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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Corrosion properties of second-generation conductive materials

Since the introduction of silver-filled epoxy adhesives and silver-filled nitrocellulose lacquer as RFI control materials, a number of new materials have been introduced. The resin carriers have been changed in an effort to make the materials more usable or more EPA acceptable and the fillers have been varied in an effort to make the materials less costly. The corrosion-related properties of second-generation materials were assessed, including adhesives, caulks, and greases. Aluminum 2024 was used as the only substrate material. Ten days of salt fog was used as the corrosive environment. If a noble material such as silver, nickel, or carbon is sandwiched with aluminum an increase in dc resistance results given enough time. If this is unsatisfactory electrically it should either not be used or have all corrosive environments excluded.

Groshart, E.↗
DOE OSTI2020

Role of Material Condition in Precursor Corrosion Damage and Stress Corrosion Crack Initiation Behavior of Alloy 600 in PWR Primary Water

Stress corrosion crack (SCC) initiation testing has been performed on a 15% cold-worked UNS N06600 (Alloy 600) heat in the mill-annealed (MA), solution annealed (SA), and thermally treated (TT) conditions to assess the role of grain boundary (GB) carbides on stress-assisted intergranular attack (IGA) and short crack nucleation and growth. The SCC initiation tests were conducted at constant load equivalent to materials yield stress in 360oC simulated PWR primary water with dissolved hydrogen at the Ni/NiO stability line. Results revealed the highest SCC initiation susceptibility in the Alloy 600 MA material followed by the TT and SA materials, suggesting the GB carbide distribution did not have a controlling effect on SCC initiation resistance. Quantitative assessments were conducted on IGA and short cracks to help understand this phenomenon and the role of GB carbides on precursor damage development that lead to differences in macroscopic SCC initiation behavior are discussed.

Zhai, Ziqing↗
NASA NTRS2015

Stress Corrosion Evaluation of Various Metallic Materials for the International Space Station Water Recycling System

A stress corrosion evaluation was performed on Inconel 625, Hastelloy C276, titanium commercially pure (TiCP), Ti-6Al-4V, Ti-6Al-4V extra low interstitial, and Cronidur 30 steel as a consequence of a change in formulation of the pretreatment for processing the urine in the International Space Station Environmental Control and Life Support System Urine Processing Assembly from a sulfuric acid-based to a phosphoric acid-based solution. The first five listed were found resistant to stress corrosion in the pretreatment and brine. However, some of the Cronidur 30 specimens experienced reduction in load-carrying ability.

Torres, P. D.↗
DOE OSTI2019

Investigation of Corrosion of 304 Stainless, Inconel 625, and Haynes 230 in a Chloride-Salt-Based Thermal Storage Medium

One of the critical challenges for latent heat thermal energy storage systems in concentrating solar power applications is corrosion of metallic alloys as containment and heat transfer fluid tube materials in corrosive salts at high temperatures. In this study, the effects of MgCl 2 on the corrosion of stainless steel 304, Inconel 625, and Haynes 230 alloys were investigated through embedded metal samples in the graphite foam/MgCl 2 storage medium. Four experimental testing modules were fabricated, and experimental tests were conducted under controlled environment by heating the testing modules to and keeping them at 750 °C for 100, 200, 500, and 1000 h. The estimated corrosion rates based on the weight losses for stainless steel 304, Inconel 625, and Haynes 230 were 94, 9, and 8 μm/year, respectively. The fitted equations for the loss of the thickness as functions of the exposure time show that the corrosion rates decrease with the exposure time. Additionally, the results on the corrosion zones or depths and chromium segregation ranges of the experimental samples are also presented.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Carburization of metals by a chemical mechanism of carbon transport through molten fluoride salts

Carburization of structural alloys used in Fluoride Cooled High Temperature Reactors (FHR) can result from the interaction between the metal and graphite components and cause changes in alloy properties. However, carburization requires transport of carbon from graphite to alloy surfaces through the molten fluoride coolant. This work introduces an alternative to previously proposed carbon transport mechanisms. The new mechanism is based on the generation of carbonate ions (CO 3 2- ) by oxide impurities in the salt reacting with graphite. CO 3 2- is then reduced on metal surfaces to deposit carbon. This work demonstrates the reduction of dissolved CO 3 2- on pure Fe, Ni, Cr, Mo, and W surfaces without an applied potential in molten FLiNaK at 700 °C. Finally, we also demonstrate that the interaction between oxide and graphite in molten FLiNaK media produces CO 3 2- .

