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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Environmentally Friendly Corrosion Preventative Compounds for Ground Support Structures

The need to use environmentally friendly technologies throughout future space-related launch programs prompted a study aimed at replacing current petroleum and solvent-based Corrosion Preventive Compounds (CPCs) with environmentally friendly alternatives. The work in this paper focused on the identification and evaluation of environmentally friendly CPCs for use in protecting flight hardware and ground support equipment from atmospheric corrosion. CPCs are used as temporary protective coatings and must survive in the aggressive coastal marine environment that exists throughout the Kennedy Space Center, Florida. The different protection behaviors of fifteen different oily film CPCs, both common petroleum-based and newer environmentally friendly types, were evaluated on various steel and aluminum substrates. CPC and substrate systems were subjected to atmospheric testing at the Kennedy Space Center's Beachside Atmospheric Corrosion Test Site, as well as cyclic accelerated corrosion testing. Each CPC also underwent physical characterization and launch-related compatibility testing. The results for the fifteen CPC systems are presented in this paper.

Montgomery Eliza L.↗
NASA NTRS2014

Smart Coatings for Launch Site Corrosion Protection

Smart, environmentally friendly paint system for early corrosion detection, mitigation, and healing that will enable supportability in KSC launch facilities and ground systems through their operational life cycles. KSC's Corrosion Technology Laboratory is developing a smart, self-healing coating that can detect and repair corrosion at an early stage. This coating is being developed using microcapsules specifically designed to deliver the contents of their core when corrosion starts.

TechPort Portfolio System↗
NASA NTRS2018

Stress Corrosion Cracking of Metals in Propellants

Stress corrosion cracking (SCC) of a fracture critical metallic material can cause a premature failure if the material is susceptible in the unique service environment. Material fluid compatibility is an area of interest for the current NASA programs leading the human exploration path to Mars. White Sands Test Facility, the agency's lead on hypergolic propellant testing, identifies a lack in stress corrosion cracking susceptibility data for metallic materials in hypergolic propellants. The development of a stress corrosion cracking screening method is necessary to bridge the knowledge gap and enable the community to more confidently select materials for the use in systems containing corrosive fluids.

Alcantara, Ilse↗
NASA NTRS2019

Pre-Demonstration Development of Controlled-Release Corrosion Inhibitors and Healing Agents as Alternatives to Hexavalent Chromium

This Limited Scope Study was directed to achieve the following objectives: (1) Scale-up of materials that can meet MIL-PRF-23377 (solvent-based primer). (2) Provide evidence of resistance to aircraft alkaline cleaners and de-icing fluids. (3) Provide formulation for initial ecological and toxicity screening. (4) Submit an interim report that will provide the basis for a future ESTCP (the Dept. of Defense's (DoD's) Environmental Security Technology Certification Program) demonstration effort.The encapsulation procedure for two corrosion inhibitors was scaled up from lab scale to 2.0 kilograms. This scale will accommodate high volume production of coatings with encapsulated corrosion inhibitors for large surface areas during a follow-on ESTCP demonstration effort. Test results provided evidence of resistance to alkaline cleaners and aircraft de-icing fluids and compliance with MIL-PRF-23377. All the MIL-PRF-23377 requirements were met with the exception of the adhesion requirement, in top coated panels, and the flexibility requirement. Work on solving these two problems will be done prior to validation and demonstration of the technology. An initial ecological and toxicity screening identified several factors that were not critical to the acceptance of the encapsulated corrosion inhibitor. This new technology will lead to environmentally friendly alternatives to hexavalent chromium that will enable DoD to protect its assets. Field demonstration, licensing, qualification, and commercialization will allow its real world utilization. Abstract for Appendix A. Toxicology Report: Corrosion controls a significant problem for military equipment. Many surface treatment materials currently in use on items of military or aerospace materiel contain chromium (VI) as a component, a source of significant human health and environmental hazard. The formulation under evaluation contains no chromium. Most of the proposed components are low to moderate toxicity and are not a significant concern. Two of the formulation components are associated with some cancer hazard - 2-mercaptobenzothiazole and formaldehyde, but both find widespread use in industry and additional investigation is not required for this project.

