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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Effectiveness of Vapor Corrosion Inhibitors Under Bacterial Activity for Aboveground Storage Tank Application

Bacterial activity is known to influence corrosion and can result in increasing soil-side corrosion of the aboveground storage tanks (ASTs) floor plates. Association for Materials Protection and Performance (AMPP) defines this phenomenon as Microbiologically Influenced Corrosion (MIC). It has been hypothesized that vapor corrosion inhibitors (VCIs) can not only function in presence of bacterial activity but can also function as biocides. Experiments were conducted to study the effect of bacterial activity on corrosion in the sand pad conditions and effect of VCIs in mitigating MIC. Various bacteria cultures were grown using commercially available culture media, and coupon exposure tests were performed with field sand mixed with the culture media. To this end, control and VCI-dosed electrolytes were prepared using the field sand plus bacteria cultures. Pre- and post-test bacteria concentration estimation and measurements, respectively, in the VCI-dosed electrolytes indicated that VCIs do not function as biocides, however, VCIs are highly effective for mitigating corrosion in presence of bacterial activity.

Shukla, Pavan K.↗
DOE OSTI2017

Fabrication of Superhydrophobic Calcium Phosphate Coating on Mg-Zn-Ca alloy and Its Corrosion Resistance

A novel superhydrophobic calcium phosphate coating was prepared on a magnesium alloy substrate by a highly effective chemical conversion process and subsequent chemical modification. Different methods were employed to characterize the surface morphology and chemical composition as well as measure the wettability of the coating. It was demonstrated that the as-prepared superhydrophobic calcium phosphate coating has a typical three-level hierarchical structure consisted of micro-protrusions, submicro-lumps and nano-grains, conferring excellent superhydrophobicity with a water contact angle of 159°. The electrochemical measurements and appropriate equivalent circuit revealed that the corrosion-resistant performance of the superhydrophobic calcium phosphate coating was significantly improved as compared with that of the substrate, the corrosion potential of the superhydrophobic coating increases from −1.56 to −1.36 V, and its corrosion current density decreases from 1.29 × 10{sup −4} to 1.3 × 10{sup −6} A/cm{sup 2}. The anti-corrosion mechanism of the superhydrophobic coating was also discussed. It can be indicated that the corrosion inhibitive properties of the coating are in accordance with its hydrophobicity, which is owing to the presence of a protective layer of air trapped in the grooves of the coating surface to isolate the underlying materials from the external environment.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Corrosion Behavior of Aqua-Blasted and Laser-Engraved Type 316L Stainless Steel

The effect of aqua blasting and laser engraving on surface microstructure development, residual stress and corrosion resistance of type 316L stainless steel has been investigated. Aqua blasting resulted in a deformed near-surface microstructure containing compressive residual stresses. Subsequent laser engraving produced a surface layer with tensile residual stresses reaching to a depth of 200 microns. Changes of surface roughness topography were accompanied by the development of a thick oxide/hydroxide film after laser engraving. The atmospheric corrosion behavior of all surfaces with MgCl{sub 2}-laden droplets was compared to their electrochemical response in 1M NaCl and 0.7 M HCl aqueous solutions. The measured total volume loss after atmospheric corrosion testing was similar for all investigated surface conditions. Laser-engraved surface exhibited the smallest number of corrosion sites, but the largest mean corrosion depth.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Sm-Rich Phase on Corrosion Behavior of Hot-Extruded AZ31-1.5Sm Magnesium Alloy

The effects of Sm on the corrosion and microstructure behavior of hot-extruded AZ31 magnesium alloy were investigated by SEM, TEM, weight loss analysis, and electrochemical measurements. The results indicated that granular Al{sub 2}Sm phase ~ 4 μm in size in the hot-extruded AZ31 magnesium alloy modified with 1.5 wt.% Sm leads to significant grain refinement. The corrosion rate decreased from 15.98 × 10{sup −4} to 11.19 × 10{sup −4} g cm{sup −2} h{sup −1} in the transverse section and from 8.57 × 10{sup −4} to 6.20 × 10{sup −4} g cm{sup −2} h{sup −1} in the longitudinal section. Compared to the unmodified alloy, the corrosion potential of the Sm-modified alloy in the transverse and longitudinal sections increased by 98 and 62 mV, respectively, and the R{sub ct} value (charge transfer resistance) in the transverse and longitudinal sections of the modified alloy increased from 1764 and 1756 to 2928 and 2408 Ω cm{sup 2}, respectively. The results showed that the corrosion resistance of hot-extruded AZ31 magnesium alloy was significantly improved by Sm addition due to the grain refinement, the decreased dislocation density, and the suppression of micro-galvanic corrosion caused by Al-Sm-(Mn) intermetallic compounds.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The Corrosion Behavior of Zn/Graphene Oxide Composite Coatings Fabricated by Direct Current Electrodeposition

