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Title: ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C

Abstract

Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Yucca Mountain Project, Las Vegas, Nevada
Sponsoring Org.:
USDOE
OSTI Identifier:
886560
Report Number(s):
UCRL-PROC-220305
MOL.20060517.0191 DC#47653; TRN: US200616%%1005
DOE Contract Number:
NA
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; HASTELLOYS; BRINES; CORROSION RESISTANCE; CREVICE CORROSION; NITRATES; CHLORIDES; CORROSION INHIBITORS; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K

Citation Formats

G.O. LLEVBARE, J.C. ESTILL, A. YILMAZ, R.A. ETIEN, and G.A. HUST M.L. STUART. ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C. United States: N. p., 2006. Web. doi:10.2172/886560.
G.O. LLEVBARE, J.C. ESTILL, A. YILMAZ, R.A. ETIEN, & G.A. HUST M.L. STUART. ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C. United States. doi:10.2172/886560.
G.O. LLEVBARE, J.C. ESTILL, A. YILMAZ, R.A. ETIEN, and G.A. HUST M.L. STUART. Thu . "ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C". United States. doi:10.2172/886560. https://www.osti.gov/servlets/purl/886560.
@article{osti_886560,
title = {ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C},
author = {G.O. LLEVBARE and J.C. ESTILL and A. YILMAZ and R.A. ETIEN and G.A. HUST M.L. STUART},
abstractNote = {Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C.},
doi = {10.2172/886560},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Apr 20 00:00:00 EDT 2006},
month = {Thu Apr 20 00:00:00 EDT 2006}
}

Technical Report:

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  • Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloymore » 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C.« less
  • Alloy 22 (UNS N60622) is a nickel-based alloy, which is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in concentrated calcium chloride (CaCl{sub 2}) brines and to evaluate the inhibitive effect of nitrate, especially to localized corrosion. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion potential of Alloy 22 was approximately -360 mV in the silver-silver chloride (SSC) scale and independent of themore » tested temperature. Cyclic polarization tests showed that Alloy 22 was mainly susceptible to localized attack in 5 M CaCl{sub 2} at 75 C and higher temperatures. The addition of nitrate in a molar ratio of chloride to nitrate equal to 10 increased the onset of localized corrosion to approximately 105 C. The addition of nitrate to the solution also decreased the uniform corrosion rate and the passive current of the alloy.« less
  • At near neutral pH and at applied potentials above the threshold potential for localized breakdown of the passive film, virtually all of the dissolved chromium appeared to be in the hexavalent oxidation state (Cr(VI)). In acidic environments, such as crevice solutions formed during the crevice corrosion of 316L and C-22 samples in 4 M NaCl, virtually all of the dissolved chromium appeared to be in the trivalent oxidation state (Cr(III)). These general observations appear to be consistent with the Pourbaix diagram for chromium (Pourbaix 1974), pp. 307-321. At high pH and high anodic polarization (pH {approximately} 8 and 800 mVmore » vs. SHE), the predominate species is believed to be the soluble chromate anion (CrO{sub 4}{sup 2{minus}}). At the same pH, but lower polarization (pH {approximately} 8 and 0 mV vs. SHE), the predominate species are believed to be precipitates such as trivalent Cr(OH){sub 3} {center_dot} n(H{sub 2}O) and hexavalent Cr{sub 2}O{sub 3}. In acidified environments such as those found in crevices (pH < 3), soluble Cr{sup 3+} is expected to form over a wide range of potential extending from 400 mV vs. SHE to approximately 1200 mV vs. SHE. Again, this is consistent with the observations from the creviced samples. In earlier studies by the principal investigator, it has been found that low-level chromium contamination in ground water is usually in the hexavalent oxidation state (Farmer et al. 1996). In general, dissolved iron measured during the crevice experiments appears to be Fe(II) in acidic media and Fe(III) in near-neutral and alkaline solutions (table 3). In the case of cyclic polarization measurements, the dissolved iron measured at the end of some cyclic polarization measurements with C-22 appeared to be in the Fe(III) state. This is probably due to the high electrochemical potential at which these species were generated during the potential scan. Note that the reversal potential was approximately 1200 mV vs. Ag/AgCl during these scans. These results are also consistent with the corresponding Pourbaix diagrams. For example, in acidic media (pH 0 to 1), Fe{sup +2} would be expected to form at relatively low potential, with conversion to Fe{sup +3} at high applied potential (greater than about 700 mV vs. SHE). In neutral to alkaline pH, precipitates of Fe(OH){sub 2}, Fe(OH){sub 3}, Fe{sub 2}O{sub 3}, or Fe{sub 3}O{sub 4} would be expected, with some hydrolyzed species of Fe{sup +3} possible.« less
  • The objective was to investigate the behavior of 97.2% tungsten alloy in tension. A modified button head specimen was heated using resistive heating techniques. The affect high temperatures, medium strain rates, and heating rates had on the stress-strain results were observed. A high speed optical pyrometer and an optical clip gage were utilized for temperature and strain measurements. The optical clip gage could measure strain at strain rates up to 11.8/s. The room temperature experiments were at strain rates of 10-(exp 4)/s, 10-(exp 2)/s, and 5/s. The high heating rate experiments were at temperatures of 727 deg C, and 1097more » deg C, heating rates of 5.4 deg C/sec and 536 deg C/sec and a strain rate of 5/s. Increase in yield point and flow stress were observed as the heating rate was increased. A modified Johnson-Cook (MJ+C) material model was proposed to include the effect of heating rate. The constants in the MJ+C model were determined based on the experimental results.« less
  • The present document describes work performed at PNL during FY 1985 and FY 1986 that was directed toward characterizing the corrosion behavior of the candidate barrier materials in salt-repository- relevant, hydrothermal brine environments. The significant degradation modes of the materials were evaluated and prioritized, and the corresponding corrosion and environmental-mechanical work was performed. The objective of the work was to augment the material performance data base that will ultimately be used in the development of the predictive degradation models required for waste package licensing. The specific experimental objectives of the work performed through FY 1986 have been to quantify, tomore » the degree possible, the rates of general corrosion of A216 steel; the susceptibility of this material to pitting, crevice corrosion, and stress-corrosion cracking; and the susceptibility of Ti Grade 12 to crevice corrosion and hydrogen absorption. These are the degradation modes judged potentially most deleterious (with the possible exception, for Ti Grade 12, of hydrogen-induced delayed failure) to the application of the two candidate barrier materials in a salt repository environment. 64 refs., 69 figs., 25 tabs.« less