Browsing by Author "Vera, Rosa"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Corrosion inhibition of copper in chloride media by 1,5-bis(4-dithiocarboxylate-1-dodecyl-5-hydroxy-3-methylpyrazolyl)pentane
    (PERGAMON-ELSEVIER SCIENCE LTD, 2008) Vera, Rosa; Bastidas, Francisco; Villarroel, Maria; Oliva, Alfonso; Molinari, Aurora; Ramirez, Daniel; del Rio, Rodrigo
    The efficiency of 1,5-bis(4-dithiocarboxylate-1-dodecyl-5-hydroxy-3-methyl-pyrazolyl)pentane (BDTCPP) as copper corrosion inhibitor in 3.5% NaCl solutions was studied by electrochemical polarization methods (Tafel extrapolation and polarization resistance method), electrochemical impedance spectroscopy and immersion assays. Results obtained in this study reveal that BDTCPP is a good inhibitor and the potentiodynamic polarization studies clearly show that BDTCPP is a mixed-type inhibitor for copper in chloride solutions. It decreases the anodic reaction rate more strongly than the cathodic reaction rate and it renders the open circuit potential of copper more positive in 3.5% NaCl solutions. The UV analysis of the protective layer of BDTCPP after corrosion experiments shows that the inhibitor prevents copper corrosion by physisorption on the metal surface, followed by chemisorption of a protective Cu(II)-complex. This Cu(II) is generated by oxidation of the Cu(I) ion formed at the beginning of the corrosion process in the aerated solution of NaCl. (C) 2007 Elsevier Ltd. All rights reserved.
  • Thumbnail Image
    Item
    Effect of surface coatings in the corrosion of reinforced concrete in acid environments
    (2013) Vera, Rosa; Apablaza, Judith; Carvajal Guerra, Ana María; Vera, Enrique
  • Thumbnail Image
    Item
    Industrial Byproduct-Based Concrete Subjected to Carbonation. Electrochemical Behavior of Steel Reinforcement
    (ESG, 2012) Aperador, Willian; Vera, Rosa; Maria Carvajal, Ana
    Samples of ASTM A-706 structural steel embedded in different concretes obtained from mixtures of alkali-activated steel slag and fly ash were exposed to accelerated carbonation under controlled conditions (4% CO2, 65% RH and 25 degrees C). Concretes prepared with Ordinary Portland Cement (OPC) (Type I) and Granulated Blast Furnace Slag Cement (GBFS) were used for comparison. Analysis of the electrochemical phenomenon taking place on the surface of the steel due to CO2 transport through the concrete matrix was performed by measurements of open circuit potential (OCP) and linear polarization resistance (LPR). The steel-concrete interface was characterized using Mossbauer spectroscopy at room temperature and X-ray diffraction (XRD). The electrochemical measurements suggest passivation of the steel in the concretes prepared using mixtures of steel slag and fly ash without cement.
  • Thumbnail Image
    Item
    Performance of Carbon Steel and Galvanized Steel in Reinforced Concrete Structures after Accelerated Carbonation
    (ESG, 2012) Vera, Rosa; Venegas, Ricardo; Carvajal, Ana Maria; Corvo, Francisco; Perez, Tezozomoc
    The aim of this paper is to study the effects of carbonation on the electrochemical properties of carbon steel and galvanized steel, immersed into cubic prisms of concrete elaborated with Portland pozzolanic cement. Reinforced concrete specimens using these two metallic materials were exposed in a carbonation chamber. In a short time period changes in carbon steel and galvanized steel potentials and in concrete resistivity indicated an increase in carbonation of steel rebar. During the test period it was observed that zinc, instead to be in active conditions, attains lower corrosion rate than carbon steel. This behavior allows to assume the use of galvanized steel as an option to enlarge useful life of reinforced concrete structures in carbonated environments.