Calle, Luz Marina↗
DOE OSTI2013

Atomistic Studies of Cation Transport in Tetragonal ZrO2 During Zirconium Corrosion

Zirconium alloys are the major fuel cladding materials in current reactors. The water-side corrosion is one of the major degradation mechanisms of these alloys. During corrosion the transport of oxidizing species in zirconium dioxide (ZrO2) determines the corrosion kinetics. Previously it has been argued that the outward diffusion of cation ions is important for forming protective oxides. In this work, the migration of Zr defects in tetragonal ZrO2 is studied with temperature accelerated dynamics and molecular dynamics simulations. The results show that Zr interstitials have anisotropic diffusion and migrate preferentially along the [001] or c direction in tetragonal ZrO2. The compressive stresses can increase the Zr interstitial migration barrier significantly. The migration barriers of some defect clusters can be much lower than those of point defects. The migration of Zr interstitials at some special grain boundaries is much slower than in a bulk oxide. The implications of these atomistic simulation results in the Zr corrosion are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Methods and apparatus for managing corrosion in buildings

Principles of the invention provide methods and apparatus for providing corrosion management in buildings. In one aspect, an exemplary method includes the step of receiving first data relating corrosion rate to a plurality of environmental conditions. This first data is subsequently utilized to determine a quantitative relationship between corrosion rate and the plurality of environmental conditions. In another step, second data indicative of one or more environmental conditions within a building is received. A corrosion rate in the building is then determined at least in part by applying the determined quantitative relationship to this second data.

42 ENGINEERING↗
DOE OSTI2018

Nanocomposite conformal corrosion barrier coating

Metals across all industries demand anti-corrosion surface treatments and drive a continual need for high-performing and low-cost coatings. Ordered thin films comprising aligned inorganic platelets dispersed in a polyelectrolyte polymer matrix provide a new class of transparent conformal barrier coatings for protection in corrosive atmospheres. For example, films assembled via layer-by-layer deposition, as thin as 90 nm, are shown to reduce copper corrosion rates by >1000× in an aggressive H 2 S atmosphere. These coatings can provide high-performing anti-corrosion treatment alternatives to costlier, more toxic, and less scalable thin films, such as graphene, hexavalent chromium, or atomic layer deposited metal oxides.

Schindelholz, Eric John↗
DOE OSTI2021

Novel Membrane-Based Corrosion Sensors For Operating In Natural Gas Pipelines

Membrane-based electrochemical sensors (MBES) provide an attractive option for real-time continuous humidity and corrosion rate measurements inside of natural gas pipelines. The MBES, can use electrochemical techniques such as linear polarization resistance and electrochemical impedance spectroscopy even when a conductive aqueous phase is intermittent or unavailable. We now present field-test performance data of our MBES operated inside a multiphase water and natural gas flow facility. The MBES measured internal corrosion and conductivity at the top, bottom, and side of the pipe spool. Tests were carried out with flow rates of 4.6, 9.1, and 18.3 m/s, temperatures of 21, 29, and 35 °C, and a pressure of 1000 psia. All sensors followed similar trends in open circuit potential, corrosion rate, and conductivity over time. Neither flow rate, temperature, nor build-up of metal-based solids on the sensor surfaces impacted the quality of the electrochemical measurements. The field-test results confirm that the membrane-based electrochemical sensors are suitable for monitoring internal corrosion of operational natural-gas pipelines.

