A study on the electrochemical polymerization, characterization, and corrosion protection of o-toluidine on steel

Poly(o-toluidine) (POT) coatings were electrochemically synthesized on 304 stainless steel using cyclic voltammetric method. These coatings were characterized by Fourier transform infrared spectroscopy, UV–vis absorption spectroscopy, and cyclic voltammetry. The corrosion performance of POT coating in aqueous 3 wt% sodium chloride was assessed by the electrochemical techniques such as open circuit potential measurements, potentiodynamic polarization technique, cyclic potentiodynamic polarization measurements, and electrochemical impedance spectroscopy. The results reveal that POT coating on 304 stainless steel prevents general and localized corrosion, and reduces the exchange current density almost by a factor of 45 than bare 304 stainless steel.     

Corrosion behavior of tantalum alloying on γ‐TiAl by double‐glow plasma surface metallurgy technique

The Ta coating with corrosion resistance is grown on the γ‐TiAl substrate by double‐glow plasma surface metallurgy technique, followed by the electrochemical test in 10 wt%, 20 wt% HCl and 10 wt%, 40 wt% H₂SO₄ solution. The data of nanohardness and elastic modulus are collected by the nanoindention test. The adhesion strength of Ta coating is investigated by means of the scratch test. The study of corrosion resistance is performed using potentiodynamic polarization and electrochemical impedance spectroscopy and measured by SEM and X‐ray diffraction. Results highlight that the Ta coating is tightly bonded to the γ‐TiAl substrate, consisting of the deposition layer and diffusion layer. Experimental data indicate that the Ta coating presents excellent corrosion resistance, which is confirmed by the high values of polarization resistance (R_p) and the low values of corrosion current density (i_corr). The surface nanohardness of the Ta coating is improved from 3.41 to 7.29 GPa, nearly twice of that of the substrate. The Ta₂O₅ formed on the coating is able to hold back the penetration of adverse ions inwardly, owing to its dense structure and adhesion effect. Copyright © 2017 John Wiley & Sons, Ltd.     

Surface Properties of Graphene Functionalized TiO2/nHA Hybrid Coatings Made on Ti6Al7Nb Alloys via Plasma Electrolytic Oxidation (PEO)

Nano-hydroxyapatite (nHA)-matrix coatings containing graphene nanosheets (GNS)-nHA were coated on Ti6Al7Nb alloys by plasma electrolytic oxidation (PEO) treatment for the improvement of their surface properties. Crystallographic properties, functional groups, and elemental analysis of coatings were characterized by XRD, ATR–FTIR, and EDS analysis. Surface morphological changes of the coated surfaces were investigated by AFM and SEM. The electrochemical corrosion behavior of the coatings was examined by using the potentiodynamic scanning (PDS) tests under in-vitro conditions in simulated body fluid (SBF). The results showed that the GNS was successfully deposited in ceramic matrix coatings on Ti6Al7Nb alloys. Also, the microstructural observations revealed that the coatings have a porous and rough structure. The XRD and ATR–FTIR quantitative analysis have proved the appearance of HA and GNS in the coating layers. An increase in the coating thickness, surface hardness, and anatase/rutile transformation rate was determined, while the GNS ratio in the coating layers was increased. The microhardness of the nHA coating reinforced with 1.5 wt% GNS was measured at 862 HV, which was significantly higher than that of GNS-free (only nHA) coating (584 HV). The best in-vitro resistance to corrosion in SBF was observed in the nHA/1.5GNS wt% coating.     

Incorporation of Reactive Corrosion Inhibitor in Waterborne Acrylic Polyurethane Coatings and Evaluation of its Corrosion Performance

Hydroxyl-epoxy phosphate (HEP) as a reactive corrosion inhibitor was innovatively synthesized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crosslinked with waterborne isocyanate curing agent, which was used to form waterborne HEP/acrylic polyurethane composite (HEP-APU) coatings on Q235 steel surfaces. Electrochemical impedance spectroscopy and polarization curves were applied to analyze the corrosion behavior of the HEP-APU coatings in 3.5wt% NaCl solutions. The results indicated that the HEP-APU coatings show a superior passivation property and efficient corrosion protection of Q235 steel. The waterborne acrylic polyurethane coating containing 0.5wt% HEP exhibited the best corrosion performance among all the coating specimens. The improved flash-rust resistance can be attributed to the introduction of the phosphate group which could form phosphate film on the steel substrate.     

