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.

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 characterizationtechniques, such as scanning electron microscopy and X-ray diffraction analysis were used in this study.

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.

Lead ions may be introduced into the environment by the flow of precipitation runoff from the surface of lead structures such as gutters, roofs, piping, siding, and sculpture. Precipitation runoff is water from rain, dew, or fog that drains from a surface and contains air or water-born deposited reactants and soluble ions from the metal surface. Analysis of precipitation runoff from sites in Newport (marine unpolluted) and Albany (rural unpolluted), Oregon, was used to characterize these sites. Typical lead concentrations found in the precipitation runoff were between 0.7 and 3.7 mg/L compared with the United States EPA lead drinking water standard of 0 mg/L (with an action level of 0.015 mg/L). Corrosion film studies indicate that lead in the runoff is primarily from the solubility of cerrusite (lead carbonate) and hydrocerrusite (lead hydroxy carbonate). After an initial induction period, the measured release rate of lead ions to the environment was a constant 0.010 millimoles Pb per liter of precipitation runoff flowing over one square meter of lead surface (2.1 mg Pb/L) at both Albany and Newport. Cumulative corrosion film dissolution rates were 14.3 and 19.6 mmol Pb/m2y for Albany and Newport, respectively. This corresponds to steady state lead corrosion rates of 0.26 and 0.36 ?m/y respectively. Ionic species dry deposited onto the lead surface were determined from precipitation runoff data, giving valuable information concerning the impact of environmental constituents and pollution on lead corrosion.

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.

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.

Dilation-balloon expandable coronary stents are made of implant grade stainless steels, UNS S31673, e.g., BioDur® 316LS. Boston Scientific/Interventional Technologies (BS/IVT) determined that addition of platinum to UNS S31673 could produce a stainless steel with enhanced radiopacity, which made such stents more visible radiographically. A goal of the program was to ensure the platinum additions would not adversely affect the corrosion resistance of the resulting 5-6 wt % PERSS® alloys. Corrosion resistance of PERSS and BioDur 316LS was determined using electrochemical tests for general, pitting, crevice and intergranular corrosion. Experimental methods included A262E, F746, F2129, and potentiodynamic polarization. The ~ 6 wt % PERSS alloy (IVT 78) had a resistance to pitting, crevice and intergranular corrosion similar to base materials. IVT 78 was a single-phase austenitic PERSS alloy with no evidence of inclusions or precipitates; it was more resistant to pitting corrosion than the ~ 5 wt % PERSS alloys. PERSS performance was not a function of oxygen content in the range 0.01 to 0.03 wt %.