Energy Technology Data Exchange (ETDEWEB)

This patent describes an improved zinc electrode for a rechargeable zinc-air battery comprising an outer frame and a porous foam electrode support within the frame which is treated prior to the deposition of zinc thereon to inhibit the formation of zinc dendrites on the external surface thereof. The outer frame is provided with passageways for circulating an alkaline electrolyte through the treated zinc-coated porous foam. A novel rechargeable zinc-air battery system is also disclosed.

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In our continued efforts for improving the performance of zinc anodes for a Zn/air battery, we now report the preparation of three alloys and improved performances of anodes made up with these alloys. The alloys contained zinc, nickel, and indium with different weight percentages and were calcined at two different temperatures. Out of the six alloys, the alloy which has a composition of zinc 90%, nickel 7.5% and Indium 2.5% and fired at 500{sup o}C is found to be the best. In the case of the hydrogen evolution reaction, this alloy had its potential shifted to a more negative potential. As far as the cyclic voltammograms were concerned, the difference between the anodic and cathodic part was minimal when compared with other alloys. Surprisingly, this alloy had ...

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The addition of ZnO, depleted in the Zn-64 isotope, to the water of boiling water nuclear reactors lessens the accumulation of Co-60 on the reactor interior surfaces, reduces radioactive wastes and increases the reactor service-life because of the inhibitory action of zinc on inter-granular stress corrosion cracking. To the same effect depleted zinc in the form of acetate dihydrate is used in pressurized water reactors. Gas centrifuge isotope separation method is applied for production of depleted zinc on the industrial scale. More than 20 years of depleted zinc application history demonstrates its benefits for reduction of NPP personnel radiation exposure and combating construction materials corrosion.

Science.gov (United States)

A number of alloys of zirconium have been investigated as part of a program aimed at improving the high-temperature tensile and creep strength of zirconium. These alloys include aluminum, beryllium, lead, magnesium, molybdenum, niobium, tantalum, tin, titanium, tungsten, vanadium, and zinc, binary and ternary alloys. The data indicate that aluminum, lead, molybdenum niobium, tin, titanium, tungsten, and vanadium can be used successfully to harden zirconium, and that aluminum, tin, titanium, and vanadium are particularly effective in maintaining the strength of zirconium at elevated temperatures.

International Nuclear Information System (INIS)

... base alloys alloys beams chemical reactions elements hardness irradiation

Science.gov (United States)

The biocompatibility and corrosion resistance of various materials for use as sacrificial anodes in in vivo hybrid fuel cells were studied. Aluminium, zinc, and magnesium alloy AZ31B were studied, and the results are discussed.

British Library Electronic Table of Contents (United Kingdom)

We present a novel fabrication route yielding Raney-platinum film electrodes intended as glucose oxidation anodes for potentially implantable fuel cells. Fabrication roots on thermal alloying of an extractable metal with bulk platinum at 200^oC for 48h. In contrast to earlier works using carcinogenic nickel, we employ zinc as potentially biocompatible alloying partner. Microstructure analysis indicates that after removal of extractable zinc the porous Raney-platinum film (roughness factor ~2700) consists predominantly of the Pt3Zn phase. Release of zinc during electrode operation can be expected to have no significant effect on physiological normal levels in blood and serum, which promises good biocompatibility. In contrast to previous anodes based on hydrogel-bound catalyst particles the ...

International Nuclear Information System (INIS)

The methods of surface modification of Ti-Zr alloy by laser treatment are considered. Characteristics of laser modification without- and with surface melting and with melting in different gaseous environments and with nickel microalloying are presented. Maximum depth, hardness and corrosion resistance are observed under nickel laser alloying.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

The principle of conservation and transferability of chemical bonds explains the recent discovery by extended x-ray absorption fine-structure measurements of two unequal anion-cation bond lengths R/sub A/C and R/sub B/C in A/sub x/B/sub 1-x/C zinc-blende semiconductor alloys despite the close adherence of the lattice constant to the average value (Vegard rule). This bond alternation, manifested as a structural distortion to a local chalcopyrite coordination around the anions, explains also most of the observed optical bowing in semiconductor alloys.

Energy Technology Data Exchange (ETDEWEB)

To improve adherent properties of electrogalvanized steel (EGS) to polymeric topcoats, the surfaces of EGS were modified by polyelectrolyte-modified zinc phosphating solution. The electrochemical reaction between phosphating solution and EGS led to the complete coverage with fully grown hopeite crystals after only 5 sec treatment, thereby improving adhesion to topcoating and providing protection of EGS against corrosion. To evaluate the ability of polyphenylene sulfide (PPS) polyaryl thermoplastic coatings to protect zinc phosphate (Zn{center_dot}Ph)treated steels from corrosion in a wet, harsh environment ( 1.0 wt % H{sub 2}SO{sub 4}, 3.0 wt % NaCl and 96.0 wt % water at temperatures from 25{degrees} to 200{degree}C), we exposed them in an autoclave to attempt heating-cooling cyclic fatigue tests (1 cycle = 12 hr at 200{degrees}C + 12 hr at 25{degrees}C) up to 90 times. The major chemical reaction at the interface between ...

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The gel electrolyte for the zinc-air cell was prepared by mixing hydroponics gel with a 6M potassium hydroxide aqueous solution. The self-discharge of cells was characterized by measuring the open-circuit voltage. The effect of a discharge rate of 50mA constant current on cell voltage and plateau hour, as well as the voltage-current and current density-power density were measured and analysed. The electrode degradation after discharge cycling was characterized by structural and surface methods. The oxidation of the electrode surface further blocked the utilization of the Zn anode and was identified as a cause for the failure of the cell. (author)

International Nuclear Information System (INIS)

A theoretical study of electron and positron band structures of zinc-blende AlN and InN and their alloy Al_0_._5In_0_._5N is presented using the first-principles full-potential linearized augmented plane-wave method. Equilibrium lattices constants are determined from the total-energy minimization method. The results are compared with previous calculations and with experimental measurement. Electron and positron charge densities are computed as function of position in the unit cell. Detailed plots of distributions are along the direction. The ionicity factors are calculated by means of three different approaches. The calculated results of the positron charge density reflect the high insight for the annihilation effect.

Energy Technology Data Exchange (ETDEWEB)

General corrosion behavior of ALLOY 800 in high temperature water was studied in relation to its surface film structure. The surface film formed in water was found to decrease the corrosion rate of ALLOY 800. This film is composed of Ni ferrite, and can be obtained by oxidation in air or steam. Based on these results, air or steam oxidation treatment to inhibit Ni and Co release of ALLOY 800 into high temperature water is proposed. (author).

International Nuclear Information System (INIS)

The possibility of Pt-Cr surface alloys formation on Pt(0 0 1) was investigated and their magnetism was calculated by the full-potential linearized augmented plane wave (FLAPW) method with eight different atomic configurations. The most stable structure was calculated to be the Pt-segregated L1_2 ferromagnetic surface alloy. A_3B types (L1_2 or D0_2_2) were more stable compared to AB types (L1_0). It implies that the A_3B type surface alloys may be formed when depositing a monolayer of Cr on Pt(0 0 1). It was found from the total energy calculations that there exists a strong tendency of the Pt segregation. The segregation further stabilizes the surface alloy significantly. The work function of the most stable surface alloy was calculated to be 6.02 eV and the magnetic moment of ...

Energy Technology Data Exchange (ETDEWEB)

Welded Ni-base alloys and Alloy 800 were exposed under metal dusting conditions at 600 C and 650 C for up to 6000 hours. Alloy 800 was attacked very strongly already in the first days and Alloy 600 also rather soon and widespread, on both materials attack started mainly in the heat affected zone. Several surface states of Alloy 600: brushed, ground, sand-blasted and pickled were tried only grinding caused a modest delay and decrease of metal dusting attack. Generally the attack was less widespread but deeper at 650 C than at 600 C, also for Alloy 601 and 602. The latter alloys show minor, mainly local attack, but especially the welds are affected. TIG welding led to better resistance than hand-welding. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Energy Technology Data Exchange (ETDEWEB)

Pitting corrosion measuring method for almunum alloys sold on the market was studied. By addition of a little quantity of Cu {sup ++} ion, corrosion potential of alminum alloys rapidly approachs to pitting corrosion potential in the solution including chloride. After Cu {sup ++} ion of 5ppm is added in advance into the solution including chrolide to measure the pitting corrosion potential, alminum alloy test pieces are imersed into the solution in the atmospheric air, then the stable corrosion potential is shown after three-minite imersion, and this potential is defined to the pitting corrosion potential. The pitting corrosion potential can be easily measured by this method stated above (copper ion method). The values measured by copper ion method is comparatively agreed with that measured by the existing potentio dynamic method. The pitting corrosion potential have a straight lined relation with the logarithm of Cl {sup -} ...

Energy Technology Data Exchange (ETDEWEB)

Carbon steel, copper, zinc and aluminium samples were exposed in different sizes with known ambient parameters in Gran Canaria Island and atmospheric corrosion was investigated. Weight-loss measurements used to determine corrosion damage were complemented with metallographic and XP S determination in order to characterize the structure and morphology of surface corrosion products. The ambient aggressiveness could be well evaluated from meteorological and pollution data. All atmospheric corrosion and environmental data were statistically processed for establishing general corrosion damage functions for carbon steel, copper, aluminium and zinc in terms of Gran Canaria extreme meteorological and pollution parameters. (Author)

DEFF Research Database (Denmark)

Zinc oxide (ZnO) and alumina (Al2O3) particles are synthesized by the combustion of their volatilized acetylacetonate precursors in a premixed air-methane flame reactor. The particles are characterized by XRD, transmission electron microscopy, scanning mobility particle sizing and by measurement of the BET specific surface area. Pure (?-)alumina particles appear as dendritic aggregates with average mobile diameter 43-93 nm consisting of partly sintered, crystalline primary particles with diameter 7.1-8.8 nm and specific surface area 184-229 m2/g. Pure zinc oxide yields compact, crystalline particles with diameter 25-40 nm and specific surface area 27-43 m2/g. The crystallite size for both oxides, estimated from the XRD line broadening, is comparable to or slightly smaller than the primary particle diameter. The specific surface area increases and the primary ...

International Nuclear Information System (INIS)

A series of ball-on-disc wear and friction measurements were made for surfaces which have a chemical vapour deposition carbon silicon alloy layer on a carbon substrate (fine grain POCO graphite). Nitrogen ion irradiation was used to improve the wear resistance of the carbon alloy surface. For comparison, measurements were also taken for alumina against alumina. It was found that the lowest friction coefficient and lowest wear occurred for ion irradiated coated samples containing 4% Si in the alloy and that the performance was superior to that of alumina. ((orig.)).

International Nuclear Information System (INIS)

The chemical properties of alloys in a given environment are to a large extent governed by the surface composition. Changes of the surface composition during passivation are important features in this respect. Previous studies of single crystal Ni-Mo alloys surfaces have been reported. The aim of this work was to obtain quantitative data, for the natural oxide and the passive films formed on Ni-6% Mo(100) and (110) alloys, using Rutherford backscattering spectroscopy and nuclear reaction analysis. (author).

International Nuclear Information System (INIS)

The hydrogen evolution reaction (HER) was studied on bare brass (B), nickel coated brass (B/Ni), nickel-zinc alloy coated brass (B/NiZn, leached Zn), nickel (under layer)/nickel-zinc alloy coated (top layer) brass electrodes (B/Ni/NiZn, leached Zn) in 1 M NaOH solution using electrolysis, cathodic polarization and electrochemical impedance spectroscopy (EIS) techniques. Long term tests were performed in order to evaluate the electrocatalytic activity and corrosion performance of the prepared electrodes with operation time. The results showed that leached electrodes, especially B/Ni/NiZn electrode, have a smaller overpotential than the others and a good electrocatalytic activity for the HER. Its electrocatalytic activity is also stable over electrolysis time. Contrary to the HER performance, B/NiZn cannot provide an adequate corrosion protection. However, when a thin Ni layer was coated under the NiZn ...

Energy Technology Data Exchange (ETDEWEB)

In a work studying the corrosion and tarnishing properties of a variety of copper alloys, the alloy Cu-A110-Sn5 was found to show an excellent corrosion resistance in neutral solutions, where copper and most conventional Cu alloys are covered by thick nonprotective surface layers. The passive films formed on this alloy were characterized with electrochemical and photoelectrochemical methods. The pH dependence of the passivation and of the photocurrent behavior of the Cu-A110-Sn5 alloy clearly indicates that the passivity of this alloy in neutral solutions is due to a formation of passive film enriched with aluminum oxide. At corrosion potential a strong increase in the corrosion resistance with time is due to a gradual enrichment of the surface with aluminum oxide. This can be seen in the photocurrent spectra which ...

Energy Technology Data Exchange (ETDEWEB)

Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based ...

Energy Technology Data Exchange (ETDEWEB)

It has been shown by recent experiments that bulk immiscible metals (e.g. Ag/Cu, Ag/Co and Au/Ni) can form binary alloys on certain surfaces where the substrate mediates the elastic misfits between the two components, thus relieving the elastic strain in the overlayer. These novel surface alloys exhibit a rich phase structure. We formulate a two-component Frenkel-Kontorova model in one dimension to study surface alloy formation. This model can naturally incorporate dislocation formation that plays a crucial role in determining the actual structure of the system. Using energy minimization calculations we provide a phase diagram in terms of average alloy composition and the energy of mixing. Monte Carlo simulations were also performed to study the structure and interaction of the emerging dislocations.

