Waterborne coatings have gained more and more attention as a method to protect the environment. However, the application of waterborne coatings to metals, especially for sufficient long-term protection in harshly corrosive environments, is still limited. Here, we report a self-curing waterborne coating with good corrosion resistance. First, a self-curing waterborne epoxy resin (SWEP) was synthesized by a chemical reaction between the epoxy resin and titanium diisopropoxide bisacetylacetonate in water. The structural characterizations via Fourier transform infrared spectroscopy and C-13 nuclear magnetic resonance spectrsocopy confirmed the successful preparation of the SWEP resin. Differential scanning calorimetry and thermogravimetric analysis showed that the SWEP resin could be cured by heating without the use of any curing agents, and the cured coating exhibited good thermal resistance. The mechanical properties of the cured coatings were discussed in the context of the corresponding standards. The results confirmed that the physical properties of the SWEP coating were as good as those of a traditional two-component waterborne epoxy resin (DCWEP) coating. The chemical resistance analysis revealed that the water, acid and alkaline resistances of the SWEP coating all have significant improvements compared to those of the DCWEP coating. The electrochemical impedance spectroscopy and potentiodynamic polarization test implied that the SWEP coating provided better corrosion protection for metal substances than the DCWEP coating.

Graphene (G) was dispersed uniformly in water and used as an inhibitor in waterborne epoxy coatings. The effect of dispersed G on anticorrosion performance of epoxy coatings was evaluated. The composite coatings displayed outstanding barrier properties against H2O molecule compared to the neat epoxy coating. Open circuit potential (OCP), Tafel and electrochemical impedance spectroscopy (EIS) analysis confirmed that the corrosion rate exhibited by composite coatings with 0.5 wt% G was an order of magnitude lower than that of neat epoxy coating. Salt spray test results revealed superior corrosion resistance offered by the composite coating.

The presence of metallic species around failed implants raises concerns about the stability of titanium alloy (Ti-6Al-4V). Graphene nanocoating on titanium alloy (GN) has promising anti-corrosion properties, but its long-term protective potential and structural stability remains unknown. The objective was to determine GN's anti-corrosion potential and stability over time.GN and uncoated titanium alloy (Control) were challenged with a highly acidic fluorinated corrosive medium (pH 2.0) for up to 240 days. The samples were periodically tested using potentiodynamic polarization curves, electrochemical impedance spectroscopy and inductively coupled plasma-atomic emission spectroscopy (elemental release). The integrity of samples was determined using Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy. Statistical analyses were performed with one-sample t-test, paired t-test and one-way ANOVA with Tukey post-hoc test with a pre-set significance level of 5%.There was negligible corrosion and elemental loss on GN. After 240 days of corrosion challenge, the corrosion rate and roughness increased by two and twelve times for the Control whereas remained unchanged for GN. The nanocoating presented remarkably high structural integrity and coverage area (>98%) at all time points tested.Graphene nanocoating protects titanium alloy from corrosion and dissolution over a long period while maintaining high structural integrity. This coating has promising potential for persistent protection of titanium and potentially other metallic alloys against corrosion.Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.

The phosphorus-containing graphene (PhA-G) was prepared by pyrolysis method with phytic acid (PhA) as raw material, and next the PhA-G/SiR composite anticorrosion coating was prepared with silicone resin (SiR) as film forming material. The structure and morphology of phosphorus-containing graphene was characterized by means of Raman spectroscope, X-ray photoelectron spectroscope (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM) and atomic force microscope (AFM). The prepared coatings with the different additive amount of PhA-G (1%~4% in mass fraction), were comparatively examined by means of measurements of contact angle, water absorption, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), as well as salt spray test. The results show that the protectiveness of PhA-G/SiR composite coatings for metal substrate is greater than that of the plain SiR coating, and graphene oxide/silicone resin (GO/SiR) coating. The PhA-G/SiR composite coating exhibits good hydrophobicity and excellent corrosion resistance when the mass fraction of PhA-G is 3%. Correspondingly, which exhibits hydrophobic contact angle of 103.5° and water absorption rate of 3.72%, while corrosion current density of 3.53×10-10 A/cm2 and electrochemical impedance as high as 3.82×107 Ω·cm2 in 3.5%(mass fraction) NaCl solution. Furthermore, the PhA-G/SiR composite coating presents excellent resistance to salt spray testing, up to above 960 h.

以植酸(PhA)为原料，采用热解法制备含磷石墨烯(PhA-G)，并以硅树脂(SiR)为成膜物制备含磷石墨烯/硅树脂(PhA-G/SiR)复合防腐蚀涂层。通过拉曼光谱和XPS分析含磷石墨烯的结构，通过SEM、TEM和AFM观察含磷石墨烯的形貌，通过接触角、吸水率、电化学阻抗谱、极化曲线和盐雾实验等研究复合涂层的耐蚀性能。结果表明：相比于纯SiR涂层和氧化石墨烯/硅树脂(GO/SiR)复合涂层，PhA-G/SiR复合涂层对金属的保护作用更好；当含磷石墨烯添加量为3%(质量分数)时，PhA-G/SiR复合涂层表现出较好的疏水性和优异的防腐蚀性能，其接触角为103.5°，吸水率为3.72%；腐蚀电流密度为3.53×10^-10 A/cm²，电化学阻抗值达到3.82×10⁷ Ω·cm²，耐盐雾达到960 h。

The present study explores the synergistic effect of Fe3O4 and heteroatom doped reduced graphene oxide (rGO) nanohybrid on anti-corrosion performance of epoxy composite coating. In this connection, Fe3O4 nanoparticles were decorated over nitrogen doped rGO (Fe3O4-NRG) and characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), and Thermogravimetric analysis (TGA). This approach to modulating the surface properties of graphene and hence the interaction with polymer matrix were quite distinct from traditional surface functionlization or decoration in a sense that the doped nitrogen atom facilitate the growth of Fe3O4 particles and at the same time augmented the interaction of rGO with polymer matrix. The prepared nanohybrid was dispersed in epoxy matrix through mechanical mixing and coated over mild steel surface via spin coating technique. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) study revealed superior anti-corrosion performance of Fe3O4-NRG/epoxy coating in 3.5 wt% NaCl solution. The corrosion inhibition was found to improve by similar to 98.5% with 0.5 wt% loading of Fe3O4-NRG. We believe that this simple solvent free approach to prepare composite coating can be exploit for practical application and thus deserves special attention..

Tailoring electrical properties of graphene by nitrogen doping is currently of great significance in a broad area of advanced applications. Bonding configuration of nitrogen atoms in graphene plays a vital role in controlling its electrical, chemical, and optical properties. Here, we report for the first time a simple bottom-up synthesis of a novel cationic nitrogen doped graphene (CNG) by a solution plasma (SP). A mixture of ionic liquid and organic solvent was used as starting precursor. CNG exhibited an orthorhombic structure possibly due to the presence cationic nitrogen in hexagonal graphene lattice. Nitrogen doping content was found to be as high as 13.4 atom %. Electrical characterization demonstrated that the CNG exhibited a p-type semiconducting behavior with superior electrical conductivity and carrier concentration. Such unique electrical characteristics of CNG are mainly attributed to the presence of cationic nitrogen with preserved planar structure.