Good Anticorrosion Properties Research Articles

The synthesis and antistatic, anticorrosive properties of polyaniline composite coating

In this paper, acrylic ester grafting epoxy (A-g-EP) with COOH functional groups was firstly designed and prepared. Then the PANI-A-g-EP composite was obtained through oxidation polymerization of aniline on A-g-EP macromolecular chains. PANI nanoparticles in the PANI-A-g-EP composite were dispersed uniformly due to the strong interactions between macromolecular carboxyl groups and PANI. The composite is characterized by FT-IR, UV–vis and cyclic voltammetry (CV). The effect of PANI content on the glass transition temperature (Tg) and the thermal decomposition temperature (Td) were studied. PANI-A-g-EP composite coating was fabricated by the solution casting. The results of surface resistance, anticorrosion performances of the composite coating demonstrate that the good anticorrosion property of A-g-EP coating is caused by the good wet adhesion. The anticorrosion mechanism of PANI in the PANI-A-g-EP composite coating is revealed to be the electron transmission and passivation catalysis.

Thử nghiệm đánh giá hiệu quả của một số loại sơn chống hà tiêu biểu cho tàu biển

In this study, six anti-fouling paints available in Vietnam (01 by Jotun, 05 by other Vietnamese companies) have been studied. The testing results showed that Jotun, Hai Van and The He Moi anti-fouling paints had relatively higher initial adhesion than that of Hai Au, Hai Phong and Dong A anti-fouling paints. After 35 days immersed in seawater, the adhesion of the first group paints had tended to decrease faster than that of the second group paints, although the values of their absolute adhesion are still higher. Jotun and Hai Au paints showed good anti-fouling and anti-corrosion properties after 27 months. The other paints maintain their high level of effectiveness in 21 months. After 21 months, the fouling process began to take place and reached 10% of sample area after 27 months.

Solvent and catalyst-free synthesis of sunflower oil based polyurethane through non-isocyanate route and its coatings properties

Bio-based Non-Isocyanate Polyurethanes (NIPUs) were synthesized by bulk polyaddition of diamine with carbonated sunflower oil (CSFO). Carbonated vegetable oils were obtained by solvent-free mixture reaction of CO2 with epoxidized sunflower oil under the conditions (120 °C, 50 bar) and characterized by FTIR, 1H NMR, and 13C NMR. Finally, the effect of the amine structure as well as CSFO/amine molar ratio (1:0.75, 1:1 and 1:2) on mechanical, and chemical properties NIPU’s were studied by using curing agents EDA (1,2-ethylenediamine), DETA (Diethyltriamine) and IPDA (Isophorone diamine). Except for IPDA based NIPU, it was seen that along with urethane formation, the amine group also reacted with ester groups to form amides. IPDA and EDA showed good thermal, mechanical, chemical and anticorrosive properties. Furthermore, DETA based NIPU displayed high elongation at break. These results highlight the potentiality of this environmentally friendly approach to prepare renewable NIPU materials for surface coatings purpose.

Experimental Evaluation of Polyester and Epoxy–Polyester Powder Coatings in Aggressive Media

Protective coatings are the most widely used corrosion protection method for construction materials in different environmental conditions. They isolate metals from aggressive media, making the structure more durable. Today, alongside good anti-corrosive properties, coatings need to be safe for the environment and harmless to those who apply them. The high volatile organic compound (VOC) content in conventional solvent-borne coatings presents a huge ecological problem. A solution for indispensable solvent emission reduction is the application of powder coatings. This study evaluates the corrosion performance and surface morphology of polyester and epoxy–polyester powder coatings. Electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) measurement, salt spray chamber and humidity chamber testing followed by adhesion testing were used to investigate the protective properties of powder coatings. Scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDX) was used to analyse the surface morphology and chemical composition, whereas the microstructure and coating uniformity were determined by optical microscope examination. The research revealed a negative influence of coating surface texture on coating thickness and consequently a lack of barrier and adhesion properties. The epoxy–polyester powder coating showed a better performance than the polyester coating. All tested coatings showed uniform structure.