Energy Technology Data Exchange (ETDEWEB)

The nickel-rich superalloys Alloy 600 and Alloy 800 have been corroded in mildly alkaline deuterated aqueous conditions typical of secondary coolant circuits in a nuclear power station. The oxide films and substrates of these alloys have been analysed by imaging SIMS depth profiling, which makes it possible to describe elemental distribution in all three dimensions. The measurement of the distribution of the secondary ions NiO[sup -], FeO[sup -] and CrO[sup -] appears useful for detailing the behaviour of nickel, iron and chromium within oxidized phases. The measurement of D[sup -] distribution outlines the extent of oxide hydration. For Alloy 800, evidence of sodium migration into the grain boundaries of the alloy substrate is found. For Alloy 600, no grain boundary sodium ingress can be identified under comparable corrosion conditions. (author).

Energy Technology Data Exchange (ETDEWEB)

Highly water-repellent surfaces have been prepared from arrayed nanowires of zinc oxide (ZnO) by a treatment with stearic acid. The layers are electrochemically deposited on a nanocrystalline seed layer from an oxygenated aqueous zinc chloride solution. An advancing contact angle (CA) as high as 176{sup 0} is obtained with a very small hysteresis {approx}1{sup 0}. These results, supplemented by infrared spectroscopy, show that the stearic acid forms a very well-packed self-assembled monolayer. The CA measurements show a very good stability of the treated surface even when exposed to harsh conditions or long-term ambient illumination.

International Nuclear Information System (INIS)

The present work describes the surface improvement and biocompatibility of TiAl_2_4Nb_1_0 intermetallic alloy using rf plasma nitriding. The nitriding process was carried out at different plasma power from 400 W to 650 W where the other plasma conditions were fixed. Grazing incidence X-ray diffractometry (GIXRD), Auger electron spectroscopy (AES), tribometer and a nanohardness tester were employed to characterize the nitrided layer. Further potentiodynamic polarization method was used to describe the corrosion behavior of the un-nitrided and nitrided alloy. It has been found that the Vickers hardness (HV) and corrosion resistance values of the nitrided layers increase with increasing plasma power while the wear rates of the nitrided layers reduce by two orders of magnitude as compared to those of the un-nitrided layer. This improvement in surface properties of the intermetallic ...

Energy Technology Data Exchange (ETDEWEB)

At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic ...

International Nuclear Information System (INIS)

Cr_2O_3 scales are found to form on Alloy 800 and a similar pure ternary alloy in air, and 1 and 50 atm. helium containing oxidizing impurities typical of those in an SGHTR. The strong temperature dependence and neglibible helium overpressure dependence indicate that gas transport through the scales is not rate controlling. Surface oxidation rates are therefore controlled by solid state diffusion and the low oxygen partial pressure dependence of the oxidation rate in Alloy 800 is ascribed to the presence of extrinsic defects in the Cr_3O_3 (due to doping by alloying elements) or to the presence of short circuit diffusion paths. (Auth.).

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Because noble dental casting alloys for metal ceramic restorations have a wide range of mechanical properties, knowledge of these properties is needed for rational alloy selection in different clinical situations where cast metal restorations are indicated. Purpose The purpose of this study was to compare the mechanical properties and examine both the fracture and polished surfaces of 6 noble casting alloys that span many currently marketed systems. Five alloys were designed for metal ceramic restorations, and a sixth Type GPT has Type IV alloy for fixed prosthodontics (Maxigold KF) was included for comparison. Material and methods Specimens (n=6) meeting dimensional requirements for ISO Standards 9693 and 8891 were loaded to failure in tension using a universal testin...

Energy Technology Data Exchange (ETDEWEB)

The invention comprises an improved rechargeable zinc-air cell/battery having recirculating alkaline electrolyte and a zinc electrode comprising a porous foam support material which carries the active zinc electrode material. 5 figs.

Energy Technology Data Exchange (ETDEWEB)

Whereas supersaturated aluminum alloys demonstrate enhanced passivity, conventional aluminum alloys spontaneously pit in air-saturated chloride solutions. We have concentrated on three areas: evaluation and characterization of Al-W alloys, which exhibit the best corrosion performance of any alloy system studied to date; characterization of the passive-film structure of Al-Mo alloys; and production and characterization of Al-W and Al-Ta powders, which will be used for compaction into bulk material. Surface analysis of the Al-W passive films formed during polarization show surprising little oxidized solute compared to other alloys. These results indicate that the barrier layer formation and electrostatic repulsion mechanisms used to explain the passivity of other alloys are not involved here. Instead the W may act to ...

International Nuclear Information System (INIS)

The effect of concentration on the corrosion behavior of Mg-based alloy AZ91D was investigated in ethylene glycol-water solutions using electrochemical techniques i.e. potentiodynamic polarization, electrochemical impedance measurements (EIS) and surface examination via scanning electron microscope (SEM) technique. This can provide a basis for developing new coolants for magnesium alloy engine blocks. Corrosion behavior of AZ91D alloy by coolant is important in the automotive industry. It was found that the corrosion rate of AZ91D alloy decreased with increasing concentration of ethylene glycol. For AZ91D alloy in chloride >0.05 M or fluoride 0.05 M for fluoride containing ethylene glycol solution, some inhibition effect has been observed. The corrosion of AZ91D alloy in the blank can be effectively inhibited by addition of 0.05 mM ...

International Nuclear Information System (INIS)

... Sergio Department of Materials, University of Oxford, Oxford (United Kingdom)

International Nuclear Information System (INIS)

(Sep 1974). United States Das, KB Marceau, JA Boeing Co., Seattle

International Nuclear Information System (INIS)

To clarify the acidic and alkaline Intergranular Stress Corrosion Cracking (IGSCC) mechanism of thermally treated alloy 690 (alloy 690 TT) and shot peened alloy 800 (alloy 800 SP), C-ring tests were conducted in deaerated HCl solutions and in deaerated NaOH solutions at 350degC, compared with the acidic and the alkaline IGSCC susceptibilities of mill-annealed alloy 600 (alloy 600 MA), full-sensitized one (alloy 600 FS) and thermally treated one (alloy 600 TT). Grain boundary characteristics, such as chromium depleted zone and chromium carbide precipitation, were examined using modified Huey test and Transmission Electron Microscopy. Potential-pH diagram for Ni, Cr, Fe-H_2O system at 350degC was constructed and the solubilities of NiO, Cr_2O_3 and Fe_3O_4 were also calculated to evaluate the stability of oxide films which ...

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The theoretical principles underlying the formation of oxide and, in particular, anodic oxide coatings on metals produced by chemical oxidation, anodizing in solutions, and anodizing in cold plasmas are reviewed. The mechanisms and conditions of anodic oxidation are described, and the structure of anodic oxide coatings on aluminum, magnesium, beryllium, zinc, cadmium, iron, cobalt, nickel, titanium, zirconium, tantalum, and chromium alloys is examined. Attention is also given to various applictins of anodized coatings. 54 references.

International Nuclear Information System (INIS)

We present a comprehensive, up-to-date compilation of band parameters for the technologically important III - V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned ...

Energy Technology Data Exchange (ETDEWEB)

One of the effective methods of deep modification of the surface of steels and alloys is the combination of ion implantation and plasma nitriding. In this work, the long-range effect is demonstrated in the case of combination of the effect of high- and low-energy ions of nitrogen on a martensitic steel for each ion implantation is usually not effective, and a titanium alloy used widely in industry.

Energy Technology Data Exchange (ETDEWEB)

Gas and plasma nitriding processes were executed in the magnesium with modification by titanium in search for an effective surface treatment method for magnesium alloys. Magnesium-nitrogen system has completely no solid solution or solubility, so that nitride should be only formed by eutectic reaction in the liquid phase. Hence, magnesium is difficult or nearly impossible to have its surface modified by nitriding. Addition of nitride forming element into magnesium enables us to lower the onset temperature of nitriding. Magnesium-titanium alloys with 1 to 5 wt% are yielded by the bulk mechanical alloying and, subjected to gas nitriding for various process conditions. Successful co-formation of Mg{sub 3}N{sub 2} as well as TiN becomes a proof to demonstrate the possibility of gas/plasma nitriding in the solid-state magnesium with aid of nitride former. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Passive films formed on Alloy UNS N06690 were investigated in simulated crevice chemistries. It was found the role of lead in corrosion processes is strongly dependent on the pH value of the testing solutions. At pH 1.5 the effect of lead is narrowly noticeable; while at pH 12.7, lead has a significant influence on the electrochemical performance of alloy UNS N06690. The lead alters the surface morphologies at both pH and account for higher hydroxide content in the surface film at pH 12.7. The lead incorporation hinders the formation of spinel oxides during the passivation in alkaline solution. Nanoindentation tests indicate a significant lead-induced degradation in the mechanical properties of passive films. The passivation degradation is attributed to detrimental effects of lead via interrupting the dehydration process and hindering the formation of protective layers on the alloy ...

International Nuclear Information System (INIS)

Research highlights: #-># The Y-intermetallic can accelerate corrosion and Y can increase the protectiveness of the surface layer. #-># In 0.1 M NaCl, the corrosion rate of Mg-Y alloys increased with increasing Y due to the Y intermetallic. #-># In 0.1 M NaCl, there was filiform corrosion. #-># In 0.1 M Na_2SO_4, the corrosion rate of Mg-Y alloys decreased with increasing Y in the range 3-7%Y. #-># Hydrogen evolution was observed from particular parts of the alloy surface. - Abstract: Corrosion of Mg-Y alloys was studied using electrochemical evaluations, immersion tests and direct observations. There were two important effects. In 0.1 M NaCl, the corrosion rate increased with increasing Y content due to increasing amounts of the Y-containing intermetallic. In 0.1 M Na_2SO_4, the corrosion rate decreased with increasing Y content above 3%, ...

International Nuclear Information System (INIS)

Resistance of Alloy 800 as a PWR S/G tube material to IGC/IGSCC and Ni, Co release into water was evaluated as compared with Alloys 600 and 690. The study to improve the resistance to IGSCC and general corrosion was also made, including the effects of shot-peening on the distribution of the residual stress of the U-bent tubes and the susceptibility to SCC, the stabilizing elements on IGC/IGSCC, and prior oxidation on general corrosion. From the results, shot-peened Alloy 800 was estimated to be the most reliable S/G tube material among the high nickel alloys tested. In addition, the Alloy 800 tube would obtain further reliability in IGSCC and general corrosion resistance by the combined addition of Ti, and Nb, and the prior oxidation of the inner tube surface, respectively.

Energy Technology Data Exchange (ETDEWEB)

Describes performance of excavator teeth manufactured with a new hard alloy. The alloy was developed by the Donetskii Politeknicheskii Institute. Its composition consists of a high-chromium steel with a larger amount of titanium than serial alloy, and a nitrogen additive. Trial tests of new alloy teeth were carried out in the Severnyi and Vershinskii coal surface mines. The teeth were attached to EhRP, EhPG and EhR bucket wheel excavators. Abrasive wear of 129 experimental teeth and 134 serial teeth was compared for different excavation conditions. Test results are tabulated; advantages of the new experimental teeth are listed. 3 refs.

Energy Technology Data Exchange (ETDEWEB)

Austenitic stainless steels (304-type) have been implanted with nitrogen ions in order to investigate the effects of implanted nitrogen on their electrochemical behaviour and on the nature of the passive film formed on the steels in acid (0.5M H{sub 2}SO{sub 4}). Alloys with two nitrogen doses have been prepared (2.5x10{sup 16} and 2x10{sup 17} N atoms/cm{sup 2}). The implanted alloys have been characterized by {sup 15}N-NRA (nuclear reaction analysis) and XPS (X-ray photoelectron spectroscopy). Alloy surfaces with well-defined N concentrations were prepared, prior to the electrochemical measurements, by argon-ion sputtering of the implanted material for a fixed time in order to reach a well-defined point on the nitrogen depth profile. The samples were then transferred without exposure to air to an electrochemical cell mounted in an inert gas glove box. The implanted nitrogen modifies the ...

Energy Technology Data Exchange (ETDEWEB)

In order to investigate the role of amorphous SiO{sub 2} particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO{sub 2} particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO{sub 2} was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO{sub 2} particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of {gamma}-phase and amorphous nano-SiO{sub 2} particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO{sub 2} particles were uniformly distributed in the alloying layer and still kept the ...

Energy Technology Data Exchange (ETDEWEB)

The wear behaviour of metallic material is influenced by the friction force, which in turn, is governed by the hardness and oxidation kinetics of the mating surface. In view of this, present investigation is undertaken to find the influence of mating surface on the high temperature wear of 253 MA alloy. This alloy is developed for high temperature application. In this work 253 MA alloy is made to slide against two different types of counter face material, namely 100Cr6 steel and PM 1000 alloy, at five different temperatures. 100Cr6 steel gets soften with increase of temperature whereas PM 1000 alloy retains its strength even at high temperature. The friction coefficient and the thickness loss of 253 MA alloy is measured and compared against both variety of mating surfaces as function of temperatures. ...

International Nuclear Information System (INIS)

Laser surface modification can lead to formation of a novel microstructure on the surface of a material resulting in improved surface properties. During the past one and half decades, a number of investigations have been reported on laser surface modification techniques for improving the corrosion resistance of various materials. This paper reviews various work reported on utilising laser modification techniques for enhancing the aqueous corrosion resistance of materials. The laser surface modification work carried out on materials like stainless steels, C-steels, low alloy steels and non-ferrous materials such as Zr, Zn, Al, Ni, Mg and their alloys has been covered in the review. General features observed in improving the corrosion resistance after laser processing have been discussed and scope for future investigations in this field has ...

Energy Technology Data Exchange (ETDEWEB)

Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni-Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr{sub 2}N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective Cr-nitride ...

International Nuclear Information System (INIS)

Nanoindentation was performed on a Mo-alloy single crystal to investigate effects of focused ion beam (FIB) milling on mechanical behavior. On a non-FIB-milled surface, pop-ins were observed on all load-displacement curves corresponding to a transition from elastic to plastic deformation. Similar pop-ins were not detected on surfaces subjected to FIB milling. This difference indicates that FIB milling introduces damage that obviates the need for dislocation nucleation during subsequent deformation. A second effect of FIB milling is that it increased the surface hardness. Together, these effects could be the source of the size effects reported in the literature on micropillar tests.

