles ◽

Stochastic Cellular Automata ◽

Scale Thickness ◽

Alloy Oxidation ◽

Ca Model ◽

Kinetics Of

AbstractWe present results from a stochastic cellular automata (CA) model developed and employed for examining the oxidation kinetics of NiAl and NiAl+Hf alloys. The rules of the CA model are grounded in diffusion probabilities and basic principles of alloy oxidation. Using this approach, we can model the oxide scale thickness and morphology, specific mass change and oxidation kinetics as well as an approximate estimate of the stress and strains in the oxide scale. Furthermore, we also incorporate Hf in the grain boundaries and observe the “reactive element effect”, where doping with Hf results in a drastic reduction in the oxidation kinetics concomitant with the formation of thin, planar oxide scales. Interestingly, although we find that grain boundaries result in rapid oxidation of the undoped NiAl, they result in a slower-growing oxide and a planar oxide/metal interface when doped with Hf.

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