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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6399-6408 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Reactive sputtering in an Al–O2/Ar system equipped with a dc power supply in constant voltage mode was simulated using a kinetics model in this article. This work showed that reactive sputtering under reactive gas flow rate control and with a constant voltage power was much different from that with a constant current power both in time-dependent and parameter-dependent behaviors. Numerical analysis predicted the continuous, N-shaped V–I characteristics curves, which agreed with the experimental curves reported by other researchers in a system which was equipped with a dc constant current power but operated under voltage control [R. McMahon et al., J. Vac. Sci. Technol. 20 376 (1982); K. Steenbeck et al., Thin Solid Films 92, 371 (1982)] and in a system with a modulated power supply [H. Ohsaki et al., Thin Solid Films 281-282, 213 (1996)]. The continuous parameter-dependent functions indicated that there is no hysteresis effect in constant voltage reactive sputtering, which is a well-known feature of dc constant current magnetron sputtering of an Al–O2/Ar system. According to the simulated kinetics curves using the same simulation parameters, the initial values of oxide coverage on the target surface had no influences on the final parameters at steady state in a constant voltage system, whereas different initial coverage may lead to different steady states (hysteresis behaviors) in a constant current system. This article showed that the films of any reactive gas contents, i.e., the M1−θ−(MOx)θ films (M=metal, MOx=compound of metal) with full range of 0≤θ≤1, could be produced in constant voltage reactive sputtering which is a system simpler than those under partial pressure control.© 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The serine-threonine kinases Pim-1 and Akt regulate cellular proliferation and survival. Although Akt is known to be a crucial signaling protein in the myocardium, the role of Pim-1 has been overlooked. Pim-1 expression in the myocardium of mice decreased during postnatal development, re-emerged ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 52 (1999), S. 463-473 
    ISSN: 1573-4889
    Keywords: Ti60 ALLOY ; CORROSION ; NaCl ; WATER VAPOR ; SYNERGISTIC EFFECT
    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 behavior of Ti60 has been studiedin oxygen containing water vapor at500-700°C, with and without a solid NaCldeposit on the surface. No measurable corrosion of theTi60 alloy was observed in atmospheres without NaCl.Corrosion of Ti60 was accelerated in the presence ofNaCl because of the formation of a nonprotectiveTiO2 oxide scale; the corrosion of Ti60 issignificantly aggravated due to the synergistic effect ofNaCl and water vapor. When the temperature was increasedup to the melting point of NaCl, the corrosion of Ti60coated with NaCl both in air-NaCl and inO2-NaCl plus water vapor became more severe. Amechanism to explain the effect of water vapor and NaClon the corrosion of Ti60 is proposed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 48 (1997), S. 381-390 
    ISSN: 1573-4889
    Keywords: TiAl intermetallics ; chromium ; oxidation kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of 10 at.%Cr on the oxidation resistance of TiAl intermetallic compound at 800–1100°C in air was investigated. The results indicated that 10 at.%Cr equally substituting for Ti and Al in TiAl alloy had duplex effects on the isothermal kinetics of DAL At lower temperatures (800–900°C), Cr increased the oxidation rates as a result of the doping effect of Cr in the scale and at higher temperatures (1000–1100°C), especially at 1100°C, Cr significantly reduced the oxidation rates as a result of the formation of a continuous Al2O3 film on the surface. 10 at.%Cr only substituting for Ti in TiAl alloy remarkably reduced the oxidation rates at all temperatures by about two orders of magnitude. Moreover, 10 at%Cr significantly improved the cyclic-oxidation rsistance of TiAl alloy.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 48 (1997), S. 511-525 
    ISSN: 1573-4889
    Keywords: TiAl intermetallic compound ; isothermal/cyclic oxidation ; TiAlCr coating ; MCrAlY coating ; interdiffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of a sputtered TiAlCr coating on the oxidation resistance of TiAl intermetallic compound was investigated in static air. The bare TiAl alloy exhibited poor isothermal and cyclic-oxidation resistance at 800–1000°C due to the formation of TiO2-base scales which tend to spall during cooling. A sputtered Ti-50Al-10Cr coating remarkably improved the oxidation resistance of TiAl, due to the formation of an adherent Al2O3 scale at 800–1000°C. After long-term oxidation (at 900°C for 1000 hr), TiAlCr coating still provided excellent protection for the TiAl alloy. Minor interdiffusion occurred due to the inward diffusion of Cr, while no Kirkendall voids were found at the coating/ substrate interface. In contrast, NiCrAlY and CoCrAlY coatings reacted extensively with the TiAl alloys. Moreover, the TiAlCr coating alloy is based on γ-TiAl and TiAlCr Laves phases, which may offer improved mechanical properties. The TiAlCr coating exhibited a better combination of oxidation resistance and substrate compatibility than conventional aluminide and MCrAlY coatings.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 50 (1998), S. 71-88 
    ISSN: 1573-4889
    Keywords: OXIDATION ; Ti3Al-Nb ; COATINGS ; SPUTTERED NiCrAlY ; ION-PLATED TIN