Facile fabrication of superhydrophilic and underwater superoleophobic chitosan–polyvinyl alcohol-TiO2 coated copper mesh for efficient oil/water separation

Organic–inorganic hybrid membranes are attractive material for oil/water separation. Here, a hydrophilic and oleophobic membrane was prepared by coating chitosan (CTS) and polyvinyl alcohol (PVA) on the surface of copper mesh using glutaraldehyde (GA) as crosslinking agent. After introduction of TiO2 nanoparticles, the surface roughness of the composite film was increased and a superhydrophilicity and underwater superoleophobicity surface was obtained due to the enhancement in wettability. The as-prepared superhydrophilic membrane was characterized by SEM, FTIR, XRD, and its surface wetting behavior was measured by contact angle meter. The effect of CTS, PVA, GA, and TiO2 on the microstructure, underwater oil contact angle, and sliding angle was comprehensively evaluated. Then, the super hydrophilic membrane was used for oil/water separation, a separation efficiency (> 99.7%) was obtained with a flux rate of 16,000 L m−2 h−1. The intrusion pressures for all tested oils that the membrane can support are above 1.0 kPa. Significantly, the super hydrophilic membrane exhibited good antiabrasion and anticorrosive properties. After repeated use for 60 times, the separating performances and average permeate fluxes showed no obvious degradation. An organic-inorganic hybrid chitosan (CTS)–polyvinyl alcohol (PVA)-TiO2 coated copper mesh with superhydrophilicity–underwater superoleophobicity was fabricated by one-step solution immersion method and can be used for efficient oil/water separation.

Studies on preparation of phosphate pigments for application in composite protective coatings

Currently, the most popular methods of protection against corrosion is the application of protective coatings containing the anticorrosive pigments, such as zinc phosphate. However, with regard to the ecological reasons, this compound has been withdrawn, and new environmentally friendly compounds are being searched. The objective of studies was to obtain zinc-free phosphate pigments containing strontium, calcium and aluminum. The chemical composition, the physicochemical and anticorrosive properties of obtained materials were determined. The oil absorption number of prepared pigments was in the range of 43–88 g of oil/100 g of the product. The average particle size was 270–400 nm. The specific surface area of obtained materials was low (2–76 m2/g). The majority of these products exhibited good anticorrosive properties for steel during an electrochemical noise tests.

Silane modification of titanium dioxide-decorated graphene oxide nanocomposite for enhancing anticorrosion performance of epoxy coatings on AA-2024

Titanium dioxide-decorated graphene oxide nanocomposite (TiO2-GO) was synthesized with the help of 3-aminopropyltriethoxysilane (APS) and characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that TiO2 was decorated to GO by chemical bonds. Then TiO2-GO nanocomposite was modified with γ- (2,3-epoxypropoxy) propyltrimethoxysilane (GPTMS) before introducing into epoxy resin to form an epoxy coating (TiO2-GO-f-EP) on AA-2024 aluminum alloy for good anticorrosion properties. The scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, salty spray and UV aging measurements were carried out to confirm that the TiO2-GO-f-EP coating exhibited good anti-corrosion performance. The corrosion current density of TiO2-GO-f-EP coating was nearly two orders of magnitude lower than that of pure epoxy coating and the adhesion loss after UV aging test changed 86%–57%, compared with pure epoxy coating. The superiority of TiO2-GO-f-EP coating is related to the TiO2-GO addition which can enhance anti-UV aging performance of the epoxy coating and the GPTMS modification that may ensure TiO2-GO nanocomposite's good dispersion into epoxy resin and improve the cross-linking density and adhesion strength of the epoxy coating.

Performance of casting aluminum-silicon alloy condensing heating exchanger for gas-fired boiler

Condensing gas boilers are widely used due to their high heat efficiency, which comes from their ability to use the recoverable sensible heat and latent heat in flue gas. The condensed water of the boiler exhaust has strong corrosion effect on the heat exchanger, which restricts the further application of the condensing gas boiler. In recent years, a casting aluminum-silicon alloy (CASA), which boasts good anti-corrosion properties, has been introduced to condensing hot water boilers. In this paper, the heat transfer performance, CO and NOx emission concentrations and CASA corrosion resistance of a heat exchanger are studied by an efficiency bench test of the gas-fired boiler. The experimental results are compared with heat exchangers produced by Honeywell and Beka. The results show that the excess air coefficient has a significant effect on the heat efficiency and CO and NOx emission of the CASA water heater. When the excess air coefficient of the CASA gas boiler is 1.3, the CO and NOx emission concentration of the flue gas satisfies the design requirements, and the heat efficiency of water heater is 90.8%. In addition, with the increase of heat load rate, the heat transfer coefficient of the heat exchanger and the heat efficiency of the water heater are increased. However, when the heat load rate is at 90%, the NOx emission in the exhaust gas is the highest. Furthermore, when the temperature of flue gas is below 57 °C, the condensation of water vapor occurs, and the pH of condensed water is in the 2.5~5.5 range. The study shows that CASA water heater has good corrosion resistance and a high heat efficiency of 88%. Compared with the heat exchangers produced by Honeywell and Beka, there is still much work to do in optimizing and improving the water heater.

