21 Matching Results

Search Results

Advanced search parameters have been applied.

High temperature corrosion of Cr-W alloys in simulated syngas

Description: Search for new high temperature materials for energy applications continues. This presentation will focus on degradation of Cr alloys containing 0-30%W by weight in a flowing gas mixture containing 30%CO, 8%CO2, 20%H2, 2%CH4, 0.8%H2S, 0.02%HCl, and 40%N2 by volume at temperatures up to 1000ºC. A pseudo-cyclic test involving heating the specimens, holding them at temperature for varying periods, and cooling them to room temperature was employed. Mass change of the specimens was determined after each cycle. Corrosion scale on the specimens was characterized using SEM, WDX, and XRD. Various sulfides, oxides, carbides, and nitrides were determined in different layers of the scale.
Date: February 1, 2007
Creator: Dogan, O.N.; Bullard, S.J. & Covino, B.S., Jr.
Partner: UNT Libraries Government Documents Department

Corrosion of Titanium Matrix Composites

Description: The corrosion behavior of unalloyed Ti and titanium matrix composites containing up to 20 vol% of TiC or TiB{sub 2} was determined in deaerated 2 wt% HCl at 50, 70, and 90 degrees C. Corrosion rates were calculated from corrosion currents determined by extrapolation of the tafel slopes. All curves exhibited active-passive behavior but no transpassive region. Corrosion rates for Ti + TiC composites were similar to those for unalloyed Ti except at 90 degrees C where the composites were slightly higher. Corrosion rates for Ti + TiB{sub 2} composites were generally higher than those for unalloyed Ti and increased with higher concentrations of TiB{sub 2}. XRD and SEM-EDS analyses showed that the TiC reinforcement did not react with the Ti matrix during fabrication while the TiB{sub 2} reacted to form a TiB phase.
Date: September 22, 2002
Creator: Covino, B.S., Jr. & Alman, D.E.
Partner: UNT Libraries Government Documents Department

Dual-environment effects on the oxidation of metallic interconnects

Description: Metallic interconnects in solid oxide fuel cells are exposed to a dual environment: fuel on one side (i.e., H2 gas) and oxidizer on the other side (i.e., air). It has been observed that the oxidation behavior of thin stainless steel sheet in air is changed by the presence of H2 on the other side of the sheet. The resulting dual-environment scales are flaky and more friable than the single-environment scales. The H2 disrupts the scale on the air side. A model to explain some of the effects of a dual environment is presented where hydrogen diffusing through the stainless steel sheet reacts with oxygen diffusing through the scale to form water vapor, which has sufficient vapor pressure to mechanically disrupt the scale. Experiments on preoxidized 316L stainless steel tubing exposed to air-air, H2-air, and H2-Ar environments are reported in support of the model.
Date: August 1, 2006
Creator: Holcomb, G. R.; Ziomek-Moroz, M.; Covino, B. S., Jr. & Bullard, S. J.
Partner: UNT Libraries Government Documents Department

Fireside Corrosion in Oxyfuel Combustion Environments,”

Description: Oxy-fired or low-nitrogen combustion is a technology that will facilitate CO2 capture while also reducing NOx formation and which offers the opportunity for near-zero emissions coal combustion via either the retrofit of existing power plants, or the design of new power plants. Because of the opportunity to improve the environmental performance of the existing coal fired fleet (currently approximately 800 GW of capacity in the US alone) and the potential for converting these plants from air-blown to oxy-fired burners, NETL’s Office of Research & Development is focusing its attention on the impact of retrofitting existing plants on the service life of the materials of construction
Date: March 1, 2009
Creator: Holcomb, G. R.; Matthes, S. A.; Rawers, J. C. & Covino, B. S., Jr.
Partner: UNT Libraries Government Documents Department

Oxidation of advanced steam turbine alloys

Description: Advanced or ultra supercritical (USC) steam power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of advanced alloys for use in USC systems, with emphasis placed on alloys for high- and intermediate-pressure turbine sections.
Date: March 1, 2006
Creator: Holcomb, G. R.; Covino, B. S., Jr.; Bullard, S. J. & Ziomek-Moroz, M.
Partner: UNT Libraries Government Documents Department