36 MATERIALS SCIENCE↗
DOE OSTI2021

Fe Thin Film-Coated Optics for Corrosion Monitoring: Optical and Electrochemical Studies

Corrosion proxy materials integrated with an optical sensing platform enable a real-time optical corrosion sensor for natural gas pipelines to prevent methane leaks and catastrophic events. Effects of CO 2 , pH, and film thickness on corrosion of Fe thin films (25, 50, 100 nm) were studied using optical and electrochemical methods in 3.5%wt. NaCl solutions at 30 °C. An increase in light transmission (T%) corresponded to corrosion of Fe thin films. CO 2 accelerated corrosion of Fe thin films due to the lower pH and the promoted corrosion reactions, resulting in a faster increase of T% than without CO 2 or at higher pH. While the corrosion rate increased with increasing film thickness, electrochemical corrosion of Fe thin films was in good agreement with that of bulk carbon steel, verifying that Fe thin films can serve as a representative corrosion proxy when integrated with the optical sensing platform.

36 MATERIALS SCIENCE↗
DOE OSTI2023

High temperature gamma radiation-induced chromium redox chemistry via in situ spectroscopic measurements

Chromium ions can make their way into the primary coolant of nuclear power reactors from the corrosion of stainless-steel reactor components, decreasing the material's corrosion resistance and resulting in increased transport of further corrosion products. Despite these potential effects, the radiation-induced redox speciation of chromium ions in aqueous solution is not well understood, especially at the elevated temperatures experienced by reactor coolants. Here, in the present work, we report new experimental results demonstrating that in aerated aqueous solution, the radiolytic oxidation of Cr(III) to Cr(VI) occurs at pH 4, while the reduction of Cr(VI) to Cr(III) occurs at pH 2. The oxidation of Cr(III) is primarily attributed to the reaction of the hydroxyl radical (˙OH) with the Cr(OH) 2+ species, while the reduction of Cr(VI) is attributed to reactions involving the hydrated electron (e aq - ) and hydrogen atom (H˙). Additionally, the steady-state equilibrium yield of Cr(VI) from the gamma irradiation of pH 4 Cr(III) solutions decreased with increasing temperature (over a range of 37–195 °C). This observation indicates that the activation energy of the Cr(VI) reduction reactions is higher than that for the Cr(III) oxidation reactions, such that it becomes relatively more favorable at higher temperatures. Overall, these data are important for the development of complementary multiscale models for the prediction of metal ion speciation in high temperature radiation environments.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Beneficial effect of copper on pitting resistance of Ni-Cr-Fe alloys

This study examines the effect of copper alloying on pitting resistance in a model solid solution FCC Ni-13%Cr-10%Fe alloy through potentiodynamic and potentiostatic polarization in 0.1 M NaCl in conjunction with an analysis using first-principles competitive electro-chemisorption modeling. The pitting potential increased with increasing Cu content in the alloy. Furthermore, the extent of metastable pit growth was suppressed and the incubation time for metastable to stable pit transition increased with Cu content. The first-principles competitive adsorption calculations suggested that Cu alloying suppresses chloride ion adsorption on the alloy surface in a simulated pit environment, which inhibits active dissolution at the pit bottom, enhances proton adsorption, and thereby increases the local pH at the pit bottom. In conclusion, we propose that these two effects of Cu in solid solution combine to reduce pit stability and may act in addition to the enrichment of Cu on the corroding pit surface.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Nickel on the Adhesion and Corrosion Ability of Pseudomonas aeruginosa on Stainless Steel