Investigation of Mentha spicata extract as Green Corrosion Inhibitor for Mild Steel in 2M Sulphuric Acid Medium

The Mentha spicata plant extract was tested as a corrosion inhibitor for mild steel in 2M H2SO4 solution by weight loss and thermometric methods. It has been found that the extract acts as an effective corrosion inhibitor for mild steel in Sulphuric acid medium. The inhibition process is attributed to the formation of an adsorbed film of inhibitor on the metal surface which protects the metal against corrosion. The inhibition efficiency (%IE) and Surface coverage (?) of M. spicata extract increased with increase in inhibitor concentration but decreased with increasing the temperature. The adsorption of plant extract constituents on the mild steel surface was discussed by Langmuir’s adsorption isotherm. The free energy value (?Gads), indicated that the adsorption of inhibitor molecules was physisorption. The surface morphology of metal plate was analyzed using scanning electron microscopy which showed the formation of protective layer on the mild steel surface. The results obtained show that M. spicata extract can be employed as an excellent corrosion inhibitor with good anticorrosion properties in 2M Sulphuric acid for mild steel.

Facile formation of super-hydrophobic nickel coating on magnesium alloy with improved corrosion resistance

The poor anti-corrosion property of Mg alloys limits their application. Super-hydrophobic coating is expected to effectively improve the anti-corrosion property of Mg alloys. In this study, super-hydrophobic nickel coating deposited on the surface of Mg alloy with good anti-corrosion property was fabricated through combing methods of etching, electroplating and chemical modification. Scanning electron microscope, X-ray diffraction, Energy dispersive spectrometer, Fourier transform infrared spectrometer were performed to measure the microstructure and surface chemical composition of the as-prepared samples and contact angle measuring instrument and electrochemical workstation were used to characterize the wettability and anti-corrosion properties. It was found that the as-prepared nickel-coated etched Mg alloy had a multi-scaled structure. Combined with chemical modification, the water contact angle on the surface of the nickel-coated etched Mg alloy modified with stearic acid with the lowest sliding angle of 7.2° was the highest and reached 153°, showing super-hydrophobic property, compared with that of the bare Mg alloy and etched Mg alloy with and without modification. The results also showed that the nickel-coated etched Mg alloy modified with stearic acid presented the best corrosion resistance and long-term durability in 3.5wt% NaCl solution. It may be due to the good anti-corrosion property of nickel coating and the super-hydrophobic surface which help to reduce the contact area of surface with NaCl solution.

Propolis as a green corrosion inhibitor for bronze in weakly acidic solution

In the present work, the inhibitive action of natural propolis on bronze corrosion in a weakly acidic solution containing Na2SO4 and NaHCO3 at pH 5 was evaluated using multiscale electrochemical techniques, namely potentiodynamic polarization, electrochemical impedance spectroscopy and scanning vibrating electrode technique measurements. The major constituents of propolis were identified by HPLC. Surface characterization was performed by SEM-EDX and AFM analysis. Experiments were performed as a function of the propolis concentration and immersion time in the corrosive electrolyte. The obtained results showed that propolis presents good anticorrosive properties on bronze, acting as a mixed-type inhibitor, but its protective effectiveness is time-dependent. The highest inhibiting efficiency of 98.9% was obtained in the presence of 100ppm propolis, after about 12h of exposure to inhibitor-containing electrolyte through the stabilization of Cu2O on the bronze surface. The inhibitive properties of propolis on bronze corrosion are likely due to the adsorption of its main constituents (flavonoids and phenolic compounds), through the oxygen atoms in their functional groups and aromatic rings, which have been evidenced by FT-IR spectra. The adsorption of propolis on bronze was found to follow Langmuir adsorption isotherm.

Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

High-velocity compaction (HVC) has been proposed as an effective approach for the fabrication of nanocrystalline Nd-Fe-B magnets. In this work, the effect of powder size on the density of HVCed magnets has been studied and the anisotropic nanocrystalline Nd-Fe-B magnets were prepared by HVC followed by hot deformation (HD). It is found that a proper particle size range is beneficial to high density. The investigations on the microstructure, magnetic domain structure, and hyperfine structure, indicate that the deformed grain structure and the magnetic domain structure with uniform paramagnetic grain boundary phase give good magnetic properties of HVC+HDed magnets. These magnets also have good mechanical and anti-corrosion properties. The results indicate that HVC is not only a near-net-shape, room temperature and binder-free process but is also able to maintain uniform nanostructure and to achieve good magnetic properties in both isotropic and anisotropic magnets. As a result, HVC can be employed as an ideal alternative process for bonding or hot pressing for the conventional MQI, MQII and MQIII magnets.

Friction-reducing, anti-wear and self-repairing properties of sulfonated graphene

The friction reducing properties of sulfonated graphene as a lubricating additive were investigated using a four-ball machine tester with high carbon chromium bearing steels GCr15 (SAE52100) friction pairs. The microscopic morphology, elemental composition, and self-repairing properties were observed and analyzed by using scanning electronic microscopy (SEM), X-ray diffraction (XRD) and digital microscopy. The relationships among sulfonated graphene ethanol solution concentration, friction coefficient, and abrasion loss were revealed. It was found that the optimal concentration of ethanol solution with the addition of sulfonated graphene was 0.15g/mL and the coefficient of friction was only 0.105 under certain condition. Then the stable chemical properties and good anti-corrosion properties of the metal-graphene layer were further confirmed using salt spray corrosion test. In summary, sulfonated graphene can be used as a new kind of self repairing additive, and it has excellent wear-resistant and self-repairing performances.

Spray-On Polymer-Clay Multilayers as a Superior Anticorrosion Metal Pretreatment

Pretreatment coatings applied to metals are essential in the overall performance of anticorrosion coating systems. Hexavalent chromium, a widely used pretreatment for aluminum is now considered harmful. Therefore, a need for environment-friendly yet efficient and scalable pretreatment coatings has emerged. Here, the authors present the spray-assisted layer-by-layer (LbL) assembly and anticorrosion performance of a highly ordered polymer–clay nanocomposite coating. This approach is an entirely water-based process, allowing for application over large surface areas. This novel pretreatment coating (25 wt% clay) presents a brick-and-mortar multilayered structure, where the montmorillonite clay (MMT) acts as a physical oxygen barrier, while preventing the dissolution of corrosion products—thus delaying corrosion. The branched polyethylenimine polymer (BPEI) mortar provides surface buffering once the corrosion process initiates. The anticorrosion properties of the LbL coating are evaluated using electrochemical measurements and salt-spray testing. This BPEI/MMT system presents good anticorrosion properties, making it a potential alternative pretreatment.

Development of poly(urethane-ester)amide from corn oil and their anticorrosive studies

ABSTRACTCorn oil-based poly(urethane-ester)amide was synthesized from corn oil-based fatty amide diol, camphoric acid, and tolylene 2,4-diisocyanate. The structure of corn polyesteramide and corn poly(urethane-ester)amide (CPEA) was confirmed by Fourier transform infrared, 1H NMR, and 13C NMR spectroscopic techniques. CPUEA coatings were made on mild steel strips and their physicomechanical analysis (scratch hardness, impact test, conical mandrel test, and pencil hardness tests) was performed by standard methods. The surface morphology of coatings was observed by scanning electron microscopy and thermal stability was assessed by thermogravimetric analysis/differential scanning calorimetry. Anticorrosion properties of CPUEA were observed in acidic, saline, and tap water medium at room temperature using potentiodynamic polarization technique. The results of CPUEA coatings exhibit good physicomechanical and anticorrosive properties and can find application up to 175°C.

Significantly enhanced osteoblast response to nano-grained pure tantalum

Tantalum (Ta) metal is receiving increasing interest as biomaterial for load-bearing orthopedic applications and the synthetic properties of Ta can be tailored by altering its grain structures. This study evaluates the capability of sliding friction treatment (SFT) technique to modulate the comprehensive performances of pure Ta. Specifically, novel nanocrystalline (NC) surface with extremely small grains (average grain size of ≤20 nm) was fabricated on conventional coarse-grained (CG) Ta by SFT. It shows that NC surface possessed higher surface hydrophilicity and enhanced corrosion resistance than CG surface. Additionally, the NC surface adsorbed a notably higher percentage of protein as compared to CG surface. The in vitro results indicated that in the initial culture stages (up to 24 h), the NC surface exhibited considerably enhanced osteoblast adherence and spreading, consistent with demonstrated superior hydrophilicity on NC surface. Furthermore, within the 14 days culture period, NC Ta surface exhibited a remarkable enhancement in osteoblast cell proliferation, maturation and mineralization as compared to CG surface. Ultimately, the improved osteoblast functions together with the good mechanical and anti-corrosion properties render the SFT-processed Ta a promising alternative for the load-bearing bone implant applications.