Duffy, Timothy↗
DOE OSTI2021

Evaluation of Corrosion Susceptibility of Structural Steels in Biomass Derived Pyrolysis Oil

Biomass derived pyrolysis oil is a promising renewable energy source. Due to the variety of biomass feedstocks, the bio-oils could contain a wide range of organic constituents which would provide unique corrosive environments for structural materials. A preliminary work exposed different classes of steels and stainless steels to selected organic constituents of biomass pyrolysis oils and found that corrosion susceptibility, assessed using electrochemical impedance spectroscopy (EIS), was prominent in the steels with Cr lower than 11 wt.%. Although this result suggests stainless steels will resist corrosion by certain organic constituents, it may not be sufficient to predict the corrosion performance in real bio-oils. Therefore, this study attempted electrochemical measurements on Cr-alloyed steels and stainless steels directly exposed to a biomass derived pyrolysis oil. To overcome the low conductivity of bio-oils, a customized Luggin capillary was designed to minimize the ohmic path in bio-oils. The results of this work will be reported.

Jun, Jiheon↗
DOE OSTI2022

Electrochemical Corrosion of SIMFUEL: Effects of dissolved H2 and noble metal particles

This report describes the results from electrochemical corrosion tests that were conducted using simulated spent fuel (SIMFUEL) materials comprised of UO2 and surrogate fission products. Two SIMFUEL compositions were tested to quantify the effect of noble metal inclusions and dissolved H2 on the UO2 dissolution rate. One material consisted of UO2 with added lanthanide oxides (UO2 N) and the other consisted of UO2 with added lanthanide oxides and noble metals (UO2-H) at concentrations to simulate high burnup fuel. The electrochemical corrosion tests on the SIMFUEL materials were conducted in aqueous electrolyte solutions (pH 10) that were either saturated with air or purged with a H2/Ar gas mixture to maintain a constant dissolved H2 concentration. The results from electrochemical corrosion tests on SIMFUEL can be applied to qualitatively understand and also quantify the separate effects of water chemistry and fuel composition on the degradation behavior of the UO2 matrix. Open circuit potential (OCP) measurements on a SIMFUEL material of known composition (i.e., known fraction of NMPs at the fuel surface) immersed in a known solution chemistry (i.e., pH, Eh, [O2], [H2]) at known temperature provide qualitative insight into the degradation behavior of the UO2 matrix. If the OCP is above the threshold potential at which the oxidative dissolution of U(IV) to U(VI) occurs, the SNF is expected to degrade by oxidative processes under the experimental conditions. The net currents that are measured during potentiostatic tests, during which the surface potential of the SIMFUEL material is fixed by a potentiostat, can be used to quantify the UO2 degradation rate and optimize the rate constant values used in the Fuel Matrix Degradation Model (FMDM) for half reactions that occur on the SNF surface. Specifically, electrochemical measurements enable the estimation of the total anodic current at ECORR–which is the surface potential at which the total anodic and total cathodic currents are equal–so that the rate constant values for key reactions can be calculated. The open circuit potential measurements, potentiostatic tests, surface property measurements (scanning electron microscopy images and electrochemical impedence spectroscopy plots), and solution elemental composition analyses are being performed to update and optimize the FMDM. A case study is presented herein to show how electrochemical corrosion test results and accompanying characterization results for the UO2 N material in air-saturated solution can be used to validate the SNF surface reaction module of the FMDM. Future electrochemical tests will be conducted to provide quantitative information on the effects of NM content (burnup), H2 concentration, water chemistry, temperature, and galvanic couples with cladding and EBS alloys on UO2 degradation that can be used to improve the accuracy and functionality of the FMDM.

Thomas, Sara↗
DOE OSTI2022

Electrochemical corrosion under controlled redox conditions

A method for predicting corrosion rates of a material during service conditions is provided, the method having the steps of determining a first phase composition of the material; exposing the material to service conditions chemical environment; applying an electrical potential to the exposed material to represent the solution redox; identifying ranges of the applied potential that correspond to different corrosion behaviors of the material; quantifying current and surface electrical properties during corrosion; and determining a second phase composition of the material to identify corroded phases. Also provided is a method for determining radionuclide source terms, the method having the steps of supplying a multiphase metallic waste containing the radionuclides; immersing the waste in a solution representing repository chemistry conditions; and oxidizing the immersed waste for a period of time and at particular imposed voltages representing solution redox values to establish a steady current representing corrosion rate of the waste.

