Effect of graphene oxide/polyaniline in epoxy nanocomposite coatings for corrosion resistance /
Rihashni a/p Thivagaran,
Effect of graphene oxide/polyaniline in epoxy nanocomposite coatings for corrosion resistance / Rihashni a/p Thivagaran - xiv, 136 pages : illustrations : 30 cm. + 1 CD-ROM
Faculty of Industrial Sciences and Technology
Thesis (Master of Science) -- Universiti Malaysia Pahang – 2025
Include bibliographical reference
Epoxy-based coatings have long been recognized for their exceptional corrosion resistance, consistent chemical characteristics, and desirable mechanical properties, making them a preferred choice for protecting metal surfaces in various industries. However, the presence of micropores, holes, and imperfections inherent in the curing process of epoxy coatings can accelerate the entry of corrosive media, leading to diminished permanent corrosion resistance, particularly in severe environments. Extensive research has focused on enhancing organic coatings' anti-corrosion and barrier performance by incorporating nanofillers to address these limitations. Graphene Oxide (GO) and Polyaniline (PANI) have emerged as promising materials for reinforcing epoxy coatings due to their unique properties. With the large surface area and excellent mechanical strength, GO can effectively reduce the formation of imperfections within the coating matrix. PANI is a highly conductive polymer that can act as a charge barrier, repelling corrosive ions and contributing to the formation of a protective iron oxide film. GO/PANI was synthesized by an in-situ polymerization process by adding aniline and ammonium persulphate to view its crystallinity and structural properties in X-ray diffraction (XRD). The as-prepared GO was then applied to mild steel substrates using the brush coating technique at different layers (3 & 5) after aiming to achieve excellent hardness on the surfaces. The methodology involved synthesizing GO using a modified Hummer's method, followed by ultrasonication to obtain different sheet sizes. The size of the GO sheets was confirmed using particle size measurement, and their morphology was examined using field emission scanning electron microscopy (FESEM). The d-spacing and crystallite size were determined using XRD, and by using Fourier transform infrared spectroscopy (FTIR) the chemical functional groups and oxygen-related band (ORB) were characterized. The ORB ratio for 3h-GO was found to be 0.67, and for 5h-GO, it was 0.56, indicating the degree of modification of the GO sheets. The GO/PANI nanocomposites were analyzed using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy, Xray photoelectron spectroscopy (XPS), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The ID/IG ratio was used to assess the quality of the prepared materials, with 5h-GO showing a higher ratio (1.78) than 3h-GO (1.37) by using Raman spectroscopy suggesting more defects due to prolonged ultrasonication. These nanocomposites showed good surface hardness and improved corrosion resistance compared to bare mild steel and pure epoxy. The 5-layer 3hGO/PANI+Epoxy coating outperformed the 5-layer 5h-GO/PANI+Epoxy coating in all tested categories. Specifically, the 3h-GO coating exhibited an Ecorr of -0.53 V, an Icorr of 0.037 μA cm- ², and a corrosion rate (CR) of 0.42 mm yr-1 , while the 5h-GO coating showed a corrosion potential (Ecorr) of -0.47 V, a corrosion current (Icorr) of 0.325 μA cm- ², and a corrosion rate (CR) of 3.77 mm yr-1 . The study provides valuable insights for developing highly effective corrosion-resistant coatings, with the 5-layer 3hGO/PANI+Epoxy emerging as the most promising candidate for long-term corrosion protection of mild steel substrates.
THE0010078 (Local)
Faculty of Industrial Sciences and Technology--Dissertations
Universities and colleges--Dissertations
Theses--Dissertations
Effect of graphene oxide/polyaniline in epoxy nanocomposite coatings for corrosion resistance / Rihashni a/p Thivagaran - xiv, 136 pages : illustrations : 30 cm. + 1 CD-ROM
Faculty of Industrial Sciences and Technology
Thesis (Master of Science) -- Universiti Malaysia Pahang – 2025
Include bibliographical reference
Epoxy-based coatings have long been recognized for their exceptional corrosion resistance, consistent chemical characteristics, and desirable mechanical properties, making them a preferred choice for protecting metal surfaces in various industries. However, the presence of micropores, holes, and imperfections inherent in the curing process of epoxy coatings can accelerate the entry of corrosive media, leading to diminished permanent corrosion resistance, particularly in severe environments. Extensive research has focused on enhancing organic coatings' anti-corrosion and barrier performance by incorporating nanofillers to address these limitations. Graphene Oxide (GO) and Polyaniline (PANI) have emerged as promising materials for reinforcing epoxy coatings due to their unique properties. With the large surface area and excellent mechanical strength, GO can effectively reduce the formation of imperfections within the coating matrix. PANI is a highly conductive polymer that can act as a charge barrier, repelling corrosive ions and contributing to the formation of a protective iron oxide film. GO/PANI was synthesized by an in-situ polymerization process by adding aniline and ammonium persulphate to view its crystallinity and structural properties in X-ray diffraction (XRD). The as-prepared GO was then applied to mild steel substrates using the brush coating technique at different layers (3 & 5) after aiming to achieve excellent hardness on the surfaces. The methodology involved synthesizing GO using a modified Hummer's method, followed by ultrasonication to obtain different sheet sizes. The size of the GO sheets was confirmed using particle size measurement, and their morphology was examined using field emission scanning electron microscopy (FESEM). The d-spacing and crystallite size were determined using XRD, and by using Fourier transform infrared spectroscopy (FTIR) the chemical functional groups and oxygen-related band (ORB) were characterized. The ORB ratio for 3h-GO was found to be 0.67, and for 5h-GO, it was 0.56, indicating the degree of modification of the GO sheets. The GO/PANI nanocomposites were analyzed using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy, Xray photoelectron spectroscopy (XPS), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The ID/IG ratio was used to assess the quality of the prepared materials, with 5h-GO showing a higher ratio (1.78) than 3h-GO (1.37) by using Raman spectroscopy suggesting more defects due to prolonged ultrasonication. These nanocomposites showed good surface hardness and improved corrosion resistance compared to bare mild steel and pure epoxy. The 5-layer 3hGO/PANI+Epoxy coating outperformed the 5-layer 5h-GO/PANI+Epoxy coating in all tested categories. Specifically, the 3h-GO coating exhibited an Ecorr of -0.53 V, an Icorr of 0.037 μA cm- ², and a corrosion rate (CR) of 0.42 mm yr-1 , while the 5h-GO coating showed a corrosion potential (Ecorr) of -0.47 V, a corrosion current (Icorr) of 0.325 μA cm- ², and a corrosion rate (CR) of 3.77 mm yr-1 . The study provides valuable insights for developing highly effective corrosion-resistant coatings, with the 5-layer 3hGO/PANI+Epoxy emerging as the most promising candidate for long-term corrosion protection of mild steel substrates.
THE0010078 (Local)
Faculty of Industrial Sciences and Technology--Dissertations
Universities and colleges--Dissertations
Theses--Dissertations