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Impedance measurements were performed for alloy 22 in the passive and transpassive range, in 1 M NaCl at 90°C. A RΩ-(R//CPE) circuit model was applied in the full passive range, where R was the film resistance. This model also applied for a wide range of chloride concentrations and pH values, at the open circuit potential. Two time constants were observed at the beginning and at the end of the passive range. In these cases, the resistances for the ion transfer might be located at the film interfaces, and not in the film itself. The protective properties of the film improved with polarization time due to the thickening and ageing of the film. The film resistance and the space charge layer thickness increased with the potential. The oxidation of Cr3+ to Cr6+ occurred in the film at high potentials, followed by the transpassive dissolution. In the pre-transpassive range of potentials, the film showed a p-type electronic character, while the ionic properties were that of a passive film. The passive film of alloy 22 was an n-type semiconductor, which changed to a p-type for the high passive potentials. ND = 2.7 × 1020 cm−3 and EFB = −0.551 VSCE were determined.

Alloy 22 (UNS N06022) is a Ni-Cr-Mo-W alloy highly resistant to localized corrosion. Alloy 22 may be susceptible to crevice corrosion in pure chloride (Cl -) solutions under aggressive environmental conditions. The effect of the fl uoride (F -) over the crevice corrosion induced by chloride ions is still not well established. The objective of the present work was to explore the crevice corrosion resistance of this alloy to different mixtures of fl uorides and chlorides. Cyclic potentiodynamic polarization (CPP) tests were conducted in deaerated aqueous solutions of pure halide ions and in different mixtures of chloride and fl uoride at 90°C and pH 6. The range of chloride concentration [pH, microbial activity, volume of electrolyte, crevice former geometry, crevicing material, etc. Internal factors include 7 the metallurgical condition of the alloy (microstructure), presence of a weld seam, type of annealing, oxide fi lm formed, surface fi nishing, etc. A more detailed discussion regarding this topic can be found elsewhere. 7 Many of the factors listed above, such as chloride concentration, temperature, and inhibitors (namely nitrate and sulfate), have been studied in some detail. 6,[8][9][10][11] The infl uences of other factors still need to be investigated. 7 In particular, the role of halides other than chloride is still not 7,12-17 and will be discussed briefl y in this paper.Meck, et al., did not fi nd crevice corrosion in prismatic Alloy 22 specimens (a variation of the ASTM G5 specimen, 18 which contained an artifi cial crevice formed by a polytetrafl uoroethylene [PTFE] compression gasket) tested in 1 M sodium chloride (NaCl), pH 6 and in 1 M sodium fl uoride (NaF), pH 9 solutions at

Alloy 22 (N06022) is a Ni–Cr–Mo alloy that offers an outstanding corrosion resistance in a wide variety of highly corrosive environments. In the present work, the general corrosion of alloy 22 in the passive and active states and the transition from passive and active states were studied in acidic chloride solutions at 90°C . Electrochemical studies, including electrochemical impedance spectroscopy and polarization tests, were performed using mill-annealed and thermally aged (10 h at 760°C ) alloy 22 specimens. The depassivation pH (pHnormalD) was 1.7 in deaerated conditions and pHnormalD=0.3 in aerated conditions. The transition from passive to active states was characterized by a 3 orders of magnitude increase in the corrosion rate (CR) and a significant increase in the interfacial capacity. The CRs obtained via electrochemical tests for mill-annealed (MA) and thermally aged alloy 22 were comparable in all the tested conditions used in the present work. Intergranular attack was observed in thermally aged alloy 22 corroding in the active state due to the presence of precipitates and adjacent depleted zones of the protective alloying elements.

