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  • 21
    Electronic Resource
    Electronic Resource
    On-line state estimation and control in glutamic acid production (1991)
    Springer
    Bioprocess and biosystems engineering 7 (1991), S. 35-39 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An automatic computer control system for glutamic acid production has been developed. A method based on empirical reaction subspace and singular value decomposition was presented for on-line estimation of cell concentration, glutamic acid, and total sugar. The only on-line measured state variable was the oxygen uptake rate. The estimated cell concentration was used as an index for the addition of penicillin. The estimated total sugar concentration was used for system identification. Adaptive control was then applied to manipulate the substrate feeding rate. The total sugar concentration was maintained at a given value during the period of fed-batch culture for glutamic acid production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00383576
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  • 22
    Electronic Resource
    Electronic Resource
    Role of platinum in the Na2SO4-Induced hot corrosion resistance of aluminum duffusion coatings (1984)
    Springer
    Oxidation of metals 22 (1984), S. 59-81 
    Details
    ISSN: 1573-4889
    Keywords: Al-diffusion coating ; platinum ; hot corrosion ; acidic and basic fluxing ; sulfate melt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Electrochemical corrosion measurements have been carried out with Pt-containing and Pt-free Al-diffusion coatings on IN 738 LC in a 90Na2SO4+ 10K2SO4 (mol%) melt at 1173 K. Pt improves the resistance to basic fluxing while there are no significant differences between both coating types in their resistance to acidic fluxing. The corrosion resistance of the Pt-containing coating is also higher in the passive potential region where protective scales rich in Al2O3 are formed. The reason for the different behavior of both coating types appears to be related to the high corrosion resistance of the Pt-rich surface layer of the coating and an increased Al2O3 content in the scale of the Pt-containing type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659249
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  • 23
    Electronic Resource
    Electronic Resource
    The Oxidation of Two Fe-Y Alloys Under Low Oxygen Pressures at 600-800°C (1998)
    Springer
    Oxidation of metals 49 (1998), S. 91-114 
    Details
    ISSN: 1573-4889
    Keywords: IRON ; YTTRIUM ; ALLOYS ; INTERNAL OXIDATION
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The corrosion of pure yttrium and of two Fe-basealloys containing approximately 15 and 30 wt.% Y wasstudied at 600-800°C in H2-CO2mixtures providing an equilibrium oxygen pressure of10-24 atm at 600°C and 10-20 atm at 700 and800°C. The corrosion of yttrium under these lowoxygen pressures resulted in the growth ofY2O3 scales and presented twoapproximately parabolic stages at 800°C, while at 600-700°C it was faster andnonprotective. The corrosion of the two alloys followedapproximately the parabolic rate law, except for Fe-15Yat 600°C which oxidized nearly linearly. At 600 and700°C, when the gas-phase oxygen pressure was in thefield of stability of iron oxide, the alloys formed alsoa thin external Fe3O4 layer, whileat 800°C, when the oxygen pressure was below thestability of FeO, a thin outermost layer of pure iron wasobserved to form. Under all conditions a region ofinternal oxidation formed in the alloy, in which theyttrium-rich phases were transformed into a mixture ofiron metal and oxides, which included double Fe-Yoxides as well as Y2O3. Themicrostructure of the internal-oxidation region followedclosely that of the original alloys, which moreover didnot undergo any yttrium depletion. These results are examinedby taking into account the low solubility of yttrium iniron and the presence of intermetallic compounds in thealloys.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018813920845
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  • 24
    Electronic Resource
    Electronic Resource
    The Oxidation of Fe-2 and 5 at.% Y Alloys at 600-800°C in Air (1999)
    Springer
    Oxidation of metals 51 (1999), S. 495-506 
    Details
    ISSN: 1573-4889
    Keywords: PURE FE ; Fe-Y ALLOYS ; OXIDATION
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of Fe-Y alloys containing 2 and 5at.% Y and pure iron has been studied at 600-800°Cin air. The oxidation of pure iron follows the parabolicrate law at all temperatures. The oxidation of Fe-Y alloys at 600°C approximatelyfollows the parabolic rate law, but not at 700 and800°C, where the oxidation goes through severalstages with quite different rates. The oxide scales on Fe-2Y and Fe-5Y at 700 and 800°C arecomposed of external pure Fe oxides containingFe2O3,Fe3O4, and FeO, with FeO being themain oxide and an inner mixture of FeO andYFeO3. The scales on Fe-2Y and Fe-5Y at 600°C consist ofFe2O3,Fe3O4, andY2O3, with a minor amount of FeO.Significant internal oxidation in both Fe-Y alloysoccurred at all temperatures. The Y-containing oxidesfollow the distribution of the original intermetalliccompound phase in the alloys. The effects of Y on theoxidation of pure Fe are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018843327998
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  • 25
    Electronic Resource
    Electronic Resource
    The identification of the sulfide NaCrS2 in nickel-base superalloys during corrosion in sulfate melts (1982)
    Springer
    Oxidation of metals 18 (1982), S. 187-194 
    Details
    ISSN: 1573-4889
    Keywords: Sulfide NaCrS2 ; basic fluxing ; nickel-base superalloy ; Na2SO4 melt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The sulfide NaCrS2 has been identified in the internal corrosion zone of several nickel-base superalloys under basic fluxing conditions at very negative potentials in a 90% Na2SO4-10% K2SO4 melt at 1173 K. It can also be formed in the presence of carbon-contaminated sulfate. NaCrS2 can dissolve some Ti, Al, Ni, and Co; other elements, e.g., K, Mo, W, Nb, Ta, and Zr, could not be detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00662037
