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1
Gibbs, Jonathan Paul. "Corrosion of various engineering alloys in supercritical carbon dioxide." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59247.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010."June 2010."
Includes bibliographical references.
The corrosion resistance of ten engineering alloys were tested in a supercritical carbon dioxide (S-CO 2) environment for up to 3000 hours at 610°C and 20MPa. The purpose of this work was to evaluate each alloy as a potential candidate for use in the S-CO2 cooled next generation nuclear reactors. The alloys that performed well in these tests will undergo further testing and those that performed poorly will be disqualified from future deployment in S-CO2 applications. The ten alloys tested in this work were classified into four categories: Ferritic-martenitic steels, austenitic stainless steels, nickel alloys, and special materials. The majority of the alloys were focused on the five alloys within the austenitic stainless steel series, followed by three nickel alloys. These alloys were F91, HCM12A, 316SS, 31OSS, AL-6XN, 800H, Haynes 230, Alloy 625, PE-16, and PM2000. The experimental procedure consisted of placing multiple samples of each alloy in an autoclave and exposing them to S-CO2 for up to 3000 hours, in 500 hour increments. At every 500 hour increment each alloy was removed from the autoclave, photo documented and weighed. One sample from each 500 hour test was reserved for future analysis while the other samples were returned to the autoclave for further testing. The 3000 hour samples were sectioned, mounted in epoxy, and polished oriented normal to its oxide growth to document the thickness and structure of each oxide layer formed. Alloys F91 and HCM12A performed poorly and experienced substantial weight gain. Each of these alloys formed a duplex oxide layer with the outside layer being iron rich and chromium depleted and the inside layer being iron depleted and chromium rich. The oxide layers were porous and were susceptible to spallation. The 3000 hour weight gain for both of these alloys was approximately 5x10-3 mg/cm2, which was two orders of magnitude higher than the remaining eight alloys. Alloys PM2000, 316SS, 31OSS, AL- 6XN, 800H, Haynes 230, Alloy 625, and PE-16 were stable oxide formers with thin, dense oxide layers and were resistant to corrosion. The weight gain of these eight alloys was on the order of 4x10 5 mg/cm 2 at 3000 hours of exposure. Overall, the alloys with high chromium and nickel contents performed the best, followed by the stainless steels with intermediate chromium content.
by Jonathan Paul Gibbs.
S.M.
2
Li, Duanjie. "Microstructure and corrosion and tribo-corrosion behaviors of Si-based and Ti-based aerospace coatings produced by PECVD." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95138.
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Microstructure and corrosion and tribo-corrosion behaviors of Ti-based and Si-based coatings have been systematically investigated. A series of Ti-based and Si-based coatings with different silicon and/or carbon contents were prepared by plasma enhanced chemical vapor deposition (PECVD). Various experimental techniques were employed for the microstructural characterization of the coatings, e.g., X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The mechanical and tribological properties were assessed using nano-indentation, micro-scratch test and pin-on-disk wear test. Corrosion resistance was measured using potentiodynamic polarization test and analyzed using electrochemical impedance spectroscopy (EIS), while the tribo-corrosion behavior was characterized using reciprocating wear test in corrosion environment in tribo-corrosion apparatus. The grain size refinement took place as the Si and C incorporated into the TiN coating. At the same time, the microstructure of the coatings changed and a transition from TiN columnar structure into densely packed homogeneous nano-composite structure was observed for nc-TiN/a-SiNx and nc-TiCN/a-SiCN coatings. This gave rise to a further improvement of the corrosion resistance by a factor of ~20 compared to TiN. Interface structure of the TiN coating system was designed in such a way that the hardness increased gradually with the distance from the substrate to the coating surface. This was done by applying a Cr interlayer in order to enhance the adhesion and simultaneously improve the load bearing capacity. In addition, the Cr interlayer further enhanced the corrosion resistance of the TiN-based nano-composite coatings. The Ti-Si-C coatings mainly consisted of nanocrystalline TiC particles embedded in the a-SiCx:H and a-C:H matrix. The refinement of the TiC grains and the increase of the amorphous fraction simultaneously tookLa microstructure et le comportement en corrosion et en tribo-corrosion des revêtements à base de titane et de silicium ont été systématiquement étudiés. Une série de ces revêtements contenant différentes composition de silicium (Si) et/ou de carbone (C) ont été préparés par déposition chimique en phase vapeur assistée par plasma (PECVD). Différentes techniques expérimentales ont été utilisées pour la caractérisation de la microstructure des revêtements. Un raffinement de la taille des grains s'est produit lors de l'incorporation du Si ou du C dans la composition du revêtement TiN. Au même temps, la microstructure du revêtement a changé et une transition de la microstructure de colonnaire à celle nanocomposite, dense et homogène a été observée pour les revêtements nc-TiN/a-SiNx and nc-TiCN/a-SiCN. Cela a permit de rehausser la résistance à la corrosion d'un facteur de ~20 comparé au TiN. La structure de l'interface du système de revêtement TiN a été conçue de façon à ce que la dureté augmente graduellement avec la distance entre le substrat et la surface du revêtement. Cela a été réalisé en appliquant une couche intermédiaire de chrome (Cr) dans le but de rehausser l'adhésion et simultanément d'augmenter la capacité de chargement. En plus, la couche de Cr a permit l'augmentation de la résistance â la corrosion des revêtements nanocomposites à base de TiN. Les revêtements Ti-Si-C sont principalement constitués de particules nanocristallines de TiC incorporées dans une matrice amorphe a-SiCx:H and a-C:H. Le raffinement de la taille des grains de TiC et l'augmentation de la fraction de phase amorphe se produit lorsque plus de Si et/ou de C sont incorporés dans les revêtements Ti-Si-C. Cela a permit d'améliorer les propriétés électrochimiques du Ti-Si-C, lequel peut être attribué à la résistance à la corrosion supérieure et a la densité et l'homogénéité de la matrice -SiCx:H and a-C:H qui e
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Li, Kwan (Kwan Hon). "Microbially influenced corrosion in sour environments." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/88382.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 119-123).
Microbially influenced corrosion (MIC) is a costly and poorly understood source of corrosion that plagues many modern industrial processes such as oil extraction and transportation. Throughout the years, many possible mechanisms for MIC have been proposed. One specific proposed mechanism was tested in this thesis: that the metal-binding characteristic of bacterial biofilms enhanced corrosion when it appears in conjunction with an iron sulfide film. Two model biogels were used: calcium alginate, which has this metal-binding property, and agarose, which does not. In pursuit of this hypothesis, iron sulfide films were grown on mild steel coupons. Two distinct forms of iron sulfides were grown: a loose black product at low sulfide concentrations, and an adherent gold product at high sulfide concentrations. Many materials characterization techniques were attempted, and the black corrosion product was found to be a mixture of greigite and marcasite. However, this composition was observed to change irreversibly with the application of a laser that caused the material to either heat and/or dry. The resulting golden-colored corrosion product was found to consist mainly of monosulfides, implying the presence of mackinawite or pyrrhotite. By using electrochemical polarization experiments, it was found that calcium alginate enhanced the rate of corrosion; agarose reduced the rate of corrosion. This is in contrast to previously published literature. Contrary to the initial hypothesis, adding an underlying iron sulfide film did not appreciably alter the measured rate of corrosion. Additionally, it was found that biofilms generated by sulfate-reducing bacteria (SRB) enhanced corrosion in a manner similar to the calcium alginate gel, and lysing the cells within the biofilm did nothing to alter this effect. This implies that the biofilm itself, even in the absence of active bacterial metabolic activity, can enhance corrosion rates observed in MIC.
by Kwan Li.