The zinc (Zn) and Zn/graphene oxide (Zn/GO) composite coatings on the mild steel were fabricated by direct current electrodeposition from an acidic chloride bath without GO and that with four different concentrations (50, 100, 200 and 300 mg/L) of GO, respectively. The GO first is synthesized by using the typical Hummer method. Physical characterizations including the surface and cross-sectional morphology, chemical composition and crystal structure of the Zn and Zn/GO composite coatings were done by scanning electron microscope, energy-dispersive x-ray and x-ray diffraction. The crystalline size, texture coefficient, water contact angle and hardness of the Zn and Zn/GO composite coatings were measured. The corrosion behavior of the Zn and Zn/GO composite coatings was studied by the electrochemical corrosion tests including the potentiodynamic polarization test and the electrochemical impedance spectroscopy test and the immersion test. The result reveals that the corrosion resistance of the Zn coating is remarkably increased by the incorporation of GO. Furthermore, it does not show a linear increase with the increase in the amount of incorporated GO and an optimal corrosion resistance is provided by the Zn/GO composite coating attained from the electrolyte containing 100 mg/L GO. The influence of the incorporation of GO on the corrosion resistance of the Zn coating is explained in combination with their physical characterizations.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Role of Centrifugal Casting on Electrochemical Corrosion Behavior of A356-SiCp Composite in 3.5 wt.% NaCl

Role of graded microstructure in a centrifugally cast A356-SiC particle (SiCp) composite alloy disk on passivity and localized corrosion behavior in 3.5 wt.% NaCl environment has been investigated. The area fraction of SiCp has been found to decrease from the outer periphery to the core of the disk, while the apparent size and area fraction of the intermetallics and Mg-rich phase increase from the periphery to the core. As a consequence, the corrosion resistance of the as-cast disk varies with the distance from the periphery in the order 45 < 65 < 25 < 5 mm. The corrosion resistance of the centrifugally cast disk can be significantly improved through solution annealing at 540 °C for 2 h and solution annealing + aging at 175 °C for 2 h. However, between the two, the former has shown a better corrosion resistance and passivity than the latter. In the latter case, the aging treatment resulted in the precipitation of Mg{sub 2}Si phase which is prone to the corrosion attack.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Laser Shock Peening on Residual Stress, Microstructure and Hot Corrosion Behavior of Damage-Tolerant TC21 Titanium Alloy

The effect of laser shock peening (LSP) on the residual stress, microstructure and hot corrosion behavior of damage-tolerant TC21 alloy was investigated. The equilateral scanning pattern was adopted to obtain a large overlapping area for LSP. The hot corrosion experiments in a salt mixture composed of 75 wt.% Na{sub 2}SO{sub 4} + 25 wt.% NaCl at 700 and 800 °C for a total exposure of 25 h were conducted. The results demonstrated that LSP caused a high compressive residual stress with a significant increase in micro-hardness and microstructural changes in the form of crystal defects, i.e., high density dislocations. The crystal defects promoted the outward diffusion of Al, Cr and Ti to form protective mixed oxides (Al, Cr, Ti)O{sub 2}. These oxides improved the adhesion of outer oxide layer and hindered the inward diffusion of O, S and Cl, which was beneficial to improve hot corrosion resistance. The mass gains of LSP-treated specimens after hot corrosion at 700 and 800 °C were, respectively, 3.72 and 4.78 mg/cm{sup 2}, which were much lower than those of untreated specimens (5.65 and 6.81 mg/cm{sup 2}). Therefore, LSP leads to an improvement in resistance to hot corrosion of TC21 alloy.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Electrochemical Corrosion Behavior of Plasma-Sprayed FeCrNiMoCBSi Amorphous/Nanocrystalline Coatings in Simulated Seawater Medium

