250 Matching Results

Search Results

Advanced search parameters have been applied.

Interim report on interaction of waste glass colloids with corrosion products

Description: Thermodynamic data for aqueous reactions of key radionuclides are needed for geochemical modeling studies of the Yucca Mountain Project. This report summarizes progress through February 1999 in a study of waste glass colloid interaction with corrosion product solids. The purpose of the present task is to investigate more directly the exchange behavior of the Pu associated with the waste glass colloids. The goal is to obtain results that will be used to improve models of colloidal transport of Pu from the repository. The major experimental subtasks are (1) synthesis of waste glass colloidal suspensions and (2) batch experiments in which the suspensions are equilibrated with Fe<sub>2</sub>O<sub>3</sub> solids of defined particle size.
Date: February 26, 1998
Creator: Wruck, D A
Partner: UNT Libraries Government Documents Department


Description: As directed by a written development plan (CRWMS M&amp;O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.
Date: December 2, 1999
Creator: Jolley, D.M.
Partner: UNT Libraries Government Documents Department

Failure Prevention by Short Time Corrosion Tests

Description: Short time corrosion testing of perforated sheets and wire meshes fabricated from Type 304L stainless steel, Alloy 600 and C276 showed that 304L stainless steel perforated sheet should perform well as the material of construction for dissolver baskets. The baskets will be exposed to hot nitric acid solutions and are limited life components. The corrosion rates of the other alloys and of wire meshes were too high for useful extended service. Test results also indicated that corrosion of the dissolver should drop quickly during the dissolutions due to the inhibiting effects of the corrosion products produced by the dissolution processes.
Date: May 1, 2005
Partner: UNT Libraries Government Documents Department

Modeling the Effects of Crevice Former, Particulates , and the Evolving Surface Profile in Crevice Corrosion

Description: Crevice corrosion may initiate in confined regions due to transport limitations, followed by an accumulation of a highly corrosive chemistry, capable of dissolving the metal. The metal and the crevice former surface roughness, the presence of particulates under the crevice former and the accumulation of solid corrosion products at the corroding site would significantly affect the current and potential distribution at the anode by increasing the ohmic potential drop. Most crevice corrosion models focus on a smooth walled crevice of uniform gap and do not account for the changing profile after crevice corrosion has been initiated. In this work we analyze the crevice (anodic) region and apply current and potential distribution models to examine the effects of the perturbed surface topography. The analysis focuses on three related issues: (1) the effects of surface roughness of the metal and the crevice former, (2) the effects of particulates under the crevice former, and (3) the evolution of the crevice profile with corrosion product accumulation at the active, anodic region.
Date: December 21, 2006
Creator: Agarwal, A.S.; Landau, U.; Shan, X. & Payer, J.H.
Partner: UNT Libraries Government Documents Department

Examination of Corrosion Products and the Alloy Surface After Crevice Corrosion of a Ni-Cr-Mo- Alloy

Description: The objective of this study is to investigate the composition of corrosion products and the metal surface within a crevice after localized corrosion. The analysis provides insight into the propagation, stifling and arrest processes for crevice corrosion and is part of a program to analyze the evolution of localized corrosion damage over long periods of time, i.e. 10,000 years and longer. The approach is to force the initiation of crevice corrosion by applying anodic polarization to a multiple crevice assembly (MCA). Results are reported here for alloy C-22, a Ni-Cr-Mo alloy, exposed to a high temperature, concentrated chloride solution. Controlled crevice corrosion tests were performed on C-22 under highly aggressive, accelerated condition, i.e. 4M NaCl, 100 C and anodic polarization to -0.15V-SCE. The crevice contacts were by either a polymer tape (PTFE) compressed by a ceramic former or by a polymer (PTFE) crevice former. Figure 1 shows the polarization current during a crevice corrosion test. After an incubation period, several initiation-stifle-arrest events were indicated. The low current at the end of the test indicated that the metal surface had repassivated.
Date: June 9, 2006
Creator: Shan, X. & Payer, J.H.
Partner: UNT Libraries Government Documents Department

