Corrosion Resistance Of Steel Substrate Research Articles

Effects of niobium pentoxide nanoparticles on the tribological properties of electrodeposited ZnNi coatings

Electrodeposited ZnNi coatings are widely used to improve the corrosion resistance of steel substrates, but their tribological properties are also relevant for loaded contacts under relative motion. This work investigates the hypothesis of improving tribological properties of electrodeposited ZnNi coatings via dispersion of niobium pentoxide nanoparticles (1 g l−1) in the electrolytic bath. The niobium pentoxide nanoparticles were produced via hydrothermal synthesis assisted by microwave. The surface morphology and chemical composition of the coatings were analysed by scanning electron microscopy coupled with x-ray dispersive energy, X-ray diffraction and x-ray photoelectron spectroscopy. The tribological performance of the coatings was assessed using dry reciprocating ball-on-flat tests at normal loads between 3 and 6 N. The use of niobium pentoxide nanoparticles resulted in significantly denser coatings, with some Nb incorporated in the coated surfaces. Under the lowest normal load, all coated specimens showed relatively low friction (∼0.2) and negligible damage. As the normal load increased, the coating produced using niobium pentoxide nanoparticles showed stronger adherence, while conventional ZnNi coating showed increased friction and spalling for the highest load. It is believed that the Nb2O5 nanoparticles increased the number of sites for heterogeneous nucleation, refining the microstructure, so that tougher and more adherent coatings were produced.

Study on properties of porous SiO2/GO modified polyurethane coatings loaded with corrosion inhibitor

Polyurethane (PU) coating can provide physical barrier for metal surface, but the penetration of corrosive ions will affect the long-term corrosion resistance of the coating. In order to improve the corrosion resistance of the coating, it is necessary to modify the coating to reduce the internal defects of the coating and improve the corrosion resistance of the coating. Using mesoporous silica (SiO2) as the carrier to support the corrosion inhibitor 2- mercaptobenzimidazole (MBI), and using the silane coupling agent GPTS as the bridging agent to compound with graphene oxide (GO) to prepare f-GO-MBI @SiO2 composite nano-materials, f-GO-MBI @SiO2 composite nano-materials are added to the polyurethane varnish in different proportions, and the f-GO-MBI @SiO2 modified PU coating is obtained on the surface of carbon steel by spraying method to improve the carbon corrosion resistance of steel substrate. The composition and loading conditions of drug-loaded composite nanomaterials were characterized by fourier infrared spectroscopy (FTIR) and laser particle size analyzer; electrochemical impedance spectroscopy (EIS) and neutral salt spray test were used to study the properties of different coatings corrosion resistance. The results shows that the addition of f-GO-MBI @SiO2 composite nano-materials significantly improves the corrosion resistance of the coating, the low addition amount will reduce the anti-corrosion effect, and the addition of too high can easily lead to agglomeration of composite nano-materials and produce paint film defects. When the addition amount of f-GO-MBI @SiO2 is 5 wt%, the low-frequency impedance of the coating is two orders of magnitude higher than that of the pure polyurethane coating, the corrosion spread width at the neutral salt spray scratches is reduced to 1.5 mm, and the coating has the best corrosion resistance.

Effect of Cu Addition on the Microstructure and Passivation Behavior of Sn Alloyed Ferritic Stainless Steel in NaCl Solution

In this work, the effect of Cu addition on the microstructure and corrosion passivation behavior of Sn alloyed ferritic stainless steel in 3.5 wt.% NaCl solution at 30 °C was investigated by optical microscope (OM), scanning electron microscope (SEM), energy-dispersion spectrum (EDS), potentiodynamic polarization curve and x-ray photoelectron spectroscopy (XPS). The results indicate that Cu addition has certain effect on grain refinement of ferritic stainless steel. Meanwhile, Cu addition has little influence on the cathodic corrosion process of ferritic stainless steel in 3.5 wt.% NaCl solution but shows beneficial effect on enhancing both the corrosion resistance of steel substrate and its passivation behavior. It has been found that the deposition of Cu particles at the bottom of corrosion pits is responsible for the better corrosion resistance and passivation behavior of ferritic stainless steel. Moreover, there is synergistic effect between Sn and Cu on enhancing the corrosion resistance of ferric stainless steel matrix and improving its passivation behavior in NaCl solution.

