Achieving strong adhesion of polymer coatings like epoxy, acrylic, and polyurethane to aluminium surfaces is a crucial focus in materials research, given its importance across the automotive, aerospace, marine, and construction sectors. Current adhesion-promoting surface treatments like anodizing, electropolishing, phosphate and chromate conversion coatings are environmentally problematic due to their chemical processes, necessitating the development of alternative solutions. With the goal of enhancing coating performance on aluminium alloys, we introduce atmospheric pressure plasma jet technology to improve the adhesion, mechanical performance, and corrosion resistance of epoxy coatings. This study investigates the impact of atmospheric pressure plasma treatment on the adhesion, scratch resistance, and corrosion resistance of graphene-reinforced epoxy (EP/G) composite coatings applied to aerospace aluminium alloy AA7075. Contact angle measurements, FTIR spectroscopy, and surface free energy (SFE) analysis were used to characterize the resulting surfaces. Test specimens were plasma-treated before applying the coating. The impact of the plasma treatment on surface wettability was studied by analyzing its effect on the dispersive () and specific polar () components of surface free energy. The removal of surface contaminants and weak boundary layers by plasma treatment increased surface reactivity, directly leading to a significant increase in surface free energy (SFE) from 43.49 mJm2 to 142.34 mJm2. This improved the surface wettability. Potentiodynamic polarization analysis revealed that the composite coating's oxidation resistance was significantly enhanced by the surface cleaning process using ionized argon ions prior to coating. This was evidenced by a shift in the Ecorr value from – 1.28 V to 0.31 V. Further, supporting the protective effect of coatings, electrochemical impedance spectroscopy (EIS) results indicated superior corrosion resistance for EP/G coating on plasma treated AA7075 than coating on untreated samples.
ZhengQChenTLiH. Enhanced mechanical properties of molybdenum-coated aluminium via laser cladding. Surf Eng2023; 39: 56–64.
2.
XuZYipWDongZ, et al.On the laser surface pre-treatment to enhance the surface texture, wettability and adhesion bonding strength of aluminium 7075-T6 laminates. Compos Interfaces2024; 31: 123–141.
3.
MusiariFMoroniFLuteyAHA. Enhanced mechanical interlocking of adhesive-bonded joints via tailored serrated patterns manufactured with laser ablation. J Adhes2025; 101: 56–90.
4.
GülçiçekEDilerEAErtugrulO. Synergistic effect of surface treatment and adhesive type on bonding performance of thin Al6061 joints for automotive applications. Int J Adhes Adhes2024; 130: 103641.
5.
PengHZhouTFanY, et al.Recent advances in aluminum alloy surface treatment technology and bonding properties. physica status solidi (a). Epub ahead of print 18 November 2024. DOI: https://doi.org/10.1002/pssa.202400715.
6.
CelińskiMSankowskaM. Explosibility, flammability and the thermal decomposition of Bisphenol A, the main component of epoxy resin. J Loss Prev Process Ind2016; 44: 125–131.
7.
ChangkaiWTianyuZTengZ, et al.Deterioration behavior of graphene-modified epoxy-primer-coated aluminum alloy in a UVA acidic alternation immersion environment. J Alloys Compd2023; 968: 171853.
8.
DiHYuZMaY, et al.Graphene oxide decorated with Fe3O4 nanoparticles with advanced anticorrosive properties of epoxy coatings. J Taiwan Inst Chem Eng2016; 64: 244–251.
9.
WuGMaLLiuL, et al.Preparation of SiO2–GO hybrid nanoparticles and the thermal properties of methylphenylsilicone resins/SiO2–GO nanocomposites. Thermochim Acta2015; 613: 77–86.
10.
ZhouYLiQAtrensA, et al.Graphene-based anti-corrosion coatings on magnesium alloys: a review. Surf Eng2023; 39: 392–412.
11.
LiJLuJZhangTC, et al.Superhydrophobic DTMS/rGO-nanocomposites modified polyurethane sponge for efficient oil–water separation. Surf Eng2023; 39: 349–360.
12.
WangHXieGZhuZ, et al.Enhanced tribological performance of the multi-layer graphene filled poly(vinyl chloride) composites. Compos Part A Appl Sci Manuf2014; 67: 268–273.
13.
BöhmS. Graphene against corrosion. Nat Nanotechnol2014; 9: 741–742.
14.
BermanDErdemirASumantAV. Graphene: a new emerging lubricant. Mater Today2014; 17: 31–42.
15.
YangZCheJZhangZ, et al.High-efficiency graphene/epoxy composite coatings with outstanding thermal conductive and anti-corrosion performance. Compos Part A Appl Sci Manuf2024; 181: 108152.
16.
WangXTangFQiX, et al.Mechanical, electrochemical, and durability behavior of graphene nano-platelet loaded epoxy-resin composite coatings. Compos B Eng2019; 176: 107103.
17.
HeidarinejadAAshrafizadehF. Influence of surface texture and coating thickness on adhesion of nickel plated coatings to aluminium substrate. J Manuf Process2024; 120: 435–448.
18.
PragathiPJenisonSJSinghGR, et al.A simple and efficient resin precoating treatment on anodised substrate surfaces for enhancing the adhesive bonding strength between aluminium and mild steel. Colloids Surf A Physicochem Eng Asp2024; 697: 134336.
ZhuHLiJ. Advancements in corrosion protection for aerospace aluminum alloys through surface treatment. Int J Electrochem Sci2024; 19: 100487.
21.
PrysiazhnyiVVasinaPPanyalaNR, et al.Air DCSBD plasma treatment of Al surface at atmospheric pressure. Surf Coat Technol2012; 206: 3011–3016.
