Effect of Hydrogen on the X-Ray Parameter and Structure of Electrolytic Manganese

Potter, E. Vernon; Huber, R. W.

doi:10.1103/physrev.68.24

Cited by 17 publications

(6 citation statements)

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“…At the end of the deposition process, however, any hydrogen present in the lattice beyond the solubility limit diffuses out of the metal; consequently, its lattice shrinks and tensile stresses arise. A large amount of hydrogen is evolved during Mn electrodeposition, and it is reasonable to assume that the hydrogen content in manganese deposits is always at its saturation level 13 and does not change with current density. The lattice shrinkage and the strain energy of the Mn lattice would thus be related to the amount of supersaturated hydrogen temporarily incorporated during electrodeposition, which increases with current density.…”

Section: Resultsmentioning

confidence: 99%

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Electrodeposition and Characterization of Manganese Coatings

Gong¹,

Zangari²

2002

J. Electrochem. Soc.

110

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Manganese coatings of high quality are electrodeposited on steel substrates from simple sulfate solutions with addition of ammonium sulfate. Potentiodynamic scans and galvanostatic experiments are used to study manganese electrodeposition in a wide range of pH and current density. The effect of these variables on the microstructure, crystallography, mechanical, and corrosion-resistance properties of manganese deposits are investigated. It is found that ammonium sulfate enhances the reduction reaction of the manganese ion and provides a buffering effect. Two types of manganese deposits can be obtained depending on current density: crystalline films (type I, body-centered tetragonal γ-Mn) at low current density and amorphous films (type II) at high current density. Bright manganese films with (002) preferential orientation are electrodeposited at low pH. Type I structures show recrystallization at room temperature with phase transformation; the rate of phase transformation from γ-Mn to α-Mn (body-centered cubic) follows a Johnson-Mehl-Avrami kinetics. Crystalline films obtained at relatively high current density and low pH tend to have higher phase transformation rates. Amorphous films show good corrosion resistance both in acidic sodium sulfate/borate and sodium chloride electrolytes. © 2002 The Electrochemical Society. All rights reserved.

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Section: Resultsmentioning

confidence: 99%

“…12 This phenomenon was ascribed to the high hydrogen content of electrolytic Mn. 13 The phase transition kinetics was investigated through the evolution of electrical resistivity with time. 12 By using modern electrochemical techniques, more recent papers [14][15][16][17][18] examined the influence of processing conditions on manganese electrodeposition.…”

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confidence: 99%

Electrodeposition and Characterization of Manganese Coatings

Gong¹,

Zangari²

2002

J. Electrochem. Soc.

110

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“…This is probably a consequence of the increased hydrogen evolution and incorporation in the coating during electrodeposition at low pH. Similar to Mn electrodeposition, [1,26] where the incorporation of interstitial hydrogen enlarges the lattice, here it is reasonable to assume that Cu-Mn coatings are always saturated with hydrogen and that the extra expansion of the lattice compared with the cast alloy with a low Cu content is due to the hydrogen incorporation. The lattice expansion due to hydrogen incorporation can be estimated from Figure 4 to be in the range 0.01 to 0.03 Å.…”

Section: Methodsmentioning

confidence: 97%

Electrodeposition and characterization of sacrificial copper-manganese alloy coatings: Part II. Structural, mechanical, and corrosion-resistance properties

Gong

Wei

Barnard

et al. 2005

Metall Mater Trans A

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The structure and properties of electrodeposited Mn-rich Cu-Mn coatings were studied in order to assess their potential to provide sacrificial galvanic protection to steels. It is found that a small amount of codeposited copper can stabilize the ductile as-deposited centered tetragonal ␥Ј phase against roomtemperature recrystallization to the stable bcc ␣ phase. The time to transformation is increasingly delayed with increasing copper content. Phase transformation of crystalline films does not follow the Johnson-Mehl-Avrami-Kolmogorov equation for nucleation and growth transformation. Amorphous coatings do not show any structural transformation at room temperature. Nanomechanical and tribological measurements showed that Cu-Mn coatings have a lower friction coefficient than reference Cd coatings. Cu codeposition reduces the coating's hardness and elastic modulus and increases the resistance to plastic penetration with respect to pure Mn. Cu-Mn coatings show a barrier or passive behavior under anodic polarization, while the sacrificial characteristics are still preserved. The corrosion appears uniform, and the formation of MnO 2 and Cu 2 O upon anodic polarization may account for the good corrosion performance of the coatings.

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“…With the increase in current density, a large amount of hydrogen diffused in the lattice, and the internal stress was greater than the strain energy of the alloy lattice, so that part of the lattices cracked. The release of hydrogen could leave the dendrites or cracks [26,27]. The surface of alloy1, as shown in Fig.…”

Section: Sem Morphologymentioning

confidence: 99%