Comparison of Ceramic, Metal and Polymer Crevice Formers on the Crevice Corrosopn Behavior of Ni-CR-Mo Alloy C22

Description: A necessary condition for crevice corrosion is that a crevice former create a sufficiently tight, restricted geometry on the metal surface to support the development of critical crevice chemistry. Crevice corrosion is affected by the crevice geometry (tightness) and the properties of the crevice former. The objective of this study is to determine the effect of the crevice former material on the evolution of localized corrosion-damage. A standard crevice corrosion test method is modified by (a) the use of ceramic, metal or polymer materials as the crevice former and (b) the variation of size and shape of the crevice. This study focuses on the post initiation stage of crevice corrosion and addresses factors that may limit the initiation of localized corrosion and also slow or stop the continued propagation of corrosion. Controlled crevice corrosion tests are performed under aggressive, accelerated conditions on Ni-Cr-Mo alloy C-22 and other alloys for comparison. Multiple techniques are used to examine the crevice corrosion damage evolution. Current measurements during the test provide a direct measure of the corrosion rate and indicate the initiation and any stifling or arrest. The localized corrosion is found to be stifled or arrested under several test conditions. The corrosion damage volume and profile are quantitatively measured with optical and SEM 3D reconstruction methods. Analysis by SEMIEDS, XPS and AES show that the corrosion products within the damaged crevice area are enriched in W, Mo, 0 , while being depleted in Cr, Ni, Fe. The results on C-22, SS3 16 and other alloys show that a PTFE tape covered ceramic was the most active crevice former, solid polymer crevice formers (PTFE or Kel-F) are less active, while no distinguishable crevice corrosion was observed with a ceramic material only as the crevice former in direct contact with the metal. The affects are ...
Date: May 8, 2006
Creator: Shan, X. & Payer, J.H.
Partner: UNT Libraries Government Documents Department


Description: Pipelines present a unique challenge to monitoring because of the great geographical distances they cover, their burial depth, their age, and the need to keep the product flowing without much interruption. Most other engineering structures that require monitoring do not pose such combined challenges. In this regard, a pipeline system can be considered analogous to the blood vessels in the human body. The human body has an extensive ''pipeline'' through which blood and other fluids are transported. The brain can generally sense damage to the system at any location and alert the body to provide temporary repair, unless the damage is severe. This is accomplished through a vast network of fixed and floating sensors combined with a vast and extremely complex communication/decision making system. The project described in this report mimics the distributed sensor system of our body, albeit in a much more rudimentary fashion. Internal corrosion is an important factor in pipeline integrity management. At present, the methods to assess internal corrosion in pipelines all have certain limitations. In-line inspection tools are costly and cannot be used in all pipelines. Because there is a significant time interval between inspections, any impact due to upsets in pipeline operations can be missed. Internal Corrosion Direct Assessment (ICDA) is a procedure that can be used to identify locations of possible internal corrosion. However, the uncertainties in the procedure require excavation and location of damage using more detailed inspection tools. Non-intrusive monitoring techniques can be used to monitor internal corrosion, but these tools also require pipeline excavation and are limited in the spatial extent of corrosion they can examine. Therefore, a floating sensor system that can deposit at locations of water accumulation and communicate the corrosion information to an external location is needed. To accomplish this, the project is divided into four main ...
Date: October 31, 2005
Creator: Sridhar, Narasi; Tormoen, Garth & Sabata, Ashok
Partner: UNT Libraries Government Documents Department

Atmospheric Corrosion of Aluminum Alloy 3105 in Coastal Environments: Interim Report After 15 Months Exposure