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A single sputtered NiCrAlY coating and a complexcoating of inner ion-plated TiN and outer sputteredNiCrAlY were prepared on the intermetallic compoundTi3Al-Nb. Their oxidation behavior wasexamined at 850, 900, and 950°C in air by thermalgravimetry combined with XRD, SEM, and EDAX. The resultsshowed that Ti3Al-Nb followed approximatelyparabolic oxi dation, forming an outer thinAl2O3-rich scale and an inner TiO2-rich layer doped withNb at the three temperatures. The TiO2-richlayer doped with Nb dominated the oxidation reaction.The single NiCrAlY coating did not follow parabolicoxidation exactly at 850 and 950°C, but oxidizedapproximately in a parabolic manner, because theinstantaneous parabolic constants changed slightly withtime. Besides the Al2O3 scale,TiO2 formed from the coating surface at the coating-substrate interface. Thedeterioration of the coating accelerated with increasingtemperature. The NiCrAlY-TiN coating showed two-stageparabolic oxidation at 850 and 900°C, and anapproximate parabolic oxidation at 950°C. The TiN layerwas effective as a barrier to inhibit coating-alloyinterdiffusion.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 51 (1999), S. 97-110 
    ISSN: 1573-4889
    Keywords: Cr-11Ni-2W-2Mo-V STEEL ; NaCl DEPOSIT ; WATER VAPOR ; CORROSION
    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 behavior of 1Cr-11Ni-2W-2Mo-Vsteel was studied in the presence of a NaCl deposit andwater vapor at 500-700°C. Results indicated thatcorrosion was not obvious without an NaCl deposit, while corrosion was accelerated remarkably by thesimultaneous presence of NaCl and water vapor at anytemperature. Optical microscopy (OM), X-ray diffraction(XRD), scanning electron microscopy (SEM), andelectron-probe microanalysis (EPMA) were used to analyze thecorrosion products. A mechanism of the synergisticeffect of water vapor and NaCl on corrosion of the steelis proposed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 51 (1999), S. 235-250 
    ISSN: 1573-4889
    Keywords: TiAl ; INTERMETALLICS ; HOT-CORROSION ; MELTS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The hot-corrosion behavior of Ti-50Al,Ti-48Al-2Cr-2Nb, and Ti-50Al10Cr alloys was investigatedin (Na, K)2SO4 andNa2SO4 + NaCl melts. TiAlintermetallics showed much better hot-corrosionresistance in (Na, K)2SO4 at900°C than the Ni-base superalloy K38G. Two types ofcorrosion products formed on Ti-50Al: some areas werecovered with a continuous Al2O3 scale, whereas otherareas formed a mixed Al2O3 +TiO2 scale; TiS existed at the scale-alloyinterface. A mixed Al2O3 +TiO2 scale formed on Ti-48Al-2Cr 2Nb, and nosulfide was found beneath the scale. An adherentAl2O3 scale, however, formed onTi-50Al-10Cr, which provided excellent hot-corrosionresistance. All three alloys suffered severe hotcorrosion in Na2SO4 + NaCl meltsat 850°C. A mixed Al2O3 +TiO2 scale formed on all three alloys andmany voids and pits existed in the scale-alloy interface. Thehot-corrosion mechanisms are discussed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-4889
    Keywords: high temperature ; oxidation behavior ; TiAl ; Co-Cr-Al coating ; alumina scale ; pore formation
    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 behavior of TiAl coupons coated with a fine-grain Co-30Cr-4Al (mass %) film of about 30-μm thickness has been studied at 1100–1400 K in a flow of purified oxygen at atmospheric pressure for up to 500 ks. Three oxidation stages were recognized: initial transient, parabolic, and accelerated stages. However, at 1100 K a parabolic stage continues for more than 800 ks. The activation energy for parabolic oxidation agrees with reported values for the oxidation of alumina-former alloys, although the mass gains during the parabolic stages are relatively small at 1200 and 1300 K. Micropores developed mainly at the scale/coating and coating/substrate interfaces as oxidation proceeded. This is attributable to recrystallization of the coating during oxidation and a Kirkendall effect due to preferential diffusion of Co into the substrate. The accelerated oxidation can be explained in terms of the formation of rutile mounds on the scale.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 43 (1995), S. 395-409 
    ISSN: 1573-4889
    Keywords: microcrystalline film ; TiAl intermetallic compound ; 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 behavior of a cast TiAl intermetallic compound and its sputtered microcrystalline film was investigated at 700–900°C in static air. At 700°C, both the cast alloy and its sputtered microcrystalline film exhibited excellent oxidation resistance. No scale spallation was observed. However, at 800–900°C, the oxidation kinetics for the cast TiAl alloy followed approximately a linear rate law, which indicates that it has poor oxidation resistance over this temperature range. The poor oxidation resistance of TiAl was due to the formation of an Al2O3+TiO2 scale which spalled extensively during cooling. Nevertheless, the sputtered, TiAl-microcrystalline film exhibited very good oxidation resistance. The oxidation kinetics followed approximately the parabolic rate law at all temperatures. Although the composition of the scales was the same as that of scales formed on the cast alloy, the scales formed on the sputtered microcrystalline-TiAl film are adherent strongly to the substrate. No scale spallation was found at 700–850°C, while a small amount of spallation was observed only at 900°C. This indicates that microcrystallization can improve the oxidation resistance of the TiAl alloy.
    Type of Medium: Electronic Resource
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