Corrosion Resistance Of Coatings Research Articles

The Improvement in Corrosion Resistance of Electroless Ni-P Coating on Micro-arc Oxidized AZ31 Alloy Prepared with Sodium Dodecyl Sulfate Additive and Post-supercritical CO2 Mixed Electrolyte

The Improvement in Corrosion Resistance of Electroless Ni-P Coating on Micro-arc Oxidized AZ31 Alloy Prepared with Sodium Dodecyl Sulfate Additive and Post-supercritical CO2 Mixed Electrolyte

Influence of defect degree on corrosion resistance of graphene coating on titanium alloy

Electrophoretic deposition (EPD) is an effective method for preparing graphene coatings with dense and uniform characteristics on complex-shaped substrates, but defects in graphene coatings prepared by EPD are unavoidable, which affects the corrosion resistance of graphene coatings. This study investigates the effect of defect levels(i.e. ID/IG values in Raman spectroscopy analysis) on the corrosion resistance of graphene coatings on titanium alloys by varying EPD parameters and graphene raw material sizes to prepare coatings with different defect levels. Raman spectroscopy and scanning electron microscopy were used to characterize and measure the defect degree of graphene coatings. Open-circuit potential analysis, electrochemical impedance spectroscopy (EIS) and polarization analysis of dynamic potential were used to study the corrosion properties and anti-corrosion mechanism of graphene coatings.The results show that the graphene coating has lower defect level at an electrophoresis voltage of 60 V, deposition time of 20 min, and graphene flakes size of 1 μm achieving a corrosion current density as low as 0.06 μA/cm2. This study reveals the corrosion resistance mechanism of graphene coatings with different defect levels. Graphene coatings with large porosity and defect levels are easily penetrated by corrosive media and then corrode in contact with the substrate. This research provides insights into developing graphene coatings with low defect levels and high compactness, which will significantly enhance the anti-corrosion efficiency of titanium alloys.

Intrinsic Self-Healable, Corrosion-Resistant Silicone Coating Based on Quadruple Hydrogen-Bonded Supramolecular Polymer.

Corrosion-resistant coatings with self-healing capabilities are still a great challenge for metal protection. In this study, a corrosion-resistant coating with intrinsic self-healing capabilities was developed by compounding hydroxy-terminated silicone oil (HTSO) with 2-ureido-4[1H]-pyrimidone (UPy) derivatives. The smooth surface of the coating was shown by scanning electron microscopy (SEM), and good smoothness was also exhibited in the cross-section, which indicated that the coating is very homogeneous from the top to the bottom. Thermogravimetric analysis (TG) was employed to illustrate the temperature-resistant characteristics of the coating, revealing its significant chemical stability up to 360 °C. The corrosion resistance of the coating is assessed through electrochemical impedance spectroscopy (EIS), the typical impedance at 0.01 Hz is 1.70 × 109 and 2.44 × 108 Ω·cm2 before and after exposure to a 3.5 wt % NaCl solution for 70 days. There was no significant change in the water contact angle of the coatings before and after immersion; however, the adhesion strength was reduced. Notably, the coating demonstrates immediate and multiple self-healing properties. The tensile stress of the associated healing sample experiences an augmentation within the temperature range of 30-120 °C, with the critical fracture strain of the healed sample reaching 235% at 120 °C. The self-healing mechanism of the coating is systematically investigated using in situ Raman spectroscopy.

Enhanced mechanical properties and corrosion resistance of electro-deposited NiCoP composite coatings with ZrB2 particle addition

This work was initiated with the purpose of expanding the utilization of nickel-based composite coatings, especially in wear and corrosion-related industrial applications. NiCoP coatings have long attracted scientific and engineering interest due to their enhanced mechanical properties reinforced by incorporation with a reinforcement phase. In the present study, NiCoP composite coatings reinforced with ZrB2 ceramic particles were synthesized by direct current deposition using a modified Watt’s type bath. The microstructures of composite coatings were studied by x-ray diffraction analysis, energy dispersive x-ray spectroscopy, and scanning electron microscopy, respectively. The hardness and tribological properties of the composite coatings were evaluated and compared. The corrosion behaviors of the deposits were investigated using electrochemical spectroscopy and potentiodynamic polarization techniques in simulated seawater. The effect of ZrB2 content on the microstructures and mechanical properties of the composite coatings was explored and discussed. The present study indicates that there is a progressive enhancement in the hardness, corrosion resistance, and wear resistance of the composite coatings with the increase in ZrB2 loading. The NiCoP-12 g/l-ZrB2 coating possesses the highest microhardness and superior wear performance, while the NiCoP-6 g/l-ZrB2 coating exhibits the best anti-corrosion properties. The present study shows a cost-effective and feasible solution for the preparation of NiCoP protective coatings with enhanced properties, which holds great potential for industrial applications requiring wear and anti-corrosion protection.

