Enhancing the corrosion protection of AA2024-T3 alloy by surface treatments based on Piperazine-modified hybrid sol-gel films Articles uri icon

authors

  • CARBONELL BOIX, DIOGENES JOSE
  • Montoya, Rodrigo
  • Gelling, Victoria J.
  • GALVAN SIERRA, JUAN CARLOS
  • JIMENEZ MORALES, ANTONIA

published in

publication date

  • January 2020

issue

  • 4

volume

  • 10

International Standard Serial Number (ISSN)

  • 2075-4701

abstract

  • The aim of this study was to develop new chrome-free surface pretreatments for AA2024-T3 aluminum alloy. These pretreatments were based on hybrid organic-inorganic sol-gel thin films prepared from mixtures of The aim of this study was to develop new chrome-free surface pretreatments for AA2024-T3 aluminum alloy. These pretreatments were based on hybrid organic&-inorganic sol&-gel thin films prepared from mixtures of &;947# -methacryloxypropyltrimethoxysilane (MAPTMS) and tetramethylorthosilicate (TMOS). Dierent MAPTMS/TMOS molar ratios were used for optimizing the physical&-chemical characteristics of the sol&-gel films. The formulation of a set of these sols was modified by incorporating piperazine (1,4-diazacyclohexane) as a corrosion inhibitor. The resulting sol&-gel films were characterized by using Fourier transform infrared spectroscopy (FTIR), liquid-state 29Si nuclear magnetic resonance spectroscopy (29Si-NMR) and viscosity measurements. The corrosion performance of the sol&-gel films was analyzed by using electrochemical impedance spectroscopy (EIS) and local electrochemical impedance mapping (LEIM). The characterization techniques indicated that piperazine behaved as a catalyst for the condensation reaction during the formation of the MAPTMS/TMOS organopolysiloxane network and produces an increase of the crosslinking degree of the sol&-gel films. EIS and LEIM results showed that piperazine is an eective corrosion inhibitor, which can be used to enhance the active corrosion protection performance of sol&-gel films.-methacryloxypropyltrimethoxysilane (MAPTMS) and tetramethylorthosilicate (TMOS). Di erent MAPTMS/TMOS molar ratios were used for optimizing the physical-chemical characteristics of the sol-gel films. The formulation of a set of these sols was modified by incorporating piperazine (1,4- diazacyclohexane) as a corrosion inhibitor. The resulting sol-gel films were characterized by using Fourier transform infrared spectroscopy (FTIR), liquid-state 29Si nuclear magnetic resonance spectroscopy (29Si-NMR) and viscosity measurements. The corrosion performance of the sol-gel films was analyzed by using electrochemical impedance spectroscopy (EIS) and local electrochemical impedance mapping (LEIM). The characterization techniques indicated that piperazine behaved as a catalyst for the condensation reaction during the formation of the MAPTMS/TMOS organopolysiloxane network and produces an increase of the crosslinking degree of the sol-gel films. EIS and LEIM results showed that piperazine is an e ective corrosion inhibitor, which can be used to enhance the active corrosion protection performance of sol-gel films.

keywords

  • aa2024-t3 aluminum alloys; active corrosion protection; corrosion inhibitors; electrochemical impedance spectroscopy; hybrid sol-gel films; local electrochemical impedance mapping; piperazine