Preparo de óxido de nióbio suportado em alumina por deposição química em fase vapor: caracterização por espectroscopia vibracional e termogravimetria

Silva, Carmen Lúcia T. da; Zotin, José Luiz; Camorim, Vera Lúcia L.; Faro, Arnaldo C.; Rocco, Maria Luiza M.

doi:10.1590/s0100-40421998000200010

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References 17 publications

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“…The main methods for deposition of niobium oxides on surfaces described in the literature are: (I) impregnation, in aqueous medium, of ammonium oxaloniabate or niobium acid (niobium oxalate) [11], (II) impregnation, in organic medium, of niobium ethoxide [12], (III) niobium ethoxide anchorage [13], the latter, provides better dispersion of niobia on the support surface, (IV) chemical composition in the steam phase [7], (V) anodic potentiostatic polarization [8], (VI) thermal aspersion [6],(VII) deposition in homogeneous solution [9], (VIII) Pechini method [10], sol-gel process [14]. The niobium pentachloride, in turn is an economically advantageous precursor in relation to the ethoxide and in the literature available there are no references regarding its use as an anchor.…”

Section: Introductionmentioning

confidence: 99%

Niobium pentoxide coating replacing zinc phosphate coating

Rodrigues

Terada

et al. 2014

Matéria (Rio J.)

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A new coating made of niobium pentoxide, obtained through the sol-gel process, was developed for the carbon steel (SAE 1010). The corrosion protection provided by this coating was evaluated through electrochemical tests such as: open circuit potential, electrochemical impedance spectroscopy and anodic potentiodynamic polarization in NaCl 0,5 mol L -1 solution. The morphology and composition of the coatings were analyzed using scanning electronic microscopy, energy dispersive spectroscopy and X-ray diffractions. A zinc phosphate coating was used as standard test for comparison of results. The electrochemical measurements revealed that: (1) The Nb 2 O 5 coating dislocates the corrosion potential towards more positive values; (2) higher impedance values were found for the Nb 2 O 5 coated samples; and (3) lower current density values were found for these samples. The electronic micrograph revealed that there was alteration in the morphology of the carbon steel surface due to the Nb 2 O 5 deposition. The EDS spectra confirmed the niobium coating deposition, as a peak regarding this element was obtained in the spectra. The X-ray diffractograms confirmed the presence of the phases in the Nb 2 O 5 coating. This new coating increases protection of the carbon steel against corrosion and presents an alternative to replace phosphating.

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