S.M.
4
Swanson, Orion John. "Corrosion of High-Entropy Alloys in Chloride Solutions." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532709505615889.
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Genkin, Jean-Marc P. (Jean-Marc Patrick). "Corrosion fatigue performance of alloy 6013-T6." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/33519.
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Zhang, Liming 1966. "Contamination and galvanic corrosion in metal chemical-mechanical planarization." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282840.
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Chemical mechanical planarization (CMP) of metals is a critical process in the manufacturing of ultra-large scale integrated (ULSI) circuit devices. The overall success of a CMP process requires minimal particulate and metallic contamination of the structures subjected to CMP. The objective of this study was to investigate alumina particle contamination during tungsten CMP, copper contamination in copper CMP, and galvanic corrosion between metal films and adhesion layers during the final stages of tungsten and copper CMP. Particular attention was paid to the use of short chain organic carboxylic acids in reducing the contamination. Both electrokinetic and uptake measurements showed that citric acid and malonic acid interact with alumina particles by electrostatic as well as specific adsorption forces. Systematic immersion contamination and polishing experiments were carried out to demonstrate the effectiveness of the acids in controlling alumina particulate contamination on wafer surfaces. The difference in the surface cleanliness was interpreted using the electrokinetic data and the calculated interaction energy between alumina particles and the wafer surface. Electrochemical tests showed no severe attack on tungsten films by the acids. Copper ions were found to adsorb onto the silicon dioxide surface, leading to copper contamination levels of upto 10¹³ atoms/cm². The extent of copper contamination was found to depend on the solution pH and the presence of additives such as hydrogen peroxide. Both electrokinetic measurements and immersion contamination experiments showed that citric acid can reduce the copper contamination on the silicon dioxide surface. TiN is more noble than tungsten in the solutions containing oxidants used in tungsten CMP slurries. The most significant corrosion of tungsten was found in the presence of hydrogen peroxide. Copper was found to be more noble than tantalum in acidic solutions. However, in alkaline ammonium hydroxide solutions, the relative nobility of copper and tantalum can be reversed by adding hydrogen peroxide. The corrosion of tungsten and copper appears to be very minimally affected by coupling with TiN and tantalum, respectively.
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Genkin, Jean-Marc P. (Jean-Marc Patrick). "Corrosion fatigue crack initiation in 2091-T351 Alclad." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41792.
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Chen, Xi. "Corrosion Resistance Assessment of Pretreated Magnesium Alloys." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282837277.
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Tamilmani, Subramanian. "Dissolution, corrosion and environmental issues in chemical mechanical planarization of copper." Diss., The University of Arizona, 2005. http://hdl.handle.net/10150/280774.
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Chemical mechanical polishing (CMP) of dielectric and metal films has become a key process in manufacturing devices with ultra large scale integration (ULSI). In a CMP process, planarization is achieved by polishing a wafer with uneven topography using colloidal slurry consisting of sub-micron sized abrasive particles, oxidant and various additives. Hydrogen peroxide and hydroxylamine are commonly used oxidants in copper CMP process. To achieve planarization, the low lying areas have to be protected while the higher areas are polished away. This requires low static dissolution rate of copper in low areas. Another major issue in copper CMP is galvanic corrosion during barrier polishing step where both copper and the barrier metal are exposed to the slurry. The main goal of the research reported in this dissertation is to understand the dissolution and corrosion issues during the removal of copper in hydroxylamine based chemistries. Electrochemical and physical methods such as profilometry were used to obtain copper removal rates. Among the variety of organic compound tested, benzotriazole and salicylhydroxamic acid were identified as potential corrosion inhibitors for copper. The passive film formed on the copper surface by the addition of benzotriazole and salicylhydroxamic acid was characterized by X-ray photoelectron spectroscopy and atomic force microscopy. The passivation and repassivation kinetics were investigated in detail and a passivation mechanism for copper in hydroxylamine in the presence of benzotriazole and salicylhydroxamic acid chemistries is proposed. Copper removal experiments were performed on a specially designed electrochemical abrasion cell (EC-AC) in the presence and absence of inhibitors. The effect of anodic potentials on the dissolution of copper in various chemistries was studied to identify suitable conditions for electro-chemical mechanical planarization process. The extent of galvanic corrosion between copper and tantalum was estimated using electrochemical polarization measurements. A novel setup was designed to make direct measurement of the galvanic current between copper and tantalum and was successfully used to measure galvanic current in various chemical systems. CMP and post CMP cleaning operations account for almost twenty five percent of the total water usage at semiconductor fabrication plants. The waste water has to be treated to remove copper and unused oxidants and organic additives before it can be recycled or disposed. Fundamental studies on the treatment of copper CMP waste water using boron doped diamond electrodes was performed. The feasibility of copper deposition and organic oxidation was established and a design for a novel reactor is proposed.
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Zhang, Bo. "Development of corrosion resistant galvanising alloys." Thesis, University of Birmingham, 2005. http://etheses.bham.ac.uk//id/eprint/221/.
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In this work an investigation into the effect of alloying additions (Mn, Cu, Sb and Zr) on microstructure and corrosion of Zn alloys and hot dip galvanised coatings was undertaken. The first part of this thesis focuses on the effect of alloying additions on the corrosion of Zn alloys. The result shows that Mn is the most beneficial addition, which can significantly improve the resistance of Zn. The effect of Cu depends on its concentration. A high level of Cu addition has a deleterious effect on the corrosion resistance as the Cu-rich particles are catalytic cathodic sites for oxygen reduction. Additions of Zr and Sb were found to have minor effect on the corrosion behaviour of Zn alloys. The effect of these additions on the microstructure of hot dip galvanised coatings was investigated in the second part. Both Zr and Mn can inhibit the layer growth of active steels with high Si content. Thus, Mn and Zr might be an alternative addition to Ni which can control the excessive reaction of the active steels. Addition of 0.8 wt % Cu significantly increases the coating thickness of the galvanised steel containing 0.02 wt % Si. The growth kinetics of the alloy layers follows a linear law. The final part of this thesis focuses on the effect of these additions on the atmospheric corrosion resistance and electrochemistry of hot dip galvanised coatings. Among the alloying additions investigated in this study, Mn is the most beneficial addition to the Zn bath and can significantly improve the resistance of the hot dip galvanised coating to atmospheric corrosion. The effect of other additions on corrosion resistance is minor. The beneficial effect of Mn addition is mainly due to the formation of a Mn-rich oxide layer on the top surface during the galvanising process, which can greatly inhibit the cathodic reactivity of the hot dip galvanised coating. Coupled with the relatively low cost and ease of alloying of this element, these various factors suggest that Mn might have broader applications in general galvanising.