Description: In May of 1994, racks of corrosion samples were installed along the Oregon coast. The aluminum alloy 3105 samples were mounted on utility poles in Astoria, Manzanita, Lincoln City, Gold Beach, Brookings, Portland, and Albany. At each coastal location, samples were placed on four different poles at various distances from the coast (from as near as 50 feet to as far as 5 miles). The inland sites (Portland and Albany) have only one pole per site and are used as control sites. Besides the 3105 alloys, 5052 and 6061 aluminum alloys were placed at all sites. Since installation, one rack was lost due to the pole being taken down by the phone company (in Lincoln City), but the rest of the poles and racks are still in place.&lt;br&gt; &lt;br&gt; In August of 1995, the aluminum samples were visually inspected, and the remaining six 3105 aluminum samples in Lincoln City were removed for laboratory examination. Non-destructive x-ray analysis was used on the Lincoln City samples to obtain information a bout the nature of the corrosion products. Because the analysis was performed while the corrosion products remained on the surface, aluminum peaks dominated the diffraction pattern, and relative peak-heights were different from normal. Nevertheless, some minerals were identified as part of the corrosion products.
Date: April 19, 1996
Creator: Holcomb, G. R.
Partner: UNT Libraries Government Documents Department

Long Term Oxidation of Model and Engineering TiAl Alloys

Description: The purpose of this research was to characterize the oxidation behavior of several model (TiAl, TiAl-Nb, TiAl-Cr, TiAl-Cr-Nb) and engineering alloys (XD, K5, Alloy 7, WMS) after long-term isothermal exposure ({approx}7000 h) at 704 C, and after shorter time exposure ({approx}1000 h) at 800 C in air. High-resolution field emission and microprobe scanning electron microscopy were used to characterize the scales formed on these alloys. Similarities and differences observed in the scales are correlated with the various ternary and quaternary microalloying additions.
Date: August 24, 2001
Creator: Locci, IE
Partner: UNT Libraries Government Documents Department

Support Services for Ceramic Fiber-Ceramic Matrix Composites

Description: To increase national energy self-sufficiency for the near future, power systems will be required to fire low-grade fuels more efficiently than is currently possible. The typical coal-fired steam cycle used at present is limited to a maximum steam temperature of 540 C and a conversion efficiency of 35%. Higher working-fluid temperatures are required to boost efficiency, exposing subsystems to very damaging conditions. Issues of special concern to materials developers are corrosion and warping of hot-gas particulate filters and corrosion and erosion of high-temperature heat exchangers. The University of North Dakota Energy and Environmental Research Center (EERC) is working with the National Energy Technology Laboratory in conjunction with NCC Engineering, Inc., to provide technical assistance and coal by-products to the Fossil Energy Materials Advanced Research and Technology Development Materials Program investigating materials failure in fossil energy systems. The main activities of the EERC are to assemble coal slag and hot-gas filter ash samples for use by materials researchers, to assist in providing opportunities for realistic tests of advanced materials in pilot-scale fossil energy systems, and to provide analytical support in determining corrosion mechanisms of the exposed materials. In this final report for the project year of September 2000 through August 2001, the facilities at the EERC that can be used by researchers for realistic testing of materials are described. Researchers can include sample coupons in each of these facilities at no cost since they are being operated under separate funding. In addition, two pilot-scale coal combustion tests are described in which material sample coupons were included from researchers involved in the development of fossil energy materials. The results of scanning electron microscopy (SEM) energy dispersive x-ray analyses of the corrosion products and interactions between the surface scales of the coupons and the products of coal combustion found on the coupons exposed ...
Date: August 16, 2001
Creator: Hurley, JP
Partner: UNT Libraries Government Documents Department

Auger parameter determination of bonding states on thinly oxidized silicon nitride

Description: Silicon nitride powders have been thermally oxidized between 700 and 1,200 C in a high purity N{sub 2}--20% O{sub 2} gas environment. The powders were subsequently analyzed by x-ray photoelectron and Auger electron spectroscopy for evidence of oxynitride surface states. Measurements were made on the Si 2p, O 1s, N 1s, C 1s, F 1s, and Si KLL transitions, the latter being obtained using bremsstrahlung radiation from the Mg x-ray source. As a function of increasing temperature the data show a clear progression of spectral binding energies and peak shapes that are indicative of more advanced surface oxidation. However, definitive analysis of these data rests on the combined use of both Auger and photoelectron data to define the oxidized surface states for a system that involves two electrically insulating end states, silicon nitride and silicon dioxide. Curve fitting the Si 2p and Si KLL transitions as a function of oxidation, coupled with use of Auger parameters for the starting silicon nitride and final silicon dioxide, reveals no measurable evidence for an interphase oxynitride in the thin oxide scales of this study, where the silicon nitride substrate is detectable. Possible incorrect assignment of oxynitride bonding, from shifted Si 2p states in the carbon referenced spectra, is attributable to band bending as the transition is made from incipient to fully formed silicon dioxide.
Date: October 1, 1997
Creator: Taylor, T.N.; Butt, D.P. & Pantano, C.G.
Partner: UNT Libraries Government Documents Department

