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1.
Wet hydrofluoric acid at concentrations below approximately 60% is highly corrosive to glass, reactive metals, carbon steel and stainless steels. Nickel alloys offer moderate corrosion resistance over a wide range of acid concentration and temperature. The corrosion behavior of eleven commercial alloys was quantified through laboratory testing. Variables that were studied included testing time, acid concentration, temperature, vapor and liquid phases and the presence of residual stresses. Results show that the corrosion rate of a Ni‐Cu and a Ni‐Cr‐Mo‐Cu alloy increased with the acid concentration and the temperature. However, both for increasing acid concentration and temperature, the corrosion rate of the Ni‐Cu alloy increased faster than the corrosion rate of the Ni‐Cr‐Mo‐Cu alloy, especially in the vapor phase. Even in unstressed coupons, nickel alloys showed internal penetration in presence of wet HF; the mode of this internal penetration varied from alloy to alloy. Considering all the studied variables that influence corrosion, the highest ranked material for wet HF service was a Ni‐Cr‐Mo‐Cu alloy. 相似文献
2.
Medium carbon steel (AISI 1040) was one of the candidate materials for rock bolts to reinforce the borehole liners and emplacement
drifts of the high-level nuclear waste repository in Yucca Mountain. The corrosion performance of this structural steel was
investigated by techniques such as linear polarization, electrochemical impedance spectroscopy (EIS), and laboratory immersion
tests in simulated ground waters. The corrosion rates of the steel were measured for the temperatures in the range from 25
°C to 85 °C, for the ionic concentrations of 1 time (1×), 10 times (10×), and a hundred times (100×) ground water concentration.
The steel corroded uniformly at penetration rates of 35 to 200 μm/year in the deaerated waters, and at 200 to 1000 μm/year in the aerated waters. Increasing temperatures in the deaerated waters increased the corrosion rate of the steel. However,
increasing ionic concentrations influenced the corrosion rate only slightly. In the aerated 1×and 10×waters, increasing temperatures
increased the rates of the steel significantly. In the aerated 100×waters, the corrosion rate increased from 25 °C to 45 °C
and decreased at higher temperatures (65 °C and up) due to the formation of oxide/hydroxide films and salt scales on the surface
of the steel specimen. The steel suffered pitting corrosion in the both deaerated and aerated hot ground water environments
after anodic polarization.
This article is based on a presentation made in the symposium “Effect of Processing on Materials Properties for Nuclear Waste
Disposition,” November 10–11, 2003, at the TMS Fall meeting in Chicago, Illinois, under the joint auspices of the. TMS Corrosion
and Environmental Effects and Nuclear Materials Committees. 相似文献
3.
Martín A. Rodríguez Ricardo M. Carranza Raúl B. Rebak 《Metallurgical and Materials Transactions A》2005,36(5):1179-1185
Alloy 22 (N06022) is the current candidate alloy used to fabricate the external wall of the high-level nuclear waste containers
for the Yucca Mountain repository. It was of interest to study and compare the general and localized corrosion susceptibility
of Alloy 22 in fluoride and chloride solutions at 90 °C. Standard electrochemical tests such as cyclic potentiodynamic polarization,
amperometry, and electrochemical impedance spectroscopy were used. Studied variables included the solution pH and the alloy
microstructure (thermal aging). Results show that Alloy 22 is highly resistant to general corrosion in all the solutions tested.
Thermal aging is not detrimental and even seems to be slightly beneficial for general corrosion at the higher solution pHs.
Pitting corrosion was never observed. Crevice corrosion was found only for high chloride-containing solutions after anodic
polarization. The presence of fluoride ions together with chloride ions seems to increase the susceptibility of Alloy 22 to
crevice corrosion compared to pure chloride solutions.
This article is based on a presentation made in the symposium “Effect of Processing on Materials Properties for Nuclear Waste
Disposition,” November 10–11, 2003, at the TMS Fall meeting in Chicago, Illinois, under the joint auspices of the TMS Corrosion
and Environmental Effects and Nuclear Materials Committees. 相似文献
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5.
