| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Davoodi, Ali, et al.
(författare)
-
In-situ investigation of localized corrosion of aluminum alloys in chloride solution using integrated EC-AFM/SECM technique
- 2005
-
Ingår i: Electrochemical and solid-state letters. - : The Electrochemical Society. - 1099-0062 .- 1944-8775. ; 8:6, s. B21-B24
-
Tidskriftsartikel (refereegranskat)abstract
- Scanning electrochemical microscopy (SECM) has been integrated with electrochemical atomic force microscopy (EC-AFM), and applied for in situ studies of localized corrosion of Al alloys in NaCl solution. The instrument utilizes a dual mode probe, which functions both as a normal cantilever and as an ultramicroelectrode. The I-/I3- redox mediator was used for mapping of local electrochemical current. Concurrent topography and electrochemical activity maps have been obtained on the same surface area with micrometer lateral resolution. Preliminary results show ongoing localized dissolution related to intermetallic particles in the Al alloys, which may occur well below the breakdown potential.
|
|
| 7. |
- Davoodi, Ali, et al.
(författare)
-
Integrated AFM and SECM for in situ studies of localized corrosion of Al alloys
- 2007
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 52:27, s. 7697-7705
-
Tidskriftsartikel (refereegranskat)abstract
- Rolled 3xxx series Al alloys, e.g., EN AW-3003, are generally used as fin or tube material in heat exchangers for automobiles. With reducing fin thickness, maintaining fin material integrity is of increasing importance. This study aimed at exploring the differences in intrinsic corrosion properties between EN AW-3003 and a newly developed Al–Mn–Si–Zr fin alloy using state-of-the-art local probing techniques. Volta potential mapping of both alloys by scanning Kelvin probe force microscopy (SKPFM) indicates a cathodic behaviour of constituent intermetallic particles (>0.5 μm) relative to the alloy matrix. Compared to EN AW-3003, the Al–Mn–Si–Zr alloy has a smaller number of particles with large Volta potential difference relative to the matrix. In situ atomic force microscopy (AFM) measurements in slightly corrosive solutions showed extensive localized dissolution and deposition of corrosion products on EN AW-3003, and only a small number of corroding sites and “tunnel-like” pits on Al–Mn–Si–Zr. Probing the ongoing localized corrosion process by integrated AFM and scanning electrochemical microscopy (SECM) revealed more extensive local electrochemical activity on EN AW-3003 than on Al–Mn–Si–Zr. In all, the lower corrosion activity and smaller tunnel-like pits resulted in lower material loss of the Al–Mn–Si–Zr alloy, a beneficial property when striving towards thinner fin material.
|
|
| 8. |
|
|
| 9. |
- Davoodi, Ali, et al.
(författare)
-
Multianalytical and in situ studies of localized corrosion of EN AW-3003 alloy : influence of intermetallic particles
- 2008
-
Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 155:4, s. C138-146
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of intermetallic particles (IMPs) on the localized corrosion behavior of an EN AW-3003 alloy was investigated in situ by conventional electrochemical measurements and high-resolution local probing techniques in chloride solutions with and without acetic acid. The open-circuit potential (OCP) fluctuations indicate local activities on the surface, and electrochemical impedance spectroscopy measurements suggest active dissolution in acidic solutions but a passivelike behavior in near-neutral solutions. Integrated atomic force microscopy/scanning electrochemical microscopy (AFM/SECM) was used to investigate the localized activities on the surface in a diluted chloride solution. The concurrent AFM and SECM images reveal cathodic activity of the IMPs and enhanced anodic current due to localized dissolution adjacent to some large IMPs upon anodic polarization. Moreover, in situ AFM imaging at OCP in solutions containing acetic acid show localized dissolution around the IMPs, leading to formation of deposits of ringlike corrosion products. The in situ observations reveal the microgalvanic effect of the IMPs, and the large IMPs are more prone to initiate localized corrosion compared to submicrometer dispersoids. Infrared absorption spectroscopy measurements after the exposure and thermodynamic calculations suggest the formation of mixtures of aluminum oxihydroxide and acetate on the surface in the presence of acetic acid.
|
|
| 10. |
- Davoodi, Ali, et al.
(författare)
-
Probing of local dissolution of Al-alloys in chloride solutions by AFM and SECM
- 2006
-
Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 252:15, s. 5499-5503
-
Tidskriftsartikel (refereegranskat)abstract
- Local dissolution of Al alloys was probed in situ in chloride solutions by using atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM). Preferential dissolution in the boundary region between some intermetallic particles (IMPs) and alloy matrix, and trench formation around large IMPs during free immersion and under electrochemical anodic polarization were observed, which indicate different dissolution behavior associated to different types of IMPs. Moreover, by using an integrated AFM/SECM system with a dual mode cantilever/microelectrode probe, simultaneous probing of electrochemical active sites and topographic changes over the same area was performed with submicron resolution. This allowed the ongoing localized corrosion processes related to the IMP to be revealed.
|
|
