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Cadmium sulfide/copper ternary heterojunction cell research. Final report, January 8, 1979-June 7, 1980

Description: Dual source, Se and CuInSe/sub 2/, coevaporation and flash evaporation of stoichiometric CuInSe/sub 2/ powder were investigated to develop a process of fabricating large area CdS/CuInSe/sub 2/ heterojunction solar cells. CuInSe/sub 2/ was seen to decompose upon evaporation, producing layered films in the dual source system. Annealing of these films and alternative dual sources have been considered. Single phase p type films have been produced but no devices have been made from such films. Flash evaporation circumvents the decomposition problem, and if one bakes the powder to obtain a small Cu excess as well as getting a Se excess in the film, p type CuInSe/sub 2/ films can be obtained. A 1% efficient device of 6 cm/sup 2/ area was made using a flash evaporated CuInSe/sub 2/ film. Annealing studies and measurements of spatial uniformity of this device are reported.
Date: January 1, 1980
Creator: Fleming, D. L.
Partner: UNT Libraries Government Documents Department

Cadmium sulfide copper ternary heterojunction cell research. Annual report, September 30, 1977--September 30, 1978

Description: Work on the first year of a project to develop the technology to produce efficient, large area CdS/CuInSe/sub 2/ heterojunction solar cells is described. Two methods of fabricating the CuInSe/sub 2/ were investigated; flash evaporation and dual source, CuInSe/sub 2/ and Se, coevaporation. Data on film structure using x-ray diffraction, film stoichiometry using x-ray fluorescence, and grain size measurements using transmission electron microscopy are presented for each method of fabrication. Preliminary 0.45% efficient CdS/CuInSe/sub 2/ devices are described.
Date: October 1, 1978
Creator: Fleming, D. L.
Partner: UNT Libraries Government Documents Department

Effect of environmental variables on localized corrosion of high-performance container materials

Description: Electrochemical cyclic potentiodynamic polarization (CPP) experiments were performed on several candidate high-performance waste package container materials to evaluate their susceptibility to localized corrosion in aqueous environments relevant to the potential underground high-level nuclear waste repository. This paper presents the results of this study showing the effects of chloride ion (Cl) concentrations, pH, temperature, and electrochemical potential scan rate on the pitting corrosion behavior of these materials.
Date: January 1, 1997
Creator: Roy, A.K.; Fleming, D.L. & Lum, B.Y.
Partner: UNT Libraries Government Documents Department

Effect of chloride concentration and pH on pitting corrosion of waste package container materials

Description: Electrochemical cyclic potentiodynamic polarization experiments were performed on several candidate waste package container materials to evaluate their susceptibility to pitting corrosion at 90 degrees C in aqueous environments relevant to the potential underground high-level nuclear waste repository. Results indicate that of all the materials tested, Alloy C-22 and Ti Grade-12 exhibited the maximum corrosion resistance, showing no pitting or observable corrosion in any environment tested. Efforts were also made to study the effect of chloride ion concentration and pH on the measured corrosion potential (Ecorr), critical pitting and protection potential values.
Date: December 1, 1996
Creator: Roy, A.K.; Fleming, D.L. & Gordon, S.R.
Partner: UNT Libraries Government Documents Department

An electrochemical approach to predicting corrosion performance of container materials

Description: As part of the effort in determining the suitability of the Yucca Mountain site in Southern Nevada for emplacement of high-level nuclear waste in a repository, possible failure modes of candidate waste package container metallic materials are being investigated. Localized forms of corrosion such as pitting attack on the metal surface or attack in creviced areas are particularly pernicious failure modes that may shorten the container lifetime. The pitting potential of nickel-rich Alloy 825 are measured in chloride-containing solutions at different temperatures and adjusted to different pH values. The pitting potentials were determined by potentiodynamic polarization of Alloy 825 test specimens from the corrosion potential until a sharp increase in the electrochemical current indicated a breakdown of the protective passive film on the metal surface. Results show that Alloy 825 is susceptible to pitting attack in aggressive electrolytes containing more than 10,000 ppm chloride at 90{degree}C and acicified to a pH value less than 2.5. 5 refs., 3 figs., 1 tab.
Date: April 1, 1991
Creator: McCright, R.D.; Farmer, J.C. & Fleming, D.L.
Partner: UNT Libraries Government Documents Department

Localized corrosion of container materials under potentiodynamic and potentiostatic controls

Description: Potentiodynamic and potentiostatic polarization experiments were performed on ten candidate waste package container materials to evaluate their pitting tendency at ambient and elevated temperatures in aqueous environments relevant to the potential underground nuclear waste repository. Results indicate that of all the materials tested, Alloys G-30, C-4 and C-22, and Ti Gr-12 exhibited the maximum corrosion resistance, showing no pitting or observable dissolution in any environment tested. These experimental results will be used in identifying a group of potential container materials having the desired corrosion resistance.
Date: May 1, 1996
Creator: Roy, A. K.; Fleming, D. L. & Gordon, S. R.
Partner: UNT Libraries Government Documents Department