Energy Technology Data Exchange (ETDEWEB)

Blow forming characteristics of 5083 Al alloy and AZ31 Mg alloy recycled by solid state recycling were investigated. Scraps with different volume were recycled by hot extrusion and hot rolling in air. Oxide layers, which were contaminants from scrap surface, were distributed parallel to the extrusion direction in the recycled specimens. In the blow-forming test, the specimen from smaller scraps exhibited lower formability. The oxygen concentration in the recycled specimens was approximately proportional to the total surface area of scraps in the recycled specimen per unit volume. The low formability of the recycled specimens is likely to be attributed to contamination level of oxide. (orig.)

International Nuclear Information System (INIS)

Transmission electron microscopy studies on solution-annealed Alloy 800 revealed small (100-200 nm), spherical-shaped titanium carbide (face centered cubic structure) and large (200 nm-5 #mu#m), faceted titanium nitride (hexagonal structure) particles randomly distributed in the austenite matrix. The volume fraction of former particles was found to be greater than that of the latter. Corrosion studies of the alloy in acidic, chlorides and acidic chloride environments at room temperature indicated that the passivity of Alloy 800 was adversely affected by the addition Cl"- ions. X-ray photoelectron spectroscopy revealed that the surface film formed on the alloy at the onset of passivity consisted of Cr"3"+ (as Cr_2O_3), without any Fe"3"+/Fe"2"+ or Ni"2"+. Scanning electron microscopy studies indicated initiation of pitting at large, faceted particles, not at small, spherical-shaped ...

British Library Electronic Table of Contents (United Kingdom)

The alloying of steel surface with aluminum (Al) using Microsecond-pulsed Intense Electron Beams (MIEB-Al) was developed and optimized in order to be used for improving the corrosion resistance of the 316, 1.4970 and T91 steels, exposed to liquid Pb and Pb-Bi-eutectic. The procedure consists in two steps: (i) coating the steel surface with Al or an Al-containing alloy layer and (ii) melting the coating layer and the steel surface layer using intense pulsed electron beam. In order to cover the steel surface with an homogeneous and crack-free Al-alloyed layer, the following experimental conditions are required: Al coating thickness range 5-10mm, electron kinetic energy 120keV; pulse duration 30ms; energy density 40-45J/cm2; number of pulses 2-3. Using the mentioned procedure, the corrosion r...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Even though metal ceramic restorations (MCRs) are widely used by clinicians, the influence of the metal on the color of overlaying porcelain is unknown. Purpose The purpose of this study was to analyze the color alterations of different types of metal ceramic alloys during several stages of metal surface preparation and to determine the effect of those changes on the resulting color of opaque porcelain (OP). Material and Methods Seven different types of alloys (3 base metal, 3 noble, and 1 high noble) were used to prepare disk-shaped specimens (1 mm x 10 mm, n=3), followed by OP application (0.1 mm). Lab values of specimens were recorded after different stages of metal surface preparation (ingot, after casting, after oxidation, and after the OP application) in addition...

CERN Document Server

The development of a replacement to the conventional film based X-ray imaging technique is required for many reasons. One possible route for this is the use of a large area film of a suitable semiconductor overlaid on an amorphous silicon readout array. A suitable semiconductor exists in cadmium telluride and its tertiary alloy cadmium zinc telluride. In this thesis the spectroscopic characteristics of commercially available CZT X- and gamma-radiation detectors are established. The electronic, optical, electro-optic, structural and compositional properties of these detectors are then investigated. The attained data is used to infer a greater understanding for the carrier transport in a CZT radiation detector following the interaction of a high energy photon. Following this a method used to fabricate large area films of CdTe on a commercial scale is described. This is cathodic electrodeposition from an aqueous electrolyte. The theory and ...

International Nuclear Information System (INIS)

This work presents results of investigations on d.c. glow discharge nitriding of #alpha#+#beta# Ti-6Al-4V titanium alloy. The treatment was performed at 843 K in nitrogen-hydrogen atmosphere, pressure 300 Pa. Special attention was paid to nitriding mechanism and determination of the role of ion bombarding in nitriding process of titanium alloys. Produced as a result of d.c. plasma nitriding surface layers were subjected to macroscopic observations, microstructure studies, microhardness testing and X-ray analysis. (author)

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Metal dusting corrosion has been a serious problem in the petroleum and petrochemical industries, such as reforming and syngas production systems. This form of deterioration has led to worldwide material loss for 50 years. For the past three years, we have studied the mechanism of metal dusting for Fe- and Ni-base alloys. In this report, we present a correlation between the weight loss and depth of pits that form in Ni-base alloys. Nickel-base alloys were also tested at 1 and 14.8 atm (210 psi), in a high carbon activity environment. Higher system pressure was found to accelerate corrosion in most Ni-base alloys. To reduce testing time, a pre-pitting method was developed. Mechanical scratches on the alloy surface led to fast metal dusting corrosion. We have also developed preliminary data on the performance of weldments of several Ni-base ...

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Surface analytical studies of high nitrogen austenitic stainless steels exposed to deaerated 0.1M HCl have revealed that nitrogen alloying additions influence the composition of salt layers and the passive film/alloy interface. In this study the authors employ electrochemical techniques and variable angle X-ray Photoelectron Spectroscopy (XPS) to examine the passive films formed on a series of austenitic stainless steels, Fe18Cr8Ni, Fe18Cr8Ni0.2N, Fe20Cr20Ni, Fe20Cr20Ni6Mo and Fe20Cr20Ni6Mo0.2N, in acidic chloride aqueous solution. In addition, several other model alloys, Fe19Cr, Fe19Cr9Ni, Fe19Cr2.5Mo, and Fe19Cr9Ni2.5Mo, were examined before and after electrochemical surface nitriding, a technique proven to have an effect analogous to N alloying. It was shown that nitrogen, nickel and molybdenum additions independently and in certain combinations stimulate ...

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Alloy 600 is commonly used in the primary systems of PWR plants because of its excellent resistance to a stress corrosion cracking and pitting. But a stress corrosion cracking and pitting corrosion are occasionally observed under PWR conditions, which may be correlated with the passive film on the Alloy 600 surface. There is little information on the composition of films growing on the surface of Alloy 600 at high temperature. Therefore, an understanding of the basic electrochemical behaviors about an anodic dissolution and the passivation of the bare surface of metals and alloys provides important information about localized corrosions like a SCC and pitting. Oxide on the steel surfaces in an aqueous solution above 100 .deg. C is composed of a duplex film structure. The inner layer of the oxide is dense and less porous, ...

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We investigate the formation of nanostructures in 2D strained alloys on face centered cubic (111) surfaces by means of equilibrium Monte Carlo simulations. In the framework of an off-lattice model, we consider one monolayer of two bulk-immiscible adsorbates A and B with negative and positive misfit relative to the substrate, respectively. Simulations show that the adsorbates partly self-organize into island or stripe-like patterns. We show how these structures depend on the relative misfits, interaction, and concentration of components. The morphology is quite different for phase separation and intermixing regimes.

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Field corrosion tests were conducted on eight single tube materials and two welded overlay materials in three typical Japanese waste incineration plants in an effort to develop new corrosion-resistant superheater tubes capable of functioning efficiently under temperature and pressure conditions of 500 C and 100 kgf/cm{sup 2}-g in high-efficiency waste-to-energy (WTE) plants. Austenitic alloys containing higher concentrations of chromium, nickel, and molybdenum [Cr + Ni + Mo] showed excellent corrosion-resistant properties, and the new alloys JHN24 and HR30M showed good corrosion resistance. Different corrosion rates found in each of the three plants were explained by differences in operating conditions, such as gas temperature, concentration of molten salts resulting from chlorine (Cl) content of deposits, heavy metal (zinc oxide [ZnO] + lead oxide [PbO]) content, etc. It was confirmed that the corrosion rate of materials ...

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The primary coolant oxidises the surfaces of construction materials in nuclear power plants. The properties of the oxide films influence significantly the extent of incorporation of actuated corrosion products into the primary circuit surfaces, which may cause additional occupational doses for the maintenance personnel. The physical and chemical properties of the oxide films play also an important role in different forms of corrosion observed in power plants. This report gives a short overview of the factors influencing activity build-up and corrosion phenomena in nuclear power plants. Furthermore, the most recent modifications in the water chemistry to decrease these risks are discussed. A special focus is put on zinc water chemistry, and a preliminary discussion on the mechanism via which zinc influences activity build-up is presented. Even though the exact mechanisms by which ...

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The corrosion behaviour of the stainless steels 304, 316 Ti, 25Cr-20Ni-Mo-Ti, nickel base alloys Hastelloy C4, Inconel 625, Incoloy 800, Ti and Ti-0.2% Pd alloy has been studied in the aerated or deaerated solutions at 20/sup 0/C and 90/sup 0/C whose compositions are representative of interstitial ground waters: granitic or clay waters or salt brine. The electrochemical techniques used are voltametry, polarization resistance and complexe impedance measurements. Electrochemical data show the respective influence of the parameters such as temperature, solution composition and dissolved oxygen, addition of soluble species chloride, fluoride, sulfide and carbonates, on which depend the corrosion current density, the passivation and the pitting potential. The inhibition efficiency of carbonate and bicarbonate activities against pitting corrosion is determined. In clay water at 90/sup 0/C, Ti and Ti-Pd show very high passivation aptitude and a broad ...

International Nuclear Information System (INIS)

Effects of PbO on the repassivation kinetics of alloy 690TT were examined using the rapid scratching electrode technique under a potentiostatic condition to elucidate the influence of PbO on SCC resistance of the alloy. The repassivation kinetics of the alloy was analyzed in terms of the current density flowing from the scratch, i(t), as a function of the charge density that has flowed from the scratch, q(t). Repassivation on the scratched surface of the alloy occurred in two kinetically different processes; passive film initially nucleated and grew according to the place exchange model in which log i(t) is linearly proportional to q(t) with a slope of 1/K, and then grew according to the high field ion conduction model in which log i(t) is linearly proportional to 1/q(t) with a slope of cBV. 1/K and cBV are parameters representing the SCC susceptibility as well as repassivation rate ...

British Library Electronic Table of Contents (United Kingdom)

Erosion-corrosion (E-C) of 3003 aluminum (Al) alloy in ethylene glycol-water solutions were studied by weight-loss and electrochemical measurements as well as surface characterization through an impingement jet system. Al alloy E-C is dominated by erosion components, i.e., pure erosion and corrosion-enhanced erosion, which account for 92-97% of the total E-C rate under the various conditions in this work. Contribution from corrosion components, including pure corrosion and erosion-enhanced corrosion, is slight. With the increase of fluid flow velocity and sand concentration, the total E-C rate increases. Compared with the significant increase of the rates of erosion components, the increase of the rate of corrosion component is negligible. Upon fluid flow, passivity of Al alloy that develo...

International Nuclear Information System (INIS)

It is generally known that a number of metallic glasses have excellent corrosion resistance in a variety of chemically hostile environments. Consequently, the use of laser cladding to coat a massive crystalline material such as aluminium with a layer of a metallic glass has obvious advantages. In this paper, the authors will show that the formation of a predominantly amorphous layer of Zr_6_0Al_1_5NI_2_5 alloy by laser processing is possible, if the obstacles to amorphization are overcome. In addition, evidence of the excellent corrosion resistance of this alloy in a NaCl solution will be given. A comparative study of the corrosion behavior of this amorphous alloy with pure aluminium and Al-Cr alloy will be done, in order to complete previous studies of laser processed coatings of aluminum substrates.

International Nuclear Information System (INIS)

FexZn1-x alloys were electrochemically deposited on aluminum substrates from a sulfate bath. The K?/K? x-ray intensity ratios of Zn and Fe in FexZn1-x thin films have been experimentally studied. The energy dispersive x-ray fluorescence (EDXRF) technique was used to measure K x-ray photons. Samples were excited by using 59.5 keV photons emitted by a 50 mCi 241Am radioactive source. The emitted K x-rays were detected by an Ultra-LEGe detector having a resolution of 150 eV at 5.9 keV. In addition, the effect of bath composition on the phase structure was investigated by x-ray diffraction (XRD) analysis. The composition of the thin films was analyzed by atomic absorption spectrometry analysis. Iron content was shown to strongly affect the structure of Zn-Fe alloys. It was found that the K-shell x-ray intensity ratio changed in FexZn1-x thin films for different values of x. The reason for this change may be that the electronegativity of iron is ...

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Nitridation of Cr-bearing alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant CrN or Cr2N base surfaces of interest for a range of electrochemical devices, including fuel cells, batteries, and sensors. This paper presents results of exploratory studies of the nitridation of commercially available, high Cr (30-35wt%) Ni-Cr alloys and a ferritic high Cr (29wt%) stainless steel for proton exchange membrane fuel cell (PEMFC) bipolar plates. A high degree of corrosion resistance in sulfuric acid solutions designed to simulate bipolar plate conditions and low ICR values were achieved. Oxygen impurities in the nitriding environment were observed to play a significant role in the nitrided surface structures that formed, with detrimental effect...

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One of the main causes of hip prostheses failure is the premature wear of its components. Wear of metal-on-metal joints is a concern due to the toxicity and biological reaction of wear debris and metallic corrosion. The main aim of the present study was to investigate the tribological and corrosion behavior of surface engineering CoCrMo alloy. Different surface conditions were obtained on surgical grade wrought CoCrMo alloy: plasma nitrided (520^oC by 7h at gas mixture of 10% N2+90% H2), PVD coated (monolayer CrN and multilayer (TiN/CrN)x3) and modified using duplex surface engineering technology (a combination of the two previous approaches: plasma nitriding followed by plasma assisted PVD). Surfaces were characterized using scanning electron microscopy, nanoindentation, AFM and scratch t...

