Formation of Salt Films during Anodic Metal Dissolution in the Presence of Fluid Flow

1983 ◽  
Vol 130 (6) ◽  
pp. 1252-1259 ◽  
Author(s):  
Richard Alkire ◽  
Antonia Cangellari
Keyword(s):  
Fluid Flow ◽  
Metal Dissolution ◽  
Anodic Metal Dissolution

scholarly journals Oxide Formation during Transpassive Material Removal of Martensitic 42CrMo4 Steel by Electrochemical Machining

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 402
Author(s):  
Daniela Zander ◽  
Alexander Schupp ◽  
Oliver Beyss ◽  
Bob Rommes ◽  
Andreas Klink
Keyword(s):  
Sodium Nitrate ◽  
Mixed Oxide ◽  
Material Removal ◽  
Nitrate Solution ◽  
Electrochemical Machining ◽  
Metal Dissolution ◽  
Oxide Formation ◽  
Current Densities ◽  
Sodium Nitrate Solution ◽  
Anodic Metal Dissolution

The efficiency of material removal by electrochemical machining (ECM) and rim zone modifications is highly dependent on material composition, the chemical surface condition at the break through potential, the electrolyte, the machining parameters and the resulting current densities and local current density distribution at the surfaces. The ECM process is mechanistically determined by transpassive anodic metal dissolution and layer formation at high voltages and specific electrolytic compositions. The mechanisms of transpassive anodic metal dissolution and oxide formation are not fully understood yet for steels such as 42CrMo4. Therefore, martensitic 42CrMo4 was subjected to ECM in sodium nitrate solution with two different current densities and compared to the native oxide of ground 42CrMo4. The material removal rate as well as anodic dissolution and transpassive oxide formation were investigated by mass spectroscopic analysis (ICP-MS) and (angle-resolved) X-ray photoelectron spectroscopy ((AR)XPS) after ECM. The results revealed the formation of a Fe3−xO4 mixed oxide and a change of the oxidation state for iron, chromium and molybdenum, e.g., 25% Fe (II) was present in the oxide at 20.6 A/cm2 and was substituted by Fe (III) at 34.0 A/cm2 to an amount of 10% Fe (II). Furthermore, ECM processing of 42CrMo4 in sodium nitrate solution was strongly determined by a stationary process with two parallel running steps: 1. Transpassive Fe3−xO4 mixed oxide formation/repassivation; as well as 2. dissolution of the transpassive oxide at the metal surface.

Effect of Alternating Current on Corrosion of Low Alloy and Carbon Steels

CORROSION ◽  
1978 ◽  
Vol 34 (12) ◽  
pp. 428-433 ◽  
Author(s):  
D. A. JONES
Keyword(s):  
Corrosion Rate ◽  
Cathodic Polarization ◽  
Low Frequency ◽  
Alternating Current ◽  
Carbon Steels ◽  
Half Cycle ◽  
Metal Dissolution ◽  
Cathodic Current ◽  
Anodic Reaction ◽  
Anodic Metal Dissolution

Abstract The corrosion rates of low alloy steel and carbon steel in 0.1 N NaCI were accelerated by factors of 4 to 6 when an alternating current density of 30 mA/cm2 (60 cps) was applied in dilute salt solutions purged with nitrogen. Tests with low frequency alternating anodic and cathodic current showed that both steels polarized more rapidly in the cathodic direction than in the anodic. Thus, the anodic half-cycle of AC did not have time to restore the potential to its original value after the preceding cathodic half-cycle. The result is a net cathodic polarization which accelerates or “depolarizes” the anodic metal-dissolution reaction by lowering the anodic Tafel slope. Depolarization of the anodic reaction was confirmed by polarization measurements in the presence of AC. Depolarization of the anodic reaction by AC was also observed in aerated solutions, but the corrosion rate was controlled by diffusion of dissolved oxygen, and no increase in corrosion rate was measured. Possible mechanisms of anodic depolarization are discussed.

Surface tension effects on cell pattern formation during anodic metal dissolution

Langmuir ◽  
1990 ◽  
Vol 6 (11) ◽  
pp. 1640-1646 ◽  
Author(s):  
M. A. Tenan ◽  
O. Teschke ◽  
M. U. Kleinke ◽  
F. Galembeck
Keyword(s):  
Surface Tension ◽  
Pattern Formation ◽  
Metal Dissolution ◽  
Cell Pattern ◽  
Anodic Metal Dissolution

Short stroke linear motor controls fluid flow

1998 ◽  
Vol 08 (PR2) ◽  
pp. Pr2-805-Pr2-808
Author(s):  
A. Basak
Keyword(s):  
Fluid Flow ◽  
Linear Motor ◽  
Motor Controls
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