Corrosion behavior of experimental and commercial nickel-base alloys in HCl and HCl containing Fe3+

Description: The effects of ferric ions on the corrosion resistance and electrochemical behavior of a series of Ni-based alloys in 20% HCl at 30ºC were investigated. The alloys studied were those prepared by the Albany Research Center (ARC), alloys J5, J12, J13, and those sold commercially, alloys 22, 242, 276, and 2000. Tests included mass loss, potentiodynamic polarization, and linear polarization.
Date: March 1, 2006
Creator: Holcomb, G. R.; Covino, B. S., Jr.; Bullard, S. J. & Ziomek-Moroz, M.
Partner: UNT Libraries Government Documents Department

Corrosion behavior of iron and nickel base alloys under solid oxide fuel cell exposure conditions

Description: Topography and phase composition of the scales formed on commercial ferritic stainless steels and experimental low CTE nickel-based alloys were studied in atmospheres simulating solid oxide fuel cell (SOFC) environments. The materials were studied under dual environment conditions with air on one side of the sample and carbon monoxide on the other side at 750°C. Surface characterization techniques, such as scanning electron microscopy and X-ray diffraction analysis were used in this study.
Date: March 1, 2006
Creator: Ziomek-Moroz, M.; Holcomb, G. R.; Covino, B. S., Jr. & Bullard, S. J.
Partner: UNT Libraries Government Documents Department

Fireside corrosion probes--an update

Description: The ability to monitor the corrosion degradation of key metallic components in fossil fuel power plants will become increasingly important for FutureGen and ultra-supercritical power plants. A number of factors (ash deposition, coal composition changes, thermal gradients, and low NOx conditions, among others) which occur in the high temperature sections of energy production facilities, will contribute to fireside corrosion. Several years of research have shown that high temperature corrosion rate probes need to be better understood before corrosion rate can be used as a process variable by power plant operators. Our recent research has shown that electrochemical corrosion probes typically measure lower corrosion rates than those measured by standard mass loss techniques. While still useful for monitoring changes in corrosion rates, absolute probe corrosion rates will need a calibration factor to be useful. Continuing research is targeted to help resolve these issues.
Date: January 1, 2007
Creator: Covino, B. S., Jr.; Bullard, S. J.; Holcomb, G. R.; Ziomek-Moroz, M. & Matthes, S. A.
Partner: UNT Libraries Government Documents Department

Oxidation of alloys targeted for advanced steam turbines

Description: Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of alloys for use in USC systems, with emphasis placed on applications in high- and intermediate-pressure turbines.
Date: March 12, 2006
Creator: Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.; Ziomek-Moroz, M. & Alman, D.E.
Partner: UNT Libraries Government Documents Department

Studies of Scale Formation and Kinetics of Crofer 22 APU and Haynes 230 in Carbon Oxide-Containing Environment for SOFC Applications

Description: Significant progress in reducing the operating temperature of SOFCs below 800oC may allow the use of chromia-forming metallic interconnects at a substantial cost savings. Hydrogen is the main fuel for all types of fuel cells except direct methanol fuel cells. Hydrogen can be generated from fossil fuels, including coal, natural gas, diesel, gasoline, other hydrocarbons, and oxygenates (e.g., methanol, ethanol, butanol, etc.). Carbon oxides present in the hydrogen fuel can cause significant performance problems due to carbon formation (coking). Also, literature data indicate that in CO/CO2 gaseous environments, metallic materials that gain their corrosion resistance due to formation of Cr2O3, could form stable chromium carbides. The chromium carbide formation causes depletion of chromium in these alloys. If the carbides oxidize, they form non-protective scales. Considering a potential detrimental effect of carbon oxides on iron- and nickel-base alloy stability, determining corrosion performance of metallic interconnect candidates in carbon oxide-containing environments at SOFC operating temperatures is a must. In this research, the corrosion behavior of Crofer 22 APU and Haynes 230 was studied in a CO-rich atmosphere at 750°C. Chemical composition of the gaseous environment at the outlet was determined using gas chromatography (GC). After 800 h of exposure to the gaseous environment the surfaces of the corroded samples were studied by scanning electron microscopy (SEM) equipped with microanalytical capabilities. X-ray diffraction (XRD) analysis was also used in this study.
Date: January 1, 2006
Creator: Ziomek-Moroz, M.; Covino, B.S., Jr.; Holcomb, G.R.; Bullard, S.J. & Penner, L.R.
Partner: UNT Libraries Government Documents Department

