Experimental evidence for the critical size of heterogeneity areas for pitting corrosion of Cr-Zr alloys in 6 M HCl

Mehmood, Mazhar; Zhang, B.-P.; Akiyama, Eiji; Habazaki, H.; Kawashima, A.; Asami, K.; Hashimoto, Kôji

doi:10.1016/s0010-938x(97)00107-8

Cited by 70 publications

(42 citation statements)

References 17 publications

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“…Therefore, the high corrosion resistance obtained for the Ti 47:5 Zr 15 Cu 30 Pd 7:4 Sn 5 ribbons in Fig. 4 may be due to the formation of nano-scale CuZr phase, 6) resulting in the enrichment of Ti and Pd in the glassy matrix, which is helpful to form protective passive film. At the same time, it is seen that the phases are in several nanometers scale as seen in Fig.…”

Section: Potentiodynamic Polarization Curvesmentioning

confidence: 98%

“…The comparisons of mircro-structure and corrosion property of the as-prepared samples indicated that the Ti 47:5 Zr 15 Cu 30 Pd 7:4 Sn 5 glassy ribbons even mixed with small size nano-particles showed high corrosion resistance in PBS(À) and Hanks' solutions. Mehmood et al 6) reported that the Cr-rich nano-crystalline phase formed after heat treatment in Cr-Zr alloys ennobled the pitting potential in aggressive HCl solution, because the formation of the hcp zirconium phase leading to an increase in the Cr content of the matrix was able to form thin protective Cr-rich passive films covering the entire alloy surface. But the pitting potential of the Cr-Zr alloys after heat treatment was also dependent on heating temperature, i.e., the size of nano-crystalline phases played an important role in controlling the corrosion behavior.…”

Section: Potentiodynamic Polarization Curvesmentioning

confidence: 99%

“…[1][2][3] However in some cases, the glassy state itself does not exhibit superior corrosion resistance in Zr-Ti-Ni-CuBe 4) and Zr-Cu-Ni-Al 5) alloy systems, even though they contain a large amount of passivating elements. Mehmood et al 6) reported that the formation of nano-crystalline phases formed by heat treatment ennobled the pitting potential in Cr-Zr glassy alloys in aggressive Cl-containing solution. Alvarez 7) also found that the crystallized alloys were more anticorrosive than the pure amorphous alloy in NaCl solution in Ni-B-Sn alloys.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and Corrosion Resistance of Ti–Zr–Cu–Pd–Sn Glassy and Nanocrystalline Alloys

et al. 2007

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The microstructure and corrosion behavior of the Ti 47:5 Zr 15 Cu 30 Pd 7:5 Sn 5 as-spun ribbons and as-cast rod have been investigated using HREM and potentiodynamic polarization study in simulated body fluids. The results of HREM reveal that, with decreasing cooling rate, the size and volume of nano-particles dispersed in glassy matrix increase for the Ti 47:5 Zr 15 Cu 30 Pd 7:5 Sn 5 as-prepared samples. The as-spun ribbons with small size nano-particle show high corrosion resistance in PBS(À) and Hanks' solution, may be due to the formation of CuZr phase, resulting in the enrichment of Ti and Pd in the glassy matrix, which is helpful to form protective passive film. Comparatively, poor corrosion resistance is observed for the as-cast rod sample with larger nano-particles in both solutions.

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Section: Potentiodynamic Polarization Curvesmentioning

confidence: 98%

Section: Potentiodynamic Polarization Curvesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microstructure and Corrosion Resistance of Ti–Zr–Cu–Pd–Sn Glassy and Nanocrystalline Alloys

et al. 2007

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“…For instance, the amorphous and nanocrystalline valve-metal alloy coatings exhibit extremely high corrosion resistance in concentrated HCl. [2][3][4][5] Among these, the highest corrosion resistance is observed for tantalum-based alloys.…”

Section: Introductionmentioning

confidence: 99%

Electro-Deposition of Tantalum on Tungsten and Nickel in LiF-NaF-CaF2 Melt Containing K2TaF7 — Electrochemical Study

Mehmood

Kawaguchi²,

Maekawa³

et al. 2003

Mater. Trans.