The oxidation behavior of SiC sintered with Al-B-C and improved oxidation resistance via heat treatments

Description: The oxidation behavior of high strength and high toughness SiC, sintered with Al, B, and C (ABC-SiC), was examined. Kinetic data were acquired and the parabolic rate constant for oxidation was determined and compared with literature data on various SiC materials. The role of secondary phases on the oxide morphology was explored. ABC-SiC was compared to commercially available SiC, Hexoloy, and SiC sintered with 10% yttrium aluminum garnet (YAG). Two-step sintering (pre-coarsening) was employed with holds for 48 hours at 600--1,600 C, prior to the typical hot-pressing conditions of 1,900 C for 1 hour, to change the chemistry and reduce the number of bubbles in the silica scale. The effects on the oxide thickness and integrity was examined as a function of the precoarsening heat treatment temperature. Additionally, the hot-pressed ABC-SiC was subjected to heat treatments (anneals) at 1,800 C for 1 hour in nitrogen, Ar, and vacuum environments, and the effects on subsequent oxidation were evaluated. The Ar and vacuum heat treatments dramatically improved the oxidation resistance of ABC-SiC. Finally, reoxidation experiments were performed to try to alter the surface chemistry of the SiC to improve the oxidation resistance. The four-point bend strengths and two-parameter Weibull plots of the most successful heat treatments were compared with the standard ABC-SiC to ensure that significant degradation did not result from altering the processing of the material.
Date: December 1, 1997
Creator: Sixta, M.
Partner: UNT Libraries Government Documents Department

Thermal-Hydraulics and Electrochemistry of a Boiling Solution in a Porous Sludge Pile A Test Methodology

Description: When boiling occurs in a pile of porous corrosion products (sludge), chemical species can concentrate. These species can react with the corrosion products and transform the sludge into a rock hard mass and/or create a corrosive environment. In-situ measurements are required to improve the understanding of this process, and the thermal-hydraulic and electrochemical environment in the pile. A test method is described that utilizes a water heated instrumented tube array in an autoclave to perform the in-situ measurements. As a proof of method feasibility, tests were performed in an alkaline phosphate solution. The test data is discussed. Temperature changes and electrochemical potential shifts were used to indicate when chemicals concentrate and if/when the pile hardens. Post-test examinations confirmed hardening occurred. Experiments were performed to reverse the hardening process. A one-dimensional model, utilizing capillary forces, was developed to understand the thermal-hydraulic measurements.
Date: May 3, 2001
Creator: Voelker, R.F.
Partner: UNT Libraries Government Documents Department


Description: The present report summarizes the accomplishments of the project during its second three-month period (from January 2003 through March 2003). The project was initiated with delay in February 2003 due to contractual issues that emerged between the NGA and Foster-Miller, Inc. The two organizations are working diligently to maintain the program's pace so that it is completed in time. The efforts of the project focused during this period in the assessment of the tether technology that is intended to be used as the means of communication between robot and operator. Preliminary results indicate that tether is a viable option under certain pipeline operating conditions but not all. The exact range of operating conditions that are viable for tether use are being determined as the study progresses. Work was also initiated regarding the design of the robotic platform.
Date: May 1, 2003
Creator: Vradis, George C.
Partner: UNT Libraries Government Documents Department

