Anticorrosion Characteristics Research Articles

Eco-friendly modified chitosan as corrosion inhibitor for carbon steel in acidic medium: Experimental and in-depth theoretical approaches

The industrial and medical sectors have a great interest in chitosan due to its unique properties, such as abundance, renewability, non-toxicity, antibacterial activity, biodegradability, and polyfunctionality. In this work, two modified chitosan Schiff bases (ChSB-1 and ChSB-2) were made using condensation methods, and their potential as corrosion inhibitor for carbon steel in 1 M HCl was investigated using chemical and electrochemical techniques. The ChSB-1 and ChSB-2 inhibitors exhibited remarkable inhibitory performance, as evidenced by the mass loss data, which showed 89.3 % and 91.5 % efficacy at 1 mM concentration, respectively. Because of the electron-donor substituent of methoxy (–OCH3), ChSB-2's active sites have more delocalized electrons than ChSB-1's. The PDP results showed that both ChSB-1 and ChSB-2 inhibitors have anti-corrosion characteristics because heteroatoms caused a protective layer to develop that functioned as mixed-typed inhibitors. The calculated adsorption-free energy ∆Gadso for ChSB-1 and ChSB-2, respectively, was found −36.1 and − 37.1 kJ mol−1. The ChSB-1 and ChSB-2 inhibitors adsorb on carbon steel in acidic conditions through physisorption and chemisorption interactions, and their adsorption is in line with the Langmuir adsorption model. Inhibited and uninhibited metallic surfaces were subjected to surface morphological assessments using contact angle (CA), the scanning electron microscopy and the energy dispersive X-ray (SEM/EDX) analysis. The DMol3 part of Materials Studio 7.0 software was used to perform the quantum chemical calculations based on DFT to visualize the structural features. Studies from quantum chemistry suggest the possibility of surface interaction between the unoccupied orbitals of the metal surface and the inhibitors ChSB-1, ChSB-2, ChSB-1H+, and ChSB-2H+. The results clearly show that the two inhibitors work well as environmentally friendly carbon steel corrosion inhibitors in acidic medium. This could be advantageous for industrial procedures such as pickling, cleaning, acidizing oil drilling in oil wells, and using citrus to de-sediment boilers.

Enhanced anti-corrosion characteristics of epoxy-functionalized graphene oxide nanocomposite coatings on mild steel substrates

This experimental investigation focused on coating of functionalized graphene oxide (FGO) on the mild steel to minimize corrosion, using a new method. Prior to the coating, the fundamental chemical and morphological structures of FGO were studied with aid of some characterization techniques: X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Various epoxy/FGO coating formulations with 10, 20, 30, 40 and 50 ppm of FGO were prepared and coated on the mild steel substrate, adopting dip coating method. Immersion test was carried out to observe the corrosion inhibition efficiency of the graphene. The adsorption isothermal behavior was also studied using various models and compared with the data obtained from the experimental results. From the results obtained, the formation of irregular rough patches and separation of platelets like zebra lines indicated the formation of graphene nanoparticles, as observed through morphological analysis. The occurrence of sharp peak at 24.3° in the XRD pattern depicted the existence of graphene in nanoscale. Electrochemical impedance (EI) and potentiodynamic polarization (PP) studies reported the maximum corrosion inhibition efficiency of 87% at 50 ppm concentration of epoxy/FGO. It was evident that an increasing concentration of graphene exhibited significant corrosion resistance in both studies. The bonding energy of randomly oriented graphene platelets reduced the removal of metal, delaying the crack propagation in tortuous path on the coated surface. These results established the significance and applicability of this study in various relevant industries.