Unraveling the detrimental effect of polymeric microcapsules on the corrosion performance of epoxy resin coatings

Organic micro- or nanocapsules are widely used as reservoirs to carry sealing agents or corrosion inhibitors to achieve the self-healing functionality of coatings. To understand the impact of the capsules' incorporation on the barrier properties of organic coatings, composite epoxy resin coatings containing different concentrations (e.g., 5 wt%, 10 wt% and 20 wt%) of urea-formaldehyde (PUF) microcapsules were deposited on the top of Q235 carbon steel. The features of PUF microcapsules and composite coatings were characterized, and the corrosion behaviors of the coating-protected carbon steel were investigated in NaCl solution. The results showed that the spherical PUF microcapsules (∼40 μm) with 290 nm thick shell and hexyl acetate core are synthesized through in situ polymerization. The prepared microcapsules can uniformly distribute within the epoxy resin coatings, which in turn deteriorates the corrosion resistance of the microcapsules-containing composite coatings (MCECs). Lower volume (5 wt%) microcapsules incorporation caused a slight reduction in the corrosion resistance (Rc) and effective capacitance (Ceff) from 4.39 × 107 Ω·cm−2 and 6.50 × 10−5 mF·cm−2 to 8.72 × 106 Ω·cm−2 and 5.63 × 10−5 mF·cm−2, respectively. For higher volume (10 wt% and 20 wt%) groups, the Rc further decreases to 7.47 × 105 Ω·cm−2 and 1.45 × 105 Ω·cm−2, whereas the Ceff increases to 5.63 × 10−5 mF·cm−2 and 5.63 × 10−5 mF·cm−2, respectively. The failure mechanism of the MCECs can be ascribed to the rupture of the PUF microcapsules during the curing process and/or immersion in NaCl electrolyte, which suggested the mechanical strength and chemical stability of the capsules should be carefully determined to avoid their negative impact on the barrier property of polymeric coatings.

Effect of different overlap cladding transition layer – Austenitic stainless steel coating and defect degree on corrosion resistance

The effects of overlap rate and defects on the corrosion resistance of laser fusion clad austenitic stainless steel coatings were studied. In this paper, the Ni transition layer and Fe-based coating were sequentially prepared on grey cast iron, and the corrosion morphology and corrosion mechanism of the coating were comprehensively analyzed through physical phase, microstructure and electrochemical tests. The coating phase was mainly γ-Fe, which formed strong selective orientation and texture strength at the (100) crystal plane; overlap ratio and defects affected the recrystallization changes, and the stresses near the defects were high. Increased overlap rate (Fe-based alloy 50 % → 66.7 %) could result in microstructure refinement, reduced corrosion rate v (A8 6.22×10−4 g/m2·h→A9 3.12×10−5 g/m2·h), and improved corrosion resistance. Corrosion cracking extended the crack and embrittled the alloy at the tips of the cracks, so that its (|Z|max 0.67 ∼ 1.31×104 Ω cm2) influence on the corrosion resistance was much higher than that of the pore (|Z|max 5.85 ∼ 10.2×104 Ω cm2). The best corrosion resistance of the process was achieved with an overlap ratio of 66.7 % for both the Ni transition layer and the Fe-based coating.

Effect of Y2O3 on Microstructure and Corrosion Resistance of Ni45 Coating by Laser Cladding with Different Flow Rates of Carrier Gas

Effect of Y2O3 on Microstructure and Corrosion Resistance of Ni45 Coating by Laser Cladding with Different Flow Rates of Carrier Gas

Self-stabilized styrene-acrylic copolymer latex with heteroatom function for improved water and corrosion resistant coatings

This approach investigates the preparation of a set of styrene-acrylic copolymers incorporated with N-heteroatom in the form of N-vinyl pyrrolidone (NVP) as the functional co-monomer at different concentrations within the range of 17–33 mol%. In this case, self-stabilized copolymer latex was obtained without using any conventional surfactant in the system. The beneficial effect of NVP for the emulsion copolymerization of styrene and butyl acrylate was quantified by preparing and analyzing a control sample of the same copolymer latex that was stabilized by a conventional surfactant. The prepared self-stabilized copolymer latexes having particle sizes of 325–371 nm showed excellent colloidal stability with a zeta potential of >+44.5 mV. The air-dried films were found to be optically transparent and comparable to the control sample. The thermal, structural, microscopic, and water/alkali resistance properties of the films were characterized with respect to the NVP content in the copolymer. The coating characteristics of the copolymers on glass slides and mild steel panels were explored by analyzing the hydrophobicity (water contact angle up to 79°) and corrosion resistance (corrosion rate: 6.03 × 10−5 mm/year) that are significantly improved from the copolymer prepared by conventional emulsion polymerization. This study reveals the impact of N-heteroatom to obtain a self-stabilized polymer latex with improved properties and additional functionalities.