Gattu, Vineeth Kumar↗
DOE OSTI2013

GRAIN BOUNDARY CHARACTERIZATION OF ALLOY 600 PRIOR TO AND AFTER CORROSION BY ATOM PROBE TOMOGRAPHY AND TRANSMISSION ELECTRON MICROSCOPY

Grain boundary composition can play a critical role in the susceptibility of a material to intergranular (IG) corrosion and stress corrosion cracking (SCC). Detailed analytical observations of grain boundaries have been obtained in nickel-base alloy 600 prior to and after corrosion in simulated PWR primary water environments with atom probe tomography (APT) and analytical transmission electron microscopy (ATEM). Several examples are shown to identify key grain boundary segregants and the effect of proximity to IG Cr carbides on interfacial compositions prior to exposure in high-temperature PWR primary water. Examples are also given to describe the effect of corrosion on grain boundaries. Alloy 600 exhibits significant IG attack consisting primarily of nanocrystalline MO-phase oxides and limited Cr2O3 precipitates. The grain boundary ahead of the IG oxidation front exhibits depletion of Cr and other oxidizing species. No evidence for solid-state grain boundary ingress of oxygen has been discovered.

Schreiber, Daniel K.↗
DOE OSTI2013

ALLOY 690 SURFACE NANOSTRUCTURES DURING EXPOSURE TO PWR PRIMARY WATER AND POTENTIAL INFLUENCE ON STRESS CORROSION CRACKING INITIATION

Alloy 690 (30 wt% Cr) is currently being used to replace lower Cr alloy 600 (16 wt% Cr) in critical pressurized water reactor (PWR) components due to its superior protection against stress corrosion cracking (SCC). The increased Cr content is believed to assist in forming a protective chromia film on the surface that inhibits corrosion and intergranular attack (IGA) in particular. A key objective for this work is to understand how surface microstructural features act as precursor sites for SCC nucleation. Unstressed alloy 690 specimens have been exposed to simulated PWR water conditions at 360°C including cold-worked materials shown to susceptible to SCC in crack-growth tests. Detailed surface and near-surface characterizations were performed on cross-section samples starting with low kV backscatter scanning electron microscopy (SEM) imaging to document the extent of general and localized corrosion. Selected surface and local corrosion regions were then prepared by focused ion beam milling for transmission electron microscopy (TEM) and atom probe tomography (APT) analyses. TEM is used to determine the oxidation microstructures as well as compositional gradients associated with the degradation, while APT is conducted to investigate the atomistic redistribution of alloying and impurity elements in the oxides and surrounding metal.

Olszta, Matthew J.↗
DOE OSTI2017

Effects of Heat Treatment on Corrosion and Wear Behaviors of Mg-6Gd-2Zn-0.4Zr Alloy in Simulated Body Fluid

Mg-6Gd-2Zn-0.4Zr (wt.%, GZ62K) alloy was processed by solution treatment under different temperatures. The microstructure, hardness, corrosion and wear behaviors in simulated body fluid (SBF) have been studied. The results indicate that the (Mg, Zn){sub 3}Gd phase decreases, the precipitated phases gradually increase, and the long-period stacking ordered structure disappears with the increase of solution temperature. The alloy has better corrosion resistance after solution treatment, and that solution treated at 490 °C for 12 h shows the best corrosion resistance. The friction coefficient of the alloy under dry sliding condition decreases slightly, but the mass loss increases with increasing the solution temperature. The alloy solution treated at 460 °C for 12 h exhibits the lowest friction coefficient and mass loss in SBF, and it also has the best wear resistance under dry sliding condition.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Effect of Mo-rich Fillers in Pulsed Current Gas Tungsten Arc Welding of Inconel 718 for Improved Strength and Hot Corrosion Resistance

