Electrospun protective self‐healing coatings for light alloys: A better understanding of the intrinsic potential of the technology

Abstract

Polymeric coating systems exhibit high potentiality to provide an effective barrier against corrosion of metallic surfaces. However, these coatings can lose their protective characteristics because of their high susceptibility to damage. Thus, the addition of corrosion inhibitors is desirable and considered as an alternative route for active corrosion protection. In the present work, ecofriendly electrospun coatings of poly(vinyl alcohol) (PVA) loaded with cerium salts have been deposited onto aluminium 6082 alloy. Two different precursors of cerium (III) (i.e., cerium nitrate and cerium acetylacetonate) were added to the electrospinning solutions and the effectiveness of the resulting nanofibrous coatings was evaluated for the healing of generated defects. The microstructural features of the electrospun coatings have been investigated by scanning electron microscopy, infraredspectroscopy, and thermal analysis. Tensile tests were performed to assess the mechanical properties of the different fibrous coatings. The electrochemical behavior of both intact and damaged coatings was evaluated in 3 wt % NaCl solution by means of electrochemical impedance spectroscopy. All the deposited PVA coatings loaded with cerium(III) salts showed remarkable corrosion resistance. In the case of artificially damaged coatings, a self-healing effect, which stops the development of the corrosion process and provides a significant recovery of the corrosion resistance, has been observed only for coatings loaded with cerium III acetylacetonate. The release of cerium from damaged PVA fibers has been demonstrated by means of inductively coupled plasma mass spectrometry. The observed self-healing effect has been ascribed to the formation of cerium hydroxide on the defective zone, which hindered the corrosion process.

Electrospinning: A Powerful Tool to Improve the Corrosion Resistance of Metallic Surfaces Using Nanofibrous Coatings

“…Electrospun coatings can self-heal by releasing corrosion inhibitors encapsulated by micro/nanocontainers incorporated into the electrospun fibres. The polymeric precursor poly(vinyl alcohol) (PVA) has been used in [64] to produce self-healing coatings for light alloys. Two different cerium salts and corrosion inhibitors, cerium nitrate and cerium acetylacetone, have been added to a PVA precursor and deposited onto aluminium alloy substrates by electrospinning.…”

“…Tafel polarization curves, immersion test and weight loss in SBF [46] PCL/HA-NPs/simvastatin Magnesium alloy (AZ31) Tafel polarization curves and Electrochemical Impedance Spectroscopy (EIS) [47] PANI/PMMA Q325 carbon steel Tafel polarization curves and Electrochemical Impedance Spectroscopy (EIS) [48] PANI/PMMA Q235 carbon steel Tafel polarization curves and Electrochemical Impedance Spectroscopy (EIS) [49] PANI/PMMA (primer) and PS (topcoat) Q235 carbon steel Tafel polarization curves and Electrochemical Impedance Spectroscopy (EIS) [50] PAN-Al 2 O 3 Zinc sheet Hydrogen evolution, Tafel polarization curves and Electrochemical Impedance Spectroscopy (EIS) [51] PVA/glyoxal Aluminium alloy (AA6082) Electrochemical Impedance Spectroscopy (EIS) [52] PVDF/SA Aluminium sheets Tafel polarization curves and Electrochemical Impedance Spectroscopy (EIS) [55] PANI-PFOA/PS Q235 carbon steel Tafel polarization curves and Electrochemical Impedance Spectroscopy (EIS) [56] PVC PS Brass Cyclic potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) [57] PVC Aluminium, copper and brass Cyclic potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) [58] PVA PVC Aluminium Cyclic potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) [59] PS Aluminium Potentiodynamic polarization curves [60] PS/Al 2 O 3 Commercial aluminium foil Electrochemical Impedance Spectroscopy (EIS) [61] PS/mod-SiO 2 Magnesium alloy (AZ31) Potentiodynamic polarization curves [62] (PFDA-co-AA)-b-PAN) Aluminium alloy (AA2024T3) Acetic acid salt spray test [63] PVA/glyoxal doped with cerium nitrate and cerium acetylacetone Aluminium alloy (AA6082) Electrochemical Impedance Spectroscopy (EIS) [64] PVA/GA doped with CeCl 3 and Li 2 CO 3 Aluminium alloy (AA2024-T3) Electrochemical Impedance Spectroscopy (EIS) [65]…”

Multifunctional Protective PVC-ZnO Nanocomposite Coatings Deposited on Aluminum Alloys by Electrospinning

“…The viscosity of the solvents was 0.92 mPa•s for DMF and 0.55 mPa•s for THF, respectively. An important aspect to remark is that the final solution viscosity depends on the polymer concentration and the volume ratio between the solvents [20,21]. The solution was prepared under vigorous stirring (600 rpm) for 12 h at room temperature by using a magnetic stirrer.…”

A Comparative Study of Multifunctional Coatings Based on Electrospun Fibers with Incorporated ZnO Nanoparticles

“…The viscosity of the solvents was 0.92 mPa s for DMF and 0.55 mPa s in the case of THF (values provided by Sigma-Aldrich and corresponding to a working temperature of 20 • C). The final solution viscosity depends on the polymer concentration and the volume ratio between the solvents [27,28]. Liu et al studied the electrospinnability of a 15 wt % PS solution with different solvent systems and they found out that the binary solvent system DMF/THF with 1:1 volume ratio provided a suitable viscosity for the electrospinning process [29].…”