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Cavanaugh, Mary Katherine. "Modeling the Environmental Dependence of Localized Corrosion Evolution in AA7075-T651." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259702063.
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Seong, Jinwook. "Inhibition of Corrosion and Stress Corrosion Cracking of Sensitized AA5083." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429701294.
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Agaponova, Anna Vladimirovna. "ENCAPSULATION METHOD FOR SURFACE ENGINEERING OF CORROSION-RESISTANT ALLOYS BY LOW-TEMPERATURE NITRO-CARBURIZATION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1439576651.
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Konda, Krishnamurthy Krishna Vigneshwaran. "Corrosion Behavior of Steel in Deficient Grout with Enhanced Sulfate Ion Concentrations." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2456.
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Recent corrosion failures of tendons in Florida post-tensioned (PT) bridges utilizing low bleed specified grout products have shown the need for better understanding of the mechanisms that cause corrosion and to determine the extent of the problem in PT tendons with similar materials. Those deficient grouts in the tendons showed low chloride content below commonly assumed threshold limits for corrosion initiation, but they showed higher concentrations of sulfate ions, high pore water pH and higher moisture content. The role of enhanced sulfate ion concentrations in the development of steel corrosion in deficient grout has not been elucidated, but the role of sulfate ions in deficient grout with high moisture content may be comparable to the role of sulfate ions in alkaline solution.
The objectives of the research were to verify the role of sulfates but also to quantify sulfate content and introduce possible sulfate limits for corrosion development in various grout conditions. To examine the cause of corrosion failure, large-scale mockup tendons of about 15 feet long were cast using expired grout materials, an excess of 15% water mix water, and enhanced chloride and sulfate concentrations to create deficiencies and corrosion conditions in the grout environment. The tendons were cast at a 30-degree incline to produce segregated grout on the upper elevation. Steel probes were embedded in the tendons on varying heights and corrosion measurements were carried on these probes. The role of pH (12.5
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du, Plessis Andrew. "Studies on atmospheric corrosion processes in AA2024." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5642/.
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Atmospheric corrosion of aluminium alloy AA2024 was investigated using in situ synchrotron micro-tomography, which allows visualisation in a non-destructive manner in real time. The effect of atmospheric variables such as salt type, humidity, exposure time and salt deposition density on the corrosion rate was investigated. It was found that corrosion fissures grow along grain boundaries parallel to the rolling direction of the alloy, reaching a limiting depth, and then spread laterally. The volume of corrosion increases with salt density and relative humidity. Salt type has a limited effect on the volume of corrosion in microtomography measurements where the droplet is constrained at the top of a pin, but in parallel lab-based experiments on plate surfaces, it was found that NaCl and simulated ocean water droplets spread laterally, leading to increased corrosion owing to an increase cathodic area, whereas pure MgCh and CaCh droplets do not spread. Preliminary microtomography work on cycling the relative humidity showed transient increases in localised corrosion during wetting and drying phases, often associated with rapid growth of pmt of a localised cmTosion site, or initiation of new sites.
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Rangel, Julio Cesar Ferreira 1963. "Pipe wall damage morphology measurement methodology development for flow assisted corrosion evaluation." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/84750.
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Thesis (Nucl.E.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.Includes bibliographical references (leaves 103-110).
by Julio Cesar Ferreira Rangel.
S.M.
Nucl.E.
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Yu, Lun Ph D. Massachusetts Institute of Technology. "The environmental effect on corrosion fatigue behavior of austenitic stainless steels." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/120869.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
Corrosion fatigue is a multivariate challenge that threatens the lifetime of service of nuclear power plant materials, especially austenitic stainless steels. Both enhancement and retardation of crack growth have been observed in laboratory tests. This thesis work performs high temperature autoclave testing, post-test characterization and mechanistic modeling to understand the corrosion fatigue behavior of austenitic stainless steels in simulated light water reactor (LWR) environments. Crack growth rate (CGR) data were generated from the autoclave testing on low (0.001 wt.%) and high (0.03 wt.%) sulfur content heat 1T compact tension (CT) specimens. Tests were controlled under constant K (22-35 MPa [square root of]m) with load ratio of 0.7 and sawtooth waveform (85% rise vs. 15% fall), and at pH =10 and 288 °C with system pressure of 9.54 MPa. Crack enhancement was observed in low sulfur content heat specimens, and the CGR increases as the loading rise time increases. The fracture surfaces of low sulfur content heat specimens showed transgranular features with facets ("river pattern") and few oxide particles. Crack retardation was observed in high sulfur content heat specimens, and the CGR decreases as the loading rise time increases. The fracture surfaces of high sulfur content heat specimens showed distinct features at different rise time step. Transgranular features ("river pattern") were observed at short rise time step, while non-descript surfaces with fine octahedral oxide particles were observed at long rise time step. Additionally, tests in deuterium water were performed to enable measurements on hydrogen/deuterium concentrations in specimens using ToF-SIMS and hot vacuum extraction techniques. Deuterium pick-up from the testing environment was observed, and the enrichment of deuterium/hydrogen ahead of crack tip was also observed. Controlled experiments were also conducted, where specimens were baked prior to the autoclave testing to remove the residual internal hydrogen. Such heat treatment removing the internal hydrogen was found to not affect the crack growth behavior. Dissolved gases, hydrogen and argon respectively, were bubbled into system during the autoclave tests, and they resulted in similar crack growth behaviors. Modeling indicates that there exists an enhancement mechanism other than corrosion mass removal driving the crack growth in simulated LWR environments. Possibly it comes from the effect of corrosion-generated hydrogen. Retardation behavior and experimental observations could be understood and explained by concept and modeling of corrosion blunting. The results suggest excess conservatism of current ASME standards N-809 for high sulfur content austenitic stainless steels.
by Lun Yu.
Ph. D.
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Holmes, John W. (John Wendell) 1956. "Thermal fatigue oxidation and SO₂ corrosion of an aluminide-coated superalloy." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/14893.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaves 124-131.
by John W. Holmes.
Ph.D.
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Carr, James. "Surface Modification Techniques for Increased Corrosion Tolerance of Zirconium Fuel Cladding." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4474.
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Corrosion is a major issue in applications involving materials in normal and severe environments, especially when it involves corrosive fluids, high temperatures, and radiation. Left unaddressed, corrosion can lead to catastrophic failures, resulting in economic and environmental liabilities. In nuclear applications, where metals and alloys, such as steel and zirconium, are extensively em- ployed inside and outside of the nuclear reactor, corrosion accelerated by high temperatures, neu- tron radiation, and corrosive atmospheres, corrosion becomes even more concerning. The objec- tives of this research are to study and develop surface modification techniques to protect zirconium cladding by the incorporation of a specific barrier coating, and to understand the issues related to the compatibility of the coatings examined in this work. The final goal of this study is to recommend a coating and process that can be scaled-up for the consideration of manufacturing and economic limits.
