An Electrochemically Sealed Al2 O 3 Passivation Layer for Aluminum Alloys

The anodic copolymerization of pyrrole and N‐(ω‐ferrocenylalkyl)pyrroles, FcPy‐n, at platinum electrodes in an electrolyte consisting of tributylammonium benzenesulfonate in moist acetonitrile is optimized with respect to the absolute and relative concentrations of the monomers and the spacer length of FcPy‐n. The copolymer composition is estimated from cyclic voltammograms of the polymer films. Only films with less than 20% FcPy‐n content show the typical polypyrrole voltammograms. Free standing copolymer films with a conductivity of ca. 10 S cm−1 can be prepared.

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The System Boron-Oxygen

Heller

1986

B Boron Compounds

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earlier literature cited therein. All formulas including radicals are written according to IUPAC nomenclature [1). Boron Oxides The Boron Monoxide Radical, [BO)"The [BO)" radical is one of the fundamental species appearing as intermediates in oxidation reactions. Hot-pressed B4C was oxidized in wet nitrogen and/or wet air atmosphere at a water vapor pressure of 1.5 to 20 kPa and in dry air of 900 up to 1400·C. The oxidation of B 4 C by water vapor and dry air at 900·C results in a weight loss; hence, it is assumed that the formation of [BO]" (and/or HB02) seems to be the major reaction. The oxidation rate of B 4 C by water vapor at 900·C could be expressed by surface chemical reaction-controlled kinetics with an apparent activation energy of 200 kJ/mol [2).In the reaction of molecular oxygen with crystalline a-boron powder, oxygen atoms in concentrations exceeding the thermodynamical equilibrium value (above an inert surface) by four to seven orders of magnitude were observed. By the use of the resonance fluorescence of oxygen atoms between 350 and 1000 ·C, the proposed mechanism of the reaction is: ( Boron ignition and combustion with its surrounding atmosphere was studied by timeresolved emission spectroscopy in the range of 0.2 to 5.5 Ilm. In one experiment, boron powder was burned in an oxygen atmosphere with initiation by a pyrotechnic device. The energy transfer by the hot gases led to a glowing phase of the boron particles, which then changed to a high-temperature combustion and ended in a second glowing phase. The two glowing phases emitted continuous emission spectra, and the burning phase emitted the bands of [BO]" and [B02]". Another experimental setup was used to feed boron particles into a hot oxidizing atmosphere, which was provided by a propane-air flame. The reaction was observed by high-speed cinematography and time-resolved emission spectroscopy. The flame contained a small amount of background radiation, and the emitted bands Of [BO]

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An Electrochemically Sealed Al2 O 3 Passivation Layer for Aluminum Alloys

Abstract: An anodization process combined with an electrochemical sealing technique provided dramatic improvement in the corrosion resistance of 5086 Al alloy. The surface quality of the oxide depends on the density and distribution of alloying elements and impurities.

Cited by 5 publications

References 4 publications

ChemInform Abstract: AN ELECTROCHEMICALLY SEALED ALUMINUM OXIDE PASSIVATION LAYER FOR ALUMINUM ALLOYS

ChemInform Abstract: AN ELECTROCHEMICALLY SEALED ALUMINUM OXIDE PASSIVATION LAYER FOR ALUMINUM ALLOYS

Preparation and electrochemistry of modified polypyrrole films by anodic copolymerization techniques

The System Boron-Oxygen

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