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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Effect of Microadding Amine Surfactant on Erosion-Corrosion Wear of Structural Steel in NPP

Corrosion processes, specifically, erosion-corrosion, are one of the causes of damage occurring in NPP equipment during operation. Measures are taken to prevent erosion-corrosion wear of thermal-power equipment and pipelines. One such measure is the development and adoption of water chemistry regimes that are capable of forming a protective fi lm on a metal surface. Octadecylamine is one such reagent. The results of laboratory tests and industrial experiments studying the effect of octadecylamine on the development of erosion-corrosion wear of NPP equipment are presented. The octadecylamine-hydrazine water chemistry regime at octadecylamine concentration 0.5 mg/dm{sup 3} reduces the rate of erosion-corrosion wear by about 15-fold. The positive effect of micro-additions of octadecylamine is confirmed by direct erosion-corrosion studies performed at the Kola NPP.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2011

Probabilistic modeling of the corrosion of steel structures in marine water-development works

Considering that corrosion takes place as a random process over time, a a probabilistic approach was utilized in this paper. The corrosion of metallic sheet piling employed in the fascia wall of a bulwerk is considered as an example. A stochastic model is constructed on the base of a modified Weibull distribution function with consideration of parameters of the corrosion process as a function of time. One of the factors defining the corrosion rate of the sheet piling is the degree of access of a section of the wall to the zone of variable water level, or the underwater zone. The type of corrosion-continuous or local-is another factor. The accuracy of corrosion prediction in the underwater zone is higher than that in the zone of variable water level.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Atmospheric Corrosion Behavior and Mechanism of a Ni-Advanced Weathering Steel in Simulated Tropical Marine Environment

Corrosion behavior of Ni-advanced weathering steel, as well as carbon steel and conventional weathering steel, in a simulated tropical marine atmosphere was studied by field exposure and indoor simulation tests. Meanwhile, morphology and composition of corrosion products formed on the exposed steels were surveyed through scanning electron microscopy, energy-dispersive x-ray spectroscopy and x-ray diffraction. Results indicated that the additive Ni in weathering steel played an important role during the corrosion process, which took part in the formation of corrosion products, enriched in the inner rust layer and promoted the transformation from loose γ-FeOOH to dense α-FeOOH. As a result, the main aggressive ion, i.e., Cl{sup −}, was effectively separated in the outer rust layer which leads to the lowest corrosion rate among these tested steels. Thus, the resistance of Ni-advanced weathering steel to atmospheric corrosion was significantly improved in a simulated tropical marine environment.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Surface Treatment on Bio-corrosion in Aluminum Alloy 2024-T3

Bio-corrosion is one of the major problems faced in any engineering/aerospace industry. The present study focuses on understanding the effect of surface treatment on AA2024-T3 on bio-corrosion in aircraft fuel tanks. The microbial attack on aluminum alloy (2024-T3) in aircraft fuel tanks by Pseudomonas aeruginosa was studied. Substrates with (1) chromate-free surface treatment (anodization; 2) Ormosil coatings doped with inhibitors/derivatives known for antimicrobial properties were evaluated for their bio-corrosion protection efficiency as compared to bare coupons. The coupons were immersed in aviation fuel spiked with the test culture. The changes in chemical parameters of test solution like pH were monitored periodically. A probable relationship between number of organisms, changes in pH and the extracellular protein (hypothesized to be produced by organisms) were evaluated. Our studies indicated that pH did not appear to play a crucial role in biofilm formation. Surface morphology of bare and anodized AA2024-T3 coupons before and after electrochemical impedance studies (EIS) was analyzed using FE-SEM. Anodized samples with least i{sub corr} value of (0.075 × 10{sup −6} A cm{sup −2}) and corrosion rate of (0.12 × 10{sup −2} mm/y) after 60 days showed distinct corrosion protection than bare and the coated samples. Additional evidence in support of corrosion protection efficiency of anodized was obtained by the biofilm barrier efficiency of 98.94%.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Welding Heat Input Influence on UNS S82441 Lean Duplex Stainless Steel Corrosion Resistance Assessed by Scanning Vibrating Electrode Technique (SVET)