硫酸盐体系三价铬沉积机理及镀层表征

在新研发的硫酸盐三价铬镀厚铬的镀液体系中, 运用线性扫描伏安法(LSV)和循环伏安法(CV)对三价铬在铜电极表面的电沉积过程进行研究, 并运用X射线荧光测厚仪、扫描电子显微镜(SEM)、X射线能量色散谱(EDS)、X射线衍射仪(XRD)、显微硬度计和Tafel曲线表征铬镀层厚度、形貌、组成、结构、显微硬度及在3.5wt% NaCl溶液中的耐蚀性. 结果表明, 在该体系中三价铬的沉积过程分两步进行(Cr³⁺ + e →Cr²⁺ , Cr²⁺ + 2e → Cr), 第一步得到1个电子, 受电化学过程和扩散过程共同控制, 第二步得到2个电子, 为扩散控制下的不可逆过程; 该镀层为瘤状纳米晶结构, 镀层中含有少量的铁元素(1.10 wt%), 显微硬度达到789.2 Hv, 镀层在3.5wt% NaCl溶液中的腐蚀电位(E_corr)为-0.29 V, 腐蚀电流密度(j_corr)为9.26×10^-5 A·dm^-2.     

水基导电聚苯胺/二氧化硅杂化材料的防腐性能研究(英文)

利用羧基同导电聚苯胺(cPANI)主链上的氮原子的相互作用,制备了静电作用型水基导电聚苯胺/二氧化硅杂化材料,研究了杂化材料涂层对冷轧钢板的防腐性能.在3.5%NaCl中,含11 wt%cPANI的杂化材料涂层的腐蚀电位比纯二氧化硅涂层正移了200 mV,腐蚀电流从13.4μA降到2.4μA,下降了5倍,表明含cPANI的静电作用型杂化涂料使冷轧钢板表面变得更惰性.阻抗分析结果表明,cPANI含量为11 wt%的静电作用型杂化材料的阻抗比纯无机二氧化硅涂层大一个数量级,而且在碱性介质中浸泡10天后,杂化材料涂层的阻抗仍然保持稳定,而纯无机二氧化硅涂层的阻抗比初始值下降了一个数量级.杂化材料的形态分析结果表明,cPANI在静电作用型cPANI/二氧化硅杂化材料中的分布比在普通cPANI/二氧化硅杂化材料中更加均匀一致,从而使得它比普通的cPANI/二氧化硅杂化材料具有更好的防腐效果.     

Excellent protection of mild steel in sodium chloride solution for a substantial period of time using a hybrid nanocoating of poly vinyl alcohol and Titania

The production of eco-friendly hybrid sol–gel coatings for long term protection of metallic substrates from aggressive environments was one of the emerging areas, competing with conventional chromate and phosphate coatings. Herein, a nanocomposite has been synthesized from TiO₂ and PVA through a novel sol-gel route and the structure and morphology of the same was characterized using X-ray diffraction, FTIR, UV–Vis spectroscopy, FESEM with EDAX, and AFM studies. The flower-like structured composite offers excellent corrosion protection properties in NaCl solution of sea water salinity. Impedance and polarization studies were carried out to monitor the anticorrosion performance of the materials coating. This coating on mild steel offers 98% inhibition efficiency in NaCl. The influence of loading PVA on TiO₂ and its effect on corrosion efficiency have also been investigated. It is found that an optimum weight of 20 wt% PVA is required in the composite for beneficial corrosion resistance. 92% inhibition efficiency is registered by the coated MS in NaCl solution after 40 days of exposure and is quite encouraging compared to many of the recent reports. The Ti–O–Ti, and Fe-Ti-O linkage along with compactness and adherence of the material together contribute to better blocking of steel corrosion.     

Improvement of hardness and anti-corrosion behavior of mild steel by plasma sprayed coating of Al2O3/GO composite

A robust and fast non-transferred plasma torch method was employed for developing coating of alumina (A₂O₃) and alumina/graphene oxide (A₂O₃/GO) on mild steel. Micro Raman analysis of GO confirms its spectroscopic behavior. The energy band gap of GO was determined as 3.44 eV. The successful coating formation of A₂O₃ and A₂O₃/GO (0.5 wt%) on mild steel was confirmed by X-ray diffraction analysis. Microhardness of mild steel was found to increase about 43.75% after coating with A₂O₃/GO (0.5 wt%) composite. The microstructure of A₂O₃/GO (0.5 wt%) coated mild steel represents better quality of coating and improved structural behavior. Mild steel becomes more corrosive resistance by reduction of corrosion potential (less negative than −0.05 V) after A₂O₃/GO (0.5 wt%) coating on it.     