Joshua Lamb Venugopal Arjunan Vinay Deodeshmukh Dhanesh Chandra Jaak Daemen Raúl B. Rebak 《Metallurgical and Materials Transactions A》2007,38(2):348-355
The electrochemical hydrogen permeation method was used to investigate hydrogen transport, trapping characteristics of low
(0.08 pct C) and medium carbon (0.44 pct C) steels proposed for the Yucca Mountain (YM) repository environment. The presence
of relatively high amounts of C, Mn, and S increased the density of trapping sites in medium carbon steel. The measured diffusivity
of medium carbon steel was lower than that of the low carbon steel due to increased trapping of hydrogen at irreversible sites
in the medium carbon steel. Hydrogen concentration values obtained for low carbon steels in YM ground water electrolytes indicate
that increased ionic concentration decreases the uptake of hydrogen. The decrease in hydrogen permeation were due the formation
of CaCO3 corrosion products on the surface of steels. 相似文献
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7.
Raul B. Rebak S. Daniel Day Tiangan Lian Phillip D. Hailey Joseph C. Farmer 《Metallurgical and Materials Transactions A》2008,39(2):225-234
Iron (Fe)-based amorphous alloys possess enhanced hardness and are highly resistant to corrosion, which make them desirable
for wear applications in corrosive environments. It was of interest to examine the behavior of amorphous alloys during anodic
polarization in concentrated salt solutions and in the salt-fog testing. Results from the testing of one amorphous material
(SAM2X5) both in ribbon form and as an applied coating are reported here. Cyclic polarization tests were performed on SAM2X5
ribbon as well as on other nuclear engineering materials. SAM2X5 showed the highest resistance to localized corrosion in 5 M
CaCl2 solution at 105 °C. Salt fog tests of 316L SS and alloy 22 coupons coated with amorphous SAM2X5 powder showed resistance
to rusting. Partial devitrification may be responsible for isolated pinpoint rust spots in some coatings.
This article is based on a presentation given in the symposium entitled “Materials Issues for Advanced Nuclear Systems,” which
occurred February 25–March 1, 2007 during the TMS Annual Meeting in Orlando, Florida under the auspices of the Corrosion and
Environmental Effects Committee of ASM-TMS. 相似文献
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Raul B. Rebak 《JOM Journal of the Minerals, Metals and Materials Society》2018,70(2):176-185
The US has currently a fleet of 99 nuclear power light water reactors which generate approximately 20% of the electricity consumed in the country. Near 90% of the reactors are at least 30 years old. There are incentives to make the existing reactors safer by using accident tolerant fuels (ATF). Compared to the standard UO2–zirconium-based system, ATF need to tolerate loss of active cooling in the core for a considerably longer time while maintaining or improving the fuel performance during normal operation conditions. Ferritic iron-chromium-aluminum (FeCrAl) alloys have been identified as an alternative to replace current zirconium alloys. They contain Fe (base) + 10–22 Cr + 4–6 Al and may contain smaller amounts of other elements such as molybdenum and traces of others. FeCrAl alloys offer outstanding resistance to attack by superheated steam by developing an alumina oxide on the surface in case of a loss of coolant accident like at Fukushima. FeCrAl alloys also perform well under normal operation conditions both in boiling water reactors and pressurized water reactors because they are protected by a thin oxide rich in chromium. Under normal operation condition, the key element is Cr and under accident conditions it is Al. 相似文献
10.
Garud Yogendra S. Hoffman Andrew K. Rebak Raul B. 《Metallurgical and Materials Transactions A》2022,53(3):773-793
Metallurgical and Materials Transactions A - The US Department of Energy is working with fuel vendors to develop accident tolerant fuels (ATF) for the current fleet of light water reactors (LWRs).... 相似文献