Microbial colonization of metal surfaces or adhesion of bacteria on metal surfaces is a crucial step in initiating microbiologically influenced corrosion. As the substrate is essential in the development of a biofilm, an understanding of how substrate properties affect adhesion of bacterial cells, including the mechanism of bacterial adhesion, may assist in designing or modifying substrates to inhibit bacterial adhesion and prevent the corrosion of materials. A study was carried out to investigate the effect of nickel on the adhesion and corrosion ability of stainless steels with the same chromium content in nutrient-rich simulated seawater containing Pseudomonas aeruginosa. These stainless steels were 201, 316, 304 and 430 stainless steels. In addition, a carbon steel sample with fully nickel coated was included for comparison. The hydrophobicity of different materials was evaluated by measuring the contact angles made by the water, glycerol and formaldehyde. The number of bacteria adhering to the material surface after short-term immersion was counted by fluorescence microscopy. For corrosion study, the corrosion rates and pitting morphology were studied after 42 days of immersion. The corrosion behavior of the samples was also observed by scanning electron microscope (SEM) coupled with energy-dispersive x-ray spectroscopy (EDX) and inductively coupled plasma mass spectrometry (ICPMS). It was found that the nickel-coated sample had the highest level of bacteria attachment and offered poor corrosion resistance under artificial seawater with Pseudomonas aeruginosa strain. Higher nickel content in stainless steel resulted in a higher level of bacteria attachment. It was found that stainless steel with molybdenum exhibited better corrosion resistance in artificial seawater containing bacteria.

36 MATERIALS SCIENCE↗
NASA NTRS2004

Electrochemical Impedance Spectroscopy of Alloys in a Simulated Space Shuttle Launch Environment

Type 304L stainless steel (304L SS) tubing is currently used in various supply lines that service the Orbiter at NASA's John F. Kennedy Space Center Launch Pads in Florida (USA). The atmosphere at the Space Shuffle launch site is very corrosive due to a combination of factors, such as the proximity of the Atlantic Ocean and the concentrated hydrochloric acid produced by the fuel combustion reaction in the solid rocket boosters. The acidic chloride environment is aggressive to most metals and causes severe pitting in many of the common stainless steel alloys such as 304L SS. Stainless steel tubing is susceptible to pitting corrosion that can cause cracking and rupture of both high-pressure gas and fluid systems. Outages in the systems where failures occur can impact the normal operation of the shuttle and launch schedules. The use of a more corrosion resistant tubing alloy for launch pad applications would greatly reduce the probability of failure, improve safety, lessen maintenance costs, and reduce downtime. A study which included ten alloys was undertaken to find a more corrosion resistant material to replace the existing 304L SS tubing. The study included atmospheric exposure at NASA's John F. Kennedy Space Center outdoor corrosion test site near the launch pads and electrochemical measurements in the laboratory which included DC techniques and electrochemical impedance spectroscopy (EIS). This paper presents the results from EIS measurements on three of the alloys: AL6XN (UN N08367), 254SMO (UNS S32l54), and 304L SS (UNS S30403). Type 304L SS was included in the study as a control. The alloys were tested in three electrolyte solutions which consisted of neutral 3.55% NaC1, 3.55% NaCl in O.1N HC1, and 3.55% NaCl in 1.ON HC1. The solutions were chosen to simulate environments that were expected to be less, similar, and more aggressive, respectively, than those present at the Space Shuttle launch pads. The results from the EIS measurements were analyzed to evaluate the corrosion susceptibility of the alloys and to predict the long-term corrosion performance of the subject materials. The results from the EIS measurements for the three alloys indicated that the higher-alloyed 254SMO and AL6XN exhibited a significantly improved resistance to corrosion than the 304L SS as the concentration of hydrochloric acid in the 3.55% NaC1 solution was increased. The polarization resistance values obtained from the EIS measurements were consistent with those from linear polarization measurements, and were indicative of the actual long-term corrosion performance of the alloys during a two-year atmospheric exposure study.

Calle, L. M.↗
NASA NTRS2005

Heat Transfer and Thermal Stability Research for Advanced Hydrocarbon Fuel Technologies