The precipitation of the intermetallic phases can impair mechanical and corrosion properties. In the case of lean duplex stainless steels, they present solidification mode as primary ferrite, with austenite precipitation in the solid state, during cooling. This means the heat-affected zone balanced microstructure can be changed during the welding by the cooling rate, which is associated to the welding heat input, the thickness of the plate and the physical properties of the material. This work intends to present the influence of welding heat input on the corrosion resistance of UNS S82441 lean duplex stainless steel. The gas metal arc welding process was used to make the weld beads, using ER2209 as filler metal, which characterizes a dissimilar welded joint. The corrosion resistance of these specimens was analyzed through scanning vibrating electrode technique. It was observed that welding heat input variation distinctly influences corrosion in different zones of the weld beads over the specimen exposure time. The weld bead under intermediate welding heat input showed the highest corrosion rate and the one under the highest welding heat input, the lowest corrosion rate intensity.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effects of Solution Treatment on Microstructure Transformation, Tensile and Exfoliation Corrosion Properties of 7136 Aluminum Alloy

The effects of solution treatment on microstructure transformation and tensile properties of 7136 aluminum alloys were investigated by means of scanning electron microscopy, electron backscatter diffraction, differential scanning calorimeter, x-ray diffraction and tensile test, electrochemical evaluations, exfoliation corrosion tests, respectively. The results indicate that solution treatment had a significant effect on the microstructure transformation and tensile properties. Soluble constituents of 7136 aluminum alloys were more likely to form the η(MgZn{sub 2}) phase rather than the S(Al{sub 2}CuMg) phase. With increasing the solution temperature, the η phase was re-dissolved into the α(Al) matrix gradually. After solution treatment of 475 °C/1 h, the η phase was completely dissolved into the matrix, with insoluble Fe-rich phases remained. The dissolution of η phase would increase the strength and the corrosion resistance of the alloys. When continuing to increase the solution temperature, the recrystallized fraction increased obviously, resulting in the decrease in the strength and the corrosion resistance. Consequently, the strength and the corrosion resistance of the alloys increased firstly and then decreased with the increase in solution temperature. After solution treatment of 475 °C/1 h, the tensile strength and yield strength of the aged alloy reached their peaks, 738 and 715 MPa, respectively. The elongation of the alloy solution treated at 475 °C/1 h reached 11.2%, and its exfoliation corrosion rating got EB level. Furthermore, after the double-stage solution treatment of 450 °C/1 h + 475 °C/1 h, the recrystallized fraction decreased, resulting in a slight increase to 12.6% of the elongation, a slight increase in the corrosion resistance and a slight decrease in the strength.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effects of the Addition of Micro-amounts of Calcium on the Corrosion Resistance of Mg-0.1Mn-1.0Zn-xCa Biomaterials

Magnesium alloys have good biocompatibility and degradability, which are considered ideal characteristics of biomedical implants. However, there are few studies on the influence of the addition of micro-amounts of Ca on magnesium alloys. In this work, the effects of adding micro-amounts of Ca on the microstructure, mechanical properties, and corrosion properties of Mg-0.1Mn-1.0Zn-xCa (x = 0.1, 0.2, and 0.3 wt.%) alloys were investigated. The results reveal that the grain size of the alloy decreased and the yield strength and elongation both increased with increasing Ca concentrations. Corrosion tests in Kokubo simulated body fluid showed that the in vitro immersion rate first slowed down and then increased (6.395 → 6.283 → 6.395 mm/year) with increasing Ca concentrations. This phenomenon was due to the addition of Ca causing grain refinement, which slowed the corrosion rate and generated an Mg{sub 2}Ca phase to accelerate corrosion. The second-phase Mg{sub 2}Ca precipitated at the grain boundary and acted as a cathode, and the metal magnesium phase acted as an anode to form a primary battery, which caused corrosion of the magnesium phase and accelerated the corrosion rate.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effects of Zr Ion Implantation on Surface Mechanical Properties and Corrosion Resistance of Pure Magnesium