Effects of dip coating parameters on the morphology and transport properties of cellulose acetate–ceramic composite membranes

This work presents the fabrication of cellulose acetate (CA)–ceramic composite membranes using dip coating technique. Ceramic supports used in this work were prepared from kaolin with an average pore size of 560 nm and total porosity of 33%. The dip coating parameters studied experimentally were the concentration of CA solution (varying from 2 wt% to 8 wt%) in acetone and dipping time (varying from 30 s to 150 s). The fabricated composite membranes were characterized using scanning electron microscope, gas permeation, pure water flux and ultrafiltration (UF) experiments using bovine serum albumin (BSA). It was observed that the membrane prepared with 2 wt% and 4 wt% CA were suitable for microfiltration applications and those with 6 wt% and 8 wt% were for ultrafiltration applications. Theoretical investigation was conducted to know the macroporous and mesoporous structure of the prepared membranes using Knudsen and viscous permeability analysis of air. A resistance in series model was applied to identify different resistances responsible for the flux decline. Phenomenological models were proposed to illustrate the dependency of hydraulic resistance of membrane on the structural parameters such as average pore size, effective porosity as well as dip coating parameters like dipping time and concentration of CA. It was found that, the growth rate of CA film on the ceramic support followed exponential growth law with respect to dipping time. The total hydraulic resistance of the membrane was evaluated to be inversely proportional to the ratio of pore sizes of top layer and ceramic support. The resistance due to the CA film was found to be depended to the order of 1.73 with respect to concentration of CA. An increase in the concentration of CA was found to be more effective than dipping time to reduce the membrane pore size.     

Curing mechanism,heat resistance,and anticorrosion properties of a furan/methyl phenyl silicone coating

A coating composed by methyl phenyl silicone resin (PSi) and furan resin (FR) was prepared, and its curing mechanism, heat resistance, and anticorrosion properties were investigated by Fourier transform infrared spectroscopy, thermogravimetric analysis, electrochemical test, and chemical resistance test. Aldol condensation reaction between FR and PSi occurred at below 200°C, and PSi underwent self‐multidehydrogenation at above 200°C. These curing reactions gave excellent thermal stability and anticorrosion properties. Compared with pure PSi, the blended containing lower than 20 wt% FR had better thermal properties, manifested as over 390°C of 5 wt% weight loss temperature and over 40% of char yield at 800°C. The adhesion property of cured blended system on the metal surface reached the first level which exceeded that of pure PSi coating (the third level). Furthermore, the corrosion resistances of coating in acid, alkali, and salt environments were all improved compared with those of monomeric polymer coating. The impedance of blended coating in 3.5% NaCl solution decreased with increasing FR content, which was 1.8 × 10⁶ Ω cm² when the FR content was 40%, being higher than that of pure PSi coating (7.12 × 10⁵ Ω cm²). This was mainly due to the formation of a cross‐linked network structure based on Si―O―C bond and the enhanced adhesion of cured blended coating. In addition, the surface roughness of cured blended coating was below 2.0 μm, which may have a positive effect on drag reduction in real applications.     

Performance of Waterborne Polyurethanes in Inhibition of Gas Hydrate Formation and Corrosion: Influence of Hydrophobic Fragments