International Nuclear Information System (INIS)

The Ti-6Al-4V alloy was treated by inductively coupled rf plasma nitriding. The effects of plasma-processing time in the range of 5-35 min on the microstructure and the mechanical properties of the plasma-nitrided Ti-6Al-4V samples were studied. The plasma power input was adjusted at 450 W and pure N_2 gas was introduced to establish a treatment pressure of 8.0-8.4 x 10"-"2 mbar. The characteristics of the nitrided layers have been investigated by microhardness testing, surface roughness measurements, optical microscopy, and x-ray diffraction. The results show that the surface microhardness increases as the plasma-processing time increases to reach 2000 HV0.1 at a plasma-processing time of 35 min. A high nitriding rate of 2.81 #mu#m"2 s"-"1 at a plasma-processing time of 25 min was achieved. The formation of the hard phases TiN, Ti_2N, and Ti(N) in the Ti-6Al-4V surfaces are found to be the reason for ...

Energy Technology Data Exchange (ETDEWEB)

Alloy 690 and Alloy600 are used as a material for the steam generator tubing in the pressurized water reactor(PWR) of nuclear power plants due to its high corrosion resistance. Although those are a highly corrosion resistance material, their stress corrosion cracking(SCC) have been found on occasion, which are deeply related to a surface oxide film on a base material which have occurred on the primary side as well as the secondary side of a tubing. And The SCC is accelerated in the existing Pb which is the impurity of secondary steam generator components. The Oxide on a steel surface in an aqueous solution above 100 .deg. C is composed of a duplex film structure. The inner layer of the oxide is dense and less porous, which is formed by a growth of the oxide layer on the metal surface. The outer layer of the oxide is less adhesive, which is formed by a dissolution and precipitation ...

British Library Electronic Table of Contents (United Kingdom)

Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr2N, CrN, TiN, V2N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of proton exchange membrane (PEM) single-cell fuel cell studies of stamped and pre-oxidized/nitrided developmental Fe-20Cr-4V weight percent (wt.%) and commercial type 2205 stainless steel alloy foils. The single-cell fuel cell behavior of the stamped and pre-oxidized/nitrided material was compared to as-stamped (no surface treatment) 904L, 2205, and Fe-20Cr-4V stainless steel alloy foils and machined graphite of similar flow field design. The best fuel cell behavior among the alloys was exhibited...

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Nitridation of Cr-bearing alloys can yield low interfacial contact resistance (ICR), electrically- conductive and corrosion-resistant CrN or Cr2N base surfaces of interest for a range of electrochemical devices, including fuel cells, batteries, and sensors. This paper presents results of exploratory studies of the nitridation of two high Cr (30-35 wt%) commercially available Ni-Cr alloys and a ferritic high Cr (29 wt.%) stainless steel for proton exchange membrane fuel cell (PEMFC) bipolar plates. A high degree of corrosion resistance in sulfuric acid solutions designed to simulate bipolar plate conditions and low ICR values were achieved via nitridation. Oxygen impurities in the nitriding environment were observed to play a significant role in the nitrided surface structures that formed, with detrimental effects for the Ni-Cr base alloys, but beneficial effects for the stainless ...

British Library Electronic Table of Contents (United Kingdom)

Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr2N, CrN, TiN, V2N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of scale-up studies to determine the feasibility of extending the nitridation approach to thin 0.1mm stainless steel alloy foils for proton exchange membrane fuel cell (PEMFC) bipolar plates. Developmental Fe-20Cr-4V alloy and type 2205 stainless steel foils were treated by pre-oxidation and nitridation to form low-ICR, corrosion-resistant surfaces. As-treated Fe-20Cr-4V foil exhibited target (low) ICR values, whereas 2205 foil suffered from run-to-run variation in ICR values, ranging up to 2x the...

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Acrylonitrile electropolymerization (in an aprotic and anhydrous medium) has been used as a way to build thin, homogeneous and covering polyacrylonitrile layers grafted on the surface of usual metals and specially on copper-based shape memory alloy: Cu-Zn-Al. The results of the study first confirm the possibility of grafting thin and covering polyacrylonitrile layers on Cu-Zn-Al surface. The morphology of the films however is influenced by the geometry of the polycristalline structure of the alloy and its superficial defects. Samples obtained after grafting polyacrylonitrile films were submitted to corrosion tests based on Electrochemical Impedance Spectroscopy (EIS) measurements in a NaCl/H{sub 2}O medium. Results show that some post-treatments of the grafted films are necessary to improve their protective role, while preserving the strong interfacial bondings. Actually, thermal and mechanical cycling ...

International Nuclear Information System (INIS)

Austenitic stainless steels have been implanted with molybdenum ions (Mo"+, 100 keV, 2.5 x 10"1"6 atoms cm"-"2). The implanted material has been characterized by XPS and RBS. The implanted region has a thickness of #approx# 1000 A with a maximum molybdenum concentration of #approx# 9 at.% Mo located at #approx# 210 A from the surface. The effects of implanted molybdenum on the passivation of the alloy in 0.5 M H_2SO_4 have been investigated by electrochemistry and XPS. After XPS analysis the samples were transferred without exposure to air into a glove-box with an inert atmosphere. The electrochemical behaviour of the alloy is significantly modified by the implanted molybdenum. The major effect is that the activation peak disappears. A bilayer structure (outer hydroxide/inner oxide) of the passive film is observed for both the implanted and non-implanted alloys and the thicknesses of the films are ...

International Nuclear Information System (INIS)

An analysis of the passive films formed on amorphous alloys of the system Fe-10% Cr-5% Mo-P-metalloid and Fe-10% Cr-5% Mo-B-Si revealed that they are more markedly enriched with chromium in silicon-free alloys. In silicon-containing amorphous alloys the passive films were highly enriched with silicon, which occurred in these films in the form of a corrosion product close to SiO_2. As shown by the investigations of a study of the anodic behavior of Fe_4_0Ni_4_0P_1_4B_6 and Fe_4_0Ni_3_8Mo_4B_1_8, phosphorus facilitates the passivation of amorphous alloys by reducing the solution current in the active state and enriching the surface layers of the metal in the form of a black prepassivation film which also contains nickel and iron. The behavior of Fe-Ni amorphous alloys containing only boron as metalloid additive differs little from that of crystalline ...

International Nuclear Information System (INIS)

Alloy 800 is an austenitic Fe-Ni-Cr steel containing relatively minor but important amounts of carbon, aluminium and titanium. Special grades of alloy 800 known as 800H, 800HT and 800LC differ in the concentrations of these elements. In addition to these industrial specifications, further melts were prepared containing phosphorous or sulphur. Using a radioactive tracer method the bulk and grain-boundary diffusion of "5"9Fe was investigated in these alloys in the temperature range 800 to 1000 C. For evaluation of the diffusion profiles the approximation of Suzuoka was used, which considers the depletion of the tracer on the surface. By autoradiography it was confirmed that such depletion occurs. In alloy 800H the activation energy of grain-boundary diffusion of "5"9Fe was found to be (209#+-#17) kJ/mol; dissolved elements, especially phosphorous, increase the activation energy. The ...

International Nuclear Information System (INIS)

Fretting wear test in room temperature water was performed to evaluate the wear coefficient of CANDU (CANadian Deuterium Uranium) steam generator (SG) tube material (Alloy 800) against 410 type martensitic stainless steels. The main focus is to compare the wear behaviors between Alloy 800 and Inconel 690. Test conditions are 10#approx#30N of normal load, 200#approx#450mm of sliding amplitude and 30Hz of frequency. The result indicated that the wear rate of Alloy 800 was higher than those of Inconel 690 at various test condition such as normal loads, sliding amplitudes etc. From the results of SEM observation, there was little evidence of plastic deformation layer that were dominantly formed on the worn surfaces of Inconel 690. Also, wear particles in Alloy 800 were released from contacting asperities deformed by severe plastic flow during fretting wear. Main cause of wear rate ...

Energy Technology Data Exchange (ETDEWEB)

As the first step for development of the corrosion resistant superheater tube materials of 500 C, 100 ata used in high efficient waste-to-energy plants, field corrosion tests of six conventional alloys were carried out at metal temperatures of 450 C and 550 C for 700 and 3,000 hours in four typical Japanese waste incineration plants. The test results indicate that austenitic alloys containing approximately 80 wt% [Cr+Ni] show excellent corrosion resistance. When the corrosive environment is severe, intergranular corrosion of 40{approximately}200 {micro}m depth occurs in stainless steel and high alloyed materials. It is confirmed quantitatively that corrosion behavior is influenced by environmental corrosion factors such as Cl concentration and thickness of deposits on tube surface, metal temperature, and flue gas temperature. The excellent corrosion resistance of high [Cr+Ni+Mo] ...

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For the development of a long-lived electrically rechargeable zinc/air battery, the structure and wettability of pasted zinc electrodes were optimized. Pasted zinc electrodes, having the same nominal capacities but containing 1% to 10% cellulose, were prepared and tested under defined charge and discharge conditions in zinc-oxygen cells. The maximum power as well as the cycle life of these cells were measured. After different times of operation, the porosity and the pore size distribution of the pasted zinc electrodes were measured by means of mercury porosimetry. (author) 4 figs., 1 tab., 6 refs.

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For the development of a long-lived, electrically rechargeable zinc-air battery the structure and wettability of pasted zinc electrodes were optimized. Pasted zinc electrodes containing 1 to 10% cellulose, but having almost the same nominal capacities, were prepared and tested in zinc/oxygen cells. The effect of discharge rate on cell voltage and delivered capacity, as well as the maximum power, were measured. Furthermore, cell charge-discharge behaviour and cycle life were examined. After different times of operation, the porosity and the pore size distribution of the pasted zinc electrodes were measured by means of mercury porosimetry. The life cycle and peak power drain capability of the Zn/oxygen battery could be substantially improved by the addition of 10 wt% cellulose to the pasted zinc electrode. (author)

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An Fe-19Cr-8Al-0.5Hf alloy has been roll bonded to Alloy 800 to form a protective clad material suitable for use in coal conversion atmospheres. The commercial producibility of both the Fe-19Cr-8Al-0.5Hf alloy and the clad composite has been demonstrated. The clad composite has been shown to exhibit resistance to sulfidation in high sulfur, coal gasification atmospheres low Btu for 2000 hrs at 1800/sup 0/F (1255K). The FeCrAlHf alloy must be preoxidized in the absence of sulfur to form fully protective alumina scales on all surfaces. Useful life of the composite at temperatures of 1400 to 2000/sup 0/F (1033 to 1366K) is governed by reactions at the FeCrAlHf clad alloy 800 interface. The rate of interdiffusion decreases with increasing Ni content and a high Ni alloy such as RA333 appears to be a better substrate than ...

International Nuclear Information System (INIS)

In this study, the corrosion behavior of commercially pure titanium (c.p. Ti), Ti-6Al-4V and five new experimental Ti-Cr alloys was evaluated through open-circuit potential (OCP) and potentiodynamic polarization measurement in an artificial saliva containing fluoride. Electron spectroscopy for chemical analysis (ESCA) was used to characterize the composition of the passive films on the alloy after potentiodynamic polarization measurement. It was found that in standard artificial saliva the OCP increases with higher Cr content in Ti-Cr alloys. In 0.5% NaF artificial saliva, the OCP decreases with decreasing Cr in Ti-Cr alloys, and all but Ti-5Cr remain consistently higher than those of c.p Ti and Ti-6Al-4V. Linear polarization results show that artificial saliva and artificial saliva containing 0.5% NaF result in different corrosion behavior in Ti-Cr alloys, c.p.Ti and Ti-6Al-4V. The ...

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Hydrogen uptake and embrittlement of tantalum by electrolytically produced hydrogen is investigated on samples of varying composition and type of pretreatment. Of decisive influence on the uptake of hydrogen are the oxide layers present on the tantalum surface. By contact with platinum group metals as alloying constituents, surface coatings or anodic protection, a protection of tantalum can be obtained depending on the experimental conditions.

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In addition to ceramics, alloys such as tool steel and nickel- and iron-based superalloys are being considered for high temperature applications such as missile bearings and low heat rejection engines. Studies were made to lubricate a nickel-based superalloy at 500{degrees}C, by using a vaporized aryl phosphate ester, at a concentration of 0.1% in air. From deposition and wear studies it was found that it was impossible to form a good polymeric coating on the superalloy surface. Energy dispersive X-ray analyzer (EDXA) analysis showed that this was due to minute quantities of aluminum in the alloy segregating to the surface, upon being heated to 500{degrees}C, forming a passive oxide coating. It was necessary to activate the surface, in order to lubricate the material successfully. A method of activation by electrodepositing the surface with a layer of iron oxide ...

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The work in the past year has primarily involved four areas of magnetic thin films: amorphous rare earth-transition metal alloys, epitaxial CoPt{sub 3} and Ni-Pt alloy thin films, amorphous rare earth doped Si (a new class of dilute magnetic semiconductor with large negative magnetoresistance which the authors have discovered), and exchange-coupled antiferromagnetic insulators. In the amorphous alloys, they made a systematic study of the effects of local anisotropy, macroscopic (perpendicular) anisotropy, and exchange constant on the fundamental (and practical) properties of these magnetic alloys, as originally described in the grant proposal. The work on the epitaxial Co-Pt (and more recently Ni-Pt) alloys was originally undertaken as a comparison study to the amorphous alloys. Crystalline Co-Pt alloys have many striking similarities to the ...

