Synthesis of Fe nanoparticles functionalized with oleic acid synthesized by inert gas condensation

In this work, we study the synthesis of monodispersed Fe nanoparticles (Fe-NPs) in situ functionalized with oleic acid. The nanoparticles were self-assembled by inert gas condensation (IGC) technique by using magnetron-sputtering process. Structural characterization of Fe-NPs was performed by transmission electron microscopy (TEM). Particle size control was carried out through the following parameters: (i) condensation zone length, (ii) magnetron power, and (iii) gas flow (Ar and He). Typically the nanoparticles generated by IGC showed diameters which ranged from ∼0.7 to 20 nm. Mass spectroscopy of Fe-NPs in the deposition system allowed the study of in situ nanoparticle formation, through a quadrupole mass filter (QMF) that one can use together with a mass filter. When the deposition system works without quadrupole mass filter, the particle diameter distribution is around +/−20%. When the quadrupole is in line, then the distribution can be reduced to around +/−2%

Síntesis y caracterización de nanopartículas de hierro

Tesis (Maestro en Ciencias) UANL, 2009.UANLhttp://www.uanl.mx

Corrosion Behavior of AA2055 Aluminum-Lithium Alloys Anodized in the Presence of Sulfuric Acid Solution

The aim of this work was to evaluate the corrosion behavior of the AA2055 Aluminum-lithium alloy anodized in a sulfuric acid (H2SO4) bath, varying the current density of 0.19 and 1 A·cm−2 and why the sealing solution was water (H2O) and sodium dichromate (Na2Cr2O7). Anodized samples were exposed to a 10 vol.% H2SO4 solution and the electrochemical technique used was electrochemical impedance spectroscopy. Scanning electron microscopy and X-ray photoelectron spectroscopy were employed to characterization of the anodizing layer, determinate morphology and thickness of coatings. The Na2Cr2O7 sealing solution tends to increase the charge transfer resistance and produces a more homogeneous and compact passive oxide layer, and imparts a corrosion inhibition protection to the AA2055. SEM observations indicated that the morphology and thickness of the anodic films formed on AA2055 aluminum-lithium alloy anodized have the best results for both current densities

Effect of sealing treatment on the corrosion behavior of anodized AA2099 aluminum-lithium alloy

The corrosion behavior of the sulphuric-anodized AA2099 using two different current densities, 0.19 or 1.0 A·cm−2, with two different sealing treatments in H2O and 6 wt.% Na2Cr2O7 at 95 °C was studied in 3.5 wt.% NaCl and 10 vol.% H2SO4 solutions. The AA2099 is widely used in aeronautical applications, thus it is essential to present good corrosion performance in chloride and acid rain environments. The surface morphology of the anodized film was characterized by scanning electron microscopy (SEM), the electrochemical corrosion behavior was studied using electrochemical impedance (EIS), and finally characterization of the surface chemical composition was revealed by X-ray photoelectron spectroscopy (XPS). It was found the 6 wt.% Na2Cr2O7 sealing treatment imparts a more homogeneous and compact passive layer, and tends to increase the charge transfer resistance, thus improving the corrosion behavior of the anodized AA2099