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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Mechanism of Na2SO4-induced corrosion of molybdenum containing nickel-base superalloys at high temperatures. I - Corrosion in atmospheres containing O2 only. II - Corrosion in O2 + SO2 atmospheres

Kinetics of the Na2SO4-induced corrosion of the molybdenum-containing nickel-base superalloys, B-1900 and Udimet 700, coated with Na2MoO4, has been studied in oxygen atmosphere at temperatures ranging from 750 to 950 C. Because the gas turbine atmosphere always contains some SO2 and SO3, the effect of atmospheric SO2 content on corrosion of Udimet-700 has also been studied. It was found that in the O2 atmosphere the melt in the catastrophic corrosion phase consists of Na2MoO4 plus MoO3, with the onset of the catastrophic corrosion coinciding with the appearance of MoO3. In the presence of low levels of atmospheric SO2 (below 0.24 percent), the melt during catastrophic corrosion contains, in addition to Na2MoO4 and MoO3, some quantities of Na2SO4. At the levels of SO2 above 1 percent, no catastrophic corrosion was observed. At these SO2 levels, internal sulfidation appears to be the primary mode of degradation.

Misra, A. K.↗
NASA NTRS1973

Introduction

Probable climatic extremes of terrestrial environment data specifically applicable for NASA space vehicles and associated equipment development are considered. Design guideline values are established for the following environmental parameters: (1) Thermal (temperature and solar radiation); (2) humidity; (3) precipitation; (4) winds; (5) pressure; (6) density; (7) electricity (atmospheric); (8) corrosion (atmospheric); (9) sand and dust; (10) fungi and bacteria; (11) atmospheric oxidants; (12) composition of the atmosphere; and (13) inflight thermodynamic properties.

Daniels, G. E.↗
DOE OSTI2024

Large Eddy Simulation and Analysis of Truck Generated Droplet Spray Transport at Bridges

Weathering steel is a particular type of steel that develops a higher level of atmospheric corrosion protection than non-weathering grades of steel. While uncoated weathering steels have the appearance of being “rusted”, there are many forms of ferric oxyhydroxides (aka. rust) that can form on steel. The predominant ferric oxyhydroxide that gives uncoated weathering steel its tightly adherent patina is goethite. The atmospheric corrosion protection comes from alloying, primarily with a copper composition greater than 0.20 percent and also small amounts of chrome, nickel, and silicon. Bare atmospheric corrosion resistant steels have been recognized as far back as 1905 with very early editions of the American Society for Testing and Materials (ASTM) A 7 “Standard Specification for Steel for Bridges and Buildings” [1]. Uncoated weathering steel (UWS) is the lowest cost corrosion protection system possible for a steel bridge based on the first cost. Provided the UWS is used in an optimal environment that allows the protective patina to form, UWS also provides the lowest life cycle cost. The protective patina on UWS does not form or degrades in continuously damp conditions, forming a higher proportion of lepidocrocite, or in the presence of a concentration of chlorine ions that is too high, forming a higher proportion of akageneite.

36 MATERIALS SCIENCE↗
NASA NTRS1981

Effects of environmental variables on the crack initiation stages of corrosion fatigue of high strength aluminum alloys

Fatigue initiation in six aluminum alloys used in the aircraft industry was investigated. Cyclic loading superimposed on a constant stress was alternated with atmospheric corrosion. Tests made at different stress levels revealed that a residual stress as low as 39% of the yield strength caused stress corrosion cracking in some of the alloys. An atmospheric corrosion rate meter developed to measure the corrosivity of the atmosphere is described. An easily duplicated hole in the square test specimen with a self-induced residual stress was developed.

Poteat, L. E.↗
NASA NTRS1980

Study program for encapsulation materials interface for low cost silicon solar array

An atmospheric corrosion model was developed and verified by five months of corrosion rate and climatology data acquired at the Mead, Nebraska LSA test site. Atmospheric corrosion rate monitors (ACM) show that moisture condensation probability and ionic conduction at the corroding surface or interface are controlling factors in corrosion rate. Protection of the corroding surface by encapsulant was shown by the ACM recordings to be maintained, independent of climatology, over the five months outdoor exposure period. The macroscopic corrosion processes which occur at Mead are shown to be reproduced in the climatology simulator. Controlled experiments with identical moisture and temperature aging cycles show that UV radiation causes corrosion while UV shielding inhibits LSA corrosion.

Kaelble, D. H.↗
NASA NTRS2013

The Behavior of Environmentally Friendly Corrosion Preventative Compounds in an Aggressive Coastal Marine Environment

The shift 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. The CPCs, while a temporary protective coating, must survive in the aggressive coastal marine environment that exists throughout the Kennedy Space Center, Florida. The different protection behaviors of fifteen different soft film CPCs, both common petroleum-based and newer environmentally friendly types, were evaluated on various steel and aluminum substrates. The 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 initial results for the fifteen CPC systems are reported : Key words: corrosion preventive compound, CPC, spaceport, environmentally friendly, atmospheric exposure, marine, carbon steel, aluminum alloy, galvanic corrosion, wire on bolt.