The design of new dual-function inhibitors simultaneously preventing hydrate formation and corrosion is a relevant issue for the oil and gas industry. The structure-property relationship for a promising class of hybrid inhibitors based on waterborne polyurethanes (WPU) was studied in this work. Variation of diethanolamines differing in the size and branching of N-substituents (methyl, n-butyl, and tert-butyl), as well as the amount of these groups, allowed the structure of polymer molecules to be preset during their synthesis. To assess the hydrate and corrosion inhibition efficiency of developed reagents pressurized rocking cells, electrochemistry and weight-loss techniques were used. A distinct effect of these variables altering the hydrophobicity of obtained compounds on their target properties was revealed. Polymers with increased content of diethanolamine fragments with n- or tert-butyl as N-substituent (WPU-6 and WPU-7, respectively) worked as dual-function inhibitors, showing nearly the same efficiency as commercial ones at low concentration (0.25 wt%), with the branched one (tert-butyl; WPU-7) turning out to be more effective as a corrosion inhibitor. Commercial kinetic hydrate inhibitor Luvicap 55 W and corrosion inhibitor Armohib CI-28 were taken as reference samples. Preliminary study reveals that WPU-6 and WPU-7 polyurethanes as well as Luvicap 55 W are all poorly biodegradable compounds; BOD_t/COD_cr (ratio of Biochemical oxygen demand and Chemical oxygen demand) value is 0.234 and 0.294 for WPU-6 and WPU-7, respectively, compared to 0.251 for commercial kinetic hydrate inhibitor Luvicap 55 W. Since the obtained polyurethanes have a bifunctional effect and operate at low enough concentrations, their employment is expected to reduce both operating costs and environmental impact.     

Corrosion and tribocorrosion behaviour of super‐thick diamond‐like carbon films deposited on stainless steel in NaCl solution

Super‐thick diamond‐like carbon (DLC) film is a potential protective coating in corrosive environments. In the present work, three kinds of DLC films whose thickness and modulation periods are 4 µm and 3, 21 µm and 17 and 21 µm and 7, respectively, were fabricated on stainless steel. The effect of different thickness and modulation periods on corrosion and tribocorrosion behaviour of the DLC‐coating stainless steel was investigated in 3.5 wt% NaCl aqueous solution by a ball‐on‐flat tribometer equipped with a three‐electrode electrochemical cell. The DLC‐coating stainless steel served as a working electrode, and its OCP and potentiodynamic polarization were monitored before and during rubbing. The wear–corrosion mechanism of the DLC films was investigated by SEM. The results showed that the increasing thickness can prolong significantly lifetime of DLC films in NaCl aqueous solution. In particular, the modulation period has a significant impact on the tribocorrosion resistance of the DLC super‐thick films. The study suggested that the increasing thickness of compressive stress layer could suppress film damage by reducing crack propagation rate. Thus, the super‐thick DLC film with thickness of 21 µm and 7 periods presented the best tribocorrosion resistance among all studied films. Copyright © 2016 John Wiley & Sons, Ltd.     

Polypyrrole coating doped by molybdo-phosphate anions for corrosion prevention of carbon steels

The polypyrrole coating was prepared from phosphoric acid aqueous solution containing the hetero-polyanion and pyrrole monomer to make new coating for corrosion prevention of carbon steels. The coating thus formed in the phosphate acid solution was doped by and by . The coating was flexible enough to cover the steel homogeneously without cracks, although many cracks were observed on the coating formed in a neutral aqueous solution of Na₂MoO₂. The 5.1-μm-thick polypyrrole coating makes the steel maintain the passive state for 48 h in neutral 3.5 wt% NaCl solution at pH 5.3 and for 80 h in acidic 3.5 wt% NaCl solution at pH 1.9. The coating decreased the corrosion rate of the steel by 1/200 in the neutral NaCl solution and by 1/340 in the acidic NaCl solution, if compared with the rate of the bare steel. The dissolution current of the steel during the immersion remained at the level of the typical passive current in the respective solutions.     

Corrosion studies of polyaniline/coconut oil poly(esteramide urethane) coatings

Advancements in the area of conducting polymers have been towards their application as effective corrosion protective coatings to replace the use of heavy metals as additives in the coatings industries, which are now considered to be an environmental as well as health hazard. With the aim to utilize a sustainable resource based polymer for the development of an anti‐corrosive conducting coating material, coconut oil based conducting blend coatings of polyaniline and poly(esteramide urethane) were prepared by loading different ratios (2, 4 and 8 wt%) of polyaniline in poly(esteramide urethane). Then their physico‐chemical, thermal, morphological, conductivity and anti‐corrosive coating characteristics were investigated. The effect of a 2 year environmental aging process on the coated samples was analyzed by thermal methods as well as by corrosion studies. Results showed that the corrosion protective performance of the blend coatings was far superior than that of plane poly(esteramide urethane). These coatings showed enhanced corrosion protection in acid as well as alkaline environments upto 360 and 192 hr respectively. Conductivity of the blends was found to be in the range 2.5 × 10^?5–5.7 × 10^?4 S/cm^?1. An increase in the thermal stability of the blend coatings and a decrease in their conductivity was noticed in the aged samples which was attributed to the crosslinking effect. The corrosion protective performance of the coatings remained almost unaffected even after 2 years of aging. Copyright © 2005 John Wiley & Sons, Ltd.     

