Modeling the environment influence on the anodic metal dissolution

2000 ◽  
Vol 36 (10) ◽  
pp. 1051-1056
Author(s):  
L. Kiss



Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 402
Author(s):  
Daniela Zander ◽  
Alexander Schupp ◽  
Oliver Beyss ◽  
Bob Rommes ◽  
Andreas Klink

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.



CORROSION ◽  
1978 ◽  
Vol 34 (12) ◽  
pp. 428-433 ◽  
Author(s):  
D. A. JONES

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.



Langmuir ◽  
1990 ◽  
Vol 6 (11) ◽  
pp. 1640-1646 ◽  
Author(s):  
M. A. Tenan ◽  
O. Teschke ◽  
M. U. Kleinke ◽  
F. Galembeck


1983 ◽  
Vol 130 (6) ◽  
pp. 1252-1259 ◽  
Author(s):  
Richard Alkire ◽  
Antonia Cangellari


Crop Science ◽  
2001 ◽  
Vol 41 (6) ◽  
pp. 1731-1736 ◽  
Author(s):  
G. J. Rebetzke ◽  
V. R. Pantalone ◽  
J. W. Burton ◽  
T. E. Carter ◽  
R. F. Wilson


2010 ◽  
Vol 52 (11) ◽  
pp. 3803-3810 ◽  
Author(s):  
Rosa Vera ◽  
Patricia Verdugo ◽  
Marco Orellana ◽  
Eduardo Muñoz


1996 ◽  
Vol 26 (5) ◽  
pp. 509-514 ◽  
Author(s):  
J. Zheng ◽  
M. Khan ◽  
S. R. La Brooy ◽  
I. M. Ritchie ◽  
P. Singh


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