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Samples of alloy 800 H (LJNS N08810) and alloy 617 (UNS N06617) were oxidized in a simulated process gas atmosphere. The principal elements of the gaseous environment were 50% H{sub 2}O, 35% H{sub 2} and 5% of CO{sub 2}, CO, and CH{sub 4}, respectively. The experiments were carried out at temperatures from 850 C to 950 C for exposures ranging from 600 to 5,000 hours. After the exposure, the alloy surfaces showed compact oxide layers, which resulted in a depleted zone of oxidizing elements in the substrate layer. Using Electron Probe Microanalysis (EPMA), concentration profiles and the extension of the depleted zone were measured. Calculated theoretical profiles were then fitted to the EPMA-measured profiles, using Fick`s second law of diffusion and resolved by a finite difference method and diffusion coefficients as fitting parameters. The diffusion coefficients for chromium may be represented as D = Do ...

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The effects of thiosulfate ion and solution pH on pitting corrosion of Alloy 690 in chloride solution were explored. Potentiodynamic polarization measurements were conducted to evaluate pitting corrosion susceptibility of Alloy 690 in these environments. The results showed that pitting corrosion occurred in the mill-annealed (1050 deg. C/5min) Alloy 690 in 1 wt% NaCl solution but not in 0.1 M Na{sub 2}S{sub 2}O{sub 3} solution. The value of pitting nucleation potential (E{sub np}) determined in 1 wt% NaCl solution (without Na{sub 2}S{sub 2}O{sub 3} ) increased with increasing solution pH value in the range of 2-10. The addition of Na{sub 2}S{sub 2}O{sub 3} to 1 wt% NaCl solution greatly affected the pitting corrosion behavior, which was dependent on concentration. The preformed nickel sulfide surface film due to the presence of Na{sub 2}S{sub 2}O{sub 3} caused Alloy 690 to become ...

International Nuclear Information System (INIS)

Classification and ranking of the solid solution on their reaction to the irradiation is suggested on the basis of binary system structure controlled by mixing enthalpy sign, melting temperatures relation of components and solidus curves slope. Several combinations of these characteristics permit to pick out three groups of substitutional elements capable of forming the vacancy-solute atom complexes either low-mobile or fast-mobile ones as compared to monovacancies migration. The radiation hardening (and embrittlement) of binary alloys should be intensified respectively either due to heterogeneous point defect clusters nucleation on solute traps or due to solute atom clusters/ precipitate formation. A local cohesion decrease may also occur especially if low-melting elements (characterized by low surface energy) are segregating on internal sinks or grain boundaries. The predicted specifics of different alloy group under ...

Energy Technology Data Exchange (ETDEWEB)

This paper reports that the co-deposition of chromium and silicon into a 2.25Cr-1.0Mo-0.15C steel, alloy 800, and type 304 stainless steel has been achieved using the pack cementation process. The ferritic coating produced on the 2.25 Cr-1.0Mo steel was approximately 225 {mu}m (9 mils) thick, whereas the inward diffusion of chromium and silicon produced a two-phase structure of ferrite and austenite for type 304. Chromium and silicon were incorporated into the austenitic solid solution upon diffusion into alloy 800. All coatings had approximately 25 to 35 wt% Cr and 2 to 3% Si at the surface. Cyclic oxidation testing in air of the coated 2.25Cr-1.0Mo steel (T = 700{degrees} C) and type 304 (T = 1035{degrees} C) showed a dramatic decrease in the oxidation kinetics compared to the original uncoated alloys. The cyclic oxidation of alloy 800 was also improved.

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This work reports studies of ethanol oxidation on Pt-Sn/C catalysts with nearly the same particle size and identical overall composition having different amounts of oxide and alloyed phases. Results of characterization of physical properties by transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and in situ dispersive X-ray absorption spectroscopy (DXAS) are presented. The variation in the amount of oxide and alloyed phases, promoted by heat treatments in mild temperature conditions, does not produce any significant particle growth. Cyclic voltammetry and oxidation of adsorbed CO in acid medium are used to probe the surface conditions. Data on the electrocatalytic activity towards ethanol oxidation, obtained by potential sweeps and chronoamperometry, are discussed and correlate well with the physical properties. This study, carried ...

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The shot peening of the outer surface of Alloy 800 is proposed by the steam generator supplier in order to increase the stress corrosion cracking resistance of the tubes. The benefits and drawbacks of such a treatment are evaluated, focusing on the main concern i.e. a possible enhanced tendency of stress corrosion cracking at the transition of the expanded tube-to-tubesheet joint. Stress corrosion tests as well as residual stresses measurements demonstrate no significant difference between peened and unpeened tubes at that location. The other concerns such as stability of the compressive stresses, increased risk of pitting or intergranular attack and pollution of the secondary circuit by fragmented beads appear the as minor concerns.

Energy Technology Data Exchange (ETDEWEB)

In order to investigate the influence of grain boundary cavities on the life time of Alloy 800 H various fatigue tests have been performed at 800/sup 0/C. Cavity formation has been observed only in asymmetrical tests. Compared to the corresponding symmetrical tests, the cyclic life time is shorter. As the cavitation damage increases, the ratio of life times in vacuum and in air steadily decreases from an initial value of 5. In extreme cases it can reach a value close to 1. In this case, cavitation damage dominates over the usual damage mechanism, which is cracks from the surface.

International Nuclear Information System (INIS)

The purpose of this experimental study is to investigate the micromechanical fatigue behavior, in terms of slip nature and preferential cracking sites, of a commercial #alpha#/#beta#-forged Ti-6Al-4V alloy. Electron backscattering diffraction is extensively used to identify the deformation (prismatic, basal, pyramidal slip) and crack formation modes activated by fatigue at the surface of several hundred primary #alpha# nodules. Some fatal crack formation sites are also characterized. Cracking in basal planes is identified as the most critical damage mode leading to fracture. An explanation is proposed which involves the resolved shear stress, taking into account the Schmid factor and the normal stress in relation to the elastic anisotropy of the #alpha#-phase. Finally, the spatial distribution of the secondary cracks is analyzed according to the crystallographic textures (macrozones) present on a mesoscopic scale in the Ti-6Al-4V ...

Energy Technology Data Exchange (ETDEWEB)

Some N-containing or S-containing organic substances and some acetylenic alcohols were tested as inhibitors of the corrosive attack suffered by Fe-based metallic glasses in deaerated 0.1 N sulfuric acid (H{sub 2}SO{sub 4}) solution at 25 C. It was verified that the specific action these compounds exerted on the corrosion process of the amorphous alloys was similar to the one these compounds exerted on polycrystalline iron. The most efficient substances were those containing a sulfur atom with available lone pairs, which chiefly inhibited the anodic reaction of both metal specimens. Owing to the chemical and physical homogeneity of the amorphous alloy, the chemisorbed inhibitor film that formed on the glassy surface was more stable and protective than that formed on the polycrystalline iron.

British Library Electronic Table of Contents (United Kingdom)

In the present work, the plasma nitriding behavior of a nickel based dental alloy was investigated. Plasma nitriding experiments carried out under constant gas mixture (15% H2?85% N2) for different process parameters including time (4, 6, 10, and 20?h) and temperature (400, 450, 500, and 550??C). Depending on nitriding parameters, it was found that triple or double layers formed on the surface of the samples. Increasing of treatment time and temperature has resulted in a double layer. ?N1 layer was in formed all nitrided samples. However, ?N2 layer is formed only at low temperatures and in short times. Layer growth of nickel based alloys increases until a critical time or a critical temperature reached. Above these critical values, it is observed that the layer thickness decreases. It was ...

Energy Technology Data Exchange (ETDEWEB)

Alloy 600 is used as a material for steam generator tubing in pressurized water reactors(PWR) due to its high corrosion resistance under PWR environment. In spite of its corrosion resistance, stress corrosion cracking(SCC) has occurred on the primary side as well as the secondary side of the tubing. Oxide on steel surfaces in aqueous solution above 100 .deg. C is composed of duplex film structure. Inner layer of the oxide is dense and less porous, which is formed by growth of oxide layer on metal surface. Outer layer of the oxide is loose adhesive, which is formed by dissolution precipitation mechanism. Growth processes occur at the metal/oxide and oxide/electrolyte interfaces and are controlled by transport of the layer forming species through the layer, i.e. by the inward diffusion of oxygen including electrolyte species and the outward diffusion of metal cations. Understanding of basic electrochemical behaviors about ...

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the results of research conducted during the sixteen month continuation of a program to develop rechargeable zinc-air batteries for electric vehicles. The zinc-air technology under development incorporates a metal foam substrate for the zinc electrode, with flow of electrolyte through the foam during battery operation. In this soluble'' zinc electrode the zincate discharge product dissolves completely in the electrolyte stream. Cycle testing at Lawrence Berkeley Laboratory, where the electrode was invented, and at MATSI showed that this approach avoids the zinc electrode shape change phenomenon. Further, electrolyte flow has been shown to be necessary to achieve significant cycle life (> 25 cycles) in this open system. Without it, water loss through the oxygen electrode results in high-resistance failure of the cell. The Phase I program, ...

Energy Technology Data Exchange (ETDEWEB)

The aim of this study as to determine the mechanisms involved in using ammonium fluoborate as a reducing atmosphere when preheating a high magnesium content aluminium alloy. Rutherford Backscattering (RBS) has been the major technique used in the analysis of samples, it revealed significant reduction in both the diffusion of magnesium to the surface and the calculated oxide thickness in the presence of NH{sub 4}BF{sub 4}. At temperatures above 500 deg C in air, SEM images revealed depressions and voids due to incipient melting at various stages, around the grain boundaries. Grain boundaries effectively acted as pipes aiding the diffusion of magnesium to the surface. These results have been verified through compositional analysis with both RBS and auger electron spectroscopy (AES). Results from NH{sub 4}BF{sub 4} atmosphere preheat conditions showed significant improvements. It was verified experimentally that above 500 deg ...

Energy Technology Data Exchange (ETDEWEB)

The recent rapid progress in surface treatment techniques dictates that the titanium alloys should have an improved resistance to frictional wear without any loss of their high corrosion resistance. These requirements can be satisfied by producing surface layers of specified microstructure and phase composition. The present paper describes a modification of the plasma discharge nitriding treatment of titanium alloys, i.e. the glow discharge-assisted oxycarbonitriding, which by introducing oxygen, nitrogen and carbon into the surface zone of the layer [a Ti(NCO) type layer] improves its useful properties, primarily the resistance to frictional wear and the resistance to corrosion [T. Wierzchon, J. Sobiecki, Vacuum, 44 (1993) 975; T. Wierzchon et al., in: G. Hecht, F. Richter, J. Hahn (Eds.), Thin Films, DGM Informationgesellschaft, Germany, 1994, p. 195] [1:2]. This is because ...

International Nuclear Information System (INIS)

Several heats of Alloy 800 are included in a survey of materials being creep tested in a simulated HTR helium atmosphere in the temperature range 650 to 800degC. The results are, as yet, incomplete, but indicate wide variations in the influence of the atmosphere on creep properties. Some heats appear, from results so far available up to 10,000 hours duration, to have greater creep strength in helium than in air, but others have the strength reduced by as much as 20%. Metallographic examination of terminated creep test bars and of unstressed samples indicates that oxidation of reactive constituents takes place, forming a surface scale and sub-surface oxide penetration. Carburisation can also occur and at 750 to 800degC this can penetrate to a depth of up to 800 #mu# m after 5000 h. (author).

International Nuclear Information System (INIS)

Smooth and notched fatigue behavior is presented for an age-hardenable metastable #beta#-titanium alloy (Ti-3Al-8V-6Cr-4Mo-4Zr). The as-solution heat treated condition exhibits low fatigue limits and high ductility, while the high-strength condition has higher fatigue limits, but poor ductility. A new thermomechanical technique employs shot peening and heat treating to selectively age-harden only the surface. The fatigue limit is improved to levels well above that of the high strength condition, while retaining appreciable ductility, since the bulk material remains in the solution heat treated condition. (orig./MM).

International Nuclear Information System (INIS)

The effect of severe plastic deformation by cold high pressure torsion (HPT) on radio frequency (RF) plasma nitriding of pure iron, as well as St2K50 and X5CrNi1810 steels was investigated. Nitriding was carried out for 3 h in a nitrogen atmosphere at a pressure of 10"-"5 bar and temperatures of 350 and 400 deg. C. Nitrided specimens were analysed by scanning electron microscopy (SEM), X-ray diffraction and micro hardness measurements. It was found that HPT enhances the effect of nitriding leading almost to doubling of the thickness of the nitrided layer for pure iron and the high alloyed steel. The largest increase in hardness was observed when HPT was combined with RF plasma nitriding at 350 deg. C. In the case of pure iron, the X-ray diffraction spectra showed the formation of #epsilon# and #gamma#' nitrides in the compound layer, with a preferential formation of #gamma#' at the expense of the #alpha#-phase at the higher nitriding temperature. The corresponding ...

Energy Technology Data Exchange (ETDEWEB)

The properties of AlN make this material very attractive for optical, electronic, and tribological application. Also, if the AlN could be formed on the Al surface to enhance its surface properties, Al could be applied for the lightening of machine parts. However, a dense oxide film exists on the surface of Al, which prevents the formation of the Al nitride even during plasma nitriding and plasma coating process. In this study, plasma nitriding has been tried to form an AlN layer on Al after the surface activation processes. During the plasma nitriding, the density of the nitrogen ions was amplified by means of controlling the power of the Al substrates. The film thickness, microstructural features and the mechanical properties such as hardness and wear properties of the AlN layer were examined as a function of the process parameters of pretreatment and plasma nitriding

International Nuclear Information System (INIS)

In VHTGR (Very High Temperature Gas-cooled Reactor), the radiation plays an important role in heat transfer through the cavity in RCCS (Reactor Cavity Cooling System). We performed the series of experiments to measure the emissivity using the infrared thermometer with wavelength range of 8#approx#14 #mu#m. As the first step, the transmittance of Zinc Selenide (ZnSe) window was measured to estimate the emissivity that can compensate the attenuation effect of window. The kind of gas with various concentrations in the cavity will be released during postulated accidents to the coolant type, so it is essential to estimate the effects of gas on the measurement of emissivity. In this manner we measured the emissivity with the air, the helium and the steam inside chamber. The results represent that the concentration of the air and the helium do not affect the emissivity significantly while the steam decreases the measured emissivity relatively. It means that the air and ...