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Electrochemical study has been carried out on the electro-deposition of tantalum in 55 mol%LiF-35 mol%NaF-10 mol%CaF 2 melt containing 1-2 mol%K 2 TaF 7 at 700 C. This has been done for determining the mechanistic features for preparing electrolytic coating of tantalum on nickel and tungsten substrates. Electro-deposition of metallic tantalum occurs primarily by electro-reduction of Ta(V), i.e., TaF 5 also undergoes reduction to form metallic tantalum. The oxide ions generated by reduction of TaOF 2À 5 are removed from the surface by an oxide ion getter in the LiF-NaF-CaF 2 melt. Pure metallic tantalum without any entrapped salt is successfully deposited on tungsten by galvanostatic polarization at reasonably low current densities. An additional feature on nickel is the formation of an intermetallic compound at potential $0:25 V nobler than that of pure tantalum as a result of underpotential deposition of tantalum. This intermetallic compound covers the surface within a short time followed by deposition of pure tantalum, although intermetallic compound keeps growing at the interface of pure tantalum deposit and the substrate as a result of diffusion. Other secondary reactions are (i) a low activity reduction of Ta(V) to Ta(II) at À0:25 V, (ii) a conproportionation reaction at the surface of electrode leading to partial dissolution of tantalum and, (iii) a corresponding disproportionation reaction that forms powdery metallic tantalum at the salt surface.

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“…[1][2][3][4][5][6][7] Tantalum is also interesting for high electric capacitance of its stable oxide film.…”

Section: Introductionmentioning

confidence: 99%

Compact Coating of Tantalum on Tungsten Prepared by Molten Salt Electrodeposition

et al. 2003

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Attempts to prepare tantalum coating on tungsten have been performed in 55 mol%LiF-35 mol%NaF-10 mol%CaF 2 melt containing K 2 TaF 7 . Electrolytic deposition of tantalum was carried out by galvanostatic polarization. A conproportionation reaction also occurred that interfered with the electrodeposition and resulted in decrease in current efficiency. However, the product of this reaction was soluble, which diffused away from the electrode without contaminating the deposit. Hence, a compact electrodeposited tantalum coating was obtained on tungsten substrate. An excellent interface was possible when coating was performed in the melt containing 2 mol% K 2 TaF 7 .

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Experimental evidence for the critical size of heterogeneity areas for pitting corrosion of Cr-Zr alloys in 6 M HCl

Cited by 70 publications

References 17 publications

Microstructure and Corrosion Resistance of Ti–Zr–Cu–Pd–Sn Glassy and Nanocrystalline Alloys

Microstructure and Corrosion Resistance of Ti–Zr–Cu–Pd–Sn Glassy and Nanocrystalline Alloys

Electro-Deposition of Tantalum on Tungsten and Nickel in LiF-NaF-CaF<SUB>2</SUB> Melt Containing K<SUB>2</SUB>TaF<SUB>7</SUB> — Electrochemical Study

Compact Coating of Tantalum on Tungsten Prepared by Molten Salt Electrodeposition

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Experimental evidence for the critical size of heterogeneity areas for pitting corrosion of Cr-Zr alloys in 6 M HCl

Cited by 70 publications

References 17 publications

Microstructure and Corrosion Resistance of Ti&ndash;Zr&ndash;Cu&ndash;Pd&ndash;Sn Glassy and Nanocrystalline Alloys

Microstructure and Corrosion Resistance of Ti&ndash;Zr&ndash;Cu&ndash;Pd&ndash;Sn Glassy and Nanocrystalline Alloys

Electro-Deposition of Tantalum on Tungsten and Nickel in LiF-NaF-CaF<SUB>2</SUB> Melt Containing K<SUB>2</SUB>TaF<SUB>7</SUB> &mdash; Electrochemical Study

Compact Coating of Tantalum on Tungsten Prepared by Molten Salt Electrodeposition

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Microstructure and Corrosion Resistance of Ti–Zr–Cu–Pd–Sn Glassy and Nanocrystalline Alloys

Microstructure and Corrosion Resistance of Ti–Zr–Cu–Pd–Sn Glassy and Nanocrystalline Alloys

Electro-Deposition of Tantalum on Tungsten and Nickel in LiF-NaF-CaF<SUB>2</SUB> Melt Containing K<SUB>2</SUB>TaF<SUB>7</SUB> — Electrochemical Study