Effects of Mn2+ on the chrome‐free colored Ti/Zr‐based conversion coating on 6063 aluminum alloy

The conversion coating with golden color and improved corrosion resistance had been prepared by adding Mn²⁺ in the Ti/Zr conversion coating solution. Comparing with that of conversion coating without Mn²⁺, the optimal treatment time of this conversion coating was much shorter and the corrosion resistance was obviously improved. The effect of Mn²⁺ on the formation of golden Ti/Zr conversion coating was thoroughly investigated by means of energy dispersive X‐ray spectroscopy, SEM, XPS, and Raman and electrochemical workstation. The results showed that the conversion coating had a double‐layer structure: the outer layer consisted of the metal‐organic complex and the inner layer was mainly made up of Na₃AlF₆. Mn²⁺ was oxidized into MnOOH in solution and precipitated on the substrate surface which provided the nucleus to Na₃AlF₆ crystal and accelerated Na₃AlF₆ crystal formation and also made the microstructure of conversion coating change to the cubic. The mechanism of the formation of the conversion coating can be deemed as nucleation, growth of Na₃AlF₆ crystal, and formation of metal‐organic complex. Copyright © 2015 John Wiley & Sons, Ltd.     

Preparation, characterization and electrochemical corrosion studies on environmentally friendly waterborne polyurethane/Na-MMT clay nanocomposite coatings

In this study, we present the first practical evaluation for the corrosion protection effect of waterborne polyurethane (WPU)/Na⁺-montmorillonite (Na⁺-MMT) clay nanocomposite coating. Typically, a series of waterborne polyurethane (WPU)/Na⁺-montmorillonite (Na⁺-MMT) clay nanocomposite materials have been successfully prepared by effectively dispersing the inorganic nanolayers of commercially purified Na⁺-MMT clay in WPU matrix through direct aqueous solution dispersion technique. First of all, WPU was prepared by polymerizing PCL, DMPA and H₁₂MDI, followed by characterized by nuclear magnetic resonance (¹H NMR), Fourier transform infrared (FTIR) and gel permeation chromatography (GPC). Subsequently, the as-prepared PU/Na⁺-MMT clay nanocomposite (Na⁺-PCN) materials were subsequently characterized by FTIR, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM).PCN materials in the form of coating at low Na⁺-MMT clay loading up to 3 wt% coated on the cold-rolled steel (CRS) coupons were found to exhibit superior corrosion protection effect over those of neat WPU based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and impedance in 5 wt% aqueous NaCl electrolyte. Effects of the material composition on the gas permeability, thermal stability and optical clarity of neat WPU along with a series of Na⁺-PCN materials, in the form of coating and free-standing film, were also studies by gas permeability analyzer (GPA), thermogravimetric (TGA), differential scanning calorimetry (DSC) and ultraviolet UV-visible transmission spectroscopy, respectively. As control experiments, a series of PU/organo-MMT nanocomposite (denoted by organo-PCN) materials were also prepared for comparative studies.     

Preparation and characterization of anticorrosion Ormosil sol–gel coatings for aluminum alloy

Organically modified silicate (Ormosil) coatings have been synthesized through the sol–gel method for corrosion protection of aluminum alloy. Silica-based unmodified coatings were also designed to investigate the effect of tetraethoxysilane (TEOS) content on the properties of the coatings. The surface morphology of the coatings was characterized by scanning electron microscopy. The corrosion resistance was evaluated by immersion test, electrochemical impedance spectroscopy and potentiodynamic polarization measurements. In addition, the surface potential differences of the coated samples were determined by scanning Kelvin probe. The results showed that a better corrosion resistance of unmodified coating was prepared by controlling the TEOS/EtOH/H₂O molar ratio of 0.109/1/1.52. Ormosil coatings provided excellent barrier properties and corrosion resistance in comparison with the unmodified sol–gel coatings. The Ormosil coating modified with triethoxyoctylsilane exhibited corrosion resistance properties superior to the other Ormosil coatings after exposure to 3.5 wt% NaCl solution for 10 days.     

Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions

The biodegradable metals, including magnesium (Mg), are a convenient alternative to permanent metals but fast uncontrolled corrosion limited wide clinical application. Formation of a barrier coating on Mg alloys could be a successful strategy for the production of a stable external layer that prevents fast corrosion. Our research was aimed to develop an Mg stable oxide coating using plasma electrolytic oxidation (PEO) in silicate-based solutions. 99.9% pure Mg alloy was anodized in electrolytes contained mixtures of sodium silicate and sodium fluoride, calcium hydroxide and sodium hydroxide. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), contact angle (CA), Photoluminescence analysis and immersion tests were performed to assess structural and long-term corrosion properties of the new coating. Biocompatibility and antibacterial potential of the new coating were evaluated using U2OS cell culture and the gram-positive Staphylococcus aureus (S. aureus, strain B 918). PEO provided the formation of a porous oxide layer with relatively high roughness. It was shown that Ca(OH)₂ was a crucial compound for oxidation and surface modification of Mg implants, treated with the PEO method. The addition of Ca²⁺ ions resulted in more intense oxidation of the Mg surface and growth of the oxide layer with a higher active surface area. Cell culture experiments demonstrated appropriate cell adhesion to all investigated coatings with a significantly better proliferation rate for the samples treated in Ca(OH)₂-containing electrolyte. In contrast, NaOH-based electrolyte provided more relevant antibacterial effects but did not support cell proliferation. In conclusion, it should be noted that PEO of Mg alloy in silicate baths containing Ca(OH)₂ provided the formation of stable biocompatible oxide coatings that could be used in the development of commercial degradable implants.     

Strontium-doped hardystonite plasma sprayed coatings with robust antimicrobial activity

A strontium-doped hardystonite (Sr-HT) bioceramic, in bulk form, demonstrates excellent bioactivity for bone regeneration with high fracture toughness and compressive strength. This work examines the antibacterial and mechanical properties of Sr-HT coatings on an alpha-beta titanium alloy with a high specific strength and excellent corrosion resistance (Ti-6Al-4V) produced by atmospheric plasma spray (APS) as the deposition coating technique. A hydroxyapatite (HAp) APS coating, a commercial bioceramic coating, is chosen as the control. The in-situ observation showed that Sr-HT powders experience temperatures during plasma processing that exceeded their melting point to form a coating well adhered to the substrate. It was demonstrated that the Sr-HT coating possessed superior antibacterial properties against Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative Pseudomonas aeruginosa. In addition, the Sr-HT coating exhibits a uniform distribution of hardness and elastic moduli, higher nanohardness and elastic moduli compared to the equivalent properties of the HAp coating. Moreover, the Sr-HT coating outperforms the HAp coating regarding scratch and wear resistance. The bonding and shear strength of the Sr-HT coating are higher than the values required for orthopedic implant coatings. The Sr-HT coating also allows efficient zinc, silicon and strontium ions release when immersed in cell culture media. In summary, the antibacterial capabilities and the mechanical properties of the Sr-HT APS coating exceed those of the commercial HAp APS coating. Therefore, Sr-HT APS coatings are candidates for bioceramic coating applications in orthopedic implants.     

hytic Acid Conversion Coatings of Magnesium

A chrome‐free conversion coating treatment for magnesium by phytic acid solution was developed. The immersion experiments were used for evaluating the effects of the processing parameters (such as conversion temperature and time, concentration and pH value of phytic acid solution) on the corrosion resistance of the phytic acid conversion coating. The morphologies and compositions of the coatings were determined by SEM and EDS respectively. The experimental results indicated that the corrosion resistance of the conversion coating formed in the solution containing 0.5% phytic acid at 25°C and pH=4 for 30 min was higher than that of natural oxide, and the conversion coating formed on the surface of magnesium was of multilayer mainly consisting of Mg, C, O and P. The thicknesses of the conversion coatings were approximately 1.0–15 µm and the conversion coatings presented obvious network‐like cracks. The electrochemical potentiodynamic polarization experiment indicated that the free corrosion potential of the magnesium with phytic acid conversion coating was increased, and its corrosion current and corrosion rate declined in 3.5% NaCl solution. Phytic acid conversion coating could improve the electrochemical property of magnesium and provide effective protection, which can improve the corrosion resistance of magnesium.