International Nuclear Information System (INIS)

Two sediment cores (Southern Branch, PC-1, and Western Branch, WB-2) were taken from the highly industrialized Elizabeth River, Virginia. The concentrations of trace metals cadmium, cobalt, chromium, copper, nickel, lead and zinc, major elements iron, manganese and aluminum, organic carbon content and the specific surface area of the sediments were determined in each of the cores. Down-core variations in metals varied significantly in each core with maximum contamination events occurring at different times in different portions of the river. In PC-1, maximum metal concentrations were seen after the appearance of "1"3"7Cs. In contrast, the highest levels in WB-2 occurred well before the appearance of "1"3"7Cs. Although stricter environmental regulations have caused a decrease in metal concentrations since the 1980s, the concentrations in the surface sediments of many trace metals were elevated to levels 2-5 times higher than ...

International Nuclear Information System (INIS)

The effect of phosphorus on the corrosion resistance of Al-bronzes is studied in detail in this work. A literature review showed that there are a lot of things known about the microstructure and the mechanical properties of Al-bronzes. In spite of their corrosion resistance the corrosion properties and the structure of the protective oxide films of Al-bronzes were seldom a matter of interest. Systematic studies of the influence of different alloying elements on the oxide film and the corrosion properties are rare. Therefore, it is not possible to predict the corrosion resistance of Al-bronzes, made by alloying particular elements. The high corrosion resistance of the new alloy CuAl_2_0P_1 was the reason to investigate the influence of phosphorus on the corrosion properties of Al-bronzes in more detail. A systematic study of the microstructure and the corrosion properties of Cu, CuP_x, CuAl_2_0 and CuAl_2_0P_x offers an ...

International Nuclear Information System (INIS)

By using a plasma nitriding procedure at the PUPR Mirror Cusp Plasma machine, surface hardness is increased in 302/304-type stainless steel samples by exposing them to high-ion-density plasma at high vacuum. This method successfully dopes the surface of the material with strengthening nitrogen ions, without the use of chemical procedures that sacrifice the resistance to corrosion of the given material. A 500 V negative bias is placed on the sample exposed to the nitrogen plasma, where high-energy ions are therefore attracted and immersed into the metallic matrix microns into the surface of the stainless steel. This potential maintains a constant surface temperature at approximately 800 deg. C. The plasma parameters including ion density and plasma temperature were diagnosed using single Langmuir probes. The stainless steel samples were then tested using scanning electron microscopy (SEM), and Vickers ...

Energy Technology Data Exchange (ETDEWEB)

The Electric Fuel Limited (EFL) refuelable zinc-air battery system is currently being tested in a number of electric vehicle demonstration projects, the largest of which is a field test of zinc-air postal vans sponsored chiefly by Deutsche Post AG (the German Post Office). The zinc-air battery is not recharged electrically, but rather is refueled through a series of mechanical and electrochemical steps that will require a special infrastructure in commercial application. As part of the German Post Office field test program, Electric Fuel designed and constructed a pilot zinc anode regeneration plant in Bremen, Germany. This plant is capable of servicing up to 100 commercial vans per week, which is adequate for the field test vehicle fleet. This paper will describe the design and operation of each of the areas and devices within the plant.

Energy Technology Data Exchange (ETDEWEB)

Magnesium alloys have replaced resins as a material for the components of electronic products such as cell phone and notebook personal computer mainly, because of their lightness and rigidity. Thin walls, a complicated shape, and high appearance quality are all needed in the external parts. Die-casting and injection molding are the main method of manufacturing magnesium alloy parts. The optimal cast conditions and mold design have been investigated in order that a few defects such as surface cracks and mold cavities in casting parts would be reduced. Instead of cast, plastic forming technologies such as warm drawing and hot forging have been developed to form thinner walls and less defects. Plastic formability of magnesium alloy in hot working is dependent on a grain size of material. The material with fine grains has advantage of being formed at high strain rate. The characteristics of forming ...

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The Heusler alloy Ni{sub 2}MnIn is a promising material as spin injector because of its predicted half-metallicity at the interface to InAs. We grow thin films of this Heusler alloy by thermal coevaporation of Nickel and the alloy MnIn. The alloy is grown on Si{sub 3}N{sub 4} membranes and amorphous carbon films for transmission-electron microscopy (TEM) as well as on Si and InAs. The degree of the transport spin polarization of the films grown on Si(100), InAs(100) and in-situ cleaved (110) surfaces of InAs is determined by point-contact Andreev reflection spectroscopy (PCAR). The almost perfect lattice match between InAs and Ni{sub 2}MnIn supports highly oriented growth, as we have proven by electron diffraction under grazing incidence. Lateral spin valves with Heusler electrodes are lithographically defined. In view of the temperature-sensitivity of the optical and electron-beam ...

International Nuclear Information System (INIS)

This work presents a comparative study of low-alloy steel nitriding for different possible techniques. Active screen plasma nitriding (ASPN) is a successful surface modification method that has many advantages over the conventional DC plasma nitriding (CPN). The corrosion behavior of 30CrNiMo8 low-alloy steel has been examined using anodic polarization tests in 3.5% NaCl solution under varying conditions of ASPN and CPN processes. The process variables included active screen setup parameters, treatment temperature (550 and 580 deg. C), gas mixture (25/75 and 75/25 of N_2/H_2) and treatment time (5 and 10 h) in 500 Pa pressure. The structure and phases composition of the compound layer was studied by X-ray diffraction (XRD), microhardness tests, optical microscopy and scanning electron microscopy (SEM). It was observed that ASPN treated samples surface enhanced corrosion resistance while the temperature ...

International Nuclear Information System (INIS)

Samples of 316L stainless steel, Vitalium and Ti6A14V titanium alloy have been implanted with doses of 1.5, 3, and 4.5 x 10"1"7 Si"+/cm"2. Transmission electron microscopy shows that during ion implantation amorphous layers are formed. When samples of titanium alloy were implanted with a dose of 0.5 x 10"1"7 Si"+/cm"2, the implanted layer consisted of a dispersion of fine silicide crystallites instead of being amorphous. The corrosion resistance was analyzed by electrochemical techniques in 0.9% NaCl at the temperature of 37 C. The increase of corrosion resistance has been observed as a result of structural modifications of the surface layer. (author). 7 refs, 4 tabs.

Energy Technology Data Exchange (ETDEWEB)

The corrosion and passivation behaviour of bulk polycrystalline martensite Ni{sub 50}Mn{sub 30}Ga{sub 20} and austenite Ni{sub 48}Mn{sub 30}Ga{sub 22} alloys was compared in electrolytes with different pH values. Linear anodic and cyclic potentiodynamic polarisation methods and anodic current transient measurements have been conducted for the alloys and their constituents to analyze free corrosion, anodic dissolution and passive layer formation processes. Electrochemically treated alloy surfaces were characterized with scanning electron microscopy (SEM) and angle-resolved x-ray photoelectron spectroscopy (XPS). The electrochemical response of both alloys is in principal similar and is dominated by the Ni oxidation. In acidic solutions (pH 0.5 and 5) a slightly higher reactivity is detectable for the martensitic alloy which is mainly attributed to enhanced ...

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Pitting corrosion is localized accelerated dissolution of metal that occurs as a result of a breakdown of the otherwise protective passive film on the metal surface. This paper provides an overview of the critical factors influencing the pitting corrosion of metals. The phenomenology of pitting corrosion is discussed, including the effects of alloy composition, environment, potential, and temperature. A summary is then given of studies that have focused on various stages of the pitting process, including breakdown of the passive film, metastable pitting, and pit growth. 120 refs.

Energy Technology Data Exchange (ETDEWEB)

Systems with small sizes show significant changes compared to the bulk system. These changes are of major interest regarding the size reduction of technological applications. The hydrogen-metal system can be used as a model alloy to study small size features: shifted phase boundaries and sloped isotherms are found and, also, new materials structures. Most features can be attributed to surface- and interface contributions as well as to mechanical stress. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

Science.gov (United States)

By using a model dielectric matrix in electron self-energy evaluations the computational effort of a quasiparticle band-structure calculation for a semiconductor is greatly reduced. Applications to various systems with or without inversion symmetry, having narrow or wide band gaps, and semiconductor alloys demonstrate the reliability and accuracy of the method. Calculations have been performed for thirteen semiconducting or insulating materials: Si, LiCl, AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, InSb, and the Al{sub 0.5}Ga{sub 0.5}As and In{sub 0.53}Ga{sub 0.47}As alloys. Excellent agreement with experimental results is obtained for the quasiparticle energies for these materials. The only three exceptions, {ital E}({Gamma}{sub 1{ital c}}) of AlP, {ital E}({ital L}{sub 1{ital c}}) of AlAs, and {ital E}({ital L}{sub 1{ital c}}) of AlSb are discussed and attributed to various experimental uncertainties. Several other ...

UK PubMed Central (United Kingdom)

Known vertebrate GATA proteins contain two zinc fingers and are required in development, whereas invertebrates express a class of essential proteins containing one GATA-type zinc finger. We isolated...Full Text Available

UK PubMed Central (United Kingdom)

1. Proteolytic enzyme activities were examined in the pancreas of zinc-deficient and control rats. 2. No change was detected in trypsin-plus-chymotrypsin activity. 3. Carboxypeptidase activity was...Full Text Available

UK PubMed Central (United Kingdom)

Zinc is an essential trace metal ion for growth, but an excess of Zn is toxic and microorganisms express diverse resistance mechanisms. To understand global bacterial responses to excess Zn, we conducted...Full Text Available

UK PubMed Central (United Kingdom)

Hemoglobin and zinc protoporphyrin (ZPP) tests are commonly used to screen for iron deficiency, but little research has been done to systematically evaluate the sensitivity and specificity of these...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundFormation of site specific genomic double strand breaks (DSBs), induced by the expression of a pair of engineered zinc-finger nucleases (ZFNs), dramatically increases the...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The surface of low alloy steel (En40B) has been engineered in the plasma of a glow discharge via plasma nitriding and ion plating of titanium nitride (TiN) coatings on the nitrided substrates with the purpose of enhancing the surface properties and fatigue strength. The nitriding response of the steel has been accessed by the evaluation of phase composition, layer thickness, hardness profile, residual stresses and nitrogen and carbon distributions. The wear and fatigue characteristics of the plasma-nitrided steel have been investigated and simple models have been developed to describe the influence of such properties as depth and strength of the nitrided case on the fatigue limit and load-bearing capacity of the nitrided steel. In order to further improve the tribological properties and load-bearing capacity of the low alloy steel, a duplex plasma surface-engineering technique has ...

British Library Electronic Table of Contents (United Kingdom)

Magnetic properties of Fe-Co-Mo-Cu-B alloy system with Co up to 26at.% were investigated. After proper thermal treatment, the nanocrystalline grain remains tiny, the density hardly increases, but the room-temperature saturation attains 1.5T mainly due to a high enough Curie temperature. The generally observed slant hysteresis loops point to ribbon surfaces, which stress the ribbon interior and induce a specific magnetoelastic contribution to hard-ribbon-axis magnetic anisotropy even after vacuum annealing. The effect does not come from cobalt but rather from the lack of silicon. Partial removal of the surfaces resulted in a decrease of the loop tilt.

Energy Technology Data Exchange (ETDEWEB)

The influence of plasma nitriding on the fatigue behaviour of AISI 4140 low-alloy steel was investigated under varying process conditions of temperature (500-600 C), time (1-12 h), heat treatment before ion nitriding (quenched and tempered, normalized) and gas mixture (50% H{sub 2}-50% N{sub 2}). A rotating bending fatigue machine was used to determine the fatigue strength. It was found that the plasma nitriding improves the fatigue strength and increases the fatigue limit depending on the surface hardness of the case depth. The microstructure of surface and diffusion layers was examined by optical microscopy. The fracture surface of specimens and the origin of fatigue cracks were observed by scanning electron microscopy.

Energy Technology Data Exchange (ETDEWEB)

We report tests of a refuelable zinc/air battery of modular, bipolar-cell design, intended for fleet electric busses and vans. The stack consists of twelve 250-cm{sup 2} cells built of two units: (1) a copper-clad glass-reinforced epoxy board supporting anode and cathode current collectors, and (2) polymer frame providing for air- and electrolyte distribution and zinc fuel storage. The stack was refueled in 4 min. by a hydraulic transfer of zinc particles entrained in solution flow.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

For the development of a rechargeable zinc/air battery, La{sub 0.6}Ca{sub 0.4}CoO{sub 3}-catalyzed (perovskite) bifunctional oxygen electrodes and pasted zinc electrodes were prepared and tested in monopolar zinc/air cells. The cells were cycled in moderately alkaline electrolyte. The maximum power as well as the cycle life of the cells were investigated. Up to 450 cycles could be reached, and attractive specific energies and powers were obtained. (author) 3 figs., 4 refs.

Energy Technology Data Exchange (ETDEWEB)

An experimental technique has been developed to examine the interaction between deformation and the exposure of certain high temperature structural alloys to oxidizing molten salt environments. The experimental program involved performing a series of long-term tensile tests over a wide range of strain rates. Fracture strain reduction in area and ultimate strength (UTS) were monitored as parameters indicative of an alloy's susceptibility to environmental degradation. For Incoloy Alloy 800 tested at 600/sup 0/C in the salt medium and at initial strain rates between 2 x 10/sup -7/ sec/sup -1/ and 1 x 10/sup -5/ sec/sup -/1 no appreciable loss of ductility, as measured by reduction in area, was observed relative to control specimens tested in air at the same temperature and strain rates. Similarly, fracture strain and UTS were essentially unaffected by exposure to the oxidizing environment. The structure of the oxide ...