This dissertation study builds on previous accident tolerant fuel cladding research, but is unique in that advanced corrosion methods are tested and considerations for implementation by industry are practiced and discussed. This work will introduce unique studies involving the materials and methods for accident tolerant fuel cladding research by developing, demonstrating, and consid- ering materials and processes for modifying the surface of zircaloy fuel cladding. This innova- tive research suggests that improvements in the technique to modify the surface of zirconium fuel cladding are likely.
Three elements selected for the investigation of their compatibility on zircaloy fuel cladding are aluminum, silicon, and chromium. These materials are also currently being investigated at other labs as alternate alloys and coatings for accident tolerant fuel cladding. This dissertation also investigates the compatibility of these three elements as surface modifiers, by comparing their mi- crostructural and mechanical properties. To test their application for use in corrosive atmospheres, the corrosion behaviors are also compared in steam, water, and boric-acid environments. Various methods of surface modification were attempted in this investigation, including dip coating, diffu- sion bonding, casting, sputtering, and evaporation. The benefits and drawbacks of each method are discussed with respect to manufacturing and economic limits. Characterization techniques utilized in this work include optical microscopy, scanning electron microscopy, energy-dispersive spec- troscopy, X-ray diffraction, nanoindentation, adhesion testing, and atomic force microscopy. The composition, microstructure, hardness, modulus, and coating adhesion were studied to provide en- compassing properties to determine suitable comparisons and to choose an ideal method to scale to industrial applications. The experiments, results, and detailed discussions are presented in the following chapters of this dissertation research.
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Lopez-Garrity, Omar A. "Corrosion Inhibition Mechanisms of Aluminum Alloy 2024-T3 by Selected non-Chromate Inhibitors." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372077968.
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SHIVANE, CHETAN. "ENVIRONMENT-FRIENDLY ANTI-CORROSION 'SUPERPRIMERS' FOR HDG." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1140205616.
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Skowronski, Natasha (Natasha C. ). "Telluridm-induced corrosion of structural alloys for nuclear applications in molten salts." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/115454.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2017.DISCLAIMER NOTICE: The pagination in this thesis reflects how it was delivered to the Institute Archives and Special Collections. Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 46-48).
The mechanism by which tellurium causes intergranular corrosion (IGC) of structural alloys in molten salt reactors is currently poorly understood. Limited corrosion testing has been performed on a few select alloys in simulated reactor conditions. In this thesis, the results of performing 50 h, 100 h, and 150 h corrosion tests on alloys Hastelloy N, Nickel-201, Incoloy 8ooH, and 316L Stainless Steel are presented. Upon inspection of the corroded surfaces of each alloy after its immersion in molten LiF-NaF-KF (FLiNaK) salt at 700 °C using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS), a consistent corrosion rate could not be determined for any of the alloys, nor could confident identification of telluride compounds within the corrosion layer or grain boundaries of any alloy be made. However, the results did appear to confirm the importance of using a low oxygen environment and avoidance of galvanic corrosion during testing. Furthermore, preliminary results from EDS analysis of one alloy sample implied that, with improved count rates taken during the elemental identification process, tellurium may be more clearly revealed in the corrosion layers and grain boundaries of the alloys tested.
by Natasha Skowronski.
S.B.
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Mginqi, Lungile Ngubekhaya. "Evaluation of stress corrosion cracking of high-nitrogen Cr-Mn stainless steel." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/17932.
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Includes bibliographical references.The stress corrosion cracking susceptibility of an experimental high nitrogen Cr-Mn stainless steel, known as Cromanite ™, and conventional AISI 304 stainless steel were investigated in order to compare their stress corrosion performance in solutions where AISI 304 stainless steel is known to be susceptible. Slow strain rate tests (SSRT) were performed on solution treated specimens a t30°C in aerated aqueous sodium chloride (NaCI) solution containing hydrochloric acid (HCI) of varying concentration at open circuit potentials. Static tests in the form of bent-beam tests were performed on both solution treated and aged specimens in 3M NaCI solution containing 0.05 M HCI. Potentiodynamic scans and Tafel plots were used to assess corrosion behaviour and corrosion rate respectively, while the electrochemical potentiokinetic reactivation (EPR) method was used to quantify the degree of sensitisation for the materials. The SSRT revealed poor corrosion behaviour of Cromanite TM in the presence of hydrochloric acid. Whilst AISI 304 could be examined for stress corrosion cracking at HCI concentrations up to 0.5 M HCI, Cromanite ™ exhibited corrosion rates which were too fast to permit assessment of stress corrosion susceptibility at HCI concentrations of 0.15 M or above. SCC started in a salt solution containing 0.05M HCI for AISI 304 while Cromanite TM cracked in both salt solution (3M NaCI) and in 0.05 M HCI +3M NaCI. The bent-beam test performed on solution treated specimens revealed no evidence of cracking for both alloys after 100 days of exposure; however, Cromanite ™ suffered substantial mass loss after this period. While aged Cromanite TM suffered intergranular cracking after only 25 days in the test solution, no cracking was observed for the aged AISI 304 after 75 days.
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Zhang, Wenping. "Formation and corrosion inhibition mechanisms of chromate conversion coatings on Al and AA2024-T3." Connect to this title online, 2002. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1037992955.
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Thesis (Ph. D)--Ohio State University, 2002.Title from first page of PDF file. Document formatted into pages; contains xv, 203 p.: ill. Includes abstract and vita. Advisor: Rudolph G. Buchheit, Dept. of Materials Science and Engineering. Includes bibliographical references (p. 192-203).
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Shittu, Jibril. "Tribo-Corrosion of High Entropy Alloys." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1752392/.
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In this dissertation, tribo-corrosion behavior of several single-phase and multi-phase high entropy alloys were investigated. Tribo-corrosion of body centered cubic MoNbTaTiZr high entropy alloy in simulated physiological environment showed very low friction coefficient (~ 0.04), low wear rate (~ 10-8 mm3/Nm), body-temperature assisted passivation, and excellent biocompatibility with respect to stem cells and bone forming osteoblast cells. Tribo-corrosion resistance was evaluated for additively manufactured face centered cubic CoCrFeMnNi high entropy alloy in simulated marine environment. The additively manufactured alloy was found to be significantly better than its as-cast counterpart which was attributed to the refined microstructure and homogeneous elemental distribution. Additively manufactured CoCrFeMnNi showed lower wear rate, regenerative passivation, less wear volume loss, and nobler corrosion potential during tribo-corrosion test compared to its as-cast equivalent. Furthermore, in the elevated temperature (100 °C) tribo-corrosion environment, AlCoCrFeNi2.1 eutectic high entropy alloy showed excellent microstructural stability and pitting resistance with an order of magnitude lower wear volume loss compared to duplex stainless steel. The knowledge gained from tribo-corrosion response and stress-corrosion susceptibility of high entropy alloys was used in the development of bio-electrochemical sensors to sense implant degradation. The results obtained herewith support the promise of high entropy alloys in outperforming currently used structural alloys in the harsh tribo-corrosion environment.
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Qin, Yang. "Grain Boundary Engineering for Improving Intergranular Corrosion resistance of Type 316 Stainless Steel." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1505210960237495.
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Cross, Samuel R. (Samuel Robert). "Computational modeling and design of multilayer corrosion coatings for galvanic protection of steel." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/103269.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, February 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 140-146).
