Investigation of the effects of graphene oxide/polyethersulfone nanocomposite coating on corrosion resistance

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Thesis Type: Postgraduate

Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2023

Thesis Language: Turkish

Student: Esma Yeliz KAYA

Supervisor: Nursel Dilsiz

Open Archive Collection: AVESIS Open Access Collection

Abstract:

The aim of the thesis study is to coat the polyethersulfone (PES) nanocomposite coatings reinforced with graphene oxide (GO) and APTES functionalized graphene oxide (fGO) on aluminum 2024T3 alloy by dip coating method, and to examine the effect of GO and fGO nanoparticles on the corrosion protection performance of the PES coating. For this purpose, firstly, GO was synthesized by Modified Hummer's method, and GO was functionalized using APTES. In the second stage, GO/PES and fGO/PES nanocomposite films containing GO and fGO in different fractions (0,2%, 0,6%, and 0,8% by mass) were prepared by solution casting method. In the last step, GO/PES and fGO/PES coating solutions containing GO and fGO in different amounts (0,2%, 0,6%, and 0,8% by mass) with a concentration of 20% (m/v) were prepared. Chemical, structural and thermal properties of synthesized GO and fGO nanoparticles were determined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). The prepared nanocomposite films were characterized by FTIR, Thermogravimetric and Differential Thermal analysis (TGA/DTA) and surface contact angle analysis. The results of FTIR, XRD and TGA confirmed the modification of GO with APTES. The results obtained from the thermal analysis of nanocomposite films showed that GO/PES and fGO/PES films prepared in different fractions maintained their thermal stability. The corrosion protection performances of aluminum 2024T3 plates coated with dip coating method were investigated in 0,5M NaCl solution using electrochemical impedance spectroscopy (EIS) and Tafel polarization methods. With tafel analysis, it was determined that the corrosion rate of uncoated aluminum 2024T3 alloy decreased from 2,851x10-2 mm/year to 1,757x10-6 mm/year with a pure PES coating. The EIS and Tafel results showed that the anti corrosion property of the PES coating was significantly affected by the increased GO and fGO content. The corrosion protection performance of the pure PES coating was adversely affected with the increased GO content. Among all nanocomposite coatings, nanocomposite coating containing 0,8% fGO was determined to be more effective in preventing corrosion of aluminum alloy. It was concluded that compared to GO, fGO is a more suitable candidate for improving the corrosion resistance of PES-based coatings.

Key Words : Graphene oxide, polyethersulfone, coating, corrosion resistance