A novel FeCrNiMoCBSi coating was fabricated on F22 marine steel by plasma spraying. The coating microstructure and composition were characterized by scanning electron microscope, transmission electron microscope, x-ray diffraction, differential scanning calorimetry, and x-ray photoelectron spectroscopy. The results showed that the coating consisted of amorphous and nanocrystalline phases. Additionally, the corrosion resistance in simulated seawater was evaluated by electrochemical corrosion methods. It was found that the coating exhibited an excellent resistance to pitting corrosion. For long-time immersion tests, the corrosion resistance was gradually decreased with the increasing through-porosity due to the permeation of the corrosive solution into the coating. The coating lost its efficacy through three stages, namely the protection stage, the permeation stage, and the failure stage.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Modeling of concrete cracking due to corrosion process of reinforcement bars

The reinforcement corrosion in Reinforced Concrete (RC) is a major reason of degradation for structures and infrastructures throughout the world leading to their premature deterioration before design life was attained. The effects of corrosion of reinforcement are: (i) the reduction of the cross section of the bars, and (ii) the development of corrosion products leading to the appearance of cracks in the concrete cover and subsequent cover spalling. Due to their intrinsic complex nature, these issues require an interdisciplinary approach involving both material science and structural design knowledge also in terms on International and National codes that implemented the concept of durability and service life of structures. In this paper preliminary FEM analyses were performed in order to simulate pitting corrosion or general corrosion aimed to demonstrate the possibility to extend the results obtained for a cylindrical specimen, reinforced by a single bar, to more complex RC members in terms of geometry and reinforcement. Furthermore, a mechanical analytical model to evaluate the stresses in the concrete surrounding the reinforcement bars is proposed. In addition, a sophisticated model is presented to evaluate the non-linear development of stresses inside concrete and crack propagation when reinforcement bars start to corrode. The relationships between the cracking development (mechanical) and the reduction of the steel section (electrochemical) are provided. Finally, numerical findings reported in this paper were compared to experimental results available in the literature and satisfactory agreement was found.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Effects of Sn addition on the microstructure, mechanical properties and corrosion behavior of Ti–Nb–Sn alloys

Ti and Ti alloys are widely used in restorative surgery because of their good biocompatibility, enhanced mechanical behavior and high corrosion resistance in physiological media. The corrosion resistance of Ti-based materials is due to the spontaneous formation of the TiO{sub 2} oxide film on their surface, which exhibits elevated stability in biological fluids. Ti–Nb alloys, depending on the composition and the processing routes to which the alloys are subjected, have high mechanical strength combined with low elastic modulus. The addition of Sn to Ti–Nb alloys allows the phase transformations to be controlled, particularly the precipitation of ω phase. The aim of this study is to discuss the microstructure, mechanical properties and corrosion behavior of cast Ti–Nb alloys to which Sn has been added. Samples were centrifugally cast in a copper mold, and the microstructure was characterized using optical microscopy, scanning electron microscopy and X-ray diffractometry. Mechanical behavior evaluation was performed using Berkovich nanoindentation, Vickers hardness and compression tests. The corrosion behavior was evaluated in Ringer's solution at room temperature using electrochemical techniques. The results obtained suggested that the physical, mechanical and chemical behaviors of the Ti–Nb–Sn alloys are directly dependent on the Sn content. - Graphical abstract: Effects of Sn addition to the Ti–30Nb alloy on the elastic modulus. - Highlights: • Sn addition causes reduction of the ω phase precipitation. • Minimum Vickers hardness and elastic modulus occurred for 6 wt.% Sn content. • Addition of 6 wt.% Sn resulted in maximum ductility and minimum compression strength. • All Ti–30Nb–XSn (X = 0, 2, 4, 6, 8 and 10%) alloys are passive in Ringer's solution. • Highest corrosion resistance was observed for 6 wt.% Sn content.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Effect of surface nanostructuring on corrosion behavior of Ti–6Al–4V alloy

