Long-time irradiation effect on corrosion behavior of aluminum alloy in pool water of low-power research reactor

This study conducted an evaluation of the corrosion behavior of an aluminum alloy utilized in the Isfahan Miniature Neutron Source Reactor (MNSR). The component analyzed, dry channel (DC), had been exposed to radiation for 12 years in a water environment within the reactor pool since its installation. To determine the effect of radiation on the corrosion of the LT-21 aluminum alloy used in the DC, different parts of the pipe were sampled and various tests were performed. These tests included mechanical strengths (impact, and micro-hardening), XRD, TEM, SEM-EDS, and potentiodynamic polarization (PDP). The parameters measured included corrosion potential, corrosion rate, changes in microscopic structure, and mechanical properties of the aluminum alloy along the entire length of the DC. The neutron and gamma dose distribution along the height of the DC, which was 540 cm, was calculated to determine the correlation between the dose distribution and observed corrosion. The study found that the corrosion mechanisms were complex and resulted from the simultaneous presence of the DC in the pool water and radiation from the reactor core. The observed results are presented and discussed in this study.

Synthesis and investigation on microstructural, mechanical features of mesoporous hardystonite/reduced graphene oxide nanocomposite for medical applications

The use of hardystonite (Ca2ZnSi2O7, HT)-based composites could be one the main strategies to improve mechanical properties closing to natural bone. However, there are a few reports in this regard. Recent findings indicate that graphene is a promising biocompatible additive in ceramic-based composite. Here, we propose a simple approach for the synthesis of porous nano- and microstructured hardystonite/reduced graphene oxide (HT/RGO) composite using a sol-gel method followed by ultrasonic and hydrothermal processes. Integrating GO to the pure HT increased the bending strength and toughness values about 27.59% and 34.33%, respectively. It also allowed the increment of compressive strength and compressive modulus by about 8.18% and 86%, respectively, and improvement in the fracture toughness about 11.8 times compared to pure HT. The formation of HT/RGO nanocomposites with different RGO weight percentages ranging from 0 to 5.0 has been investigated by scanning electron microscopy (SEM) and X-ray diffraction and the efficient incorporation of GO nanosheets into HT nanocomposite as well as the mesoporous structural properties were also confirmed by Raman, FTIR and BET analyses. The cell viability of HT/RGO composite scaffolds was assayed by methyl thiazole tetrazolium (MTT) test in vitro. In this regard, the alkaline phosphatase (ALP) activity and the proliferation rate of mouse osteoblastic cells (MC3T3-E1) on the HT/1 wt. % RGO composite scaffold enhanced in comparison with the pure HT ceramic. The adhesion of osteoblastic cells on the 1% wt. HT/RGO scaffold was interesting as well. In addition, the effect of 1% wt. HT/RGO extract on the proliferation of osteoblast human G-292 cells was successfully evaluated and remarkable observations were obtained. All together it can be said that the proposed bioceramic hardystonite/reduced graphene oxide composites can be a promising candidate for designing hard tissue implants.

Low-Mass Liquid Crystalline Materials Blended in Recycled Thermoplastic Polyester Elastomer for Corrosion Inhibitor Application

In this work, the development and application of multicomponents obtained from recycled polyethylene terephthalate (r-PET) waste and monotropic liquid crystals as anticorrosion coatings are reported. The r-PET raw material was alcoholyzed and reproduced as a thermoplastic polyester elastomer (TPEE) with different amounts (n%, n = 0, 1, 3, and 5) of 1,6-hexanediamine (HDA). Then, a fluorine-containing liquid crystal (4-cyano-3-fluorophenyl 4-ethylbenzoate (4CFE)) was incorporated into the TPEE mixture via solvent blending to modify and enhance the water resistance. The adhesion behavior of the coating on glass and iron substrates was evaluated by cross-cut tests and immersion tests in aqueous NaCl. In the corrosion resistance measurements, all of the coating samples fabricated with 10 ± 1 mm thickness were less active toward electrochemical corrosion (P_EF% > 99%) than the bare iron plate, indicating that our work provided better protection against corrosion of the iron plate.

Effect of Functionalization of Reduced Graphene Oxide Coatings with Nitrogen and Sulfur Groups on Their Anti-Corrosion Properties

Electrophoretic production of anticorrosion carbonaceous coatings on copper could be successfully performed by anodic oxidation of negatively charged graphene platelets suspended in an aqueous solution. The various platelets were synthesized by Hummer’s method followed by a hydrothermal reduction in the presence of NH₄SCN which was expected to substitute some parts of graphene structure with nitrogen and sulfur groups. X-ray photoelectron spectroscopy analysis confirmed that the graphene precursors, as well as the coatings, contained typical nitrogen groups, such as pyridinic and pyrrolic, and sulfur groups, such as thiol, thiophene, or C-SO₂. However, due to oxidation during deposition, the qualitative and quantitative composition of the graphene coatings changed relative to the composition of the precursors. In particular, the concentration of nitrogen and sulfur dropped and some thiophene groups were oxidized to C-SO₂. Studies showed the functionalized coatings had a uniform, defect-free, hydrophobic, more adhesive surface than nonmodified films. The corrosion measurements demonstrated that these coatings had better protective properties than the ones without these heteroatoms. This behavior can be assigned to the catalytic activity of nitrogen towards oxidation of C-SO₂ groups to C-SO₃H with oxygen.

Review of the Application of Graphene-Based Coatings as Anticorrosion Layers

Due to the excellent properties of graphene, including flexibility that allows it to adjust to the curvature of the substrate surface, chemical inertness, and impermeability, graphene is used as an anticorrosion layer. In this review, we present the current state-of-the-art in the application of graphene in the field of protective coatings. This review provides detailed discussions about the protective properties of graphene coatings deposited by different methods, graphene-based organic coatings, the modification of graphene-based coatings, and the effects of graphene functionalization on the corrosion resistance of protective coatings.