Zirconium (Zr) was implanted into pure Mg by metal vapor vacuum arc (MEVVA) at the dose of 2 × 10{sup 16} ions/cm{sup 2} at room temperature. The surface characteristics of Zr-implanted Mg were analyzed by the Stopping and Range of Ions in Matter software (SRIM) and x-ray photoelectron spectroscopy (XPS), the surface nanohardness and tribological behavior were measured through nanoindentation and a friction-abrasion testing machine, and the corrosion resistance of Zr-implanted Mg was evaluated by electrochemical measurement and immersion test in simulated body fluid (SBF). The results demonstrated that a gradient modified layer composed of MgO, Mg(OH){sub 2}, ZrO{sub 2} and Zr was formed on the near surface of pure Mg and the nanohardness of pure Mg was improved by 48%. Furthermore, the Zr-implanted Mg exhibited a more positive corrosion potential of − 1.43 V (versus SCE) and a lower corrosion current density of 19.9 μA/cm{sup 2}, and localized corrosion was effectively retarded during 24 h immersion in SBF, suggesting that the corrosion resistance of pure Mg was remarkably improved after Zr ion implantation. The mechanisms of surface strengthening and improved corrosion resistance were also discussed in this paper.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Corrosion Behavior of Annealed Steels with Different Carbon Contents (0.002, 0.17, 0.43 and 0.7% C) in Freely Aerated 3.5% NaCl Solution

Four annealed carbon steels with different carbon contents (0.002, 0.17, 0.43, and 0.7% C), consisting of ferrite, ferrite-pearlite and fully pearlite microstructures, were selected to understand the corrosion behavior of carbon steel as a function of carbon content in freely aerated 3.5% NaCl solution. Dynamic polarization, electrochemical impedance and linear polarization methods were used. The corrosion rate obtained from the different carbon steels was found to increase greatly from ultra-low carbon steel (0.002%) to low carbon steel (0.17%) due to the presence of pearlite in the low carbon steel. However, the increase in corrosion rate was marginal with the increase in carbon content from low carbon (0.17%) to medium (0.43% C) and high carbon steels (0.7% C). The mirostrucural evolution of the steels before and after polarization test without etching as observed by scanning electron microscopy could show that the corrosion behavior of the steels with the presence of pearlite was due to the combined effect from % pearlite, interlamellar spacing and cementite/ferrite area ratio in pearlite. Pearlite morphology also led to the differential corrosion within the pearlite colony in all the steels except the steel with 0.002% C. Catalytic activity of cementite on enhancing oxygen reduction reaction attributes to the higher corrosion rates in case of the steels with the presence of pearlite.

36 MATERIALS SCIENCE↗
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 OSTI2019

Corrosion of Mild Steel Buried Underground for 3 Years in Different Soils of Varying Textures

The effect of moisture content and soil texture on the corrosion behavior of mild steel coupons buried for 3 years in different soils was estimated from weight loss measurements and electrochemical techniques such as Tafel plots and electrochemical impedance spectroscopy. The results showed that the rate of corrosion and intensity of corrosion attack significantly depend on the soil’s moisture content and on the soil type. Corrosion was found to be severe in clayey soil compared to that in mixed and sandy soils. Morphological analysis of the corroded specimens performed using optical microscopy and scanning electron microscopy showed the presence of amorphous oxides and low-intense crystalline phases of goethite and hematite on the surface of the mild steel coupons, indicating only the initial stage of corrosion. It is concluded from this study that mild steel undergoes only less intense surface-level corrosion in 3 years when buried underground.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Corrosion Response of Ni-19Cr-5Fe in Molten NaCl-MgCl 2 Salt

Ni-based alloys are strong candidates for use in high-temperature molten salt reactors due to their superior corrosion resistance and mechanical stability compared to stainless steels. In this study, the static corrosion behavior of a Ni-19Cr-5Fe model alloy was systematically evaluated in a purified molten NaCl-MgCl 2 salt at 700°C for 30, 240, and 500 h. Post-exposure analyses were conducted to assess microstructural evolution, corrosion depth, and elemental depletion profiles. Corrosion rates, quantified by chromium depletion depth, followed an inverse power-law trend with increasing exposure time, indicating diffusion-limited kinetics. This trend is attributed to limitations in mass transport in the static salt and to the progressive local depletion of reactive chromium species. Coupled electron backscatter diffraction and energy dispersive X-ray spectroscopy analysis further revealed that the grain boundary character significantly influences corrosion susceptibility: high-angle grain boundaries exhibited pronounced Cr depletion and pitting, while low-angle and Σ3 boundaries remained comparatively resistant. These results offer valuable insight into the role of microstructure in corrosion processes and reinforce the importance of time-dependent material evaluation in molten salt environments relevant to advanced reactor designs.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Open-air plasma-assisted deposition of organosilicon coating for corrosion protection of AZ91D Mg alloy