Preparation of lanthanide aluminate‐encapsulated silica nanoparticles toward long‐persistent photoluminescent polymer paint with superhydrophobic and anticorrosion properties

AbstractSmart afterglow paints can function as energy‐saving products that are able to persist lighting in the dark. Additionally, polyurethane paints (PURPs) have shown some limitations, including weak adhesion, poor mechanical performance, poor corrosion, and low water resistance as compared with solvent‐based paints. Herein, nanoparticles of lanthanide aluminate (NLA; 16–24 nm) were mixed with polyurethane and silica to develop novel photoluminescent nanocomposite paints. A precursor of NLA‐encapsulated silica nanoparticles (NLA@Silica; 200–225 nm) can be described as a SiO2‐coated NLA pigment prepared by the heterogeneous precipitation method. Steel was coated with nanocomposite paints made of PURP, silica, and NLA. Using emission spectra and Commission Internationale de l'Eclairage (CIE) Lab coordinates, the coloring and transparency of painted films were investigated. Upon excitation at 365 nm, the UV‐irradiation of transparent painted films showed green emission at 518 nm. The hydrophobic activity and hardness properties were examined. Using electrochemical impedance spectroscopy (EIS), the anticorrosion of coatings applied to mild steel was studied. Improved anticorrosion characteristics were observed due to the fluorescence of NLA@Silica in the applied coatings. The optimal long‐lasting luminous characteristics were observed for nanocomposite films containing 12.5% of NLA@Silica.

Novel numerical approach toward hybrid nanofluid flow subject to Lorentz force and homogenous/heterogeneous chemical reaction across coaxial cylinders

The combination of AA7075 and Ti6Al4V aluminum alloys provides an effective balance of endurance, corrosion resistance, and lightness. Some potential applications include aviation components, marine structures with anti-corrosion characteristics, surgical instruments, and athletic apparel. Therefore, the hybrid nanofluid (Hnf) consists of aluminum alloys (AA7075-Ti6Al4V), water (50%), and ethylene glycol (EG-50%) in the current analysis. The Hnf flow subject to heat radiation and Lorentz force is studied through coaxial cylinders. In addition, the flow has been observed under the impacts of homogeneous-heterogeneous (HH) chemical reaction and exponential heat source/sink. The modeled equations (continuity, momentum, HH, and heat equations) are renovated into the non-dimensional form through the similarity approach, which are further numerically computed by employing the ND-solve technique coupling with the shooting method. It can be noticed from the graphical results that the flow rate of Hnf drops with the rising effect of porosity and magnetic field parameters. The addition of AA7075-Ti6Al4V nanoparticles (NPs) also reduces the fluid temperature and velocity profile. Furthermore, the concentration distribution diminishes with the flourishing effect of HH parameters.

Improving corrosion and conductivity of Ti-doped amorphous carbon film coated on 316L stainless steel bipolar plates by nitrogen atoms doping

Amorphous carbon films have recently attracted extensive attention as surface functional films for bipolar plates with excellent conductivity and anti-corrosion properties. In this research, to determine the influence of the amorphous carbon film doped with titanium and nitrogen on the efficiency of proton exchange membrane fuel cells (PEMFCs) and clarify the effect of N atoms on Ti doped amorphous carbon, a series of Ti, N co-doped amorphous carbon films are built on 316L stainless steel at different N2 flow rates. This study provides detailed research about the influence of N atoms content on the microstructure, morphology evolution, corrosion resistance and interfacial contact resistance (ICR) of Ti, N co-doped amorphous carbon films. The results reveal that the N doping of the Ti-doped amorphous carbon film has the potential to enhance the C-sp2 content and refine the grain. The characterization results indicate that introducing N atoms into Ti doped amorphous carbon can reduce the ICR of the film to 2.38 mΩ cm2. The introduction of N atoms can also enhance the anti-corrosive characteristics of the titanium singly doped amorphous carbon film. The Ti, N co-doped film can be used as candidate materials applied to metal bipolar plates.