22.
Díaz-BenitoBVelascoF. Atmospheric plasma torch treatment of aluminium: improving wettability with silanes. Appl Surf Sci2013; 287: 263–269.
23.
GuthrieJDSparrBJ. Infrared reflectance spectra of oxide films on aluminum-magnesium alloys. Thin Solid Films1977; 43: 303–309.
24.
NiuCHanJHuS, et al.Surface modification and structure evolution of aluminum under argon ion bombardment. Appl Surf Sci2021; 536: 147819.
25.
HashimotoTMurakamiJKusunokiI. Positive ion fractions of recoiled A1 and O from O-adsorbed Al surfaces by low-energy ion bombardment. Surf Sci1994; 319: 353–362.
26.
LiLHuangTLeiJ, et al.Robust biomimetic-structural superhydrophobic surface on aluminum alloy. ACS Appl Mater Interfaces2015; 7: 1449–1457.
27.
YeYKlimchukSShangM, et al.Acoustic bubble suppression by constructing a hydrophilic coating on HDPE surface. ACS Appl Mater Interfaces2019; 11: 16944–16950.
28.
MuiTSMSilvaLLGPrysiazhnyiV, et al.Surface modification of aluminium alloys by atmospheric pressure plasma treatments for enhancement of their adhesion properties. Surf Coat Technol2017; 312: 32–36.
29.
AsmatuluRErukalaKSShindeM, et al.Investigating the effects of surface treatments on adhesion properties of protective coatings on carbon fiber-reinforced composite laminates. Surf Coat Technol2019; 380: 125006.
30.
KangW-SRheeKYParkS-J. Influence of surface energetics of graphene oxide on fracture toughness of epoxy nanocomposites. Compos B Eng2017; 114: 175–183.
31.
OwensDKWendtRC. Estimation of the surface free energy of polymers. J Appl Polym Sci1969; 13: 1741–1747.
32.
FowkesFM. Determination of interfacial tensions, contact angles, and dispersion forces in surfaces by assuming additivity of intermolecular interactions in surfaces. J Phys Chem1962; 66: 382–382.
33.
LeeCJLeeSKKoDC, et al.Evaluation of surface and bonding properties of cold rolled steel sheet pretreated by Ar/O2 atmospheric pressure plasma at room temperature. J Mater Process Technol2009; 209: 4769–4775.
34.
PrimcGMozetičM. Surface modification of polymers by plasma treatment for appropriate adhesion of coatings. Materials2024; 17: 1494.
35.
KumarAMukhopadhyayA. Investigation of Ni-Cu-B and Ni-Cu-Sn-B coatings developed by electroless method. J Indian Chem Soc2023; 100: 101102.
36.
HuHZhaoSSunG, et al.Evaluation of scratch resistance of functionalized graphene oxide/polysiloxane nanocomposite coatings. Prog Org Coat2018; 117: 118–129.
37.
LiLZhangYLeiJ, et al.A facile approach to fabricate superhydrophobic Zn surface and its effect on corrosion resistance. Corros Sci2014; 85: 174–182.
38.
SherifE-SAbdoHKhalilK, et al.Corrosion properties in sodium chloride solutions of Al–TiC composites in situ synthesized by HFIHF. Metals (Basel)2015; 5: 1799–1811.
39.
LatiefFHSherifE-SMAlmajidAA, et al.Fabrication of exfoliated graphite nanoplatelets-reinforced aluminum composites and evaluating their mechanical properties and corrosion behavior. J Anal Appl Pyrolysis2011; 92: 485–492.
40.
UzomaPCLiuFXuL, et al.Superhydrophobicity, conductivity and anticorrosion of robust siloxane-acrylic coatings modified with graphene nanosheets. Prog Org Coat2019; 127: 239–251.
41.
ZhangDFZhengRChenXW, et al.Effect of SeO 2 on corrosion resistance of micro-arc oxidation. Surface Engineering2023; 39: 797–806.
42.
LiYLiuSFengF, et al.Preparation and characterization of graphene oxide/carbon nanotube/polyaniline composite and conductive and anticorrosive properties of its waterborne epoxy composite coatings. Polymers (Basel)2024; 16: 2641.
43.
JindalRRajaVSGibsonMA, et al.Effect of annealing below the crystallization temperature on the corrosion behavior of Al–Ni–Y metallic glasses. Corros Sci2014; 84: 54–65.
44.
GuLLiuSZhaoH, et al.Facile preparation of water-dispersible graphene sheets stabilized by carboxylated oligoanilines and their anticorrosion coatings. ACS Appl Mater Interfaces2015; 7: 17641–17648.
45.
WeiHDingDWeiS, et al.Anticorrosive conductive polyurethane multiwalled carbon nanotube nanocomposites. J Mater Chem A Mater2013; 1: 10805.
46.
MorksMFColeICorriganP, et al.Electrochemical characterization of plasma sprayed alumina coatings. J Surf Eng Mater Adv Technol2011; 01: 107–111.
47.
KrishnanMAAnejaKSShaikhA, et al.Graphene-based anticorrosive coatings for copper. RSC Adv2018; 8: 499–507.
48.
ParhizkarNRamezanzadehBShahrabiT. Corrosion protection and adhesion properties of the epoxy coating applied on the steel substrate pre-treated by a sol-gel based silane coating filled with amino and isocyanate silane functionalized graphene oxide nanosheets. Appl Surf Sci2018; 439: 45–59.
49.
ObaidANAl-BermanyE. Performance of functionalized graphene oxide to improve anti-corrosion of epoxy coating on 2024-T3 aluminium alloy. Mater Chem Phys2023; 305: 127849.