Steels represent an economically vital class of alloys for use in structural applications, due to low cost and high strength and toughness, but often suffer from high susceptibility to corrosion in relevant environments. Use of metallic coatings, particularly zinc alloys, has long been a widely employed method for corrosion protection of steel, by acting both as a physical barrier to the aggressive environment, and providing sacrificial protection due to the preferential dissolution of the coating. Recent advances in processing techniques has permitted the efficient deposition of multilayer metallic coatings, which offer tremendous potential for dramatic improvements in performance relative to single layer coatings. However, development of multilayer corrosion coatings is hampered by a number of obstacles, in particular the lack of theoretical or computational tools to predict the corrosion behavior of multilayer coating structures. While existing numerical models for corrosion are well validated for simple geometries and short timescales, there are no models with demonstrated ability to be applied to composite materials such as multilayer coatings, or to incorporate the effects of corrosion damage over time on the effectiveness of the coating. This thesis seeks to address this deficiency through development and validation of two corrosion modeling techniques. The first modeling technique uses standard techniques for numerical modeling of galvanic corrosion to produce time-dependent corrosion simulations for multilayer or compositionally graded coatings, under the assumptions of completely generalized corrosion. The second modeling technique attempts to capture the effect of localized corrosion on multilayer coatings by treating the coating material as a porous electrode with properties calculated through an effective medium approximation. The output of the corrosion models is validated through comparison to a number of quantitative and qualitative corrosion tests on a variety of coatings, and is demonstrated to accurately capture a wide range of phenomena relevant to corrosion of multilayer thin films. Finally, this thesis demonstrates the potential application of the developed corrosion models as a design tool, by applying optimization techniques to determine coating configurations with maximized protective ability.
by Samuel R. Cross.
Ph. D.
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Attanasio, Steven A. 1967. "Corrosion and environmentally-assisted cracking of rapidly solidified neodymium-iron-boron permanent magnets." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/39748.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996.Vita.
Includes bibliographical references (p. 383-388).
by Steven A. Attanasio.
Ph.D.
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Fricano, Joseph William. "Chemical and structural analysis of grain boundaries in Inconel 690 for corrosion resistance." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53286.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 72-74).
Stress Corrosion Cracking (SCC) is a failure mechanism that results from the combination of tensile stress, corrosive environment and material susceptibility; it is frequently an intergranular attack. Material-environment combinations for SCC readily exist in nuclear power plants, and are critical for to the longevity of the reactor components. Inconel 690 (alloy 690 UNS N06690) is an alloy that has been put into service in the nuclear industry over the past 20 years due to its relatively good resistance to SCC. A new generation of nuclear plants is likely to be built in the US and the life of existing and new nuclear plants are expected to extend to 60-80 years. The study of alloy 690, as well as other structural metals, is important in order to understand, predict, and avert costly and dangerous failures that could occur due to SCC later in the life of the plants. The microstructure of an alloy has an important effect on its corrosion and SCC behavior. In particular, high energy grain boundary structures in austenitic Ni-base alloys and stainless steels have been shown to have greater SCC susceptibility. This thesis studies the fundamental structural and chemical properties of grain boundaries in alloy 690, to better understand the SCC resistances and susceptibilities of different grain boundary structures. In order to investigate the grain boundaries based on their structure, an integrated approach was developed to allow for site-specific chemical and mechanical characterization.
(cont.) The chemical analysis, which was the focus of this thesis, was accomplished using a Transmission Electron Microscope (TEM) for imaging and a Scanning Transmission Electron Microscope (STEM) with Energy Dispersive X-ray Spectroscopy (EDS) for elemental analysis. TEM samples from selected grain boundaries were prepared in a site-specific manner using a Focused Ion Beam (FIB). The mechanical analysis of the grain boundaries was accomplished through nanoindentation by a collaborator in the same research group. To identify grain boundaries of interest, for TEM sample creation by FIB or nanoindentation, the surface crystallographic structure was mapped using Orientation Image Microscopy (OIM). Microindents on the surface were utilized as fiduciary markers in the navigation of the surface. The three structures examined were low 1, low angle, and high angle grain boundaries. Boundaries were characterized in a: 1) solution annealed state, 2) Thermomechanically Processed (TMP) state consisting of a 5% compression followed by annealing at 10000 C with a water quench, 3) TMP state consisting of a 5% compression followed by annealing at 9500 C with a furnace cooling. Chemical composition differences, major element segregation or precipitation, were not found at grain boundaries in the solution annealed material or the TMP material that was water quenched. Cr-carbide precipitation was observed at the grain boundaries in the furnace cooled samples. The structural character and distribution of the carbides was dependent on structure of the host grain boundary.
(cont.) Low E grain boundaries exhibited a thin band of Cr-carbide on the boundary that was approximately 50 nm thick. On low angle grain boundaries, coarsened Cr-carbides were observed in semi-continuous form; with an average size of 230 nm. On high angle grain boundaries, further coarsening of the carbides resulted in a discontinuous distribution with an average precipitate size of 430 nm. Cr depletion occurred in the vicinity of the carbides; depletion was the most severe on high angle grain boundaries, down to 20wt-%. The suspected cause of the varying degree of coarsening of the Cr-carbides was the differences in diffusivity that control the kinetics of precipitation at the grain boundary. The "mean field" model for the coarsening of a distribution of carbides was used for quantitatively comparing the diffusivity of Cr at the high and low angle grain boundaries. The result indicated that diffusivity of Cr at high angle grain boundaries was an order of magnitude higher than at low angle grain boundaries, at the temperature of Cr-carbide formation 600-950' C. High angle grain boundaries have been shown to be the most susceptible to corrosion and SCC previously. The results of this work suggest that the higher diffusivity of Cr at the high angle boundaries of alloy 690 could contribute to SCC susceptibility through two mechanisms: 1) The coarser carbides, formed because of higher diffusivity, can more easily initiate microcracks if they are present. 2) The higher diffusivity leads to greater Cr redistribution, which could leave the boundary in a chemical state more prone to corrosion.
by Joseph William Fricano.
S.M.
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Huang, Xuejun Ph D. Massachusetts Institute of Technology. "Experimental and modelling studies of pit-to-crack transition under corrosion fatigue conditions." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113720.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 184-205).