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  • 26
    Electronic Resource
    Electronic Resource
    Acidic and basic fluxing of Ni-base superalloys in a 90Na2SO4-10K2SO4 melt at 1173 K (1983)
    Springer
    Oxidation of metals 19 (1983), S. 201-229 
    Details
    ISSN: 1573-4889
    Keywords: Acidic and basic fluxing ; hot corrosion ; sulfate melt ; superalloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of the electrode potential on the corrosion behavior of a series of Ni-base superalloys has been investigated in a (mole %) 90Na2SO4-10K2SO4 melt at 1173 K. Acidic fluxing occurs at positive potentials and basic fluxing at negative potentials. A protective scale is formed in an intermediate (neutral) potential range on high chromium-containing alloys such as IN-738LC, IN-939, IN-597, and IN-657. The breakthrough potentials for acidic and basic fluxing depend on the composition of the alloy. Alloys with low chromium contents such as IN-100 and IN-713LC do not form stable protective scales at any potential. Numerous sulfide phases have been identified in the scale and subscale, depending on potential, severity of attack, and material composition. NaCrS2 only forms under basic fluxing conditions. Its presence can therefore be considered as an indication that basic fluxing conditions have existed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00666645
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  • 27
    Electronic Resource
    Electronic Resource
    Electrochemical-Impedance Study of the Corrosion of Ni and FeAl Intermetallic Alloy in Molten (0.62Li, 0.38K)2CO3 at 650°C (2000)
    Springer
    Oxidation of metals 53 (2000), S. 289-302 
    Details
    ISSN: 1573-4889
    Keywords: Ni ; FeAl ; molten carbonates ; electrochemical impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The corrosion of Ni and FeAl in molten (0.62Li, 0.38K)2CO3 mixtures at 650°Cin air has been examined by the electrochemical-impedance spectroscopy (EIS)technique. The impedance spectra for Ni showed the typical characteristics ofa diffusion-controlled reaction, i.e., a semicircle at the high-frequency portand a line at the low-frequency port. The corrosion of FeAl also presentedthe feature of a diffusion-controlled reaction during initial immersion. However,the impedance spectra were composed of two capacitance loops after someimmersion time. The change of the impedance spectra with immersion time maybe ascribed to the formation of continuous external LiFeO2 and an innerAl2O3 layer. Equivalent circuits representing the featuresof the corrosion of Ni and FeAl were proposed to fit the impedance spectra andelectrochemical parameters in the equivalent circuits were also calculated. Basedon the measurement of diffusion impedance, the diffusion ofO− 2 was proposed to be the predominant feature of oxygen reduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004589103992
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  • 28
    Electronic Resource
    Electronic Resource
    Inhibition of Hot Corrosion by MgSO4 and BaSO4 and its potential dependence (1984)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 35 (1984), S. 139-149 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Inhibition der sulfat-induzierten Heißgaskorrosion durch MgSO4 und BaSO4 und ihre PotentialabhängigkeitElektrochemische Korrosionsuntersuchungen wurden mit IN 100 in einer Schmelze aus (Mol-%) 90 Na2SO4—10 K2SO4 mit verschiedenen Zusätzen an MgSO4 und BaSO4 bei 1173 K durchgeführt, um die Inhibition dieser Verbindungen und ihre Potentialabhängigkeit zu untersuchen. Es wurden sowohl potentiostatisch kontrollierte als auch Versuche beim Freien Korrosionspotential mit Messung des Polarisationswiderstandes durchgeführt.Die Inhibition von MgSO4 ist stark potentialabhängig. Bei negativen Potentialen, bei denen in elektrochemischen Nebenreaktionen Sauerstoffionen gebildet werden, wird MgO auf der Werkstoffoberfläche abgeschieden und teilweise in die Zunderschicht eingebaut. Diese MgO-reiche Zunderschicht ist beständig gegen basischen Aufschluß, weil MgO in basischen Schmelzen unlöslich ist. Bei positiven Potentialen, bei denen durch Entladen von SO4-Ionen die Säure SO3 entsteht, wird keine oder nur sehr geringe Inhibition gefunden.Zusätze von BaSO4 allein ergeben keinen Inhibitionseffekt. Zusätze von BaSO4 zu einer MgSO4-haltigen Schmelze verbessern jedoch erheblich die Inhibitionswirkung von MgSO4. Der Mechanismus dieses synergistischen Effektes wird nicht vollständig verstanden.
    Notes: Electrochemical corrosion measurements have been performed with IN 100 in a (mole %) 90 Na2SO4—10 K2SO4 melt with different additions of MgSO4 and BaSO4 at 1173 K in order to investigate the inhibition effect of these compounds and its potential dependence. Potentiostatically controlled measurements as well as free corrosion potential measurements with the determination of the polarization resistance have been performed.The inhibition effect of MgSO4 is strongly potential dependent. At negative potentials, where oxygen ions are produced by electrochemical side reactions, MgO is precipitated at the surface of the metal and becomes incorporated into the scale. This kind of MgO-rich scale is resistant to basic fluxing because MgO is not dissolved in basic media. At positive potentials, where acid SO3 is produced by discharge of SO4-ions, MgSO4 yields no or only very little inhibition.BaSO4 additions alone do not yield inhibition effects. However, additions of BaSO4 to melts containing MgSO4 improve the inhibition effect of the latter. The mechanism of this synergistic effect is not completely understood.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19840350402
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