Influences of Al particles on structure and properties of Ni–Al composite coatings with nanoscale twin structure

Nickel-aluminum (Ni–Al) composite coatings containing nickel nanoscale twins have been prepared by co-electrodeposition on copper substrate. Effects of Al particles on microstructure, chemical composition, friction properties, and corrosion resistance of Ni–Al coatings were investigated. It presents an even and compact structure with granular surface that Al are evenly dispersed in pyramidal-like nickel lattice. Adding Al could alter crystal orientation, refine grains and promote strengthening effects induced by nanoscale twinning. It can enhance anti-corrosion properties and decrease the coefficient of friction (COF). The minimum COF was obtained at 10 g L−1 Al. The larger amounts and even dispersion of Al, the better corrosion resistance and the smaller COF. Increasing Al from 20 to 40 g L−1, incorporated Al in top surface rose from 20.86 to 30.13 wt%, which was larger than in cross section from 13.93 to 18.86 wt%. As the incorporated depth increased, the particle color changed from grey to dark. Nano-twins were generated around enveloped Al particles. The roughness increased as Al rose from 10 to 40 g L−1. The average roughness (Ra) was of 191–231 nm. Ni–Al-5g and Ni–Al-80g have excellent anti-corrosion features, owning the maximum Rct of 1437.2 and 1565.1 kΩ cm2, respectively, associated with the amount and distribution of Al particles, preferred orientation, grain sizes, and twinned structure. The enhanced corrosion resistance might be due to the generation of uniform, compact aluminum oxide layer by doping Al in nickel.

Zinc–cobalt bimetallic metal-organic framework (Zn/Co-MOF) nanoparticles as potent pH stimuli anti-corrosive agent for development of a self-healable epoxy composite coating

The impressive BET-surface area and the design versatility have made Z67(ZIF-67) MOF a potent nanomaterial for anti-corrosion applications. Despite excellent anti-corrosion features the Z67(ZIF-67) suffers poor stability in water media, making it improper for application in polymeric systems. One strategy to enhance the stability of Z67 is its structure modification via a mixed-metal organic framework approach. This study involved the synthesis of a series of Z67 nanoparticles through the incorporation of zinc cation (Zn) at different percentages. Specifically, three different compositions were synthesized: Zn10-Z67, Zn20-Z67, and Zn30-Z67 denoting the addition of 10 %, 20 %, and 30 % molar percent of Zn, respectively. FTIR, FE-SEM, XRD, TEM, ICP-OES, and XPS, as well as BET analyses, were conducted for the Zinc–Cobalt bimetallic MOF structure. Subsequently, the properties attributed to the particles' active and barrier anti-corrosion feature in solution (NaCl) as well as coating (epoxy) phases were investigated. The EIS test performed in the solution phase, after 72h of metal exposure to Zn30-Z67 containing saline media, revealed a 590 % and 30 % increase in total resistance, respectively, compared to the uninhibited sample. Due to the increased stability of Zn10-Z67 in a saline environment, the active corrosion inhibition of the scratched coating containing these particles was increased by approximately 140 % compared to the Z67-containing composite. The incorporation of zinc cations into the structure of Z67 has enhanced the stability and control release features in aqueous environments, thereby enhancing the barrier properties of the epoxy coating. The reduction rate of log|Z|0.01Hz of the Zn10-Z67/EPC was 9 % which was lower than that of the Neat EPC (epoxy coating) (24 %).

Incorporating GO in PI matrix to advance nanocomposite coating: An enhancing strategy to prevent corrosion

Abstract This research endeavors to advance the anti-corrosive characteristics, mainly the physico-mechanical properties, by incorporating graphene oxide (GO) into a polyimide (PI) matrix. So, a nanocomposite coating is fabricated for an aluminum alloy substrate. Results reveal that the coating was uniformly dispersed across the surface signifying that the inclusion of GO increased the PI dispersion. The π–π stacking interactions between the aromatic rings of PI and GO contribute to their stability and improved anticorrosive properties. The incorporation of GO to PI films significantly enhances hydrophobicity, as evidenced by the increased contact angles. Assessing the corrosion resistance of the coating in a 3.5 wt% NaCl solution through electrochemical impedance spectroscopy and potentio-dynamic polarization establishes a prominent correlation between the percentage of GO and the anticorrosion efficiency of the composite coating. Precisely, the nanocomposite coating containing 5 wt% GO exhibits an impressive impedance modulus value of 107, and the corrosion current density (I cor) is drastically reduced by over three orders of magnitude, reaching 4.8 × 10−9 A cm−2, as indicated by the polarization curve. Also, prolonged immersion tests confirm the exceptional protective ability of the S5 coating (5 wt% GO), effectively shielding the metal for up to 100 h. After conducting diagnostic measurements, the hybrid nanocomposites of GO/PI examined in this study showcased their effectiveness as inhibitors in anticorrosive coatings. These composites played a vital role to hinder the oxidation of underlying aluminum alloy when exposed to oxidizing chemicals, water, or air, thereby extending the protective duration.