As a corrosion barrier layer, open-air plasma-assisted organosilicon coating was applied on AZ91D Mg alloy. Organosilicon-coated AZ91D samples, prepared from two different plasma coating processes, were used for corrosion evaluation based on multistep electrochemical and H 2 collection measurements in 3.5 wt% sodium chloride (NaCl) solution. Some coated AZ91D samples were characterized with and without corrosion exposure in NaCl solution using electron microscopies and X-ray chemical analysis techniques. Further, the results indicate that the organosilicon coatings from open-air plasma processes are effective to delay the initiation of corrosion attack and also reduce the corrosion rate for AZ91D substrate. The corrosion attack was considered to develop after permeation of NaCl solution through the coating layer.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of neutron and ion irradiation on the metal matrix and oxide corrosion layer on Zr-1.0Nb cladding alloys

A detailed study has been carried out on recrystallised Zr-1.0Nb alloys corroded and irradiated under different conditions, including ex-autoclave and ex-reactor samples. After 540 days in reactor and damage around 5 dpa, the neutron irradiated sample shows no serious evidence for radiation enhanced corrosion and is still in pre-transition stage. The good corrosion resistance of the neutron irradiated Zr-1.0Nb can be related to the higher volume fraction of tetragonal phase and fewer interconnected nano porosity/cracks in the oxide. This indicates less tetragonal to monoclinic transition, leads to more protective oxide in the neutron irradiated sample, containing little evidence for short circuit paths for the penetration of oxygen or water towards the metal-oxide interface. These observations on a sample with a slow overall oxidation rate are consistent with the hypothesis that interconnected porosity can lead to early transitions and rapid oxidation. Tetragonal oxide can be either stabilised by irradiation, or stabilised by local release of impurity species from SPPs such as dissolution of Fe from Zr-Nb-Fe precipitates or radiation introduced precipitates (RIPs) which is likely to be small β-Nb clusters. The oxide consists of well-aligned columnar-equiaxed microstructure in the autoclave sample while a more complex oxide grain structure was observed in the neutron-irradiated sample. As oxide continues to grow, there are more < a > and < c > loops, dissolved Fe and RIPs in the metal matrix, however, the corrosion rate is low enough for the tetragonal oxide to stabilise and suboxide + Zr(Osat) phases exist for protectiveness, so there is no enhanced corrosion after radiation. In situ ion irradiation in the TEM revealed no visible defect clusters or voids in the oxide, suggesting that radiation damage to the metal matrix rather than oxide may have a stronger effect on corrosion mechanisms after neutron irradiation, however, cascade damages are not visible in this case. Neutron irradiation also seems to have little effect on promoting fast oxidation or dissolution of β-Nb precipitates into the surrounding oxide or metal during irradiation. Furthermore, these results are discussed in the light of the current mechanisms for corrosion of nuclear fuel cladding alloys.

(S)TEM↗
DOE OSTI2022

Origins of wear-induced tungsten corrosion defects in semiconductor manufacturing during tungsten chemical mechanical polishing

During chemical mechanical polishing (CMP) process optimization, a unique corrosion defect was identified in the tungsten (W) contact plugs, which were investigated to develop practical solutions to improve CMP mass productivity. The corrosion defect occurred in the absence of external incident energy and was observed to occur only at the W plugs connected to the P + /n-well close to the wafer edge. To examine the root cause of the corrosion, a series of experiments was carried out at each W CMP step, using in-line defect inspection. Additional experiments were conducted using on-line inductively coupled plasma mass spectrometry (ICP-MS) to understand pH- and potential-dependent electrochemical dissolution behaviors of W. Experimentally, W corrosion was confirmed to be exacerbated if the surface oxide of the W plugs is removed by the deionized water (DIW) rinsing step under wafer pressurization, then exposed to DIW and alkaline cleaning solution. Although the DIW rinsing step is commonly performed to clean polishing pads right after the main polishing, a small amount of applied pressure (0.5 psi) without slurry supply can lead to corrosion defects. Finally, this wear-induced corrosion of the W plugs can be prevented by removing the applied pressure during the post DIW rinsing step of W CMP.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Approaches to investigate the role of chelation in the corrosivity of biomass-derived oils