L-cysteine reduced/functionalized graphene oxide application as a smart/control release nanocarrier of sustainable cerium ions for epoxy coating anti-corrosion properties improvement

One of the main limitations for large scale mass production of reduced graphene oxide is the application of some toxic and hazardous reducing agents such as hydrazine and borohydride. In this study, the effectiveness of the l-Cys (HSCH₂CH(NH₂)CO₂H) molecules, as a green amino acid in the GO reduction, as well as its active corrosion inhibition capacity were explored. The l-Cys/GO nanosheets were then modified by trivalent-cerium ions to obtain a nanocarrier with excellent controlled release activity. The electrochemical impedance spectroscopy (EIS) and polarization tests were used to measure the smart corrosion inhibition activity of the cerium modified l-Cys/GO nanocarrier in the saline solution and epoxy coating. The results showed that the cerium ions adsorption on the l-Cys/GO nanosheets obeyed a Langmuir isotherm model. The l-Cys/GO sample showed cerium ions adsorption capacity about 66% higher than the unmodified GO nanosheets. Furthermore, the EIS tests results revealed that in the presence of cerium modified l-Cys/GO nanocarriers the improvement in the corrosion resistance of bare steel in the solution phase and coated sample was about 7.5 times (after 24 h) and 950 times (after 40 days) higher than the blank saline solution and the pure epoxy sample, respectively.

Fabrication and characterization of a Fe3O4/polyvinylpyrrolidone (Fe3O4/PVP) nanocomposite as a coating for carbon steel in saline media

Corrosion of carbon steel (CS) is a security and financial concern for numerous industries involving oil, petroleum, and automotive industries.

Polydopamine modified polyaniline-graphene oxide composite for enhancement of corrosion resistance

In this study, the composite of two-dimensional graphene oxide (GO) nanosheets and button-shaped polyaniline (PANI) was synthesized and further modified by polydopamine (PDA). The obtained PDA-PANI-GO composite was used to enhance the corrosion protection ability of nontoxic water-based alkyd varnish (WAV). The chemical composition, functional groups and surface morphologies of GO, PANI-GO and PDA-PANI-GO composites were characterized by XRD, FT-IR XPS and SEM. The anticorrosion performance was demonstrated by electrochemical impedance spectroscopy measurements and polarization tests. Due to the physical barrier effects and surface hydrophobicity of PANI-GO composite, the approaches of the caustic substances to the surface of the metal was inhibited, while the highly adhesive PDA molecules reinforced compatibility between fillers and WAV. As results, PDA-PANI-GO composite introduced WAV enhanced corrosion prevention performance. Under the optimal conditions, where the ratio of PDA to PANI-GO was kept at 2:1, the impedance values increased by over two orders of magnitude compared with bare steel.

Preparation of graphene/polyaniline nanocomposite by in situ intercalation polymerization and their application in anti-corrosion coatings

This study reports a strategy for further simplifying the synthesis process of polyaniline-modified graphene (An/G) nanocomposite. For this purpose, the An/G nanocomposite was prepared by expanded graphite (EG) and aniline (An) via in situ polymerization. The structures and morphologies of the An/G nanocomposite were examined by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, ultraviolet–visible spectroscopy and atomic force microscopy. The results show that the An/G nanocomposite was synthesized successfully. The coatings were prepared using polyaniline (PANI) and An/G as the fillers and epoxy resin as the matrix. The anti-corrosion performance was evaluated by electrochemical impedance spectroscopy, Tafel polarization curve and salt immersion test. When An/G100 nanocomposite with a mass ratio of An to EG of 100:1 as a filler is used, the coating on the steel exhibited superior anti-corrosion effect. In particular, the impedance at 0.01 Hz of the coating with the An/G100 nanocomposite at a low loading of 2 wt% (An/G100-2) remained constant above 1 × 1010 Ω·cm2 for up to 35 days in 3.5 wt% sodium chloride solution. The Tafel plots reveal that the undamaged zone of the An/G100-2 coating possessed a high corrosion potential of −0.16 V, and the corrosion current density was only 1.5 × 10−11 A cm−2. The protective mechanism of graphene and PANI is discussed.

B, Justin Thomas KR. Experimental and computational studies of a graphene oxide barrier layer covalently functionalized with amino acids on Mg AZ13 alloy in salt medium

Leucine functionalized graphene oxide chemisorbed on a 111 surface AZ13 magnesium alloy via edge functional groups.

Experimental and Theoretical Studies on Corrosion Inhibition of Niobium and Tantalum Surfaces by Carboxylated Graphene Oxide

The corrosion of two different metals, niobium and tantalum, in aqueous sulfuric acid solution has been studied in the presence and absence of carboxylated graphene oxide. Potentiodynamic measurements indicate that this nanomaterial inhibits corrosion due to its adsorption on the metal surfaces. The adsorbed layer of carboxylated graphene hinders two electrochemical reactions: the oxidation of the metal and the transport of metal ions from the metal to the solution but also hydrogen evolution reaction by acting as a protective barrier. The adsorption behavior at the molecular level of the carboxylated graphene oxide with respect to Nb, NbO, Ta, and TaO (111) surfaces is also investigated using Molecular Dynamic and Monte Carlo calculations.

A simple route to surface functionalization of graphene nanosheets by benzoic acid and its application toward Pb(ii) sensing

Grafting of benzoic acid to graphene nanosheets for construction of a simple Pb(ii) sensor

Protection of carbon steel corrosion in 3.5% NaCl medium by aryldiazonium grafted graphene coatings

Modification of CS/G by 1,8 ND containing two phenyl rings and two azo groups led to higher protection efficiency.