Graphene nanosheet reinforcement of polyurethane nanocomposite for green and sustainable photoluminescence, superhydrophobic, and anticorrosive paint.

A simple and environmentally friendly method was developed for smart and efficient waterborne polyurethane (PUR) paint. Sugarcane bagasse was recycled into reduced graphene oxide nanosheets (rGONSs). Both lanthanide-doped aluminate nanoparticles (LAN; photoluminescent agent, 7-9nm) and rGONSs (reinforcement agent) were integrated into a waterborne polyurethane to produce a novel photoluminescent, hydrophobic, and anticorrosive nanocomposite coating. Using ferrocene-based oxidation under masked circumstances, graphene oxide nanosheets were produced from sugarcane bagasse. The oxidized semicarbazide (SCB) nanostructures were integrated into polyurethane coatings as a drying, anticorrosion, and crosslinking agent. Polyurethane coatings with varying amounts of phosphor pigment were prepared and subsequently applied to mild steel. The produced paints (LAN/rGONSs@PUR) were tested for their hydrophobicity, hardness, and scratch resistance. Commission Internationale de l'éclairage (CIE) Laboratory parameters and photoluminescence analysis established the opacity and colourimetric properties of the nanocomposite coatings. When excited at 365 nm, the luminescent transparent paints emitted a strong greenish light at 517 nm. The anticorrosion characteristics of the coated steel were investigated. The phosphor-containing (11% w/w) polyurethane coatings displayed the most pronounced anticorrosion capability and long-persistent luminosity. The prepared waterborne polyurethane paints were very photostable and durable.

Experimental investigation of conductive heat transfer and fire protection in a polymer-based plate heat exchanger

Polymer-based heat exchangers offer several attractive features for thermal management applications such as low-cost, lightweight, antifouling, and anti-corrosion characteristics. However, their thermal performance is compromised primarily by the low thermal conductivity and high-flammability. This work consists of developing new polymer-based plate heat exchangers, which are made from epoxy resin reinforced by banana fibres and manufactured using the vacuum bag resin transfer moulding technique. The aim of this research is to improve both the heat transfer efficiency and thermal protection. The proposed approach involves incorporating silicon carbide powder as charge into samples to increase their thermal conductivity, and applying an intumescent fire-retardant coating to improve their capacity to withstand heat and flames. To determine the efficacy of this approach, a cone calorimetry test was performed to examine the thermal distribution within the plate heat exchanger samples and to assess fire reaction parameters during a fire scenario. The results revealed a notable increase in thermal conductivity, due to the addition of silicon carbide powder. Furthermore, the intumescent fire-retardant coating substantially improved the samples’ thermal resistance. This result has been verified by thermogravimetric analysis conducted during this work. These findings suggest that using banana fibres-reinforced epoxy resin, combined with silicon carbide powder and intumescent fire-retardant coating, has the potential to enhance the overall thermal performances of plate heat exchangers. The addition of silicon carbide powder increases the thermal conductivity by 36%. This demonstrates the feasibility of utilizing sustainable and biodegradable materials to manufacture heat exchangers that are more efficient and eco-friendly.