Montgomery, Eliza L.↗
NASA NTRS1986

Hermetic Edge Seals for Photovoltaic Modules

Corrosive atmospheric agents excluded to prolong cell life. Combination of two sealing techniques makes possible to protect solar cells from water vapor, oxygen, and other corrosive atmospheric constituents. Using three-step process, glass-to-metal hermetic seal formed around edge of solar-cell module. Elastomer seals used previously not as effective because they are permeable to water vapor and atmospheric gases.

Nowlan, M. J.↗
DOE OSTI2024

Accelerating FEM-Based Corrosion Predictions Using Machine Learning

Atmospheric corrosion of metallic parts is a widespread materials degradation phenomena that is challenging to predict given its dependence on many factors (e.g. environmental, physiochemical, and part geometry). For materials with long expected service lives, accurately predicting the degree to which corrosion will degrade part performance is especially difficult due to the stochastic nature of corrosion damage spread across years or decades of service. The Finite Element Method (FEM) is a computational technique capable of providing accurate estimates of corrosion rate by numerically solving complex differential Eqs. characterizing this phenomena. Nevertheless, given the iterative nature of FEM and the computational expense required to solve these complex equations, FEM is ill-equipped for an efficient exploration of the design space to identify factors that accelerate or deter corrosion, despite its accuracy. In this work, a machine learning based surrogate model capable of providing accurate predictions of corrosion with significant computational savings is introduced. Specifically, this work leverages AdaBoosted Decision trees to provide an accurate estimate of corrosion current per width given different values of temperature, water layer thickness, molarity of the solution, and the length of the cathode for a galvanic couple of aluminum and stainless steel.

36 MATERIALS SCIENCE↗
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 NTRS2018

Sixty Earth-Days Test of a Prototype Pt/HTCC Alumina Package in Simulated Venus Environment

This paper presents experimental results of a prototype high temperature co-fired ceramic (HTCC) package with Au/Pt metallization in a three-phase harsh environment test that culminated with 60-day demonstration in simulated Venus surface environment of 465 degC with corrosive atmosphere at 90 bar pressure. The prototype package is based on previously developed and reported HTCC package successfully tested with multiple analog and digital silicon carbide (SiC) high temperatures semiconductor integrated circuits (ICs) at NASA Glenn Research Center in 500 degC Earth air ambient for over ten thousands hours, and short-term tested at temperatures above 800 degC. The three-phase harsh environment test started with 48 hours in 465 degC Earth air, followed by 48 hours in 465 degC nitrogen at 90 bar pressure and 1400 hours in simulated Venus surface environment of 465 degC with corrosive atmosphere at 90 bar. Initial analytical results of the package materials and surfaces after exposure to Venus environment are discussed to assess the stability of the packaging materials in the tested environments. The test in simulated Venus environment was implemented in the NASA Glenn Extreme Environment Rig (GEER). The results of this study suggest that an effective encapsulation of areas of surface metallization and vicinities may help to improve electrical performance of a HTCC alumina packaging system in Venus environment.

Chen, Liangyu↗
NASA NTRS2018

Sixty Earth-Days Test of a Prototype Pt/HTCC Alumina Package in Simulated Venus Environment

This paper presents experimental results of a prototype high temperature co-fired ceramic (HTCC) package with Au/Pt metallization in a three-phase harsh environment test that culminated with 60-day demonstration in simulated Venus surface environment of 465 degrees Centigrade with corrosive atmosphere at 90 bars pressure. The prototype package is based on a previously developed and reported HTCC package successfully tested with multiple analog and digital silicon carbide (SiC) high temperatures semiconductor integrated circuits (ICs) at NASA Glenn Research Center in 500 degrees Centigrade Earth air ambient for over ten thousand hours, and short-term tested at temperatures above 800 degrees Centigrade. The three-phase harsh environment test started with 48 hours in 465 degrees Centigrade Earth air, followed by 48 hours in 465 degrees Centigrade nitrogen at 90-bar pressure and 1400 hours in simulated Venus surface environment of 465 degrees Centigrade with corrosive atmosphere at 90 bars. Initial analytical results of the package materials and surfaces after exposure to the Venus environment are discussed to assess the stability of the packaging materials in the tested environments. The test in a simulated Venus environment was implemented in the NASA Glenn Extreme Environment Rig (GEER). The results of this study suggest that an effective encapsulation of areas of surface metallization and vicinities may help to improve electrical performance of a HTCC alumina packaging system in Venus environment.