The formation of Laves phase in the fusion zone of Inconel 718 welds is considered to be detrimental and requires major attention, as this phase deteriorates the mechanical properties and high-temperature corrosion resistance. This present study addresses the use of current pulsing technique on the gas tungsten arc welding of 5-mm-thick Inconel 718 plates. Nb-free fillers, namely ERNiCrMo-10 and ERNiCrMo-14, are chosen for joining these plates. Microstructure studies revealed the segregation of Mo-rich phases at the inter-dendritic regions of the fusion zone of both the weldments. Further, the occurrence of detrimental Laves phase was minimized while employing Mo-rich fillers. It is inferred from the tensile studies that the fractures occurred in the parent metal for ERNiCrMo-10 filler and at the fusion zone while employing ERNiCrMo-14. Room-temperature Charpy impact studies also affirm that the impact toughness of ERNiCrMo-10 welds is significantly greater than that of ERNiCrMo-14. Hot corrosion studies were performed on the coupons by exposing them to a synthetic molten salt environment comprising Na{sub 2}SO{sub 4} + 60%V{sub 2}O{sub 5} at 800 °C for 50 h. Owing to the presence of higher amounts of Cr{sub 2}O{sub 3} and NiO, both fusion zones exhibited better hot corrosion resistance than the parent metal. The novel outcome of the study reiterates that with the use of current pulsing and Mo-rich fillers, the detrimental phase shall be controlled.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microstructure, Tensile Properties, and Corrosion Behavior of Die-Cast Mg-7Al-1Ca-xSn Alloys

The microstructure, tensile properties, and corrosion behavior of die-cast Mg-7Al-1Ca-xSn (x = 0, 0.5, 1.0, and 2.0 wt.%) alloys were studied using OM, SEM/EDS, tensile test, weight loss test, and electrochemical test. The experimental results showed that Sn addition effectively refined grains and intermetallic phases and increased the amount of intermetallic phases. Meanwhile, Sn addition to the alloys suppressed the formation of the (Mg,Al){sub 2}Ca phase and resulted in the formation of the ternary CaMgSn phase and the binary Mg{sub 2}Sn phase. The Mg-7Al-1Ca-0.5Sn alloy exhibited best tensile properties at room temperature, while Mg-7Al-1Ca-1.0Sn alloy exhibited best tensile properties at elevated temperature. The corrosion resistance of studied alloys was improved by the Sn addition, and the Mg-7Al-1Ca-0.5Sn alloy presented the best corrosion resistance.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microstructure, Chemical Composition and Local Corrosion Behavior of a Friction Stud Welding Joint

In this paper, friction stud welding technology was used to join a stud and base metal, which were composed of X65 steel. The scanning vibrating electrode technique (SVET) and localized electrochemical impedance spectroscopy (LEIS) were used to investigate the localized corrosion behaviors of the welded joint. Scanning electron microscopy, metallographic microscopy and a micro-hardness tester were used to observe the microstructure and measure the hardness of the welded sample. Raman spectrometry and energy-dispersive spectrometry were used to measure the composition of the weldment before and after corrosion, respectively. The results show that there are the maximum micro-hardness and the densest microstructure in the welded zone compared with the other zones. In addition, α-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} are present in the welded zone. The SVET and LEIS data indicate that the welded zone has the lowest current density and the largest impedance due to the presence of iron oxides and the densest microstructure, thus showing the excellent corrosion resistance. The relationship among microstructure, micro-hardness, chemical composition and local electrochemical behavior was discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microstructure, Corrosion and Magnetic Behavior of an Aged Dual-Phase Stainless Steel

In the present work, the effect of the precipitation phenomena on corrosion and magnetic behavior of an aged dual-phase stainless steel was investigated. Aging treatment caused the precipitation of the σ phase, chromium carbides and secondary austenite, which was accompanied by the shifting of the δ/γ interfaces inside the δ ferrite grains. Aging between 700 and 850 °C strongly deteriorated the pitting corrosion resistance of the studied material. Magnetic investigation of the aged material using the vibration sample magnetic technique revealed the sensitivity of the intrinsic magnetic properties to the smallest microstructural change. This was confirmed by the Eddy current technique that led also to the evaluation of the aging-induced localized corrosion.

36 MATERIALS SCIENCE↗