Highly efficient anti-corrosion polyetherimide (PEI) coating encapsulated with aluminum di-hydrogen tri-polyphosphate

Protective composite coatings based on polyetherimide (PEI) incorporated with aluminum di-hydrogen tri-polyphosphate (ATP) particles for the protection of carbon steel are reported here. The ATP particles were used as an inhibiting pigment. The layers were applied by the dip coating method leading to a full uniform coverage as confirmed by microscopic and Raman spectroscopy techniques. The anti-corrosion characteristics of the PEI-coated samples were investigated in a 3.5 wt.% NaCl solution by electrochemical impedance spectroscopy. The results revealed that PEI-ATP composite coating exhibited higher impedance values above 109 Ω.cm2 (up to 30 days) compared to a Blank-PEI coating. The active protection was studied by the scanning vibrating electrode technique revealing clear signs of inhibition in the artificial defects. The proposed mechanistic insights into the protective properties of PEI-ATP coating was further supported using X-ray photoelectron spectroscopy.

Оценка коррозионных свойств вольфрамового покрытия контейнеров для РАО, нанесенного газофазным методом

The article summarizes the study exploring the anti-corrosion characteristics of tungsten coatings produced by chemical gas-phase deposition in a solution simulating the geochemical conditions at the Yeniseiskiy site. The study shows that a 30-micron-thick tungsten-based coating appears to be quite stable with an average corrosion rate of 1.4 microns/year. It also notes the high stability of tungsten coatings under microbial fouling conditions.

Understanding the anti-corrosion characteristics of surface modification of h-BN and carbon nanotubes/magnesium composites in simulated seawater.

In order to address the issues of wettability and scattering between matrix and reinforcement and enhance corrosion resistance, the effects of incorporating hexagonal boron nitride (h-BN) into magnesium-carbon nanotubes (Mg-0.5 wt% CNTs) nanocomposites were successfully investigated. An inventive coating with h-BN using a novel electroless chemical deposition technique and double stir casting were used. The composites were produced by varying weight percentages of h-BN (0, 2, 4, and 6). The corrosion testing, microstructural analysis, and physical testing of the samples were carried out. A corrosion resistance of 75.1% was obtained when the 4 weight percent of h-BN content was compared to Mg-0.5% wt% CNTs. Even though the relative density increased noticeably, this was due to the uniform dispersion of h-BN nanoparticles over the entire surface. Researchers have established that adding 4 wt% h-BN to the Mg-0.5 wt% CNT nanocomposite can improve the wettability between Mg and CNTs and enhance the corrosion resistance properties.

Fabricating epoxy composite coating having self-healing/barrier anti-corrosion functions utilizing ion-exchange/pH-sensitive phosphate-doped ZIF8 MOF decorated Zn-Al-LDH nano-layers

Recently, the development of epoxy composite coatings with smart anti-corrosion features has been considered in many studies. Using inhibitor-loaded nanocarriers, i.e., layered double hydroxides (LDH) and metal-organic frameworks (MOFs) has attracted recent attention. In this work, the hybrid LDH@ZIF8 was constructed and applied in the epoxy coating as a dual-functional nanocarrier.In this study, firstly, LDH nano-size lamellar was synthesized followed by surface modification with nano-porous ZIF8 3D structures. Afterward, to provide further corrosion inhibition properties, phosphate ions were doped and the resultant particles were introduced into the epoxy coating. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD) analysis were utilized to characterize the nanoparticles and they were a good indicator to prove the successful surface modification. Via inductively coupled plasma (ICP), the inhibitor pH/ion-responsive release (i.e., PO43− anions, Zn2+ cations) ability at various pHs was screened. Electrochemical measurements proved the inhibitive action of the phosphate-doped LDH@ZIF8 structures in the solution state (75.99 % inhibition index). EIS results revealed that after incorporating the phosphate-doped LDH@ZIF8 nano-hybrid into the epoxy coating its barrier properties were significantly improved (impedance values>1010 Ω.cm2). Besides, the phosphate-doped LDH@ZIF8 filled epoxy (with artificial scratch) showed about 57 % self-healing index. The adhesion bond durability was significantly improved after the addition of phosphate-doped LDH@ZIF8. About 69 % improvement in the wet adhesion (pull-off test) and 73 % reduction of cathodic delamination diameter (CD test) were recorded for the epoxy coating loaded with phosphate-doped LDH@ZIF8 compared to the blank epoxy. Generally, using phosphate-doped LDH@ZIF8, both barrier and active corrosion protection properties of the epoxy coating were significantly improved, and compared to similar works reported in literature better anti-corrosion durability was reached.