International Nuclear Information System (INIS)

As an unconventional surface alloying process, ion implantation has been utilized to improve the active-passive behavior and the pitting resistance of martensitic M50 engineering alloy. In a field simulation study, Cr-implantation only at 150 kev to a fluence of 2 x 10"1"7 ions/cm"2 prevented pitting. The best pitting resistance of the steel was obtained with multiple implantations of Cr and Mo. The intermixing effect of high fluence P-implantation into 304 stainless produced an amorphous surface alloy. The removal of the grain boundaries and the uniformity of the resulting structure had a great influence on corrosion properties. REED analysis indicated that the anodic passive films formed on P-implanted 304 stainless steel at 250 mV (SCE) in 0.5M H_2SO_4 was amorphous. Phosphorus and boron were implanted into 316 stainless steel to study the passivity of 316 stainless. ...

Energy Technology Data Exchange (ETDEWEB)

This report presents the results of cladding technology development under the Coal-Fired Combined Cycle DOE Project. Clad Alloy Development, involved the selection, fabrication and burner rig evaluation of advanced clad alloy composition diffusion-bonded to IN-738. Testing was conducted for up to 5800 hours at 1600/sup 0/F in a simulated PFB environment. Metallographic evaluation showed Co-base cladding alloys PFB-5PM and PFB-6PM (aluminided) and Fe-base alloy GE-2541 to be the most corrosion resistant. The formability and fabricability of sheet material was significantly improved for these alloys by utilizing powder metallurgy techniques. Clad Process Development encompassed processing activities to evaluate sheet alloy formability, bucket surface preparation techniques, platform clad forming, and the activated diffusion bonding (ADB) of ...

International Nuclear Information System (INIS)

The physical, chemical and mechanical properties of magnesium alloys make them attractive materials for automotive and aerospace applications. However, these materials are susceptible to corrosion and wear. This work discusses the potential of using sol-gel based coatings consisting of ZrO_2 and 15 wt.% of CeO_2. The CeO_2 component provides enhanced corrosion protection, while ZrO_2 impart corrosion as well as wear resistance. Coating deposition was performed by the dip coating technique on two magnesium alloy substrates with different surface finishes: AZ91D (as-casted, sand-blasted, and machined) and AZ31 (rolled and machined). All as-deposited coatings (xerogel coatings) were then subjected to 10 h annealing: a temperature of 180 C was applied to the AZ91D alloy and 140 C to the AZ31 alloy. Morphological and structural properties of the annealed coatings were investigated by ...

British Library Electronic Table of Contents (United Kingdom)

In this study structural and magnetic character of the expanded austenite phase (gN) layer formed on a medical grade CoCrMo alloy by a low-pressure Radio-Frequency plasma nitriding process was investigated. The formation of the expanded austenite phase is facilitated at a substrate temperature near 400^oC for 1, 2, 4, 6 and 20h under a gas mixture of 60% N2-40% H2. The magnetic state of the gN layers was determined by a surface sensitive technique, magneto-optic Kerr effect (MOKE), and with a scanning probe microscope in magnetic force mode (MFM). Strong evidence for the ferromagnetic nature of the gN-(Co,Cr,Mo) phase is provided by the observation of stripe domain structures and the hysteresis loops. The ferromagnetic state for the gN phase observed here is mainly linked to large lattice ...

International Nuclear Information System (INIS)

Titanium and its alloy Ti6Al4V enjoy widespread use in various biomedical applications because of favourable local tissue response, higher corrosion resistance and fatigue strength than the stainless steels and cobalt-chromium alloy previously used. The study reported in this paper aims to optimize the conditions of nitrogen ion implantation on commercially pure titanium and to correlate the implantation parameters to the corrosion resistance. X-ray photoelectron spectroscopy was used to analyse surface concentration and the implantation processes. An improvement in the electrochemical behaviour of the passive film was shown to occur with nitrogen ion implantation on titanium, in simulated body fluids. (UK).

Energy Technology Data Exchange (ETDEWEB)

A test program was conducted under contract to Sandia National Laboratories to investigate water/steam effects on elevated temperature low cycle fatigue and creep-fatigue of Alloy 800. This report presents interpretation and analysis of the test results. Tubular specimens with water sealed inside were cycled to failure under strain control. Tests were conducted to 616K (650/sup 0/F) and 922K (1200/sup 0/F); some at 922K included tensile or compressive hold periods to simulate creep-fatigue conditions. The tubular specimens showed significantly lower lives than solid bar specimens cycled at equivalent strain ranges. Rough internal surfaces contributed to early crack initiation with these specimens. Inclusion of hold periods caused further large reductions in cycles to failure.

British Library Electronic Table of Contents (United Kingdom)

In this work, effects of coolant chemistry, including concentrations of chloride ions and ethylene glycol and addition of various ions, on corrosion of 3003 Al alloy were investigated by electrochemical impedance spectroscopy measurements and scanning electron microscopy characterization. In chloride-free, ethylene glycol-water solution, a layer of Al-alcohol film is proposed to form on the electrode surface. With the increase of ethylene glycol concentration, more Al-alcohol film is formed, resulting in the increase in film resistance and charge-transfer resistance. In the presence of Cl- ions, they would be involved in the film formation, decreasing the stability of the film. In 50% ethylene glycol-water solution, the threshold value of Cl- concentration for pitting initiation is within ...

Energy Technology Data Exchange (ETDEWEB)

This poster presentation dealt with a brief overview of the practices in effect in British Columbia related to metal leaching and acid mine drainage. The metals mined in the province include coal, gold, silver, copper, molybdenum, lead, and zinc. Some mines operate under the surface, while others are strip mines, etc. under a variety of climactic conditions and a host of different mining companies, such as Cominco, Placer Dome and Noranda. The primary objective is the prevention of negative environmental impacts on land and in the water. Salmon and other fish need to be protected. A secondary objective is the minimization of impacts on the biota, which requires a detailed study of ecological risks. The solution often lies in soil covering. To illustrate, the author described the situation at Huckleberry Mines Ltd. and the remedial action that was implemented, and discussed the results on the beavers. In conclusion, the author discussed the ...

British Library Electronic Table of Contents (United Kingdom)

Water and soil samples from the area were therefore analyzed for their lead and zinc content. Computation of pollution statuses of lead and zinc revealed topsoil lead geoaccumulation indices of ?0.143 and ?0.069 and zinc geoaccumulation indices of 1.168 and 0.713 for Ishiagu and Uburu respectively. The pollution indices were determined to be 0.499 and 0.3564 for soil in Ishiagu and Uburu respectively and also 5.11 and 2.42 for water in Ishiagu and Uburu communities respectively. Water/soil concentration ratio were found to be 0.0018 and 0.0014 for lead in Ishiagu and Uburu respectively. On the other hand, the water/soil concentration ratio for zinc was computed to be 0.001 and 0.0008 for Ishiagu and Uburu respectively. These results seem to suggest that the pollution of the environment by ...

International Nuclear Information System (INIS)

We provide a numerically efficient procedure to perform LDA+Hubbard I calculations including self-consistency over the charge density in the FP-LAPW basis. The method is applied to Pu, Am, and PuAm and PuCe alloys. Our results for valence photoemission spectra (PES) agree with experimental data and with previous LDA+DMFT calculations. Analysis of the J=5/2 and J=7/2 contributions to the f-occupation supports the intermediate-coupling picture of f-states in heavy actinides. The electronic specific heat coefficient is calculated for PuAm and PuCe alloys in reasonable agreement with recent experiments. We show that Pu atoms keep their mixed-valence character in these alloys. Next, we study electronic and spectral properties of Pu-based superconductor PuCoGa_5 and obtain good agreement with experimental PES. Finally, we analyze surface effects. In Pu monolayer, we find substantial modification of PES due to ...

International Nuclear Information System (INIS)

As a hardening process, the attractiveness of nitriding lies in its low treatment temperature. Although the thickness of the case is less than that obtained by higher temperature processes such as carburising, there are a range of alloys and applications for which nitriding is the only possible alternative. Indeed, there are some alloys and applications for which even the normal nitriding temperatures (between 500 deg C and 600 deg C for ferrous alloys) are too high. In this paper, we report on developments, specifically the use of low pressure plasmas and high energy ion bombardment, which can extend the benefits of nitriding to lower temperatures. In this poster, we will present results from these collaborative projects, concentrating on the nitriding of austenitic stainless steel at temperatures below 450 deg C. In this temperature range, the hardness and wear resistance of the surface can be ...

International Nuclear Information System (INIS)

In situ spectroscopic ellipsometry was employed to investigate the initial regime of rare earth metal (REM) conversion coatings formation on AZ31 magnesium alloy. Three REM salts solutions, 0.05 mol.dm"-"3 Ce(NO_3)_3, La(NO)_3 and Sm(NO)_3 solutions, were used for REM conversion coatings preparation. By deconvoluting the ellipsometric data, the surface of the fresh well-polished AZ31 magnesium alloy was found to be covered with 15.80 nm thick native (hydr)oxide film; the refractive indices and the thickness of Ce, La and Sm conversion coatings were obtained. The formation kinetics of three REM coatings follows different exponential functions and the coatings exhibit different optical properties. La conversion coating has the largest n values and the lowest k values while Sm conversion coating is just opposite. Moreover, the pH variation of the bulk conversion solutions upon the coatings formation was recorded. It is ...

Energy Technology Data Exchange (ETDEWEB)

Ti and its alloys (Ti-6Al-4V) have been used in different engineering applications due to their several outstanding properties. Nevertheless, their use in practical applications is limited in many cases due to their poor tribological property. Researches are ongoing on surface modification of Ti based materials by different plasma and ion based techniques to overcome this problem. However, the conventional plasma nitriding techniques have several problems such as formation of an arc, increased possibility of surface contamination due to a comparatively higher operating pressure, production of a very thin nitrided layer after a long processing time, etc. In this present work, the possibility of a new low-pressure plasma nitriding process using a Plasma Enhanced Chemical Vapor Deposition (PECVD) based saddle field fast atom beam source on a Ti-6Al-4V alloy sample is investigated. Plasma nitriding was ...

Energy Technology Data Exchange (ETDEWEB)

Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr{sub 2}N, CrN, TiN, V{sub 2}N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of proton exchange membrane (PEM) single-cell fuel cell studies of stamped and pre-oxidized/nitrided developmental Fe-20Cr-4V weight percent (wt.%) and commercial type 2205 stainless steel alloy foils. The single-cell fuel cell behavior of the stamped and pre-oxidized/nitrided material was compared to as-stamped (no surface treatment) 904L, 2205, and Fe-20Cr-4V stainless steel alloy foils and machined graphite of similar flow field design. The best fuel cell behavior among the alloys was exhibited by the pre-oxidized/nitrided Fe-20Cr-4V, which exhibited ...

Energy Technology Data Exchange (ETDEWEB)

Titanium alloys are characterized by poor tribological properties, and the traditional use of titanium alloys has been restricted to nontribological applications. The deposition of a well adherent diamond coating is a promising way to solve this problem. In this study, the tribological properties of diamond-coated titanium were studied using a pin-on-disk tribometer, and the results were compared with those of pure titanium and plasma nitrided titanium. The tribological behavior of pure titanium was characterized by high coefficient of friction and rapid wear of materials. Plasma nitriding improved the wear resistance only under low normal load; however, this hardened layer was not efficient in improving the wear resistance and the friction properties under high normal load. Diamond coating on pure titanium improved the wear resistance of titanium significantly. Surface profilometry measurement indicated that little or no ...

International Nuclear Information System (INIS)

The effect of mean stress, or the stress ratio (R), on the fatigue-crack growth (FCG) behavior of #alpha#-aged and #omega#-aged microstructures of the beta titanium alloy Ti-10V-2Fe-3Al was investigated. While the mean stress had a negligible effect on the FCG behavior of the #alpha#-aged microstructure, a strong effect was observed in the #omega#-aged microstructure. In particular, the values of the threshold stress-intensity range (#DELTA#K_t_h) exhibited a strong dependence on R in the #omega#-aged microstructure, while this dependence was weak in the #alpha#-aged microstructure. These effects seem to arise primarily from fracture-surface roughness-induced crack closure. The crack closure levels for the #alpha#-aged microstructure were found to be very low compared to those for the #omega#-aged microstructure. Transmission electron microscopy and scanning electron microscopy studies of microstructures and fracture ...

Energy Technology Data Exchange (ETDEWEB)

Maximum metal loss rate of Alloy 800 coupons was about 0.5 mil/year and occurred at the maximum temperature of 600/sup 0/C. Significantly greater oxide penetration into the alloy occurred in unabraded as-received tubing. Since the corrosion rate of unabraded tubing was less temperature sensitive than polished coupons, and attained a maximum value at temperatures in the range of 550 to 565/sup 0/C, a value of 1 mil/year should be used as the corrosion rate for design purposes. Because daily thermal cycling is inherent in solar central receiver operation, oxidation and chromium depletion rates can be expected to increase if surface oxide layers spall. The oxide layers formed on Alloy 800 appeared to be adherent, and adherence will benefit further from growth-derived compressive stresses in oxide layers on the salt-exposed inner diameter of receiver tubes. Since the lower duty factor in diurnal solar ...