In recent years there has been increased interest in the development of a new generation of high performance boost rocket engines. These efforts, which will represent a substantial advancement in boost engine technology over that developed for the Space Shuttle Main Engines in the early 1970s, are being pursued both at NASA and the United States Air Force. NASA, under its Space Launch Initiative s Next Generation Launch Technology Program, is investigating the feasibility of developing a highly reliable, long-life, liquid oxygen/kerosene (RP-1) rocket engine for launch vehicles. One of the top technical risks to any engine program employing hydrocarbon fuels is the potential for fuel thermal stability and material compatibility problems to occur under the high-pressure, high-temperature conditions required for regenerative fuel cooling of the engine combustion chamber and nozzle. Decreased heat transfer due to carbon deposits forming on wetted fuel components, corrosion of materials common in engine construction (copper based alloys), and corrosion induced pressure drop increases have all been observed in laboratory tests simulating rocket engine cooling channels. To mitigate these risks, the knowledge of how these fuels behave in high temperature environments must be obtained. Currently, due to the complexity of the physical and chemical process occurring, the only way to accomplish this is empirically. Heated tube testing is a well-established method of experimentally determining the thermal stability and heat transfer characteristics of hydrocarbon fuels. The popularity of this method stems from the low cost incurred in testing when compared to hot fire engine tests, the ability to have greater control over experimental conditions, and the accessibility of the test section, facilitating easy instrumentation. These benefits make heated tube testing the best alternative to hot fire engine testing for thermal stability and heat transfer research. This investigation used the Heated Tube Facility at the NASA Glenn Research Center to perform a thermal stability and heat transfer characterization of RP-1 in an environment simulating that of a high chamber pressure, regenerative cooled rocket engine. The first step in the research was to investigate the carbon deposition process of previous heated tube experiments by performing scanning electron microscopic analysis in conjunction with energy dispersive spectroscopy on the tube sections. This analysis gave insight into the carbon deposition process and the effect that test conditions played in the formation of deleterious coke. Furthermore, several different formations were observed and noted. One other crucial finding of this investigation was that in sulfur containing hydrocarbon fuels, the interaction of the sulfur components with copper based wall materials presented a significant corrosion problem. This problem in many cases was more life limiting than those posed by the carbon deposition process. The results of this microscopic analysis was detailed and presented at the December 2003 JANNAF Air-Breathing Propulsion Meeting as a Materials Compatibility and Thermal Stability Analysis of common Hydrocarbon Fuels (reference 1).

DeWitt, Kenneth↗
DOE OSTI2019

Collective Summary of sCO2 Materials Development Part II: High-Temperature Alloy Corrosion Behavior within Compact Heat Exchangers.

Materials compatibility is a major concern for the design and operation of supercritical carbon dioxide (sCO2) power cycles. Two areas were recently identified for which very little prior knowledge was available. These were the behavior of polymer materials in low-temperature sCO2 environments as well as the high-temperature corrosion behavior for alloys that have been fabricated into compact heat exchangers. A critical need exists to increase understanding in both areas. As such, the Sandia sCO2 Materials Development program initiated a series of experiments for both areas in FY19. The progress that has been made in understanding the behavior of polymers in sCO2 was summarized in the Part I report, while this Part II report describes progress in the area of compact heat exchanger corrosion. For the compact heat exchangers being developed for use in supercritical CO2 power cycles, alloy corrosion is important to understand as it may lead to reduced flow path area, reduced heat transfer, and blocked flow channels. The fabrication of these heat exchangers involve thermal processes such as brazing or diffusion bonding, where the influence of these processes on the corrosion behavior of the alloys is unknown. Candidate alloys for these heat exchangers are typically evaluated for corrosion behavior as witness coupons, without being subjected to these thermal processes. To close this gap in understanding, a series of experiments were completed that utilized small heat exchanger samples subjected to flowing CO2 for 500 hours at 750°C. Small sections of the heat exchanger samples were characterized before and after the 500 hour exposure in order to characterize the oxide growth in the channels as well as the hardness of the alloys. Results are compared to witness coupons of the same alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2025

CO2 Streams Captured From Industrial Processes and Corrosion of Steel Pipelines

Based on the knowledge accumulated in the last decade related to Carbon Capture and Storage (CCS) processes and the identified gaps in knowledge, our study identifies and quantifies the key issues that impact the corrosion of materials, specifically relating to the integrity of structures for the CO2 transport pipelines and provides a better understanding of the materials’ compatibility with CO2 steams with impurities. This will help to understand the corrosion risks associated with CO2 transport and injection and leverage existing infrastructure or rebuild new pipeline networks to transport CO2 with impurities for EOR or geological storage.

CO2 corrosion↗