| 1. |
- Fleury, E., et al.
(författare)
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Fe-based amorphous alloys as bipolar plates for PEM fuel cell
- 2006
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 159:1, s. 34-37
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Tidskriftsartikel (refereegranskat)abstract
- Two compositions of Fe-based Fe50Cr18Mo8Al2Y2C14B6 and Fe44Cr15Mo14Y2C15B6N4 amorphous alloys were developed as alternative bipolar plate material for polymer electrolyte membrane fuel cell (PEMFC). In this paper, we present results of an investigation on the electrical, mechanical, corrosion properties and processing ability of these amorphous alloys. The combination of excellent properties indicated that Fe-based amorphous alloys could be potential candidate materials as bipolar plates in PEMFC.
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| 2. |
- Haribabu, S., et al.
(författare)
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Effect of Al Addition on the Microstructure and Phase Stability of P91 Ferritic-Martensitic Steel
- 2019
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer Science and Business Media LLC. - 1073-5623 .- 1543-1940. ; 50:3, s. 1421-1436
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of an experimental and computational study carried out to elucidate the effect of Al on the microstructure and phase stability of P91 F/M steel in as-cast, homogenized and normalized conditions. Al-added steels followed ‘Ferritic-Austenitic’ mode of solidification and the as-cast microstructures consisted of δ-ferrite + α′-martensite, the volume fraction of ferrite and hardness of martensite increased with Al concentration. Heat treatments and DSC experiments confirmed increased stability for δ-ferrite with Al addition. Systematic change in the phase transformations temperatures and volume fraction of equilibrium phases due to Al addition was estimated with the help of Thermo-Calc®. Al addition promoted the formation of AlN which was confirmed through electron microscopy-based investigations. AlN dissolution temperature was always above γ-loop which made it impossible to dissolve during austenization. With the help of Scheil and equilibrium simulations using Thermo-Calc®, elemental partitioning between δ-ferrite and α′ phases was found to be the reason for higher hardness of martensite. Based on experimental evidences, it is concluded that except in the case of 0.48 wt pct Al-added steel it is impossible to obtain single phase γ-field (without ferrite) at high temperature thereby a fully martensite structure on cooling.
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| 3. |
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| 4. |
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| 5. |
- Jayamani, Jayaraj, et al.
(författare)
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Corrosion behavior and surface film characterization of TaNbHfZrTi high entropy alloy in aggressive nitric acid medium
- 2017
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Ingår i: Intermetallics (Barking). - : Elsevier BV. - 0966-9795 .- 1879-0216. ; 89, s. 123-132
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Tidskriftsartikel (refereegranskat)abstract
- Corrosion behavior of TaNbHfZrTi high-entropy alloy (HEA) was investigated in nitric and fluorinated nitric acid at ambient (27 °C) and boiling (120 °C) conditions. The alloy passivated spontaneously during potentiodynamic polarization in 11.5 M HNO3 at ambient condition. The corrosion rate was negligible in boiling 11.5 M HNO3, exposed for 240 h. Scanning electron microscopic (SEM) studies did not show any significant corrosion attack. The high corrosion resistance of TaNbHfZrTi HEA was attributed to its single phase bcc structure. X-ray photoelectron spectroscopic (XPS) analysis revealed that the protective passive film formed in boiling nitric acid was predominantly composed of Ta2O5, in contrast to the presence of ZrO2 and HfO2 in air-formed native film. Potentiodynamic polarization studies indicated a pseudo-passivation behavior of the HEA in 11.5 M HNO3 + 0.05 M NaF at ambient condition. In boiling fluorinated nitric acid, SEM images of TaNbHfZrTi HEA displayed a severely corroded morphology indicating the instability of the metal-oxides of the alloying elements. XPS investigations confirmed the presence of ZrF4, ZrOF2 and HfF4 along with un-protective oxides of Ta, Nb and Ti on the film, resulting in decreased corrosion resistance of TaNbHfZrTi HEA in fluorinated nitric acid.
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| 6. |
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| 7. |
- Jayamani, Jayaraj, et al.
(författare)
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Corrosion behaviors of Fe45−xCr18Mo14C15B6Y2Mx (M=Al, Co, Ni, N and x=0, 2) bulk metallic glasses under conditions simulating fuel cell environment
- 2007
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 434-435, s. 237-239
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Tidskriftsartikel (refereegranskat)abstract
- The corrosion properties of the Fe45−xCr18Mo14C15B6Y2Mx (with M=Al, Co, Ni, N and x=0, 2) bulk metallic glasses have been investigated in a 1M H2SO4+2ppm F− solution at 80°C with H2 and air bubbling, which simulate environments of the polymer electrolyte membrane fuel cell. The partial replacement of 2at.% Fe led to significant modification of the corrosion behavior and resulted in corrosion resistances superior to that of stainless steel.
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| 8. |
- Jayamani, Jayaraj, et al.
(författare)
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Corrosion behaviour of Ni–Zr–Ti–Si–Sn amorphous plasma spray coating
- 2006
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 48:4, s. 950-964
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Tidskriftsartikel (refereegranskat)abstract
- Ni59Zr20Ti16Si2Sn3 amorphous material was deposited by a vacuum plasma spraying technique onto steel and copper substrates in order to investigate their behaviour in a corrosive environment. For comparison, the same alloy was prepared as amorphous ribbons by melt spinning. The amorphous nature of the coatings and ribbons was characterized by XRD, DSC and TEM, while XPS and AES analyses were performed to understand the origin of passivation and mode of corrosion. The corrosion behaviour of the coating was studied in H2SO4 and HCl solutions open to air at room temperature. Potentiodynamic polarisation and galvanic coupling tests were carried out on the substrate and the coating. It was found that the formation of Zr-, Ti- and Si-rich passive oxide layers provide a high corrosion resistance in H2SO4 solution while the breakdown of the passive layer by chloride ion adsorption was responsible for pitting corrosion of the Ni59Zr20Ti16Si2Sn3 amorphous ribbons in HCl solution. Galvanic corrosion was the dominant corrosion mechanism for the coating/copper hybrid structure, in contrast to the Ni59Zr20Ti16Si2Sn3 amorphous coating, which efficiently protected the steel substrate in the corrosive environment.
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| 9. |
- Jayamani, Jayaraj, et al.
(författare)
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Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions
- 2016
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 473, s. 157-166
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO3 + 0.05 M NaF. Complexing the fluoride ions either with Al(NO3)3 or ZrO(NO3)2 aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO3+0.05 M NaF, when complexed with 0.15 M ZrO(NO3)2. XPS analysis confirmed the presence of TiO2 and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance.
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| 10. |
- Jayamani, Jayaraj, et al.
(författare)
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Corrosion mechanism of N-containing Fe–Cr–Mo–Y–C–B bulk amorphous alloys in highly concentrated HCl solution
- 2007
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 449-451, s. 517-520
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Tidskriftsartikel (refereegranskat)abstract
- The Fe49Cr15.3Mo15Y2C15B3.4N0.3 (numbers indicate at.%) amorphous alloy in concentrated HCl solution was found to have a corrosion resistance of at least one order of magnitude higher than the N-free Fe-base amorphous alloy. X-ray photoelectron spectroscopy analyses were performed to understand the corrosion mechanism. It was found that the enrichment of Cr oxide and the presence of MoN nitrides on the surface in the passive layer were at the origin of the high corrosion resistance of the N-containing Fe-base amorphous alloy.
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