Corrosion fatigue cracking is a material degradation mechanism which occurs when materials are under cyclic loading and in a corrosive environment. The joint effect of both mechanical and environmental factors makes it one of the most challenging topics in the study of material degradation. The corrosion fatigue cracking process can be separated into four phases, namely development of crack initiation sites (e.g. film breakdown, compositional inhomogeneity, processing variables), development of crack precursors (e.g. pit initiation/growth, grain boundary or localized corrosion), short crack growth and long crack growth. While the mechanism in the long crack growth regime is relatively well understood, the other three regimes are still the subject of much research. The primary goal of this project is to study the transition from the phase 2 to 3, specifically, initiation of cracks from a pit. The material under current investigation is X65 pipeline steel. A galvanostatic method was applied to artificially generate pits on a smooth surface of the material to produce a pitted specimen. The specimen was then cyclically loaded in four-point bending in air, NaCl solution and CO2-saturated NaCl solution at room temperature and 120°C. An alternating current potential drop (ACPD) system was developed and used to detect crack initiation from an existing pit and thus the incubation time to pit-to-crack transition was experimentally obtained. An autoclave system was built in order to apply the desired corrosive environment. Pit-to-crack transition has been successfully captured under fatigue loading and in the environments identified above. Results of experiments in different environments show that the pit-to-crack transition is dominated by a combination of mechanical factors and corrosion processes that facilitate subsequent crack initiation and growth by promoting microstructural barrier removal. A finite element isotropic model with kinematic hardening has been developed to simulate local fatigue ratcheting around the pit up to large strain levels. An approximate value for the plastic strain level at crack initiation was experimentally determined using electron backscatter diffraction (EBSD) techniques. Given the critical strain level, the model can be used to predict the number of cycles of pit-to-crack transition. Based on the experimental and modelling results, the underlying mechanism of pit-to-crack transition under current test conditions is proposed to be local ratcheting around the pit that provides sufficient strain accumulation when coupled to an appropriate corrosive environment. This combination provides the necessary crack "precursors". Environmental effects on crack propagation are also identified and discussed.
by Xuejun Huang.
Ph. D.
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Zhu, Yakun. "Integrated modeling of mixed surfactants distribution and corrosion inhibition performance in oil pipelines." Thesis, The University of Utah, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10010817.
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Among the existing corrosion control methods, surfactant inhibitors have widely been used for corrosion inhibition of pipelines in water-oil-steel pipe (WOS) environments. This dissertation includes a systemic review of the causes of pipeline corrosion in WOS environments containing carbon dioxide (CO2), general corrosion control using surfactant inhibitors and associated concerns, and commonly used classes of surfactants and their properties, various processes and phenomena that affect overall surfactant performance. This dissertation also provides a review of experimental evaluation techniques and various developed models (semi-empirical model, mechanistic model, and multiphysics model) in evaluation of surfactant inhibition efficiency. An integrated corrosion inhibition (ICI) model is proposed, developed, and validated based on the current understanding of the inhibition of CO2 corrosion in WOS environments using surfactants. The developed ICI model for the modeling and prediction of corrosion inhibition efficiency of mixed surfactant inhibitors is a multiphysics model, based on the fundamentals from many areas of corrosion science, electrochemistry, metallurgical engineering, and chemical and analytical engineering, etc., and the integration of several submodels, including a water-oil surfactant distribution submodel, the aqueous cmc prediction submodel, and the modified Langmuir adsorption (MLA)/ modified quantitative structure activity relation (MQSAR) submodel. Software is developed based on the ICI model and the use of computational and programming resources. The phenomena and processes integrated into the ICI model include surfactant partitioning between oil and water, micellization and precipitation, adsorption/desorption at surfaces and interfaces, surfactant-solvent interactions, surfactant-counterion pairing, lateral interactions between surfactant molecules, and fluid flow. These phenomena are incorporated into three main processes and associated modeling: partitioning between oil and water, micellization/precipitation, and effective adsorption on metal substrate and water/oil interface. The framework of multiphysics ICI model is intended to serve as a basic framework in the understanding of mixed surfactant inhibitor performance with a focus on the application in salt-containing WOS environments. Beyond this, other potential applications may be extended to the design of surfactants, selection of optimal surfactants for specific applications, experimental validation of developed models, simulation of conceivable processes and phenomena, and the integration into more comprehensive lifetime prediction models in which all the surfactant efficiency-affecting factors may be evaluated.
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Espartero, Jennifer C. "Polymeric Materials for Corrosion Protection in Geothermal Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1427901218.
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Miller, Jacob T. "Sulfuric Acid Corrosion to Simulate Microbial Influenced Corrosion on Stainless Steel 316L." Youngstown State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ysu151621775594905.
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Weimer, William Eugene. "Corrosion of Magnesium, Aluminum, and Steel Automotive Sheet Metals Joined by Steel Self-Pierce Rivets." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420818436.
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Li, Sirui. "A Study of Corrosion Monitoring Techniques Used in URLs for Metals." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6624.
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With the increasing use of fission-type nuclear power generation, particularly high-levels radioactive nuclear waste are generated, so the safe use of nuclear energy requires proper disposal of high-level radioactive nuclear waste. The selected treatment method is deep geological disposal. Therefore, underground research laboratory (URL) to prepare for deep geological disposal will also be carried out. Corrosion of metallic materials, which are closely related to the safety of URL, is the focus of this research project. This study selected monitoring techniques for URL and developed a rough monitoring scheme for temperature and resistivity in URL. In this study, corrosion-temperature and corrosion-resistivity monitoring experiments were carried out in different bentonite samples to simulate the experiments in URL. The results show that the self-compensating high-precision inductance corrosion monitoring system and multifunction soil corrosion rate measurer proved to be a good system for monitoring the corrosion-temperature and corrosion-resistivity of metals. However, the life span limitation makes them unable to meet the requirements of URL. The results also show that the corrosion rate of metal in bentonite is positively correlated with temperature. The existing electrochemical probes are suitable for monitoring the corrosion rate, but not suitable for soil corrosion rate monitoring.
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Qin, Peng. "Corrosion behavior of titanium-based materials produced by selective laser melting." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2018. https://ro.ecu.edu.au/theses/2113.
Full textAbstract:
Recently, the additive manufacturing techniques (e.g., selective laser melting and electron beam melting) have attracted great attention in manufacturing titanium and titanium alloys because the additive manufacturing techniques could produce parts with almost no geometric constraints. Many researchers have studied the mechanical properties of additive manufactured titanium and titanium alloys, and the results indicated that the additive manufactured titanium and titanium alloys have different degrees on enhanced mechanical properties compared with the alloy manufactured by traditional methods. However, the titanium alloys in applications usually encounter the environment of corrosion, such as biomedical, aerospace, chemical implants, etc. Unfortunately, rare studies have addressed the corrosion behavior of the additive manufactured titanium products. The present corrosion studies on additive manufactured titanium alloys show that the α’ phase presented in the selective laser melted samples has a detrimental effect on the corrosion resistance in simulated seawater and simulated human body fluids. Even the α’ phase in the selective laser melted titanium alloys was eliminated by heat treatment, the selective laser melted titanium alloys still show inferior corrosion resistance in simulated seawater and human body fluids compared to the counterparts produced by traditional methods. By contrast, the electron beam melted titanium alloy have a slightly better corrosion resistance than the wrought sample as the microstructure of electron beam melted titanium alloy only contain α phase and β phase. Therefore, the current issue is arising and to whether the unique phase produced by selective laser melted titanium alloys affect the corrosion resistance? By overviewing the current literature, the corrosion study of the additive manufactured titanium alloys are mainly focused on the Ti-6Al- 4V, CP-Ti, and Ti-Al alloys but rare research on the other titanium alloys.