Corrosion protective and antibacterial epoxy coating via benzyldisulfide‑sulfur-doped graphene oxide with machine-learning simulation support

This paper presents a novel approach to enhancing corrosion resistance and antibacterial properties of polymer coatings. Using benzyldisulfide (BDS) as a precursor, sulfur-doped graphene oxide (BGO) nanoflakes were fabricated through a hydrothermal method. The sulfur atoms were successfully integrated into the GO structure and its reduction through high-temperature treatment was validated by a number of experiments, including FE-SEM/EDS, FTIR, Raman, and XPS studies. The GO and BGO nanoflakes were then embedded in an epoxy‑silicone matrix. The prepared BGO-incorporated coating exhibited remarkable hydrophobicity and superior performance in electrochemical impedance spectroscopy (EIS) than the GO-containing counterparts. According to the study, the exceptional corrosion protection observed in BGO-incorporated coating can be attributed to the hydrophobic nature and corrosion inhibition properties of the sulfur provided by the S-doped nanosheets. Furthermore, a neural network was applied to EIS data. Results showed that long-term EIS curves could be acceptably predicted using short-term EIS data. Moreover, the presence of BGO nanoparticles increased the generation of reactive oxygen species and significantly improved the coating's antibacterial activity. Overall, this study highlights the potential of BGO in improving coating antibacterial activity and corrosion protection.

Corrosion protection of mild steel by superhydrophobic magnetite coating

Corrosion-resistant hydrophobic magnetite coatings on mild steel surfaces were developed by immersion method. The effect of steel surface roughness (Ra) on its hydrophobicity was systematically studied using contact angle measurement (CAM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The corrosion resistance of hydrophobic magnetite coatings was evaluated using a potentiodynamic polarization test. The durability of the coatings was assessed in air, tap water, and 3.5 wt% NaCl environments. Hydrophobic magnetite coating with a water contact angle of 146-152° showed excellent resistance to corrosion, longevity in atmospheric air, and significant self-cleaning properties. The primary focus of this study was to develop a quick and simple immersion technique to create hydrophobic surfaces on mild steel. Results suggest that surface roughness plays a significant role in surface hydrophobicity, and enhancing the hydrophobicity of mild steel improves its corrosion resistance.

Effect of SiC fillers on the microstructure, adhesive strength and corrosion resistance of polycarbosilane-derived coating on steel

Polycarbosilane-derived (PCS-derived) coating containing SiC fillers with enhanced adhesive strength and corrosion resistance were fabricated on Q235 steel by a simple method of dip coating. The effects of content and particle size of SiC fillers on the phase composition, surface morphology, adhesive strength and corrosion resistance of PCS-derived coatings were studied. Addition of SiC fillers could reduce the microcrack width on the coating surface. The microcrack width decreases with the decrease in particle size of SiC fillers. Addition of 2.5 wt% SiC fillers with particle size of 30 nm could make the coating surface crack-free. Different from particle size, the effect of filler content on the microcracks has a moderate value which is corresponding to lower microcrack width. In addition to the microcracks, SiC filler content and particle size have significant effects on the adhesive strength between coatings and substrates. The higher adhesive strength is 319.1 MPa for coatings fabricated with a particle size of 500 nm and a content of 10 wt%. SiC fillers can improve the corrosion resistance of the PCS-derived coatings. In comparison with particle size of filler, filler content has a greater effect on the corrosion resistance of the coatings. The corrosion mechanism was analyzed. Appropriate content of fillers reduce the microcrack width and further improve the corrosion resistance of the coatings.