Underground Corrosion after 32 Years: A Study of Fate and Transport

Description: In 1970, the National Institute of Standards and Technology (NIST) implemented the most ambitious and comprehensive long-term corrosion behavior test to date for stainless steels in soil environments. Over 32 years have passed since scientists buried 6,324 specimens from stainless steel types, specialty alloys, composite configurations, and multiple material forms and treatment conditions at six distinctive soil-type sites throughout the country. Today, there are more than 190 specimens per site, exceeding a total of 1000 specimens that remain undisturbed, a buried treasure of subsurface scientific data. This research project advocates the completion of the NIST corrosion study along with a thorough examination of the soil and environment surrounding the specimens. The project takes an interdisciplinary research approach that will correlate the complicated interrelationships among metal integrity, corrosion rates, corrosion mechanisms, soil properties, soil microbiology, plant and animal interaction with corrosion products, and fate and transport of metallic ions. The results will provide much-needed data on corrosion rates, underground material degradation, and the behavior of corrosion products in the near-field vadose zone. The data will improve the ability to predict the fate and transport of chemical and radiological contaminants at sites throughout the DOE complex. The research scope of work is limited to one of the six available sites.
Date: June 1, 2003
Creator: Flitten, Kay Adler
Partner: UNT Libraries Government Documents Department

Microbially Promoted Solubilization of Steel Corrosion Products and Fate of Associated Actinides

Description: The ultimate goal of this project was to demonstrate that metal-reducing bacteria could be used to remove heavy metal and radionuclide contaminants from the surfaces of corroding steel surfaces. Toward this end, fundamental scientific issues regarding (1) factors influencing the adhesion and colonization of DIB on mineral surfaces, (2) the enzymatic activity of cells once they have adhered to mineral surfaces, (3) and (4) methods for recovering bacteria and attendant radionuclides following release from mineral surfaces were addressed. The fate of radionuclides (plutonium) contaminants following reduction by DIRB.
Date: February 28, 2003
Creator: Gorby, Yyri A.; Geesey, Gill G.; Frank Caccavo, Jr. & Fredrickson, James K.
Partner: UNT Libraries Government Documents Department


Description: This development program is a joint effort among the Northeast Gas Association (formerly New York Gas Group), Foster-Miller, Inc., and the US Department of Energy (DOE) through the National Energy Technology Laboratory (NETL). The DOE's contribution to this project is $572,525 out of a total of $772,525. The present report summarizes the accomplishments of the project during its third three-month period (from April 2003 through June 2003). The project was initiated with delay in February 2003 due to contractual issues that emerged between NGA and Foster-Miller, Inc. The two organizations are working diligently to maintain the program's pace and expect to complete it in time. The efforts of the project focused during this period in finalizing the assessment of the tether technology, which is intended to be used as the means of communication between robot and operator. Results indicate that the tether is a viable option under certain pipeline operating conditions, but not all. Concerns also exist regarding the abrasion resistance of the tether, this issue being the last studied. Substantial work was also conducted on the design of the robotic platform, which has progressed very well. Finally, work on the MFL sensor, able to negotiate all pipeline obstacles (including plug valves), was initiated by PII following the successful completion of the subcontract negotiations between Foster-Miller and PII. The sensor design is at this point the critical path in the project's timetable.
Date: July 1, 2003
Creator: Vradis, George C.
Partner: UNT Libraries Government Documents Department


Description: This development program is a joint effort among the Northeast Gas Association (formerly New York Gas Group), Foster-Miller, Inc., GE Oil & Gas (PII), and the US Department of Energy (DOE) through the National Energy Technology Laboratory (NETL). The total cost of the project is $772,525, with the National Energy Technology Laboratory of the US Department of Energy contributing $572,525, and the Northeast Gas Association contributing $200,000. The present report summarizes the accomplishments of the project during its fifth three-month period (from October 2003 through December 2003). The efforts of the project focused during this period in completing the assessment of the tether technology, which is intended to be used as the means of communication between robot and operator, in completing the design of the MFL sensor modules, and in completing the kinematic studies and tractor design. In addition, work on the ovality sensor has been completed, while work on system integration is nearly complete. Results to date indicate that the robotic system under design will be able to meet most of the design specifications initially prescribed. The kinematic analysis shows that from a locomotor point of view an inspection of a 16 inch-24 inch pipe size range with a single platform is most likely possible. However, the limitations imposed by the sensor are more restrictive, final preliminary design results showing that in order to cover this pipe range, two different sensor systems will be needed; one for the 16 inch-20 inch pipe size range and one for the 20 inch-24 inch range. Finally, the analysis has shown that tether operation will be limited to flows of less than 30 ft/sec; these results will have to be confirmed experimentally during the next phase of work.
Date: February 1, 2004
Creator: Vradis, George C.
Partner: UNT Libraries Government Documents Department


