Dois tipos de superfícies, de aço e poliéster revestidos por poliéster revestido com uma camada de nanopartículas de sílica, foram estudados. Ambas as superfícies foram expostas à luz solar, o que se verificou causar alterações substanciais na química e nanoescala topografia da superfície.
Corrosão de superfícies metálicas é prevalente no ambiente e é de grande preocupação em muitas áreas, incluindo as indústrias militares, transporte, aviação, construção e alimentos, entre outros. Poliéster e revestimentos que contêm poliéster e nanopartículas de sílica (SiO 2 NPS) têm sido amplamente utilizados para proteger substratos de aço contra a corrosão. Neste estudo, utilizou raios-X espectroscopia de fotoelétrons, reflexão total atenuada infravermelho micro-espectroscopia, medidas de ângulo de contato com água, profiling óptica e microscopia de força atômica para fornecer uma visão sobre como a exposição ao sol pode causar alterações na micro e nanoescala integridade dos revestimentos. Nenhuma mudança significativa na superfície micro-topografia foi detectada utilizando perfilometria óptica, no entanto, alterações estatisticamente significativas em nanoescala à superfície foi detectado usando microscopia de força atómica. Análise da espectroscopia de fotoelétrons de raios-X e infravermelho micro reflexão total atenuadaespectroscopia de dados revelou que a degradação dos grupos éster tinha ocorrido através da exposição à luz ultravioleta para formar COO ·, -H 2, -O C · · ·, -CO radicais. Durante o processo de degradação, CO e CO2 foram também produzidos.
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 increase the lifespan of steel material6. In humid and subtropical climates, however, water tends to condense into small pockets or grooves within the surface of the galvanized steel, leading to the acceleration of corrosion rates through pit corrosion7,8. Thermosetting polymer coatings based on polyesters have been developed to coat the galvanized steel substrata increasing their ability to withstand humid weathering conditions for items such as satellite dishes, garden furniture, air-conditioning units or agricultural construction equipment9-11. Unfortunately polymer coatings on steel surfaces have been found to be considerably adversely affected by the presence of high levels of ultraviolet (uv) radiation12-14. Coatings comprised of silica nanoparticles (SiO2) spread over a polymer layer have been widely used with a view to increasing their corrosion-, wear-, tear- and degradation-resistance15,16. The tendency of the protective polymeric coatings to form pores and cracks can be reduced by incorporating nanoparticles (NPs), which contribute to the passive obstruction of corrosion initiation17,18. Also, the mechanical stability of the protective polymeric layer can be improved by NPs inclusion. However, these coatings act as passive physical barriers and, in comparison to the galvanization approach, cannot inhibit corrosion propagation actively.
An in-depth understanding of the effect that high-levels of ultraviolet light exposure under humid conditions upon these metal coatings is yet to be obtained. In this paper, a wide range of surface analytical techniques, including X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared micro-spectroscopy (ATR IR), contact angle goniometry, optical profiling and atomic force microscopy (AFM) will be employed to examine the changes in the surface of steel coatings prepared from polyester- and silica nanoparticle-coated polyester (silica nanoparticles/polyester) after exposure to sunlight. Furthermore, the aim of this work is to give a concise, practical overview of the overall characterization techniques to examine weathered samples.
Os revestimentos de poliéster têm sido amplamente utilizados para proteger substratos de aço a partir da corrosão que ocorreria numa superfície não revestidas devido à acumulação de poluentes e de humidade. A aplicação de revestimentos de poliéster pode proteger o aço contra a corrosão; No entanto, a eficácia a longo prazo destes revestimentos é comprometida se eles estão expostos a altos níveis de luz ultravioleta sob condições húmidas, como ocorre em climas tropicais. nanopartículas de sílica po…
The authors have nothing to disclose.
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.
polyester-coated steel silica nanoparticle-polyester coated steel substrata |
BlueScope Steel | Samples provided by company | |
Millipore PetriSlideTM | Fisher Scientific | PDMA04700 | Storing samples |
Thermo ScientificTM K-alpha X-ray Photoelectron Spectrometer |
Thermo Fisher Scientific, Inc. | IQLAADGAAFFACVMAHV | Acquire XPS spectra |
Avantage Data System | Thermo Fisher Scientific, Inc. | IQLAADGACKFAKRMAVI | Analyse XPS spectra |
A Bruker Hyperion 2000 microscope | Bruker Corporation | Synchrotron integrated instrument | |
Bruker Opus v. 7.2 | Bruker Corporation | ATR-IR analysis software | |
Contact angle goniometer, FTA1000c | First Ten Ångstroms Inc., VA, USA | Measuring the wettability of surfaces | |
FTA v. 2.0 | First Ten Ångstroms Inc., VA, USA | Anaylyzing water contact angle | |
Optical profiler, Wyko NT1100 | Bruker Corporation | Measure surface topography | |
Innova atomic force microscope | Bruker Corporation | Measure surface topography | |
Phosphorus doped silicon probes, MPP-31120-10 | Bruker Corporation | AFM probes | |
Gwyddion software | http://gwyddion.net/ | Software used to measure optical profiling and AFM data |