Highly conductive and corrosion-resistant NbN coatings on Ti bipolar plate for proton exchange membrane water electrolysis

Proton exchange membrane water electrolysis (PEMWE) is one of the most promising strategies to produce green hydrogen energy, and it is crucial to exploit highly conductive and good corrosion-resistant coatings on bipolar plates (BPs), one of the core components in PEMWE cells. In this work, NbN coatings are deposited on Ti BPs by magnetron sputtering to improve the corrosion resistance and conductivity, for which the critical process parameters, such as the working pressure, partial nitrogen pressure and deposition temperature are well optimized. It is found that the compact microstructure, highly conductive δ-NbN and uniform nanoparticles play a dominant role in the synergistic improvement of the corrosion resistance and electrical conductivity of NbN coatings. The optimized NbN coatings exhibit excellent corrosion resistance with the low corrosion current density of 1.1 × 10−8 A cm−2, a high potential value of -0.005 V vs. SCE and a low ICR value of 15.8 mΩ cm2 @ 1.5 MPa. Accordingly, NbN coatings can be a promising candidate for the development of the low-cost and high-anti-corrosion Ti BPs of PEMWE.

Ultrasonic-assisted pulse electrodeposition process for producing nanocrystalline nickel films and their corrosion behavior: Competition between mass transport and nucleation

Ultrasonic-assisted pulse electrodeposition of nanocrystalline nickel (NC-Ni) coatings from Watts bath on copper substrate was investigated. Direct (DC), pulsed (PC), and pulse reversed (PRC) current electrodeposition techniques were employed to electrodeposit NC-Ni coatings in the absence and presence of ultrasound wave with a nominal power ranging from 95 W to 200 W and their surface morphology, hardness, and crystalline microstructure were compared. We observed that as the ultrasound power increases, the cathodic efficiency and the microhardness increase, whereas the crystallite size and surface roughness decrease for NC-Ni electrodeposited by the three techniques in the same way. However, the effect of pulse waveform is dominant. The finest crystallite size (24 nm) and highest hardness (585 HV) were achieved for NC Ni coatings PC electrodeposited using an ultrasound with 200 W nominal power. It is believed that the coating produced by PC and PRC techniques develops a preferential orientation in (111) and (100) planes, respectively. The application of ultrasound wave and increasing its nominal power changes the preferential orientation of all obtained coatings to (111) planes. The corrosion behavior of NC Ni coatings, as investigated by potentiodynamic polarization and electrochemical impedance spectroscopy in NaOH solution, demonstrates the effect of nanocrystalline on the passivation and corrosion resistance of NC-Ni coatings.

Bacterial and corrosion resistance of polytetrafluoroethylene-silver composite coatings by magnetron sputtering

Titanium alloy and stainless steel implants have been widely applied in orthopedics. However, harmful ions released from implant corrosion caused by human body fluids and bacterial infections may inhibit patients’ recovery. In this work, a polytetrafluoroethylene-silver composite coating was prepared by RF unbalanced magnetron sputtering to improve the bacterial and corrosion resistance of the SS316L. The removal rates of the composite coatings for Escherichia coli and Staphylococcus aureus reached 97.27% and 99.99%, respectively. The contact angle of 131.5° and fluorescence staining experiments show that the composite coating has an antiadhesive effect on bacteria and less cytotoxicity against osteoblasts. The corrosion voltage of the composite coating was much higher than that of the control SS316L substrate, and the corrosion current density was reduced to 1/3, implying the enhancement of the corrosion resistance of the SS316L substrate.

Effect of SiC and TiC content on microstructure and wear behavior of Ni-based composite coating manufactured by laser cladding on Ti–6Al–4V

The low hardness and poor wear resistance of titanium alloys limit their widespread industrial use. In this study, a composite coating made of Ni60, SiC, and TiC powders using laser cladding technology was used to improve the wear resistance of Ti–6Al–4V (TC4), with the microstructural characteristics, phase style, microhardness, wear behavior, and corrosion resistance studied to clarify the effects of SiC and TiC contents. The experimental results show that the main phases in the composite coatings are TiC, Ti5Si3, and Ti2Ni, which change little with changes in the TiC and SiC content. The prepared composite coatings significantly improved the hardness and wear resistance of the TC4 substrate with the 20% SiC coating showing the lowest wear rate. The main wear mechanisms of the composite coatings were the complex modes of adhesive, abrasive, and oxidative wear, and that of the TC4 substrate was microcutting. The corrosion potential (Ecorr) of TC4 is lower than that of the prepared composite coatings, and the corrosion current (Icorr) of TC4 is also higher. The corrosion resistance of the composite coatings—with intracrystalline corrosion as the primary corrosion mechanism—was better than that of the TC4 substrate.