Corrosion Performance of Ferritic Steel for SOFC Interconnect Applications

Description: Ferritic stainless steels have been identified as potential candidates for interconnects in planar-type solid oxide fuel cells (SOFC) operating below 800ºC. Crofer 22 APU was selected for this study. It was studied under simulated SOFC-interconnect dual environment conditions with humidified air on one side of the sample and humidified hydrogen on the other side at 750ºC. The surfaces of the oxidized samples were studied by scanning electron microscopy (SEM) equipped with microanalytical capabilities. X-ray diffraction (XRD) analysis was also used in this study.
Date: November 1, 2006
Creator: Ziomek-Moroz, M.; Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.; Jablonski, P.D. & Alman, D.E.
Partner: UNT Libraries Government Documents Department

Task 2: Boiler Corrosion,

Description: For continued use of coal for power generation, there are needs to: –Improve efficiency –Decrease emissions (esp. CO2) –Use alternate fuels or fuel mixes
Date: April 1, 2009
Creator: Holcomb, G. R.; Covino, B. S., Jr.; Shim, H.-S.; Davis, K.; Eden, D. A.; White, M. et al.
Partner: UNT Libraries Government Documents Department

Microclimate Corrosion Effects in Coastal Environments

Description: The Albany Research Center is conducting atmospheric corrosion research in coastal environments to improve the performance of materials in the Nation's infrastructure. The corrosion of bare metals, and of painted, thermal-sprayed, and galvanized steels are presented for one-year exposures at sites located on bridges and utility poles along the Oregon coast. The effects of microclimates (for example distance from the ocean, high wind zones, and salt-fog prone regions) are examined in conjunction with sample orientation and sheltered/unsheltered comparisons. An atmospheric corrosion model examines the growth and dissolution of corrosion product layers to arrive at a steady-state thickness and corrosion rate.
Date: March 24, 1996
Creator: Holcomb, G.R.; Covino, B.S. Jr.; Bullard, S.J. & Cramer, S.D.
Partner: UNT Libraries Government Documents Department

ULTRA-SUPERCRITICAL STEAM CORROSION

Description: Efficiency increases in fossil energy boilers and steam turbines are being achieved by increasing the temperature and pressure at the turbine inlets well beyond the critical point of water. To allow these increases, advanced materials are needed that are able to withstand the higher temperatures and pressures in terms of strength, creep, and oxidation resistance. As part of a larger collaborative effort, the Albany Research Center (ARC) is examining the steam-side oxidation behavior for ultrasupercritical (USC) steam turbine applications. Initial tests are being done on six alloys identified as candidates for USC steam boiler applications: ferritic alloy SAVE12, austenitic alloy Super 304H, the high Cr-high Ni alloy HR6W, and the nickel-base superalloys Inconel 617, Haynes 230, and Inconel 740. Each of these alloys has very high strength for its alloy type. Three types of experiments are planned: cyclic oxidation in air plus steam at atmospheric pressure, thermogravimetric ana lysis (TGA) in steam at atmospheric pressure, and exposure tests in supercritical steam up to 650 C (1202 F) and 34.5 MPa (5000 psi). The atmospheric pressure tests, combined with supercritical exposures at 13.8, 20.7, 24.6, and 34.5 MPa (2000, 3000, 4000, and 5000 psi) should allow the determination of the effect of pressure on the oxidation process.
Date: April 22, 2003
Creator: Holcomb, G.R.; Alman, D.E.; Bullard, S.B.; Covino, B.S., Jr.; Cramer, S.D. & Ziomek-Moroz, M.
Partner: UNT Libraries Government Documents Department

Atmospheric Corrosion and Precipitation Runoff From Zinc and Zinc Alloys Surfaces