Stress corrosion cracking of Fe-Ni-Cr-Mo, Ni-Cr-Mo and Ti alloys in 90{degrees}C acidic brince

Description: Susceptibility to stress corrosion cracking (SCC) of candidate materials for the inner container of the multi-barrier nuclear waste package was evaluated by using wedge-loaded precracked double- cantilever-beam (DCB) specimens in deaerated acidic brine (pH at 2.70) at 90{degrees}C. Materials tested include Alloys 825, G-30, C-4, 625 and C-22; and Ti Grade- 12. Duplicate specimen of each material was loaded at different initial stress intensity factor (K) values ranging between 23 and 46 ksi/in. Both metallography and compliance method were used to determine the final crack length. The final stress intensity for SCC (K{sup ISCC}) was computed from the measured final wedge load and the average crack length. The results indicate that in general, the final crack length measured by metallography and compliance was very close to each other, thus, providing very similar K{sup ISCC} values. While tests are still ongoing, the preliminary results suggest that, compared to other five alloys tested, Alloy 825 may exhibit the maximum tendency to SCC.
Date: November 1, 1997
Creator: Roy, A.K.; Fleming, D.L. & Lum, B.Y.
Partner: UNT Libraries Government Documents Department

Electrochemical and metallographic evaluation of alloys C-22 and 625

Description: Electrochemical cyclic potentiodynamic polarization (CPP) experiments were performed on Alloys C-22 and 625 to evaluate their susceptibility to localized corrosion in acidic brines of various salt content at 90{degrees}C. The microstructures of both tested and untested specimen`s were evaluated by optical microscopy. This paper presents the results showing the effect of chloride ion concentration on the pitting and crevice corrosion behavior of these alloys, and the relationship of the observed microstructures to the resulting surface degradation modes.
Date: May 1, 1997
Creator: Roy, A. K.; Fleming, D. L. & Lum, B. Y.
Partner: UNT Libraries Government Documents Department

Localized corrosion of candidate container materials in ferric chloride solutions

Description: Localized corrosion behavior of candidate inner and outer container materials of currently-designed nuclear waste package was evaluated in aqueous solutions of various concentrations of ferric chloride (FeCl{sub 3}) at 30 C, 60 C and 90 C using the electrochemical cyclic potentiodynamic polarization (CPP) technique. Materials tested include A 5 16 carbon steel and high-performance alloys 825, G-3, G-30, C-4, 625. C-22, and Ti Gr-12. A 516 steel suffered from severe general and localized attack including pitting and crevice corrosion. High-nickel alloys 825 and G-3 also became susceptible to severe pitting and crevice corrosion. The extent of localized attack was less pronounced in alloys G-30 and C-4. Alloy 625 experienced severe surface degradation including general corrosion, crevice corrosion and intergranular attack. In contrast, only a slight crevice corrosion tendency was observed with nickel-base alloy C-22 in solutions containing higher concentrations of FeCl{sub 3} at 60 C and 90 C. Ti Gr-12 was immune to localized attack in all tested environments. The test solutions showed significant amount of precipitated particles during and after testing especially at higher temperatures.
Date: October 1, 1998
Creator: Fleming, D L; Lum, B Y & Roy, A K
Partner: UNT Libraries Government Documents Department

Galvanic corrosion-effect of environmental and experimental variables

Description: Galvanic corrosion behavior of A 516 steel coupled to alloy C-22 and Ti Gr-12, respectively was evaluated in an acidic brine (pH {approx} 2.75) at 30 C, 60 C and 80 C using zero resistance ammeter method. A limited number of experiments were also performed in a neutral brine involving A 516 steel/alloy C-22 couple. The steady-state galvanic current and galvanic potential were measured as functions of anode-to-cathode (A/C) area ratio and electrode distance. Results indicate that the galvanic current was gradually reduced as the A/C area ratio was increased. No systematic trend on the effect of A/C area ratio on the galvanic potential was observed. Also, no significant effect of electrode distance on the galvanic current and galvanic potential was evident. In general, increased galvanic current was noticed with increasing temperature. The limited data obtained in the neutral brine indicate that the galvanic current was reduced in this environment, compared to that in the acidic brine. Optical microscopic examination was performed on all tested specimens to evaluate the extent of surface damage resulting from galvanic interaction. A 516 steel suffered from general corrosion and crevice corrosion in all environments tested. Very light crevice corrosion mark was observed with alloy C-22 and Ti Gr-12 in the acidic brine at 60 C and 80 C. However, this mark appears to be a surface discoloration and no actual crevice was detected.
Date: November 1, 1998
Creator: Fleming, D L; Lum, B Y & Roy, A K
Partner: UNT Libraries Government Documents Department