Corrosion-Resistive ZrO2 Barrier Films on Selected Zn-Based Alloys.

This work presents the enhanced corrosion resistance of newly developed two-layer composite coatings deposited on low-carbon steel: electrodeposited zinc alloy coatings (Zn-Ni with 10 wt.% Ni (ZN) or Zn-Co with 3 wt.% Co (ZC), respectively) and a top ZrO2 sol-gel layer. Surface morphology peculiarities and anti-corrosion characteristics were examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), atomic force microscopy (AFM), water contact angle (WCA) measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) analyses, potentiodynamic polarization (PDP) curves, corrosion potential (Ecorr), polarization resistance (Rp) measurements (for a prolonged period of 25 days) and open-circuit potential (OCP). The results were compared with the corrosion peculiarities of usual zinc coating. The zirconia top coatings in both systems were amorphous and dense, possessing hydrophobic nature. The experimental data revealed an increased corrosion resistance and protective ability of the ZC system in comparison to that of ZN due to its smooth, homogeneous surface and the presence of poorly crystallized oxides (ZnO and Co3O4), both later playing the role of a barrier for corrosive agents.

Development of Multicomponent Nanostructured Nitride Coatings to Protect against Corrosion Products from Titanium Alloy

Phase-structural characteristics and the corrosion resistance of coatings ZrN, (Zr,Ti)N, (Zr,Hf)N, (Zr,Nb)N, (Ti,Zr,Hf)N and (Ti,Zr,Nb)N, which were deposited on a Ti6Al-4V titanium alloy substrate, were investigated. It was found that the titanium substrate has a crystalline structure, including grains with high (up to 24 at.%) and low (less than 2 at.%) vanadium content. Thus, during the deposition process, the coating can form adhesive bonds with local areas of the substrate that have quite different compositions. The diffusion of the coating elements into the substrate takes place up to a depth of 200 nm. The diffusion of titanium alloy elements (primarily titanium and vanadium) into the adhesive sublayer of the coating to a depth of 100 nm is also observed. Corrosion studies were carried out in 1M solutions with acidic (H2SO4), alkaline (NaOH) and neutral (NaCl) media at a constant temperature of 50 °C. The actual change in the mass of the samples during corrosion tests is extremely small. The protective coatings under study have very high anti-corrosion characteristics and practically do not react with solutions that imitate the liquid environments of the human body.

Enhancing corrosion resistance in reinforced concrete structures by using innovative eco-friendly composite pigments

This is the first study to look into the use of modified feldspars as anticorrosive pigments in the coatings industry. Herein, novel anticorrosive composite pigments were prepared by the chemical deposition of thin films of different oxides (e.g., zinc oxide and vanadium oxide with doloresite phase) on the surface of feldspar, which comprises 80% of the whole structure. A new vanadium oxide (e.g., doloresite) was chosen due to its IV oxidation state and excellent anticorrosive characteristics. ZnO is also well-known for its high resistance to corrosion. Firstly, the synthesis of the composite pigments was done, and then, they were characterized via XRD, SEM/EDX, XRF, and TGA. The composite pigments were incorporated into solvent-based epoxy coatings to evaluate their anticorrosive performance on reinforced concrete steel. Their corrosion resistances were determined using linear polarization resistivity and electrochemical impedance spectroscopy techniques. The physico-mechanical properties of the dry coats containing the prepared composite pigments were also evaluated. The results revealed that the polarization resistivity (Rpo) of coatings containing Zn/F ranged from 5900 to 3900 Ohm.cm2 and that of V/F ranged from 7077 to 5500 Ohm.cm2, while the resistivity of uncoated rebar was from 1900 to 1300 Ohm.cm2. These results confirm that these novel pigments (e.g., ZnO/feldspar and doloresite/feldspar) could provide high corrosion resistivity for concrete structures that are immersed in chloride-laden environments. These composite pigments will be eco-friendly with a low impact on humans and the environment as they contain very low concentrations of heavy metals, besides their high efficiency and economic feasibility.