Description: The long-term atmospheric corrosion performance of rolled zinc and three thermal-sprayed (TS) zinc materials (Zn, Zn-15Al, and Al-12Zn-0.2In) was characterized by measuring corrosion product concentrations in precipitation runoff at coastal marine and inland sites. Corrosion rates and average zinc concentrations in the runoff were greater at the site having higher annual rainfall. Higher chloride concentrations did not seem to affect either the corrosion rates or the zinc concentrations in the runoff at the coastal site compared to those of the inland site. Zinc runoff concentrations were higher for TS Zn than rolled zinc due to the greater surface area of the thermal-sprayed surface. Average cumulative zinc runoff losses for the two sites were: 64 {micro}mol Zn/L for TS Zn, 37 {micro}mol Zn/L for rolled Zn, 24 {micro}mol Zn/L for TS Zn-15Al, and 1.8 {micro}mol Zn/L for TS Al-12Zn-0.2In. Cumulative zinc runoff losses were directly related both to the precipitation rate and to the availability of Zn in metal surfaces, a consequence of surface roughness and surface chemistry properties of the metal.
Date: March 16, 2003
Creator: Matthes, S.A.; Cramer, S.D.; Bullard, S.J.; Covino, B.S., Jr. & Holcomb, G.R.
Partner: UNT Libraries Government Documents Department

Electrochemical Aging of Thermal-Sprayed Zinc Anodes on Concrete

Description: Thermal-sprayed zinc anodes are used in impressed current cathodic protection systems for some of Oregon's coastal reinforced concrete bridges. Electrochemical aging of zinc anodes results in physical and chemical changes at the zinc-concrete interface. Concrete surfaces heated prior to thermal-spraying had initial adhesion strengths 80 pct higher than unheated surfaces. For electrochemical aging greater than 200 kC/m{sup 2} (5.2 A h/ft{sup 2}), there was no difference in adhesion strengths for zinc on preheated and unheated concrete. Adhesion strengths decreased monotonically after about 400 to 600 kC/m{sup 2} (10.4 to 15.6 A-h/ft{sup 2}) as a result of the reaction zones at the zinc-concrete interface. A zone adjacent to the metallic zinc (and originally part of the zinc coating) was primarily zincite (ZnO), with minor constituents of wulfingite (Zn(OH){sub 2}), simonkolleite (Zn{sub 5}(OH) {sub 8}C{sub l2}{sup .}H{sub 2}O), and hydrated zinc hydroxide sulfates (Zn{sub 4}SO{sub 4}(OH){sub 6}{sup .}xH{sub 2}O). This zone is the locus for cohesive fracture when the zinc coating separates from the concrete during adhesion tests. Zinc ions substitute for calcium in the cement paste adjacent to the coating as the result of secondary mineralization. The initial estimate of the coating service life based on adhesion strength measurements in accelerated impressed current cathodic protection tests is about 27 years.
Date: October 1, 1996
Creator: Holcomb, G.R.; Bullard, S.J.; Covino, B.S. Jr.; Cramer, S.D.; Cryer, C.B. & McGill, G.E.
Partner: UNT Libraries Government Documents Department

Fireside corrosion probes for fossil fuel combustion

Description: Electrochemical corrosion rate probes have been constructed and tested along with mass loss coupons in environments consisting of N2/O2/CO2/SO2 plus water vapor. Temperatures ranged from 450° to 700°C. Results show that electrochemical corrosion rates for ash-covered mild steel are a function of time, temperature, and gaseous environment. Correlation between the electrochemical and mass loss corrosion rates was poor.
Date: March 1, 2006
Creator: Covino, B. S., Jr.; Bullard, S. J.; Ziomek-Moroz, M.; Holcomb, G. R. & Eden, D. A.
Partner: UNT Libraries Government Documents Department

Determining the Cause of a Header Failure in a Natural Gas Production Facility

Description: An investigation was made into the premature failure of a gas-header at the Rocky Mountain Oilfield Testing Center (RMOTC) natural gas production facility. A wide variety of possible failure mechanisms were considered: design of the header, deviation from normal pipe alloy composition, physical orientation of the header, gas composition and flow rate, type of corrosion, protectiveness of the interior oxide film, time of wetness, and erosion-corrosion. The failed header was examined using metallographic techniques, scanning electron microscopy, and microanalysis. A comparison of the failure site and an analogous site that had not failed, but exhibited similar metal thinning was also performed. From these studies it was concluded that failure resulted from erosion-corrosion, and that design elements of the header and orientation with respect to gas flow contributed to the mass loss at the failure point.
Date: March 1, 2007
Creator: Matthes, S. A.; Covino, B. S., Jr.; Bullard, S. J.; Ziomek-Moroz, M. & Holcomb, G. R.
Partner: UNT Libraries Government Documents Department