The need to provide the U.S. market with a renewable liquid fuel energy source from a non-food feedstock stream has gained considerable traction due to benefits such as improved energy efficiency, reduced environmental impacts, and enhanced national security. Practical achievement of these goals via biomass and bio-waste utilization involves production of liquid intermediates containing corrosive, reactive species like carboxylic acids, ketones, aldehydes, and hydroxyaldehydes. Such mixtures challenge materials of containment, processing, and transport. It is widely recognized that the smaller organic acids, such as acetic and formic, are corrosive and can remove protective surface oxides on alloys used in bio-oil processing infrastructure, and ketones can swell sealing polymers. However, literature shows, and findings herein confirm, larger carboxylic acids and bidentate alcohols are present. This highlights the potential for synergistic, detrimental effects of constituents in bio-oil corrosion, including direct reactivity of small acids compounded with the possibility of mobilization of protective metal oxide layers via chelation by larger acids and oxygenates. The question of whether species beyond small acids can significantly contribute to corrosion requires analytical approaches previously not applied to bio-oil corrosion studies and certainly not previously applied corroboratively. As such, this work introduces a combination of optical, mass spectral, and electrochemical impedance spectroscopies with an incubation approach to study metal mobilization, to facilitate elucidating chelation's role in bio-oil corrosive pathways. To enable systematic study of these oxygenates' material compatibility individually and in combination, a model matrix of bio-oil constituents was also developed based on identification of key components of real bio-oils.

09 BIOMASS FUELS↗
DOE OSTI2019

Self-healing, re-adhering, and carbon-steel corrosion mitigating properties of fly ash-containing calcium aluminum phosphate cement composite at 300 °C hydrothermal temperature

This study assesses here the ability of calcium aluminate phosphate (CAP)/fly ash F (FAF) blend composite to self-heal at early age; to re-adhere to the casing surfaces after debonding and to protect carbon steel (CS) against brine-caused corrosion before and after the re-adherence. The composite was damaged after autoclaving for 24 h at 300 °C and then exposed to the same conditions for 5 more days for the self-healing and re-adhering processes. The ability of the blend to self-heal and re-adhere to CS was evaluated 1) by measurements of the recovery of compressive and bond strengths and Young's modulus; 2) by performing the 3-dimensional micro-image analysis of sealed cracks; 3) by phase identification in composite matrix and in the cracks after the healing; 4) by measurements of CS corrosion impediment by the re-adhered composite after 300°C-5-day restoration period. After the healing, the two factors, sealing effect of cracks by reaction products and change in phase composition of cement matrix, essentially governed the recovery of the original mechanical strength. For the former, analcime phase derived from pozzolanic FAF autogenous healing aid played the major role in sealing the cracks, while the well-formed hydroxyapatite phase contributed to the latter factor. The lap-shear bond with the strength of 1.11 MPa at CS plate/composite adhesive/CS plate joint failed cohesively, showing higher bond strength than strength of the composite matrix. The rebonded composite-CS plates developed a 0.37 MPa bond strength after the 5-day restoration period. The results of electrochemical polarization corrosion tests revealed that the re-adhered composite covering CS plate significantly inhibited the brine-caused corrosion of CS, leading to 0.011 mm/year corrosion rate, corresponding to 50% reduction compared with that of before re-adhering. There were two factors governing such corrosion mitigation: enhanced adhesive contact of composite with CS and increased coverage by the re-adhering composite.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Chloride induced reinforcement corrosion behavior in self-healing concrete with encapsulated polyurethane

Cracks in reinforced concrete structures accelerate the ingress of chlorides and therefore cause a higher risk for corrosion. In this research, autonomous healing of cracks by encapsulated polyurethane was investigated as a possible method to reduce reinforcement corrosion. Reinforced concrete beams were exposed weekly to a chloride solution and electrochemical parameters were measured to determine the influence of the self-healing mechanism on the corrosion process. The rebars were visually examined afterwards. For the cracked beams an active state of corrosion was detected within an exposure period of 10 weeks and clear pitting corrosion was observed on the rebars. Autonomous crack healing with low viscosity polyurethane could significantly reduce the corrosion in the propagation stage. For these specimens no visual damage to the rebars was detected. In conclusion, the application of self-healing concrete with a low viscosity polyurethane is able to enhance the durability of reinforced concrete structures in marine environments.

36 MATERIALS SCIENCE↗