In this thesis, the corrosion behavior of Ti-5Cu and Ti-24Nb-4Zr-8Sn produced by the selective laser melting has been systematically investigated and discussed. The electrochemical testing methods, such as open circulate potential, electrochemical impedance spectroscopy, and potentiodynamic polarization curve has been employed. Transmission electron microscopy, scanning electron microscopy, optical microscopy, and X-ray diffraction has been jointly used to characterize the microstructure and surface morphology of the samples. The inductively coupled plasma has been applied to examine the released ions in the electrolyte after electrochemical corrosion tests. The selective laser melted Ti-5Cu has a severe pitting phenomenon which can be alleviated by heat treatment. The heat-treated Ti-5Cu samples produced by selective laser melting exhibit a significant passivation behavior instead of pitting phenomenon in potentiodynamic polarization test. Such a phenomenon is attributed to that the present α’ phase in melting pool boundary forms a galvanic couple, causing severe pitting corrosion. In another study, the selective laser melted Ti-24Nb-4Zr-8Sn and wrought Ti-24Nb-4Zr-8Sn only contain single β phase and they display similar corrosion results. The above results suggest that the selective laser melted titanium alloys have a great potential to replace the conventionally manufactured titanium alloys in the simulated seawater environment and simulated body fluid environment.
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Mohamed, Mohd Farid. "Water Chemistry and Corrosion Inhibition in High Pressure CO2 Corrosion of Mild Steel." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1429223819.
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Orzalli, John Clarke. "Preliminary corrosion studies of candidate materials for supercritical water oxidation reactor systems." Thesis, Springfield, Va. : Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283845.
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Akhoondan, Mersedeh. "Corrosion Evaluation and Durability Estimation of Aluminized Steel Drainage Pipes." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4273.
Full textAbstract:
Aluminized steel pipes are expected to have a long service life, e.g. 75 years. Spiral ribbed aluminized pipes (SRAP) have been widely specified and used by the Florida Department of Transportation (FDOT) for drainage of runoff water. Confidence in the long term durability of SRAP has been challenged by recent unexpected early corrosion failures in various Florida locations. SRAP premature corrosion incidents have occurred in two modalities. Mode A has taken place in near-neutral soil environments and has often been associated with either gross manufacturing defects (i.e. helical cuts) or corrosion concentration at or near the ribs. Mode B took place in pipes in contact with limestone backfill and corrosion damage was in the form of perforations, not preferentially located at the ribs, and not necessarily associated with other deficiencies. These failures motivated this research. The objectives of this work are to establish to what extent the Mode A corrosion incidents can be ascribed to manufacturing defects, that can be rectified by appropriate quality control, as opposed to an intrinsic vulnerability to corrosion of regularly produced SRAP due to ordinary forming strains and to determine the mechanism responsible for Mode B corrosion including the role that limestone backfill played in that deterioration. To achieve those objectives, laboratory experiments were conducted to replicate the conditions for Mode A and Mode B. Overall, the findings of this and previous work suggest that much of the corrosion damage observed in the Mode A incidents were promoted more by manufacturing deficiencies and less by any possible inherent susceptibility of corrosion at the ribs of SRAP that was produced following appropriate quality control. Experiments to explore the causes of Mode B corrosion showed that high pH values, sufficient to cause dissolution of the passive film on aluminum, can develop under exposure of limestone to flowing natural water. The findings substantiate, for the first time, an important vulnerability of aluminized steel in limestone soils and provide an explanation for the rapid onset deterioration observed at the field under Mode B. The findings also provide strong evidence in support of service guidelines to disallow the use of limestone bedding for aluminized steel pipe, including SRAP.
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Kim, Hojong 1974. "An investigation of corrosion mechanisms of constructional alloys in supercritical water oxidation (SCWO) systems." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16636.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.Includes bibliographical references (leaves 179-186).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Supercritical water oxidation (SCWO) is a technology that can effectively destroy aqueous organic waste above the critical point of pure water. These waste feed streams are very aggressive and pose material performance issues. As potential alloys in construction of SCWO systems, nickel-base alloys are tested. Corrosion in aqueous feed streams of ambient pH values of 2, 1 and 7 is studied both at supercritical (-425⁰C) and subcritical (-300-360⁰C) temperatures with a constant pressure of 24.1MPa. Dealloying of Ni and Fe, and oxidation of Cr and Mo are observed at subcritical temperatures at a pH value of 2. At a pH value of 1, even chromium is selectively dissolved and only molybdenum forms a stable oxide at the subcritical temperature. At supercritical temperatures, normal thin oxidation occurs at both pH values of pH 2 and 7. In contrast, in the neutral pH solution, dealloying is not observed at any temperature. Stress corrosion cracking (SCC) in acidic feed streams is observed both at the supercritical and subcritical temperatures. In order to understand the corrosion mechanisms, the chemistry of a feed stream, the formation of the dealloyed oxide layer, and the level of stress are investigated.
(cont.) The suppression of dealloying at supercritical temperatures comes from the low proton concentration associated with the low dissociation constant of HCl and water. However, the growth rate of the dealloyed oxide layer at subcritical temperatures is very fast, which is primarily due to the dealloying and the high diffusivity of the nickel in this defective oxide layer. SCC at subcritical temperatures results from the dealloyed oxide layer formation along the grain boundary as intrusions, which act as a precursor to the crack initiation and propagation. SCC at the supercritical temperature is thought to result from the direct chemical attack of associated HC1 molecules. SCC is not observed in the neutral solution.
by Hojong Kim.
Ph.D.
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Lim, Jeongyoun. "Effects of chromium and silicon on corrosion of iron alloys in lead-bismuth eutectic." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41288.
Full textAbstract:
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.Includes bibliographical references.
The high power densities and temperatures expected for next generation nuclear applications, including power generation and transmutation systems, will require new types of heat transport systems to be economic. Present interest in heavy liquid metal coolants, especially in lead and lead-bismuth eutectic, originates from such requirements as increased heat removal capacity and enhanced safety features. However, corrosion of structural metals represents a major limiting factor in developing advanced liquid Pb-alloy coolant technology. In fact, the development of advanced structural and cladding alloys that are resistant to corrosion over a wide range of oxygen potentials in this environment would represent the enabling technology for these systems. The goal of this research was to develop a class of Fe-Cr Si alloys that are resistant to corrosion in Pb and Pb alloys at temperatures of 6000C or higher. As a necessary part of this development effort, an additional goal was to further develop the fundamental understandings of the mechanisms by which corrosion protection is achieved. A series of alloys based on the Fe-Cr-Si system were proposed as potential candidates for this application. These alloys were then produced and evaluated. The results of this evaluation verified the hypothesis that an Fe alloys with suitable levels of Cr (>12 wt%) and Si (> 2.5 wt%) will be protected by either a tenacious oxide film (over a wide range of oxygen potentials above the formation potential for Cr and Si oxides) or by a low solubility surface region (at low oxygen potentials) Experimental results obtained from model alloys after lead-bismuth eutectic exposure at 6000C demonstrated the film formation process.
(cont.) The hypothesis that Si addition would promote the formation of a diffusion barrier was confirmed by the actual reduction of oxide thickness over time. The Si effect was magnified by the addition of Cr to the system. Based on a kinetic data assessment on the experimental results of Fe-Si and Fe-Cr-Si alloys, the synergetic alloying effect of Cr and Si was revealed. An improved understanding on the kinetic process and its dependence on the alloying elements has been achieved.
by Jeongyoun Lim.