Description: Shipping package 9975-02130 was examined in K-Area following the identification of a nonconforming condition; the axial gap between the drum flange and upper fiberboard assembly exceeded the maximum allowed value of 1 inch. The average measured axial gap was 1.1 inches. The fiberboard assembly in this package contained moisture levels of {approx}14-24% wood moisture equivalent ({approx}12-19 wt%) This is moderately higher than typically seen in conforming packages, but not as high as seen on most packages which have exceeded the allowed axial gap. Small patches of mold were growing on portions of the lower fiber assembly, but the fiberboard appeared intact and with little apparent change in its integrity. The lead shield had a heavy layer of corrosion product, some of which flaked off easily. The thickness of several flakes was measured, and varied from 0.0016 to 0.0031 inch. However, additional corrosion product remained on the shield under the flaked regions, so the total thickness of corrosion product exceeds 0.0031 inch.
Date: July 12, 2010
Creator: Daugherty, W. & Murphy, J.
Partner: UNT Libraries Government Documents Department

Investigations of Localized Corrosion of Stainless Steel after Exposure to Supercritical CO2

Description: Severe localized corrosion of a 316 stainless steel autoclave occurred during investigating Type H Portland cement stability in 0.16 M CaCl{sub 2} + 0.02 M MgCl{sub 2} + 0.82 M NaCl brine in contact with supercritical CO{sub 2} containing 4% O{sub 2}. The system operated at 85 C and pressure of 29 MPa. However, no corrosion was observed in the same type of autoclave being exposed to the same environment, containing Type H Portland cement cylindrical samples, also operating at pressure of 29 MPa but at 50 C. The operation time for the 85 C autoclave was 53 days (1272 hours) while that for the 50 C autoclave was 66 days (1584 hours). Debris were collected from the base of both autoclaves and analyzed by X-ray diffraction (XRD). Corrosion products were only found in the debris from the 85 C autoclave. The cement samples were analyzed before and after the exposure by X-ray florescence (XRF) methods. Optical microscopy was used to estimate an extent of the 316 stainless steel corrosion degradation.
Date: March 11, 2012
Creator: Ziomek-Moroz, M.; O’Connor, W. & Bullard, S.
Partner: UNT Libraries Government Documents Department

Activated Corrosion Product Analysis. Analytical Approach.

Description: The presence of activated corrosion products (ACPs) in a water cooling system is a key factor in the licensing of ITER and affects nuclear classification, which governs design and operation. The objective of this study is to develop a method to accurately estimate radionuclide concentrations during ITER operation in support of nuclear classification. A brief overview of the PACTITER numerical code, which is currently used for ACP estimation, is presented. An alternative analytical approach for calculation of ACPs, which can also be used for validation of existing numerical codes, including PACTITER, has been proposed. A continuity equation describing the kinetics of accumulation of radioactive isotopes in a water cooling system in the form of a closed ring has been formulated, taking into account the following processes: production of radioactive elements and their decay, filtration, and ACP accumulation in filter system. Additional work is needed to more accurately assess the ACP inventory in the cooling water system, including more accurate simulation of the Tokamak cooling water system (TCWS) operating cycle and consideration of material corrosion, release, and deposition rates.
Date: January 1, 2010
Creator: Golubov, Stanislav I.; Busby, Jeremy T. & Stoller, Roger E.
Partner: UNT Libraries Government Documents Department