Investigating the CMAS corrosion resistance and thermal cycling failure behavior of porous thermal barrier coatings with different morphologies prepared by plasma spraying

This study investigates the influence of two-phase powder feeding spacing on the thermal cycling and CMAS corrosion resistance of the thermal barrier coatings (TBCs). Porous thermal barrier coatings with varying microstructures were prepared using the embedded micro agglomerated particle (EMAP) coating preparation method, which is based on conventional yttrium stabilized zirconia (YSZ) coatings. The method involved changing the powder feeding spacing. TBCs' failure mode and microstructure are investigated under complex service conditions. The corrosion resistance, thermal cycling life, hardness, and elastic modulus of TBCs are investigated by thermal cycling-CMAS experiments and isothermal corrosion tests. The EMAP coating has a good service life in the thermal cycling-CMAS tests, with a lower hardness, lower elasticit modulus and larger surface roughness than conventional coatings. This research aims to provide a strategy to optimize structure for TBCs with excellent comprehensive performance.

The Effect of Preheating Temperature on the Corrosion Resistance and Porosity Defects Development Behaviour of Ni60A Coating

The laser cladding of nickel-based fusion alloys makes them prone to cracks and defects that affect the overall performance of the coating. In this study, Ni60A coatings were prepared at different preheating temperatures (25 °C, 200 °C, 400 °C and 600 °C). The effect of the preheating temperature of the substrate on the corrosion resistance of the coating as well as on the development of defects were investigated by electrochemical tests and immersion experiments in a 65 wt% H2SO4 solution at 60 °C. The results indicate that preheating the substrate to 200 °C can completely eliminate cracks in the coating and reduce porosity. Preheating leads to a decrease in the corrosion resistance of the coating. The size of the porosity defects is related to the law of longitudinal development of the defects. Porosity defects with diameters smaller than 100 μm have a more pronounced tendency to expand vertically than those with diameters larger than 100 μm.

Effect of solution temperature on the microstructure and properties of ceramic coating on the surface of 2024 aluminum alloy

This study investigates the influence of the 2024 aluminum alloy was treated with solution before ceramic treatment on the microstructure and characteristics of ceramic coatings applied to 2024 aluminum alloy substrates. The microhardness, corrosion resistance, and microstructural properties of these ceramic coatings were assessed using a microhardness tester, an electrochemical workstation, and a scanning electron microscope. The findings indicate that pre-treatment involving solution treatment significantly enhances the hardness and corrosion resistance of 2024 aluminum alloy ceramic coatings. Notably, when the solution temperature was maintained at 460 °C, the most rapid decrease in current density was observed during the ceramization process, resulting in the attainment of the lowest final stable current density. This particular condition yielded ceramic coatings with optimal hardness and corrosion resistance, with hardness exhibiting a remarkable increase of 48.9 HV, self-corrosion potential rising by 0.207 V, and polarization resistance surging by 5310.7 Ω. Moreover, the surface of the ceramic coating displayed remarkable smoothness and was devoid of discernible defects such as cracks or looseness. In light of these findings, it can be concluded that the optimum solution temperature for achieving these desirable properties is 460 °C. This conclusion is derived from a comprehensive analysis encompassing both the morphology and corrosion resistance of ceramic coatings.

Corrosion Resistance of Magnesium Ammonium Phosphate Cement-Based Coatings Modified by Calcium Sulfoaluminate Cement on Carbon Steel in a Saline Medium

Corrosion Resistance of Magnesium Ammonium Phosphate Cement-Based Coatings Modified by Calcium Sulfoaluminate Cement on Carbon Steel in a Saline Medium

Microstructure Evolution and Molten Salt Corrosion Resistance Dependent on Pre-Oxidation Treatment of NiAl Coatings

The chloride-infused molten salt shows the most potential as the medium for the upcoming generation of concentrated solar power system. However, the molten salt put for ward higher corrosion resistance demand on the critical components of concentrated solar power system. The application of NiAl coating proves to be a highly efficient method for preventing corrosion. In this paper, the microstructure, adhesion, and corrosion resistance of NiAl coatings on 310S stainless steel with/without pre-oxidation treatment were studied. The coating predominantly consisted of β-NiAl phase nanocrystals with an Al content of 41.0 at.%. Continuous α-Al2O3 oxide film was formed and no obvious cracks were observed after pre-oxidation. The adhesion strength of NiAl coating was increased by about 70% to 40.0 N through pre-oxidation. Importantly, the corrosion results of NiAl coatings by pre-oxidation treatment in the mixed salt of NaCl/MgCl2/KCl at 1073.15 K for 10 h showed no obvious diffusion of molten salt elements into the coatings. Compared to 310S stainless steel, the pre-oxidized coating sample exhibited a significant reduction of 50.2% in corrosion mass loss. The pre-oxidation of the NiAl coating creates an Al2O3 oxidation layer that effectively blocks corrosion, offering a new method for protecting stainless steels in concentrated solar power system plants.