Surface nanostructure was induced in Ti–6Al–4V alloy by ultrasonic shot peening (USSP) for different durations, from 15 s to 30 min, and the modified surface was characterized by optical, scanning, atomic force and transmission electron microscopy. Nano size grains were observed to form on surface of the USSPed samples and surface roughness was increased with duration of USSP. Polarization study was carried out in Ringer's solution to examine the effect of surface nanostructuring on corrosion resistance of this alloy. Electrochemical corrosion was carried out for all the USSPed specimens as well as the non-USSPed sample in Ringer's solution. Surface morphology of the corroded samples was examined by SEM. In general, corrosion resistance was improved by USSP up to the duration of 15 min and there was maximum improvement in the specimen USSPed for 1 min. However, corrosion resistance was drastically reduced due to USSP for long duration of 30 min. - Highlights: •Nanostructure was induced by USSP on alloy Ti–6Al–4V of about 28 nm. •Grain refinement was confirmed by XRD and TEM. •USSP is an effective technique for the improvement in corrosion resistance. •Nanostructured surface promotes formation of protective surface layer of TiO{sub 2}.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Characterization of wellbore casing corrosion product as a permeable porous medium

Leakage along wellbores is of concern for a variety of applications, including sub-surface fluid storage facilities, geothermal wells, and CO 2 storage wells. We have investigated whether corroded casing is permeable to gas and can serve as a leakage pathway along wellbores. Three specimens were prepared from laboratory steel plates corroded using different mechanisms to reflect different possible field conditions and produce a variety of corrosion rates. Single-phase gas flow measurements were made under a range of gas pressures to investigate flow in both the viscous and visco-inertial flow regimes. Tests were conducted at different confining stresses (range from 3.45 to 13.79 MPa) following both loading and unloading paths. The gas flow test results imply corroded casing can serve as a significant leakage path along the axis of a wellbore. Transmissivity was discovered to be sensitive to the variation in confining stress suggesting that the corrosion product is deformable. Gas slip factors and the coefficients of inertial resistance of the corrosion product were comparable to those available in the literature for other porous media. Post-test examination of the corrosion product revealed it to be a heterogeneous, mesoporous material with mostly non-uniform slit type porosity. There was no discernable difference in the composition of corrosion product from specimens corroded by different mechanisms.

02 PETROLEUM↗
DOE OSTI2023

Time-Dependent Corrosion Behavior of Aluminum Using Advanced Electrochemical and Characterization Techniques

The time-dependent corrosion behavior of pure aluminum (Al) in a chloride-containing environment was investigated using various electrochemical and characterization techniques for up to 336 h. Transmission electron microscopic and secondary ion mass spectroscopic analysis revealed the continuous dissolution of the surface film over the immersion time. In the meantime, the increasing passive oxide thickness resulted in the surface film resistance enhancement over the immersion time, as indicated by the electrochemical impedance spectroscopic analysis. The electrochemical noise measurements showed an increase in the corrosion kinetics with immersion time until 60 h because of the accelerated localized corrosion in the early stage of immersion. However, an inhibition in corrosion kinetics occurred after longer immersion times due to corrosion product deposition inside the pit.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Boiler Corrosion and Monitoring

Results of a collaborative effort to investigate and develop solutions for key material issues affecting the performance of large-scale coal-fired boilers operating at advanced conditions is presented. Advanced conditions include advanced steam temperatures, oxyfuel firing, and co-firing biomass materials. A series of laboratory experimental results are presented on fireside corrosion in environments representing air-, and oxy-fired conditions, and with coal and/or biomass as the fuel. The effects of fluctuating reducing atmospheres and heat flux effects were examined. A variety of boiler corrosion probes and sensors were developed and tested. The probes measured corrosion by section loss and the sensors by electrochemical techniques including electrochemical noise. The probes were tested in coal and waste-to-energy boilers. Correlations between section loss probes and electrochemical noise sensors allow for real-time corrosion rate measurements to be made that allow for changes in boiler operations to be tracked in terms of corrosion effects.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2014

Hanford double shell waste tank corrosion studies - final report FY2014

SRNL tasks for FY14 included studies to evaluate the susceptibility of carbon steel to vapor space corrosion (VSC), liquid-air interface (LAI) corrosion, and pitting corrosion. Additionally, SRNL evaluated the susceptibility of carbon steel to pitting corrosion under buffered waste conditions, with the objective of determining the adequate amount of inhibitor (e.g., nitrite) necessary to mitigate pitting corrosion. Other CPP experiments were performed in historical waste simulants and the results were compared to previously gathered results. The results of these activities were utilized to assess the robustness of the standardized CPP protocol