Energy Technology Data Exchange (ETDEWEB)

A method for using in situ X-ray absorption near edge spectroscopy to determine the composition of passive, transpassive, and nonreducible thin oxide films is described. The method is demonstrated by determining the composition of the passive films formed in pH 4.5, 0.1 M acetate buffer, on 100 {angstrom} thick Fe-yCr alloys (y = 8.5, 15, 19, 23 atom %) at potentials: (1) low in the passive region ({minus}0.3 V vs. mercurous sulfate reference electrode, MSE); (2) high in the passive region; (3) in the transpassive region; and (4) in the cathodic region where the air-formed film is not fully reduced. The nonreducible film at {minus}1.2 V is entirely a Cr{sup 3+} oxide/hydroxide. This nonreducible film persists at anodic potentials. At {minus}0.3 V, the passive film on each alloy is significantly enriched in Cr. The film at {minus}0.3 V consists primarily of the nonreducible Cr{sup 3+} oxide/hydroxide plus a very small amount of additional ...

International Nuclear Information System (INIS)

Nano-indentation has been used to assess the hardness of equiaxed grains of #alpha#-Ti as a function of orientation. Surface normals of these grains in metallographic sections were assessed using orientation imaging microscopy. Thin membranes of material from below a series of nano-indentations were excised by use of a dual-beam focused ion beam instrument. In this way, the dislocation substructures beneath individual indentations were characterized using transmission electron microscopy, permitting an identification of both statistically stored and geometrically necessary dislocations.

International Nuclear Information System (INIS)

Nickel ion radiation at 500 C was shown to have a strong effect on the surface electrochemistry and intergranular corrosion (IGC) of stainless steel (SS). Measured current densities in a 1 N sulfuric acid solution at room temperature were increased at active-passive, passive, and transpassive potentials. Radiation effects on the current decay behavior and susecptibility to IGC were similar for a fine-grained (FG) S alloy and for a very large-grained (LG) SS. Radiation-induced segregation (RIS) at the surface was believed to promote higher currents at short times, whereas segregation at grain boundaries was responsible for IG attack. Analytical electron microscopy (AEM) measurements revealed chromium and iron depletion plus Ni and silicon enrichment at grain boundaries in irradiated specimens. Si enhanced dissolution at transpassive potentials, whereas Cr depletion did the same at active-passive and passive potentials.

British Library Electronic Table of Contents (United Kingdom)

The electroless nickel plating/poly(dl-lactide-co-glycolide) composite coating (EN-plating/PLGA composite coating) was fabricated on the surface of the micro-arc oxidation (MAO) film of the magnesium alloy AZ81 to double control the corrosion and drug release in the hanks' solution. The EN-plating was fabricated on the MAO coating to improve the corrosion resistance by overlaying most pores and micro-cracks on the surface of the MAO film. Meanwhile, a double layered organic poly(dl-lactide-co-glycolide)/paclitaxel (PLGA/PTX) drug releasing coating with a top layered PLGA drug controlled releasing coating on EN plating was prepared to control the drug release rate by adjusting the different lactide: glycolide (LA:GA) ratio of PLGA. Scanning electron microscopy (SEM) and the X-ray powder dif...

International Nuclear Information System (INIS)

Two plasma chemistries, i.e., CH_4/H_2/Ar and Cl_2/Ar, were compared for the etching of InGaP, AlInP, and AlGaP under inductively coupled plasma (ICP) conditions. While the etching with CH_4/H_2/Ar discharges appears to be ion driven, Cl_2/Ar discharges showed an additional strong chemical enhancement. The highest etch rate (#approx#1 #mu#m/min) for InGaP was achieved at high ICP source power (#>=#750 W) with the Cl_2/Ar chemistry. Cl_2/Ar discharges provided very smooth surfaces in all three materials with root-mean-square roughness measured by atomic force microscopy around 2 nm. This result may be due to the efficient ion-assisted product desorption in this chemistry. The etched near-surface region of InGaP (#approx#100 Angstrom) with Cl_2/Ar maintained almost the same stoichiometry as that of the unetched control. By contrast, the CH_4/H_2/Ar plasma chemistry produced somewhat rougher surfaces and depletion of ...

International Science & Technology Center (ISTC)

The New Titanium Alloys With Increased Mechanical Properties and Corrosion Resistance for Medical Instruments and their Coatings

CERN Document Server

Metals and alloy - Atmospheric corrosion testing

Energy Technology Data Exchange (ETDEWEB)

This document reports the progress and accomplishments of a 16 month program to develop a rechargeable zinc-air battery for electric vehicle propulsion, from October 1988 through January 1990. The program was the first stage in the transition of alkaline zinc electrode technology, invented at Lawrence Berkeley Laboratory, to private industry. The LBL invention teaches the use of a copper metal foam substrate for the zinc electrode, in combination with forced convection of electrolyte through the foam during battery operation. Research at LBL showed promise that this approach would avoid shape change (densification and dendrite growth), the primary failure mode of this electrode. The program comprised five tasks; (1) cell design, (2) capacity maximization, (3) cycle testing, (4) materials qualification, and (5) a cost/design study. The cell design contemplates a plate and frame stack, with alternating ...

Science.gov (United States)

Nanosized particles are important because of their unique properties, different from the bulk, which leads to their enhanced catalytic, photocatalytic and electronic properties. This work has dealt with three different nanoparticle systems in the context of three different aspects of nanoparticle properties: (a) photocatalytis (TiO2/metal) system, (b) luminescence (CdSe) (c) alloying (Pt-Ag and Pd-Ag). The initial photocatalytic enhancement obtained by adding noble metal on semiconductor nanoparticles, degrades as fast as in 15 minutes and questions their long-term performance. XANES measurements on such irradiated systems like TiO2/Au, TiO2/Pt, TiO2/Ir indicates a positive oxidation state of these noble metals which renders them as recombination centers for photo-excited electrons and explains the decreased photocurrent. The oxidation is caused by holes. The EXAFS results also indicate a change of the interfacial structure under the effect of UV-irradiation, thus ...

Energy Technology Data Exchange (ETDEWEB)

A numerical model has been developed to simulate the charging and discharge behaviour of an electrically rechargeable alkaline zinc-air battery. Further a galvanostatic experiment including three charge/discharge cycles has been performed. The cell voltages, the Zn electrode potentials versus a Zn reference, and the O{sub 2} electrode potentials versus a Zn reference calculated with the model are in fairly good agreement with the corresponding experimental data. The model is expected to be useful for zinc-air battery design and for analysis of experimental data. (author)

Energy Technology Data Exchange (ETDEWEB)

Micron-size Ni-base alloy (NBA) powders were mixed with both 1.5 wt.% (hereinafter %) micron-size CeO{sub 2} (m-CeO{sub 2}) and also 1.5% and 3.0% nano-size CeO{sub 2} (n- CeO{sub 2}) powders. These mixtures were coated on low-carbon steel (Q235) by 2.0 kW CO{sub 2} laser cladding. The effects on the microstructures, phases and electrochemical corrosion of the coatings upon the addition of m- and n- CeO{sub 2} powders to NBA (m- and n- CeO{sub 2} /NBA) have been investigated. The results showed that a smooth coating was prepared under suitable processing parameters (P= 2.0 kW, V= 180 mm min{sup -1}) by adding 1.5% n- CeO{sub 2}. In addition to the primary phases of {gamma}-Ni, Cr{sub 23} C{sub 6} and Ni{sub 3} B in the Ni-base alloy coating, CeNi{sub 3} was formed in Ni-base alloy coatings with both n- CeO{sub 2} and m-CeO{sub 2} particles, and CeNi{sub 5} appeared in the coating upon decreasing the size of CeO{sub 2} ...

Energy Technology Data Exchange (ETDEWEB)

Electric Fuel Ltd. is engaged in the design, development and commercialization of its proprietary zinc/air battery technology for electric vehicles, consumer electronic products and defence applications. To meet the challenging requirements for propelling an all-electric bus, the Vehicle Division sought a unique solution: an all electric battery-battery hybrid propulsion system. The high energy zinc/air battery is coupled with a high-power auxiliary battery. The combined system offers zero emission, high power and long range in an economically viable package. The consumer battery group has developed a high power primary zinc/air cell aimed at cellular phone users, offering extended use, convenience and low cost. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Micro-batteries are one of the key components that restrict the application of autonomous Microsystems. However little efforts were made to solve the problem. We have proposed a new planar zinc/air micro-battery, suitable for autonomous microsystem applications. The micro-battery has a layered structure of zinc electrode/alkaline electrolyte/air cathode. A 3D zinc electrode with a high density of posts was designed to obtain a high porosity, hence to offer a best performance. A model of the micro-battery is developed and the device performances were simulated and discussed. A four-mask process was developed to fabricate the prototype micro-batteries. The preliminary testing results showed the micro-batteries is able to deliver a maximum power up to 5 mW, and with an average power of 100 {mu}W at a steady period for up to 2hrs. Fabrication process is still under optimization for further improvement.

British Library Electronic Table of Contents (United Kingdom)

Abstract Micronutrient deficiencies are a public health concern among young children in low-income countries, and novel strategies are needed to improve the nutritional status of children at risk. One promising approach is the use of lipid-based nutrient supplements (LNS), which can be added to complementary food at the time of consumption. The optimal amount of zinc to include in LNS is uncertain, and concerns have been expressed about possible adverse effects of zinc on sensory characteristics of LNS. We conducted a series of acceptability studies of LNS containing either 0 or 10-mg of zinc per daily 20-g LNS dose among Burkinabe children 9-15 months old and their mothers. These acceptability studies included observations of children's consumption, maternal and child sensory reaction to ...

Energy Technology Data Exchange (ETDEWEB)

Airbag pressure vessels for the north-American market mainly are made by forging and by the use of steel alloys. In Europe aluminum alloys are common and the manufacturing process is extrusion of circular blanks - made from cold rolled plates - in a form applying a 100 t press at room temperature. Then by heat treatment the strength/hardness of the material is properly adjusted and after that the pressure vessel parts have to be continuously inspected with an inspection and handling cycle time of 3 s. Inspection of the axis-symmetric parts is asked for surface breaking extrusion defects as well as for surface parallel delaminations in the bulk volume. Furthermore, the material strength is a quality characteristic that has to be nondestructively registered and documented. The inspection is performed by eddy current probes and an EMAT, of which the eddy current impedance measurements are used for ...

International Nuclear Information System (INIS)

Proposals for use of Alloy 800 as a H.T.R. boiler material have prompted studies of its creep and high temperature fatigue properties in impure helium with comparative tests in air. In impure helium, as expected in a H.T.R., reactions of potential importance are selective oxidation (of chromium, aluminium and titanium) and possibly carburisation from carbon monoxide or methane. In air, general oxidation will occur, possibly accompanied by nitridation. The effects of these reactions will depend on specimen geometry and the nature of the deformation. Two important possibilities are: (i) that environment affects the structure and properties of a surface zone of material undegoing uniform deformation (this may modify creep rate and crack nucleation); and (ii) that environment affects behaviour of a small region (e.g. at the root of a notch or ahead of a crack) in a specimen undergoing non-uniform deformation (this will modify crack growth and hence ...

Energy Technology Data Exchange (ETDEWEB)

Positron annihilation experiments on Fe-Cu model dilute alloys of nuclear reactor pressure vessel (RPV) steels have been performed after neutron irradiation in JMTR. Nanovoids whose inner surfaces were covered by Cu atoms were clearly observed. The nanovoids transformed to ultrafine Cu precipitates by dissociating their vacancies after annealing at around 400degC. The nanovoids and the ultrafine Cu precipitates are strongly suggested to be responsible for irradiation-induced embrittlement of RPV steels. Effects of Ni, Mn and P addition on the nanovoid and Cu precipitate formations were also studied. The nanovoid formation was enhanced by Ni and P, but suppressed by Mn. The Cu precipitates after annealing around 400degC were almost free from these doping elements and hence were pure Cu in the chemical composition. Furthermore the Fermi surface of the 'embedded' Cu precipitates with a body centered cubic ...

International Nuclear Information System (INIS)

The construction materials used in coolant systems in nuclear power plants become covered with oxide films as a result of exposure to the aqueous environment. The susceptibility of the materials to different forms of corrosion, as well as the extent of the incorporation of radioactive species on the surfaces of the primary circuit, are greatly influenced by the physical and chemical properties of these oxide films. The composition and characteristics of the oxide films in turn depend on the applied water chemistry. This work was undertaken in order to collect and evaluate the present views on the structure and behaviour of oxide films formed on iron- and nickel-based materials in aqueous environments. This survey should serve to recognise the areas in which more understanding and research effort is needed. The review begins with a discussion on the bulk oxides of iron, nickel and chromium, as well as their mixed oxides. In addition to bulk oxides, the structure and ...

Energy Technology Data Exchange (ETDEWEB)

An investigation was conducted into alternative techniques for zinc and electrolyte regeneration and reuse in the refuelable zinc/air battery that was developed by LLNL and previously tested on a moving electric bus using cut wire. Mossy zinc was electrodeposited onto a bipolar array of inclined Ni plates with an energy consumption of 1.8 kWh/kg. Using a H{sub 2}-depolarized anode, zinc was deposited at 0.6 V (0.8 kA/m{sup 2}); the open circuit voltage was 0.45 V. Three types of fuel pellets were tested and compared with results for 0.75 mm cut wire: spheres produced in a spouted bed (UCB); coarse powder produced by gas-atomization (Noranda); and irregular pellets produced by chopping 1-mm plates of compacted zinc fines (Eagle-Picher, Inc.). All three types transported within the cell. The coarse powder fed continuously from hopper to cell, as did the compacted pellets (< ...

International Nuclear Information System (INIS)

German (Dec 1973). Germany Carlen, JC Blom, U. Sandvik Steel Works,

International Nuclear Information System (INIS)

Observations concerned with the formation of isothermal #omega# in the beta-titanium alloy RMI (38-6-44) are presented as part of a more general study of the aging characteristics of the alloy.