Fluorine-Induced Superhydrophilic Ti Foam with Surface Nanocavities for Effective Oil-in-Water Emulsion Separation

Recently, oil/water separation has attracted intensive attention because of frequent crude oil spill accidents and the increasing amount of industrial wastewater. Ti-based materials are nontoxic and environment-friendly for oil/water separation; however, there is little attention focused on this field. In the present work, we introduce, for the first time, surface −O–Ti–F groups onto Ti foam by a simple anodization in a fluorine-containing electrolyte to form a superhydrophilic membrane for oil-in-water emulsion separation, which was proven to be excellent with the assistance of surface nanocavities. The water permeability of anodized Ti foam is elevated by about 10 times as compared to that of the original one, and the oil/water separation efficiency is above 99% with good anticorrosive properties. In addition, this fluorine-induced superhydrophilicity can be applied to metals and semimetals for many other applications such as self-cleaning, surface modification of catalysts, removal of heavy metal ions,...

Experimental characterization of heat transfer in an additively manufactured polymer heat exchanger

In addition to their low cost and weight, polymer heat exchangers offer good anticorrosion and antifouling properties. In this work, a cost effective air-water polymer heat exchanger made of thin polymer sheets using layer-by-layer line welding with a laser through an additive manufacturing process was fabricated and experimentally tested. The flow channels were made of 150μm-thick high density polyethylene sheets, which were 15.5cm wide and 29cm long. The experimental results show that the overall heat transfer coefficient of 35–120W/m2K is achievable for an air-water fluid combination for air-side flow rate of 3–24L/s and water-side flow rate of 12.5mL/s. In addition, by fabricating a very thin wall heat exchanger (150μm), the wall thermal resistance, which usually becomes the limiting factor on polymer heat exchangers, was calculated to account for only 3% of the total thermal resistance. A comparison of the air-side heat transfer coefficient of the present polymer heat exchanger with some of the commercially available plain plate fin heat exchanger surfaces suggests that its performance in general is superior to that of common plain plate fin surfaces.

Graphene enhanced anti-corrosion and biocompatibility of NiTi alloy

Due to their unique shape memory effect and superelasticity, NiTi shape memory alloys have been considered for a wide range of biomedical applications. However, they are still controversial because of the potential toxic, carcinogenic and allergic effects caused by Ni2+ release for a long term use. Wrapping protective layers with good flexibility and biocompatibility is significant for inhibiting the poisonous Ni2+ releasing from NiTi. Here, we report a novel method to protect the NiTi and enhance its biocompatibility by using graphene fabricated via a modified chemical vapour deposition (CVD) technique. The graphene layer not only prevents effectively the leak of Ni2+ but also improves the biocompatibility of NiTi upon deformation. The detailed mechanism for enhancing the anti-corrosion and biocompatibility of NiTi alloy by using graphene is also explored. Compared with traditional surface modification layer, graphene obtained by CVD is chemically inert and highly flexible, possesses both good anti-corrosion and biocompatibility properties, which may improve the surface coatings for NiTi alloys and promote more application of graphene in biomedical materials.

Tribological properties study of N-containing heterocyclic imidazoline derivatives as lubricant additives in water-glycol

Tribological and anticorrosion behaviors of imidazoline as water soluble additives is one of research hotspot. Two kinds of N-containing heterocyclic (benzotriazole and mercaptobenzothiazole) imidazoline compounds were synthesized and their tribological, antirust and anticorrosion behaviors were investigated. Results showed that they showed good anticorrosion, extreme pressure and antiwear properties. However, mercaptobenzothiazole-containing imidazoline showed excellent tribological property than benzotriazole-containing imidazoline. Their different tribological properties are closely corresponded to the different structure. There exist a synergistic tribological effect of the N-containing heterocyclic species and imidazoline group in additive, and the synergistic effect improves the tribological performances of water-glycol. The boundary tribofilm which contained organic nitrogen compounds, iron oxide, sulfide and so on, was the main factor to improve the tribological performances of water-glycol.