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Corrosivity Screening of Pyrolysis Bio-Oils by Short-Term Alloy Exposures. Laboratory Analytical Procedure (LAP), Issue Date: May 12, 2022

Bio-oils contain organic acids and oxygenated compounds that can lead to corrosion issues during bio-oil processing and storage. This Laboratory Analytical Procedure (LAP) allows for rapid screening of a bio-oil's corrosivity without the need for complex equipment and long-term exposures. A robust and repeatable method for assessing the corrosivity of bio-oils is necessary in order to remove materials degradation as an obstacle to research, upgrading, use and storage of bio-oils. This LAP involves the incubation of a representative alloy, 410 stainless steel (410 SS), specimen in bio-oil over a period of 48 hours at 50 degrees C in a sealed container. The corrosive species in the bio-oil react with and deplete alloy elements such as iron (Fe) and/or chromium (Cr) from the specimen into the bio-oil solution. The depletion of Fe and Cr from the specimen results in a significant mass loss that can be recorded. The mass loss is directly correlated to the corrosivity of a bio-oil. Examples of bio-oils in scope include the ones produced by fast pyrolysis and catalytic fast pyrolysis, as well as liquids produced from hydrothermal liquefaction.

09 BIOMASS FUELS↗
DOE OSTI2022

Effect of Carboxylic Acids on Corrosion of Type 410 Stainless Steel in Pyrolysis Bio-Oil

Biomass-derived oils are renewable fuel sources and commodity products and are proposed to partially or entirely replace fossil fuels in sectors generally considered difficult to decarbonize such as aviation and maritime propulsion. Bio-oils contain a range of organic compounds with varying functional groups which can lead to polarity-driven phase separation and corrosion of containment materials during processing and storage. Polar compounds, such as organic acids and other oxygenates, are abundant in bio-oils and are considered corrosive to structural alloys, particularly to those with a low-Cr content. To study the corrosion effects of small carboxylic acids present in pyrolysis bio-oils, type 410 stainless steel (SS410) specimens were exposed in bio-oils with varying formic, acetic, propionic and hexanoic acid contents at 50 °C during 48 h exposures. The specific mass change data show a linear increase in mass loss with increasing formic acid concentration. Interestingly, a mild corrosion inhibition effect on the corrosion of SS410 specimens was observed with the addition of acetic, propionic and hexanoic acids in the bio-oil.

09 BIOMASS FUELS↗
DOE OSTI2016

Corrosion and interdiffusion studies of U{sub 3}Si{sub 2}

U{sub 3}Si{sub 2} is a candidate fissile phase for use in accident tolerant fuel systems in light-water reactors because of its higher fissile density, higher thermal conductivity when compared to uranium dioxide. It is also expected to have acceptable performance in contact with high temperature water (e.g., a leaker event from breached cladding) and in regards to interaction with different cladding materials. In high temperature water, U{sub 3}Si{sub 2} is expected to form a protective SiO{sub 2} coating. However, the resistance of U{sub 3}Si{sub 2} to corrosion under light water reactor service conditions has been previously unknown. In this study, the corrosion tests of sintered U{sub 3}Si{sub 2} discs were conducted in pressurized water at 300 C. degrees in an autoclave. The exposure times to corrosion were 6 hours and 24 hours. Detailed composition and microstructural analysis were carried out using a combination of techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectroscopy (EDS). Only slight weight change of U{sub 3}Si{sub 2} discs can be detected in corrosion tests up to 24 hours. A layered structure of corrosion products formed on U{sub 3}Si{sub 2}, with a glassy silicon oxide layer at the top followed by a nanocrystalline UO{sub 2} layer, a Si-rich oxide layer and then a mixture oxide layer of U and Si. A diffusion couple of U{sub 3}Si{sub 2} in contact with Zircaloy-4 has been tested at 800 C. degrees up to 100 hours. The resulting microstructure and interdiffusion have been studied with SEM/EDS. Some limited interdiffusion has been observed in these tests as well as a layer containing Zr and Si forms between the U{sub 3}Si{sub 2} disc and the Zircaloy-4 disc. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