Chen, Liang-Yu↗
DOE OSTI2023

Model for Humidity-Mediated Diffusion on Aluminum Surfaces and Its Role in Accelerating Atmospheric Aluminum Corrosion

Bare aluminum metal surfaces are highly reactive, which leads to the spontaneous formation of a protective oxide surface layer. Because many subsequent corrosive processes are mediated by water, the structure and dynamics of water at the oxide interface are anticipated to influence corrosion kinetics. Here, using molecular dynamics simulations with a reactive force field, we model the behavior of aqueous aluminum metal ions in water adsorbed onto aluminum oxide surfaces across a range of ion concentrations and water film thicknesses corresponding to increasing relative humidity. We find that the structure and diffusivity of both the water and the metal ions depend strongly on the humidity of the environment and the relative height within the adsorbed water film. Aqueous aluminum ion diffusion rates in water films corresponding to a typical indoor relative humidity of 30% are found to be more than 2 orders of magnitude slower than self-diffusion of water in the bulk limit. Connections between metal ion diffusivity and corrosion reaction kinetics are assessed parametrically with a reductionist model based on a 1D continuum reaction–diffusion equation. Our results highlight the importance of incorporating the properties specific to interfacial water in predictive models of aluminum corrosion.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Controlled thermal pre-treatment of ZMG232G10® for corrosion mitigation under simulated SOFC interconnect exposure conditions

The IT-SOFC candidate interconnect material ZMG232G10® was thermally pre-treated in air and in H 2 – 3% H 2 O to mitigate dual atmosphere corrosion. Bare and pre-treated steel samples were exposed to a dual atmosphere exposure condition (dry air/metal/4% H 2 – N 2 (bal.) + 3% H 2 O) for 500h at 600°C. Corrosion products and oxide morphology developed on the air-exposed surfaces were analyzed. Pre-treatments of the metal in oxidizing (air) and reducing (H 2 – 3% H 2 O) gas atmospheres provide improved passivation against dual atmosphere corrosion compared to bare steel. Further, the uniform and iron-free oxide scale developed during the pre-treatment of alloy in the low pO 2 H 2 – 3% H 2 O gas atmosphere provides an effective diffusion barrier against the outward transport of cations and oxidation of iron observed under dual atmosphere conditions.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Long-Term Corrosivity at NASA Kennedy Space Center as a Function of Distance and Time from the Atlantic Ocean

Long-term data to record both seasonal and notional bounding values for corrosivity at multiple sites at NASA Kennedy Space Center was needed to make better materials choices for NASA-based ground and spaceflight programs. The data was valuable for two key reasons, 1) to measure corrosion rate and chloride concentration as a function of time and distance from the Atlantic Ocean, and 2) compare the corrosivity at launchpad and site-specific areas to the more accelerated conditions at the KSC Beachside Atmospheric Corrosion Test Site for coating and materials performance prediction. Sites were chosen from 45 meter (150 feet) to 8 kilometers (5 miles) from the Atlantic Ocean and corrosion variables at each site were measured throughout each year from June 2017 to April 2023, except the Beachside site, which includes data from November 2010. The summary includes corrosivity data and coating performance comparisons at select sites, which will be used as the updated NASA corrosivity standard for corrosion control requirements.

NASA↗
NASA NTRS1969

Renewal of corrosion protection of coated aluminum after welding

Effectiveness of conversion coatings designed to protect aluminum alloys against atmospheric corrosion is reduced after exposure to high temperature or welding. Damaged coating should be manually stripped six inches from the weld and then recoated by sponge or spray with the original solution.

Higgins, R. H.↗
NASA NTRSDate not supplied

Evaluation Of Corrosion-Resistant Alloys for Use in Acidic and Marine Launch Environments at NASA Kennedy Space Center: 20-Year Study

After the completion of an initial three-year study to qualify corrosion-resistant stainless steel tubing for use in NASA Kennedy Space Center’s acidic and marine launch environment, test specimens remained exposed at the KSC Beachside Atmospheric Corrosion Test Site for long-term exposure. NASA KSC’s lifetime requirement for most ground support equipment is twenty years. After twenty-one years of marine exposure, NASA KSC took the unique opportunity to reevaluate the tubing after long-term exposure to better understand the corrosion resistance of these alloys as they reached their expected lifetime requirement. Metallurgical and corrosion analysis was performed on the CRES tubing components and the alloys were rated on performance. A summary of CRES alloy tubing corrosion-related performance after 20 years of exposure in a marine launch environment is presented in this work.

NASA KSC↗
DOE OSTI2021

Long-Term Effects of Humidity on Stainless Steel Pitting in Sea Salt Exposures

Ground 304 stainless steel (SS) samples were exposed to sea salt particles at 35 °C and two relative humidity (RH) levels for durations ranging from 1 week to 2 years. For all exposure times, pit number density and total pit volume at 40% RH were observed to be considerably greater than those at 76% RH. Statistical analysis of distributions of pit populations for both RH conditions showed that pit number density and total pit volume increased rapidly at first but slowed as exposure time increased. Cross-hatched features were observed in the 40% RH pits while ellipsoidal, faceted pits were observed at 76% RH. Optical profilometry indicated that most pits were not hemispherical. X-ray tomography provided evidence of undercutting and fissures. Piecewise curve fitting modeled the 40% RH data closely, predicting that corrosion damage would eventually plateau. However, a similar treatment of the 76% RH data suggested that corrosion damage would continuously increase, which implied that the piecewise power-law fit was limited in its ability to model atmospheric corrosion generally. Based on these observations, the operative mechanisms determining long-term corrosion behavior were hypothesized to be different depending on the RH of exposure.

36 MATERIALS SCIENCE↗