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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Disclosures
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.

Abstract

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO·, -H2C·, -O·, -CO· radicals. During the degradation process, CO and CO2 were also produced.

Introduction

Environmental corrosion of metals in the environment is both prevalent and costly1-3. A recent study conducted by the Australasian Corrosion Association (ACA) reported that corrosion of metals resulted in a yearly cost of $982 million, which was directly associated with the degradation of assets and infrastructure through metallic corrosion within the water industry4. From an international perspective, the World Corrosion Organization estimated that metallic corrosion was responsible for a direct cost of $3.3 trillion, over 3% of the world's GDP5. The process of galvanizing as a corrosion preventative method has been widely used to inc....

Protocol

1. Steel Samples

  1. Obtain steel samples of 1 mm thickness from a commercial supplier.
    NOTE: Samples were coated with either polyester or polyester coated with silica nanoparticles.
  2. Expose samples to sunlight at Rockhampton, Queensland, Australia: collect samples after one-year and five-year intervals over a total 5-year period. Cut sample panels into round discs of 1 cm diameter using hole puncher.
  3. Prior to surface characterization, rinse samples with double-distilled water, and then dry using nitrogen gas (99.99%). Keep all samples in air-tight containers to prevent any air contaminants adsorbing to the surface (<....

Representative Results

The coated steel samples that had been subjected to exposure to the sunlight for either one or five years were collected, and water contact angle measurements were carried out to determine whether the exposure had resulted in a change in the surface hydrophobicity of the surface (Figure 2).

figure-representative results-395
Figure 2. Wettability variation of surfaces with polyester or silica nanopa.......

Discussion

Polyester coatings have been widely used to protect steel substrata from the corrosion that would occur on an uncoated surface due to the accumulation of moisture and pollutants. The application of polyester coatings can protect the steel from corrosion; however the longer-term effectiveness of these coatings is compromised if they are exposed to high levels of ultraviolet light under humid conditions, as occurs in tropical climates. Silica nanoparticles can be applied to the surface of the polyester to improve the robus.......

Disclosures

The authors have nothing to disclose.

Acknowledgements

Funding from the Australian Research Council Industrial Transformation Research Hubs Scheme (Project Number IH130100017) is gratefully acknowledged. Authors gratefully acknowledge the RMIT Microscopy and Microanalysis Facility (RMMF) for providing access to the characterisation instruments. This research was also undertaken on the Infrared Microscopectroscopy beamline at the Australian Synchrotron, Victoria, Australia.

....

Materials

NameCompanyCatalog NumberComments
polyester-coated steel
silica nanoparticle-polyester coated steel substrata
BlueScope SteelSamples provided by company
Millipore PetriSlideTM Fisher ScientificPDMA04700Storing samples
Thermo ScientificTM K-alpha
X-ray Photoelectron Spectrometer
Thermo Fisher Scientific, Inc.IQLAADGAAFFACVMAHVAcquire XPS spectra
Avantage Data SystemThermo Fisher Scientific, Inc.IQLAADGACKFAKRMAVIAnalyse XPS spectra
A Bruker Hyperion 2000 microscope Bruker CorporationSynchrotron integrated instrument
Bruker Opus v. 7.2Bruker CorporationATR-IR analysis software
Contact angle goniometer, FTA1000cFirst Ten Ångstroms Inc., VA, USAMeasuring the wettability of surfaces
FTA v. 2.0First Ten Ångstroms Inc., VA, USAAnaylyzing water contact angle
Optical profiler, Wyko NT1100 Bruker CorporationMeasure surface topography
Innova atomic force microscope Bruker CorporationMeasure surface topography
Phosphorus doped silicon probes, MPP-31120-10Bruker CorporationAFM probes
Gwyddion softwarehttp://gwyddion.net/Software used to measure optical profiling and AFM data

References

  1. Fathima Sabirneeza, A. A., Geethanjali, R., Subhashini, S. Polymeric corrosion inhibitors for iron and its alloys: A review. Chem. Eng. Commun. 202 (2), 232-244 (2015).
  2. Gupta, R. K., Birbilis, N.

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Silica NanoparticlePolyester CoatingsSteel SurfacesSunlight ExposureSurface ChemistryAttenuated Total Reflection Infrared Microspectroscopy ATR IRSurface WettabilityWeathering ConditionsNano CoatingsAnticorrosion

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