Corrosion behavior of rebar for intermittent cathodic protection of coastal bridges

Description: A number of reinforced concrete bridges on the Oregon coast are protected against chloride-induced corrosion damage by means of impressed current cathodic protection (ICCP). Thermal-sprayed Zn serves as the anode in these systems. Rebar in the concrete can remain passive and protected for some period of time after the CP system is turned off. The active-passive corrosion behavior of rebar in simulated pore solution (SPS) was investigated as a function of pH and Cl- concentration as part of a study of intermittent ICCP operation. Rebar corrosion rates in SPS were determined from polarization curves by fitting the Butler-Volmer equation and the linear polarization equation. Analysis of the passive film in SPS by x-ray diffraction and surface enhanced Raman spectroscopy showed it to be largely Fe3O4. However, the Fe(OH)2 content increased with cathodic polarization time.
Date: February 1, 2001
Creator: Ziomek-Moroz, M. | Cramer, S.D. | Covino, B.S., Jr. | Bullard, S.J. | Holcomb, G.R. | Russell, J.H. | Windisch, Jr., C.F. (PNNL)
Partner: UNT Libraries Government Documents Department

Role of Ash Deposits in the High Temperature Corrosion of Boiler Tubes

Description: Ash deposits cause accelerated corrosion of waterwall boiler tubes in waste to energy (WTE) incinerators. To study this effect, a series of experiments were planned to determine the mechanism of corrosion of carbon steel boiler tubes under ash deposits. Results reported here were for carbon steel tubes exposed to an environment consisting of O{sub 2}, CO{sub 2}, N{sub 2}, and water vapor. Future experiments will include HCl and SO{sub 2}. Test procedures included both isothermal and thermal gradient tests. Temperatures ranged from 300 C to 510 C for the isothermal tests and a metal/gas temperature of 450/670 C for the thermal gradient test. Initial results indicated that increasing temperature caused the isothermal corrosion rates of ash-covered samples to increase. A shakedown test of a thermal gradient test apparatus was conducted at a metal/gas temperature of 450/670 C, a more severe environment than normally encountered in WTE waterwalls. Results showed that the corrosion rate under those conditions exceeds the isothermal corrosion rates at the same metal temperature by a factor of 2 or more.
Date: March 16, 2003
Creator: Covino, B.S., Jr.; Russell, J.H.; Cramer, S.D.; Holcomb, G.R.; Bullard, S.J.; Ziomek-Moroz, M. et al.
Partner: UNT Libraries Government Documents Department

Laboratory Evaluation of an Electrochemical Noise System for Detection of Localized and General Corrosion of Natural Gas Transmission Pipelines

Description: Gas transmission pipelines are susceptible to both internal (gas side) and external (soil side) corrosion attack. Internal corrosion is caused by the presence of salt laden moisture, CO{sub 2}, H{sub 2}S, and perhaps O{sub 2} in the natural gas. Internal corrosion usually manifests itself as general corrosion. However, the presence of chlorides in entrained water also can lead to pitting corrosion damage. The electrochemical noise technique can differentiate general from localized corrosion and provide estimates of corrosion rates without external perturbation of the corroding system. It is increasingly being applied to field and industrial installations for in situ corrosion monitoring. It has been used here to determine its suitability for monitoring internal and external corrosion damage on gas transmission pipelines. Corrosion measurements were made in three types of environments: (1) aqueous solutions typical of those found within gas pipelines in equilibrium with th e corrosive components of natural gas; (2) biologically-active soils typical of wetlands; and (3) a simulated, unpressurized, internal gas/liquid gas pipeline environment. Multiple sensor designs were evaluated in the simulated pipe environment. Gravimetric measurements were conducted in parallel with the electrochemical noise measurements to validate the results.
Date: March 16, 2003
Creator: Bullard, S. J.; Covino, B. S., Jr.; Russell, J. H.; Holcomb, G. R.; Cramer, S. D.; Ziomek-Moroz, M. et al.
Partner: UNT Libraries Government Documents Department