The synergistic effect of 2-mercaptobenzotiazole and zinc nitrate as corrosion inhibitor on carbon steel in saline solution

Abstract In this study, the synergistic effects of 2-mercaptobenzotiazole molecules and zinc nitrate on the corrosion behavior of carbon steel were investigated using electrochemical techniques in 3.5% NaCl solution. The experimental results revealed that combination of 2-mercaptobenzoimidazole (MBT) and zinc nitrate with ratio of 100 ppm : 100 ppm, resulted in the least corrosion current (1.03 lA cm-2) and the highest corrosion inhibition efficiency. Polarization results showed that the inhibition mechanism of inhibitor was mixed-type (anodic and cathodic mechanism) corrosion inhibition which was predominantly influenced by a reduction in dissolution rate of the substrate (decrease in anodic current density). Electrochemical impedance spectroscopy analysis yielded more accurate results about the formation mechanism and stability of the inhibitor film over prolonged time. The precipitation of chelate from inhibitor molecules and zinc cations on steel surface was found to be the main mechanism for increasing the corrosion resistance of steel substrate.

The synergistic effect of 2-mercaptobenzotiazole and zinc nitrate as corrosion inhibitor on carbon steel in saline solution

Abstract In this study, the synergistic effects of 2-mercaptobenzotiazole molecules and zinc nitrate on the corrosion behavior of carbon steel were investigated using electrochemical techniques in 3.5% NaCl solution. The experimental results revealed that combination of 2-mercaptobenzoimidazole (MBT) and zinc nitrate with ratio of 100 ppm : 100 ppm, resulted in the least corrosion current (1.03 lA cm-2) and the highest corrosion inhibition efficiency. Polarization results showed that the inhibition mechanism of inhibitor was mixed-type (anodic and cathodic mechanism) corrosion inhibition which was predominantly influenced by a reduction in dissolution rate of the substrate (decrease in anodic current density). Electrochemical impedance spectroscopy analysis yielded more accurate results about the formation mechanism and stability of the inhibitor film over prolonged time. The precipitation of chelate from inhibitor molecules and zinc cations on steel surface was found to be the main mechanism for increasing the corrosion resistance of steel substrate.

Designed a novel EP + GO/ZRC + GO coating with bilayered structure for enhancing corrosion resistance of steel substrate

The study aimed to provide an effective way to combine the advantages of both the zinc-rich epoxy coating and the graphene-based coating. Herein, we introduce ZRC + GO/EP + GO and EP + GO/ZRC + GO coatings with bilayered structure. In addition, the bilayered ZRC, ZRC + GO and EP + GO coatings were also fabricated to comparatively investigate the anticorrosion mechanisms of the coatings. In order to obtain better dispersion of GO in waterborne coatings, ionic liquid (1-aminoethyl-3-methylimidazolium bromide) was successively grafted on GO, which was confirmed by XPS, Raman and FT-IR results. The results obtained from electrochemical impedance spectroscopy (EIS) and salt spray test proved that the as-prepared EP + GO/ZRC + GO coating presented superior corrosion protection which was derived from the synergistic effect of barrier property and cathodic protection endowed by the special bilayered structure of the coating. Besides, SEM, EDS and XRD results of the coating-exfoliated steel substrates also revealed the steel substrate coated by EP + GO/ZRC + GO was not obviously corroded at the end of the immersion.

Statistical, morphological, and corrosion behavior of PECVD derived cobalt oxide thin films

Experimental parameters have direct influences on materials properties and therefore their applications. The effect of plasma power on the properties of cobalt oxide thin films, prepared using plasma-enhanced chemical vapor deposition technique, on stainless steel substrates have been addressed in this paper. The structural, morphological, and compositional properties of these films were investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) technique. The XRD patterns demonstrated the growth of polycrystalline Co3O4 thin film with a cubic spinel structure such that the intensity of (511) and (311) peaks increase as the plasma power increases to 100 W. It is observed that crystallite size increases by increasing the plasma power and the maximum crystallite size is found to be 64.8 nm for 100 W. The AFM results illustrate that the surface roughness and grain size increase by increasing the plasma power, and the film deposited at lower plasma power has more uniform and smoother surface, mainly owing to the increase in surface diffusion that in turn causes the coalescence of the grains. The results of XPS spectra indicated the formation of Co3O4 thin films on stainless steel substrates and there were no other elements other than Co, O in the XPS spectra. Additionally, stereometric analysis and fractal dimension of the 3-D surface microtexture of the AFM micrographs were analyzed and the Kolmogorov–Smirnov test was used to assess the normal distribution of quantitative variables. The results of statistical analysis corroborated the experimental results and proved that the surface roughness increased upon an increase in plasma power. Moreover, the corrosion behavior and the surface morphology of the cobalt oxide thin films were investigated using the potentiodynamic method and scanning electron microscopy. The results of these analysis proved that as the plasma power increases the corrosion resistance improves against the H2SO4. The sample which deposited at 100 W plasma power has the minimum corrosion current and the corrosion resistance of steel substrate was improved by controlling the anodic reactions resulted from a protective Co3O4 thin film. These results are useful for building and designing stainless steel devices in corrosive environments.