Sc.D.
42
Sydnor, Christopher R. (Christopher Russell) 1975. "General reviews of electrochemical and corrosion phenomena under conditions associated with supercritical water oxidation." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/58166.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002.Leaves 87 and 88 blank.
Includes bibliographical references.
Supercritical Water Oxidation (SCWO) is a promising technology for destroying highly toxic organic compounds present in aqueous waste streams. Organic wastes that have been identified as possible targets for destruction by SCWO include EPA-regulated organic wastes, organic components of DOE mixed low-level radioactive wastes, and DOD chemical weapons stockpiles. SCWO capitalizes on the properties of water in the supercritical phase to affect spontaneous and rapid oxidation of hydrocarbons to form CO2, H2O, and, depending on the species of heteroatom present in the organic waste, one or more acids. HCl, H2SO4, and H3PO4 are the acids most frequently encountered in SCWO process streams. The formation of acids in SCWO feeds at high temperatures and pressures under highly oxidizing conditions leads to severe corrosion of the process unit for even the most corrosion resistant constructional alloys. Currently, the existence of a constructional material that can withstand the extremely aggressive conditions present in all sections of the SCWO process stream for all candidate organic wastes is extremely unlikely. Previous attempts to identify such materials have proved unsuccessful. This has led to more fundamental research addressing physical chemistry, electrochemistry, and corrosion phenomena in aqueous systems under hydrothermal conditions. This review addresses this research as it pertains to SCWO technology, and based on these findings, discusses potential methodologies for reducing corrosion damage in SCWQ systems. Currently, it appears that proper selection and/or development of construction materials in conjunction with precise control of feed stream chemistry may be a promising option for corrosion control in SCWO process environments.
by Christopher R. Sydnor.
S.M.
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Wallace, Suzanne L. (Suzanne Lin) 1975. "The correlation of electrochemical and magnetic techniques for use in characterization of underfilm corrosion." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/84761.
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Bafna, Shakhar M. "Environmentally-Friendly Polyurethane-Silane Superprimer for Corrosion Protection of AA2024-T3." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1171480907.
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Cotterrell, M. H. "The influence of water composition on the pitting behaviour of newly developed corrosion resistant steels." Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/21134.
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Bibliography: pages 96-103.The mechanisation of the working stapes in South African gold mines has required the introduction of a fundamentally new technology, hydro-power, in which machines are powered hydraulically using mine water fed from above ground. Mine water is aggressive and has a variable acidity and pH, and contains high concentrations of sulphate, chloride and nitrate ions. In order to minimise the pitting corrosion of piping and stoping machinery a compromise between selecting a suitable corrosion resistant material and treating the mine water to an acceptable level of corrosiveness is being sought.
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ZHU, DANQING. "CORROSION PROTECTION OF METALS BY SILANE SURFACE TREATMENT." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1115992852.
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Dehghanghadikolaei, Amir. "Enhance its Corrosion Behavior of Additively Manufactured NiTi by Micro-Arc Oxidation Coating." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1525475381922659.
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Sanchez, Andrea Nathalie. "Forecasting Corrosion of Steel in Concrete Introducing Chloride Threshold Dependence on Steel Potential." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5303.
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Corrosion initiates in reinforced concrete structures exposed to marine environments when the chloride ion concentration at the surface of an embedded steel reinforcing bar exceeds the chloride corrosion threshold (CT) value. The value of CT is generally assumed to have a conservative fixed value ranging from 0.2% to - 0.5 % of chloride ions by weight of cement. However, extensive experimental investigations confirmed that CT is not a fixed value and that the value of CT depends on many variables. Among those, the potential of passive steel embedded in concrete is a key influential factor on the value of CT and has received little attention in the literature. The phenomenon of a potential-dependent threshold (PDT) permits accounting for corrosion macrocell coupling between active and passive steel assembly components in corrosion forecast models, avoiding overly conservative long-term damage projections and leading to more efficient design. The objectives of this investigation was to 1) expand by a systematic experimental assessment the knowledge and data base on how dependent the chloride threshold is on the potential of the steel embedded in concrete and 2) introduce the chloride threshold dependence on steel potential as an integral part of corrosion-related service life prediction of reinforced concrete structures. Experimental assessments on PDT were found in the literature but for a limited set of conditions. Therefore, experiments were conducted with mortar and concrete specimens and exposed to conditions more representative of the field than those previously available. The experimental results confirmed the presence of the PDT effect and provided supporting information to use a value of -550 mV per decade of Cl- for the cathodic prevention slope βCT, a critical quantitative input for implementation in a practical model. A refinement of a previous corrosion initiation-propagation model that incorporated PDT in a partially submerged reinforced concrete column in sea water was developed. Corrosion was assumed to start when the chloride corrosion threshold was reached in an active steel zone of a given size, followed by recalculating the potential distribution and update threshold values over the entire system at each time step. Notably, results of this work indicated that when PDT is ignored, as is the case in present forecasting model practice, the corrosion damage prediction can be overly conservative which could lead to structural overdesign or misguided future damage management planning. Implementation of PDT in next-generation models is therefore highly desirable. However, developing a mathematical model that forecasts the corrosion damage of an entire marine structure with a fully implemented PDT module can result in excessive computational complexity. Hence, a provisional simplified approach for incorporating the effect of PDT was developed. The approach uses a correction function to be applied to projections that have been computed using the traditional procedures.
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Cain, Robert J. "Aqueous Processing of Corrosion Inhibiting Hybrid Nanocomposite Bulk Coating." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1138375716.
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Price, Capri Ann. "Early Detection of Corrosion via Hydrogel-based Spectroelectrochemical Sensors." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4637.
Full textAbstract:
The backbone of the industrialized world is comprised of refined, zerovalent metal, a material which thermodynamically favors an oxidative return to more chemically stable states. There are many methods used to slow or delay this process, such as protective coatings, sacrificial anodes, and alloys, but no method can entirely prevent corrosion. This body of work instead proposes detecting the earliest chemical markers of corrosion: that is, metal ions as they solubilize from a metal surface. Such information would allow maintenance personnel to make informed decisions about the necessity or lack thereof of preventive maintenance, and intervene before advanced damage has a chance to occur.
This dissertation finds that hydrogel-based sensors are capable of such detection and offer a multisensory response, with colorimetric, electrical, volumetric and vibrational changes. Both the colorimetric and electrical trends were calibrated and used for quantification of metal ions both in solution and directly from metal substrate surfaces. Observing how the hydrogels responded to various metal ions contributed to a greater understanding of how ion-headgroup associations can affect the sensory responses of a hydrogel, something that can be exploited in future sensor work. The ability of the sensors to detect ions directly from metal surfaces allowed for an investigation of the protective quality of fatty acids as corrosion inhibitors. A range of chain lengths were tested using the hydrogels, and the comparison to current characterization techniques showed good correlation. This accessible technique, beyond contributing to the current meager literature of fatty acids as corrosion inhibitors, can also allow for the determination of acceptable benchmarks of corrosion, information that is sorely needed to efficiently steward global infrastructure.