Laser-cleaned surface of hot-rolled AA7024-T4 alloy exhibited higher corrosion resistance in 3.5 wt.% NaCl solution than the as-received, due to the removal of the original less protective oxide ...layer consisting of MgO and MgAl2O4 and formation of more protective oxide layer containing Al2O3 and MgO.
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•Laser cleaning removed the original oxide layer comprising of MgO+MgAl2O4.•Laser cleaning induced a formation of oxide layer consisting of Al2O3+MgO.•Laser-cleaned surface exhibited higher corrosion resistance than the as-received.•Newly formed oxide film by laser cleaning offered better protection against corrosion.
Laser cleaning has been considered as a promising technique for the preparation of aluminium alloy surfaces prior to joining and welding and has been practically used in the automotive industry. The process is based on laser ablation to remove surface contaminations and aluminium oxides. However the change of surface chemistry and oxide status may affect corrosion behaviour of aluminium alloys. Until now, no work has been reported on the corrosion characteristics of laser cleaned metallic surfaces. In this study, we investigated the corrosion behaviour of laser-cleaned AA7024-T4 aluminium alloy using potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). The results showed that the laser-cleaned surface exhibited higher corrosion resistance in 3.5 wt.% NaCl solution than as-received hot-rolled alloy, with significant increase in impedance and decrease in capacitance, while SVET revealed that the active anodic points appeared on the as-received surface were not presented on the laser-cleaned surfaces. Such corrosion behaviours were correlated to the change of surface oxide status measured by glow discharge optical emission spectrometry (GDOES) and X-ray photoelectron spectroscopy (XPS). It was suggested that the removal of the original less protective oxide layer consisting of MgO and MgAl2O4 on the as-received surfaces and the newly formed more protective oxide layer containing mainly Al2O3 and MgO by laser cleaning were responsible for the improvement of the corrosion performance.
The Asia-Pacific Conferences on Few-Body Problems in Physics tackle cover the various aspects of few-body systems in physics, with high caliber contributions from internationally renowned ...researchers. Readers will gain a clear picture of the latest developments in the field in both the theoretical and experimental sectors. The scope of these proceedings covers research in the following areas: three-body forces and few-nucleon dynamics, hadron structure and QCD; exotic hadrons and atoms; effective field theory in few-body physics; electromagnetic and weak processes in few-body systems; few-body dynamics in atoms, molecules, Bose-Einstein condensates and quantum dots; few-body approaches to unstable nuclei, nuclear astrophysics and nuclear clustering aspects; and hypernuclear physics.
Strong interactions in pionium Yan, Y.; Suebka, P.; Kobdaj, C. ...
Nuclear physics. A,
06/2007, Volume:
790, Issue:
1
Journal Article
Peer reviewed
Pionium is investigated in various pion-pion strong interactions which reproduce well the pion-pion scattering data. It is found that the ground-state pionium wave functions in those realistic ...pion-pion strong interactions are considerably different from the hydrogen-like one at small distance. One may suggest that some pion-pion interactions may need to be largely improved before applied to the pion-pion atomic system.
The p¯D atoms are studied in various realistic, popular N¯N potentials. The small energy shifts and decay widths of the atoms, which stem from the short-ranged strong interactions between the ...antiproton and deuteron, are evaluated in a well-established, accurate approach based on the Sturmian functions. The investigation reveals that none of the employed potentials, which reproduce the N¯N scattering data quite well, is able to reproduce the experimental data of the energy shifts of the 2pp¯D atomic states. The energy shifts of the 2pp¯D atomic states are very sensitive to the N¯N strong interactions, hence the investigation of the p¯D atoms is expected to provide a good platform for refining the N¯N interaction, especially at zero energy.
Kaonic hydrogen is studied with realistic potentials in an accurate numerical approach based on Sturmian functions. It is found that the ground-state wave function of the exotic atom with realistic ...strong interactions is considerably different from the hydrogen-like ones at small distances. The
K
−
p
scattering length extracted from the 1
s
energy shift of the kaonic hydrogen by applying the Deser-Trueman formula is severely inconsistent with the one derived directly by solving the Schödinger equation. We pay special attention to the recent measurement of the energy shift and decay width of the 1
s
kaonic hydrogen state by the DEAR Collaboration. Our work strongly supports the argument that the DEAR data of the
K
−
p
scattering length extracted with the Deser-Trueman formula from the measured 1
s
energy shift and decay width are not accurate, if not to say, unreliable.
The investigation in the work of the reaction e{sup +}e{sup -}{yields}{omega}{pi}{sup 0} in the {sup 3}P{sub 0} nonrelativistic quark model reveals that the e{sup +}e{sup -}{yields}{omega}{pi}{sup 0} ...process at the energy region from the {omega}{pi} threshold to 2.0 GeV is dominated by the two-step process in which the primary qq pair first forms {rho} and {rho}{sup '} mesons and then the vector mesons decay into {omega} and {pi}. With {rho}(1450) and {rho}(1700) mainly in 2S and 1D states, respectively, the experimental data for the cross section of the reaction e{sup +}e{sup -}{yields}{omega}{pi}{sup 0} are well produced in the {sup 3}P{sub 0} quark model. The work supports the argument that {rho}(1450) is mainly a 2S meson and {rho}(1700) a 1D meson.
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