Effect of Graphene Oxide/ZSM-5 Hybrid on Corrosion Resistance of Waterborne Epoxy Coating

In this study, the preparation of modified graphene oxide (GO) synergistic structure (ZSM-5-NH-GO) and the effect of this structure on the corrosion performance of epoxy coatings were investigated. The structural and morphological properties of ZSM-5-NH-GO were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The corrosion performances were studied by electrochemical impedance spectroscopy (EIS) and salt spray tests. The EIS results showed that the corrosion resistance of steel substrate was considerably improved by ZSM-5-NH-GO. The salt spray tests demonstrated that the ZSM-5-NH-GO coating provided strong corrosion performance for steel substrate. The mechanical properties of the epoxy-composite coatings containing ZSM-5-NH-GO were studied by adhesion tests. The above results indicated that the composite coating containing 0.7 wt % ZSM-5-NH-GO composite possessed most excellent anti-corrosion performance compared with other epoxy coatings.

Enhancement of the Pitting Corrosion Resistance of AISI 316LVM Steel with Ta-Hf-C/Au Bilayers for Biomedical Applications

Tantalum carbide (TaC), hafnium carbide (HfC), and Ta-Hf-C mixed coatings with and without a gold (Au) interlayer were deposited on 316LVM steel substrates by the magnetron cosputtering technique in order to improve the corrosion resistance of steel substrates in a simulated biological fluid. To study the effect of the gold interlayer on pitting corrosion, the different systems were placed in contact with Ringer’s solution at pH 7.4 and a temperature of 37°C. The electrochemical properties of the coatings were determined using polarization curves. Subsequently, the surface morphologies were observed using scanning electron microscopy (SEM) in order to analyze the corrosion processes on the different surfaces. The gold interlayer was found to significantly improve the electrochemical properties of the system, showing a decrease in the pitting corrosion and deterioration rate, while it is expected that the binary and ternary carbides provide mechanical stability to the bilayers protecting the gold.

Investigation and characterization of electrospark deposited chromium carbide-based coating on the steel

This study deals with some structural characteristics, mechanical properties and corrosion behaviour of the chromium carbide coatings produced on microalloy steel by using electrospark deposition (ESD) process. The present study was primarily focused on the electrical parameters of deposition process to achieve a hard and thick coating. Thus, the electrical parameters of process and material transfer were investigated systematically and then the average thicknesses of deposited layers were determined. Using electrical pulses with 0.032C electricity (current amplitude of 300A, pulse duration of 100μs), it has been possible to obtain a uniform coating layer with an average thickness of 80μm after the third coating pass. The results indicate that the coating consists of fairly hard Cr7C3 and Cr0.19Fe0.70Ni0.11 phases and the wear resistance of steel substrate, which is coated by using ESD process, is noticeably enhanced under dry sliding wear conditions. Also, while the microhardness of steel substrate is 227Hv on average, the microhardness of coating reaches 1381Hv onto the surface. In addition to that, the corrosion resistance of steel substrate has been improved by approximately 30%.

Microstructures, mechanical properties and corrosion resistance of Hastelloy C22 coating produced by laser cladding

The Hastelloy C22 coatings H1 and H2 were prepared by laser cladding technique with laser scanning speeds of 6 and 12mm/s, respectively. Their microstructures, mechanical properties and corrosion resistance were investigated. The microstructures and phase compositions were studied by metallurgical microscope, scanning electron microscope and X-ray diffraction analysis. The hardness and scratch resistance were measured by micro-hardness and nanoindentation tests. The polarization curves and electrochemical impedance spectroscopy were tested by electrochemical workstation. Planar, cellular and dendritic solidifications were observed in the coating cross-sections. The coatings metallurgically well-bonded with the substrate are mainly composed of primary phase γ-nickel with solution of Fe, W, Cr and grain boundary precipitate of Mo6Ni6C. The hardness and corrosion resistance of steel substrate are significantly improved by laser cladding Hastelloy C22 coating. Coating H2 shows higher micro-hardness than that of H1 by 34% and it also exhibits better corrosion resistance. The results indicate that the increase of laser scanning speed improves the microstuctures, mechanical properties and corrosion resistance of Hastelloy C22 coating.