In this work, electrochemical and surface characteristics of 316L stainless steel manufactured by laser powder bed fusion (LPBF) were studied in the 0.1 M H2SO4 solution containing methionine as a ...corrosion inhibitor. Electrochemical studies such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and adsorption isotherm, and characterization methods such as field emission scanning electron microscopy integrated with an energy dispersive x-ray spectroscopy (FESEM‐EDS), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) were performed to evaluate the effect of the inhibitor on the corrosion behavior of LPBF processed stainless steel. FESEM micrographs of the LPBF processed alloy showed the presence of cellular/columnar morphology, most probably due to the effect of a high cooling rate during the LPBF process. The results of the electrochemical tests indicated that the charge transfer resistance of stainless steel in the presence of methionine increases from 4810 up to 13,300 Ω cm2, and Ecorr shifted about 250 mV toward the noble direction. Besides, corrosion current density decreases from 3.24 to 0.45 μA cm−2 as the concentration of methionine increases from 0 to 500 ppm in the sulfuric acid. Adsorption isotherm revealed a physical-chemical interaction of inhibitor with the surface. It is assumed that the methionine can adsorb on the anodic sites of the alloy during the immersion period and block the immigration of aggressive species toward the surface.
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Graphene oxide (GO), due to its large surface area and suitable active sites, is receiving significant attention as a good additive in various coatings due to its excellent chemical resistance, ...anticorrosion, and high mechanical performances. Furthermore, due to its unique structural dimensions and electrical, thermal, optical, and chemical properties, GO has attracted notable interest in diverse areas, including biomedical and antibacterial applications. This review focuses on the polymer nanocomposite coatings embedded with GO, their synthesis methods, and the role of GO to improve the corrosion protection performance, mechanical and electrical properties, antibacterial application, and thermal conductivity.
Graphene oxide (GO) nanosheets were in-situ functionalized via polypyrrole (POP) nanoparticles using ammonium persulfate and afterward doped with sodium molybdate (GPM) and finally incorporated into ...the epoxy resin for achieving a nano-composite coating with dual barrier and self-healing properties. The synthesized nanoparticles were characterized by field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), and thermal gravimetric analysis (TGA) techniques. The release mechanism of the inhibitors from the GPM was investigated in both solution and coating phases. In addition, the modified coatings were tested electrochemically using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization as well as the pull-off test, cathodic disbonding, and salt spray. Results from FE- SEM /EDS, FT-IR, TGA, and XRD investigations supported the successful synthesis of the GPM complex and molybdate adsorption on the surface of GP. Electrochemical measurements revealed that the release of MoO4−2 from GPM resulted in the creation of a compact protective layer on the steel surface, enhanced inhibitive ability, and a low corrosion rate (1.41 A cm−2). It was shown that the charge transfer resistance of the bare steel sample in the blank solution enhanced from 2360 Ω cm2 to 8530 Ω cm2 in the presence of GPM after 1 h immersion time. The epoxy coating's ability to prevent corrosion was also improved by the GPM nanoparticles, reaching 99%.
AZ31 Mg alloy surface was coated with polyethyleneimine (PEI) coating with anticorrosive properties in a two-step process to improve corrosion resistance. In the first step, alkaline passivation was ...followed by a PEI cationic polymer dip coating based on chemical and electrostatic interactions. AZ31 Mg alloy coated with PEI showed better corrosion resistance in PBS than uncoated alloy, based on electrochemical tests including potentiodynamic polarization and electrochemical impedance spectroscopy. Biocompatibility and in vitro cell behavior tests revealed good adhesion and proliferation in the presence of amine groups in the PEI structure. Furthermore, the antibacterial research showed that PEI-coated AZ31 had a great antibacterial activity. These findings suggest that PEI-coated AZ31 Mg implants are suitable for orthopedic applications as bioactive and protective biomaterials.
Welding of AISI H13 tool steel which is mainly used in mold making is difficult due to the some alloying elements and it high hardenability. The effect filler metal composition on the microstructural ...changes, phase evolutions, and hardness during gas tungsten arc welding of AISI H13 hot work tool steel was investigated. Corrosion resistance of each weld was studied. For this purpose, four filler metals i.e. ER 312, ER NiCrMo-3, ER 80S, and 18Ni maraging steel were supplied. Potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) were used to study the corrosion behavior of weldments. It was found the ER 80S weld showed the highest hardness owing to fully martensitic microstructure. The hardness in ER 312 and ER NiCrMo3 weld metals was noticeably lower than that of the other weld metals in which the microstructures mainly consisted of austenite phase. The results showed that the corrosion rate of ER 312 weld metal was lower than that other weld metals which is due to the high chromium content in this weld metal. The corrosion rate of ER NiCrMo-3 was lower than that of 18Ni maraging weld. The obtained results from EIS tests confirm the findings of potentiodynamic polarization tests.
The study investigated the microstructures and corrosion behaviors of Hastelloy X (HX) and HX reinforced by cerium oxide particles (HX-C) produced by selective laser melting (SLM) and compared to the ...wrought equivalent (HX-W). The aim was to eliminate hot cracking and investigate the HX's corrosion behavior in the presence of cerium oxide particles. The HX samples showed fine cellular and columnar solidification structures with uniform-size sub-cells and severe microcracking. Incorporating cerium oxide particles (1 wt%) resulted in finer and relatively equiaxed grains without microcracking. The HX-W alloy contained a micron-sized carbide (Mo-rich M6C type) within the matrix. The HX-C sample displayed higher porosities compared to the HX sample (1.8 % against 0.3 %). Potentiodynamic polarization and electrochemical impedance spectroscopy tests were conducted in a standard NaCl solution at temperatures of 25, 50, and 70 °C to assess the corrosion behavior of Hastelloy samples. The HX-C matrix showed superior corrosion resistance compared to the HX-W and HX samples due to its finer grain structure and stable passive layer formation. Cerium oxide particles were found to be efficient in decreasing hot cracking and improving corrosion resistance.