Alloy 22 (N06022) is the current candidate alloy used to fabricate the external wall of the high-level nuclear waste containers for the Yucca Mountain repository. It was of interest to study and compare the general and localized corrosion susceptibility of Alloy 22 in fluoride and chloride solutions at 90°C. Standard electrochemical tests such as cyclic potentiodynamic polarization, amperometry, and electrochemical impedance spectroscopy were used. Studied variables included the solution pH and the alloy microstructure (thermal aging). Results show that Alloy 22 is highly resistant to general corrosion in all the solutions tested. Thermal aging is not detrimental and even seems to be slightly beneficial for general corrosion at the higher solution pHs. Pitting corrosion was never observed. Crevice corrosion was found only for high chloride-containing solutions after anodic polarization. The presence of fluoride ions together with chloride ions seems to increase the susceptibility of Alloy 22 to crevice corrosion compared to pure chloride solutions.The maximum allowed temperature by design specifications is 350 °C. [1] Previous studies have shown that the mechanical and corrosion properties of this alloy did not change when it was aged for up to 40,000 hours at 427 °C. [5,6,7] Microstructural changes that occur in the base material have been evaluated at temperatures from 427 °C to 760 °C. Tetrahedral close-packed (TCP) phases precipitate in the Alloy 22 at temperatures of 593 °C and higher. [8,9,10] These phases could have a detrimental effect upon corrosion resistance and cause loss of mechanical ductility. A long-range ordering (LRO) reaction can occur at lower temperatures and produce an ordered Ni 2 (Cr,Mo) phase. [7,8] This ordering reaction is thought to cause little or no effect on corrosion and causes only a slight loss in ductility.Alloys that rely on passive oxide films for protection against corrosion are susceptible to localized corrosion, especially in the presence of halide ions. [11,12] Different concentrations of fluorides and chlorides can be naturally found in ground waters. While the effects of chlorides on the passive state and localized corrosion have been extensively studied for austenitic alloys that form chromium oxide films, the effects of fluorides have not been fully characterized. [13][14][15][16] The aim of this study was to investigate the effects of pH and thermal aging on the susceptibility of Alloy 22 to general and localized corrosion in chloride, fluoride, and mixtures of chloride-fluoride solutions. The results presented in this study correspond to solutions containing a much larger amount of chloride and fluoride than in the ground water at Yucca Mountain, which are approximately 7 and 2 mg/L, respectively. One M fluoride represents 19,000 mg/L and one M chloride represents 35,000 mg/L; these values are 5000 to 10,000 times the concentration of halide in the ground water. [12] II. EXPERIMENTAL PROCEDURE Specimens of Alloy 22 were prepared from wrought mill annealed plate stoc...

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If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to examine the external macro-environmental forces along with the internal country-specific attributes of Argentina as they influence entrepreneurship. The experiences with Argentina's financial crisis of 2001-2002 have highlighted concerns as to whether the past prosperity can ever be regained. Entrepreneurial ability has received much attention in public discussions as a means to revitalize the lagging economy. Design/methodology/approach -The popular strategic management tool of strengths, weaknesses, opportunities, threats (SWOT) analysis is used to group a number of current and emerging issues for the country. Their impact on entrepreneurship is then evaluated. Findings -Argentina has numerous natural resources that can be developed into new businesses. The slow growth of new venture creation in Argentina can be attributed to the difficulties in obtaining capital financing as well as the new business start-up licenses and procedures. Further limiting entrepreneurship is corruption, the lack of copyright protection, and difficulty hiring employees. However, the government of Argentina has implemented monetary changes to provide funds and other services for supporting new start-up companies and a key strength of Argentina for entrepreneurship is the country's resources and products. Major opportunities exist in tourism and investments in the growing wine production industry. The major threat to new venture creation, however, is the current worldwide recession. Research limitations/implications -Research implications for applying SWOT analysis to a country are discussed. While this tool is largely focused on companies and their issues for strategy development, this paper discusses ways to use the methodology to include ranking or weighting variables in their importance to entrepreneurship. A larger sample of experts is suggested for future research along with surveys of industry leaders to refine the ordering of variables. Practical implications -Implications for practitioners and policy makers within the country and areas for future research are discussed. Originality/value -The paper adds value to the existing research about new venture...