Antibacterial Calcium Phosphate Coatings with Zinc Oxide Nanoparticles

Porous calcium phosphate coatings (C-P) with ZnO nanoparticles were obtained via the micro-arc oxidation method on a titanium substrate. ZnO nanoparticles were added to the C-P coatings to change the zeta potential and improve the coatings’ bioactivity and antibacterial properties. The samples with coatings were studied via scanning electron microscopy (SEM), X-ray diffraction, energy dispersive microanalysis, potentiodynamic polarization, and zeta potential measurement. The coatings modified with ZnO nanoparticles showed improved physical, electrochemical, and electrical properties, compared to the initial unmodified coatings. Modification with ZnO nanoparticles contributed to an increase in zeta potential from −60 mV to −53 mV. Functionalization of the coatings with ZnO nanoparticles allowed us to increase the anticorrosion characteristics by about 30%. The biological studies showed that the coatings had no cytotoxic effect on L929 fibroblast cells. The antibacterial activity of the coating rose by 99% after the addition of ZnO nanoparticles against the bacterium Staphylococcus aureus.

MICROSTRUCTURAL EVOLUTION AND ANTI-CORROSION CHARACTERISTICS OF AS-CAST AND LPBF PRINTED INCONEL PLATES IN SEAWATER ENVIRONMENT

Inconel 718 (IN 718) belongs to the category of nickel-based superalloys with outstanding mechanical characteristics such as high strength, better corrosion resistance, greater hardness, fatigue and wear resistance. This alloy is mostly implemented in manufacturing the components of aeroengines, nuclear reactors, space shuttles, pressurized boilers and so on. In most cases, the parts made from this alloy work in severe aggressive environments. A prolonged exposure of this alloy in such environments will pave the way for corrosion phenomenon which will minimize the service life of the components. It is reported that the parts made via additive manufacturing will exhibit better mechanical characteristics than the casted and forged parts. This work is aimed to investigate the anti-corrosion characteristics of both as-cast and LPBF printed IN 718 samples at various time intervals in the seawater environment. By means of FESEM micrographs, the microstructural evolution in both as-cast and LPBF printed IN 718 samples was analyzed. The anti-corrosion characteristics of both samples were investigated in the environment containing 3.5 wt.% NaCl (seawater) in terms of EIS and potentiodynamic polarization curves along with the corroded morphology. The results showed that the LPBF printed IN 718 samples exhibit fine cellular and columnar grains decorated with the NbC precipitates along their boundaries, whereas the casted samples have larger and coarser grains with uneven segregation of NbC precipitates. From the Tafel and EIS (Nyquist and Bode) plots, the LPBF IN 718 sample showed greater corrosion resistance in terms of current density and polarization resistance values. In particular, the 15 h LPBF sample has a strong, compact passive film formed on it. This compact passive film paved the way for this sample to exhibit lower current density (3.03 × 10[Formula: see text] A/cm2) and higher polarization resistance (3678 Ω · cm2) when compared with the LPBF and cast samples at other intervals.

Synthesis and Characterization of Cresol based Benzoxazine–Polyurethane Copolymer for Anti-corrosion Performance of Mild Steel

The cresol based polymeric materials were synthesized by using benzoxazine and polyurethanes as copolymer. Three copolymers were synthesized by varying the quantity of polyurethane content and studied their corrosion inhibition properties. The synthesized monomer, which has cresol as the center core was characterized by the NMR, FT-IR and UV-visible spectroscopic methods. All the obtained benzoxazine polymers were also analyzed by the FT-IR and UV-visible spectroscopy. In relation to corrosion inhibition studies, Tafel and impedance experiments were conducted, revealing that benzoxazine-polymer with a higher polyurethane content has improved anti-corrosive characteristics. Additionally, the physical properties of the materials were also studied such as water absorption and gel content studies. Furthermore, the density functional theory calculation was also carried out for the monomer, which explores the better results that are matched with the other experimental studies.