Corrosion is a big challenge in various fields that needs to be addressed, especially where metallic components are involved. In this regard, different types of materials have been used and studied ...to improve the anticorrosion properties of metallic substrates among which conducting polymers (CPs) have gained tremendous attention as anticorrosive coatings. This has opened a new research area for preparing cost-effective coatings with high performance. Among CPs, polypyrrole (PPy) is one of the most promising materials owing to its intrinsic anti-corrosion properties. Various protection mechanisms have been proposed for the PPy-coated metals and alloys, including ennobling or anodic passivation, cathodic protection, mediation of oxygen reduction, barrier protection, controlled inhibitor release mechanism, etc. In this paper, these mechanisms and the effect of different parameters (i.e. the substrate type, using co-polymerized PPy or its derivatives, and using nano-materials) are reviewed and discussed.
•Polypyrrole is a conducting polymer which could inhibit the corrosion as the coating.•PPy can be applied to metals and alloys by chemical and electrochemical methods.•PPy affects the corrosion behavior of various substrates including steels, Al, Cu, etc.•Ennobling or anodic passivation, cathodic protection, barrier protection, controlled inhibitor release mechanism, and etc. are the main protection mechanism of Ppy.
In this paper, polypyrrole (PPy) conductive polymers were created in the presence of ferric chloride (FeCl3) and ammonium peroxodisulfate (APS) oxidants. Sodium molybdate (Na2MoO4) is used for the ...PPy corrosion inhibitory effect in NaCl solution. According to the electrochemical impedance spectroscopy (EIS) results, the corrosion resistance of steel plates subjected to the Na2MoO4 containing solution with different ratios of PPy-FeCl3 and PPy-APS was significantly improved, revealing that the barrier properties of the PPy film have drastically improved in the presence of Na2MoO4. The polarization test results revealed noticeable corrosion rate decrement with the incorporation of molybdate to the PPy-FeCl3-containing solution.
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•Two types of polypyrrole (PPy) polymer were created in the presence of ferric chloride and ammonium persulfate oxidants.•NaMoO4 impact on the protection performance of PPy in a chloride-containing solution was studied.•The presence of NaMoO4 in the solution containing PPy-FeCl3 improved its inhibition performance.•The greatest corrosion resistance improvement was related to the solution containing 500 ppm PPy-FeCl3 + 500 ppm NaMoO4.
Sodium molybdate (Na2MoO4) doped graphene oxide/polypyrrole nanocomposite (GO-PPy + Na2MoO4) was synthesized and considered as a multi-functional corrosion inhibitor container to be embedded into the ...epoxy coating. To ensure the decoration of GO surface by PPy nanoparticles and doping of molybdate ions into the GO-PPy structure, several analyses such as FT-IR, Raman, ICP-OES, zeta potential, FE-SEM/EDS, and TEM were used. The active-barrier anti-corrosion features of GO-PPy and GO-PPy + Na2MoO4 in 3.5 wt% NaCl solution were screened by EIS, salt spray, pull-off, and cathodic disbanding tests. Potentiodynamic polarization analyses showed 77% inhibition efficiency in the solution containing GO+PPy + Na2MoO4 compared to the blank solution. The GO-PPy + Na2MoO4 reinforced epoxy coating exhibited the highest impedance (log ׀Z׀10 mHz = 10.58 Ω·cm2, after 63 days) and the lowest delamination values (3.58%, after 63 days) in comparison with the pure epoxy coating (EP) (log ׀Z׀10 mHz = 6.1 Ω·cm2 and delamination value = 48.75%, after 63 days). The interaction of the NH bonds in the PPy chain with the oxide layer, and the formation of molybdate-containing compounds resulted in a considerable enhancement of the epoxy coating adhesion to the metal surface in the presence of GO-PPy + Na2MoO4.
•Sodium molybdate (Na2MoO4) doped graphene oxide/polypyrrole (GO-PPy + Na2MoO4) nano-container was synthesized.•Potentiodynamic polarization analyses showed 77% inhibition efficiency in the GO+PPy + Na2MoO4 containing solution.•The GO-PPy + Na2MoO4 reinforced epoxy coating exhibits the highest corrosion resistance.
It is the purpose of this study to investigate the effects of heat treatment on the microstructure, corrosion, and biological behavior of Ti-6Al-4V alloy manufactured using electron beam melting ...(EBM). The EBM parts were exposed to different heat treatments at 1000 °C and various cooling rates (HT-1, HT-2, and HT-3) to obtain a combination of α and β phases. Electrochemical analyses indicate that the non-heat treated alloy (Ref) exhibits superior corrosion resistance during early immersion, while all samples display similar corrosion performance after one month of immersion. The higher corrosion performance was associated with the content of β phases in the manufactured alloy. The Ref, HT-1, HT-2, and HT-3 EBMed alloys had corrosion current densities of 0.46, 0.66, 0.67, and 0.92 µA cm−2, respectively, after one month of immersion. Cell adhesion and durability were shown to be excellent on HT-3 samples. In conclusion, a suitable heat treatment can improve the biological performance of the EBMed alloy, despite resulting in lower corrosion performance in the early stages of corrosion.
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