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Journal of magnesium and Alloys 2023年第2期11卷 641-656页

作者： Z.Jamshidipour m.Toorani m.aliofkhazraei m.mahdavian Department of materials Engineering Tarbiat Modares UniversityTehranIran Department of Surface Coatings and Corrosion Institute for Color Science and Technology(ICST)TehranIran

This research was undertaken to study the effect of Zr-enhanced plasma electrolytic oxidation(PEO) as a pretreatment on the corrosion performance of epoxy coating applied on magnesium in 3.5 wt.% Na Cl solution. The parameters of delamination index along with coating damage index were extracted through electrochemical impedance spectroscopy(EIS) tests to determine how Zr may affect the corrosion protection of duplex PEO/epoxy coated samples. Pull-off adhesion tests were also accomplished to form a better understanding of Zr-enhanced PEO coating’ function. According to the obtained results, the presence of Zr can reduce the damage to the coating system by almost twice.

关键词： magnesium EIS Pretreatment PEO Epoxy Zirconyl nitrate

Effect of the duty cycle of pulsed current on nanocomposite layers formed by pulsed electrodeposition

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Rare metals 2010年第2期29卷 209-213页

作者： m.aliofkhazraei Sh.Ahangarani A.Sabour Rouhaghdam Department of materials Engineering Faculty of Engineering Tarbiat Modares University Department of Advanced materials & Renewable Energies Iranian Research Organization for Science and Technology(IROST)

Nickel-tungsten/carbon nanotube nanocomposite layers with high content and uniform dispersion of carbon nanotubes were fabricated using pulsed electrodeposition technique.Nanocomposite layers were analyzed by scanning electron microscopy, atomic force microscopy, microhardness, and Tafel polarization tests.The effect of the duty cycle of pulsed current or concentration of carbon nanotubes in the metallic matrix on electrochemical and mechanical properties of obtained layers has been investigated.It has been shown that both the electrochemical and mechanical properties of nanocomposite layers that formed by pulsed current were improved significantly with respect to un-composed Ni-W layer.The results were not only concerned by the concentration of carbon nanotubes in the layer but also influenced by the distribution of nanoparticulates in the metallic matrix.

关键词： nanocomposite corrosion nanostructure carbon nanotubes

Effect of surface nanocrystallization and PPEC time on complex nanocrystalline hard layer fabricated by plasma electrolysis

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Transactions of Nonferrous metals Society of China 2010年第3期20卷 425-431页

作者： m.aliofkhazraei SH.AHANGAR ANI A.SABOUR ROUHAGHDAm Department of materials Engineering Faculty of EngineeringTarbiat Modares University Department of Advanced materials and Renewable Energies Iranian Research Organization for Science and Technology(IROST)

Size distribution of nano-carbides produced by duplex treatments of surface nanocrystallization(by surface severe plastic deformation) and plasma electrolytic carburizing on CP-Ti was investigated.Skewness and kurtosis of Gussian shape distribution curves were studied and the effect of time was determined.The usage of longer time is more suitable for achieving less size of complex nano-carbides.Surface roughness of treated samples was measured.It is observed that there is an optimum level for time on surface roughness increasing(difference between two measured data).

关键词：表面纳米化电解制备时间等离子体表面粗糙度分布曲线塑性变形尺寸分布

Systematic Study of Nanocrystalline Plasma Electrolytic Nitrocarburising of 316L Austenitic Stainless Steel for Corrosion Protection

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Journal of materials Science & Technology 2007年第5期23卷 665-671页

作者： m.aliofkhazraei P.Taheri A.Sabour Rouhaghdam Ch.Dehghanian materials Engineering Department Faculty of EngineeringTarbiat Modares UniversityTehranIran materials Engineering Department Faculty of EngineeringTehran UniversityTehranIran

A number of studies have been reported on the use of nanocrystalline plasma electrolytic nitrocarburising technology for surface hardening of stainless steels for higher corrosion resistance resulted from this technique. However, very few studies have focused on the optimization of the nanocrystalline plasma electrolytic nitrocarburising process parameters. In this study, a design of experiment （DOE） technique, the Taguchi method, has been used to optimize the nanocrystalline plasma electrolytic nitrocarburising not only for surface hardening but also for the corrosion protection of 316L austenitic stainless steel by controlling the coating processes factors. The experimental design consisted of four factors （Urea concentration, electrical conductivity of electrolyte, voltage and duration of process）, each containing three levels. Potentiodynamic polarization measurements were carried out to determine the corrosion resistance of the coated samples. The results were analyzed with related software. An analysis of the mean of signal-to-noise （S/N） ratio indicated that the corrosion resistance of nanocrystalline plasma electrolytic nitrocarburised 316L stainless steel was influenced significantly by the levels in the Taguchi orthogonal array. The optimized coating parameters for corrosion resistance are 1150 g/L for urea concentration, 360 mS/cm for electrical conductivity of electrolyte, 260 V for applied voltage, 6 min for treatment time. The percentage of contribution for each factor was determined by the analysis of variance （ANOVA）. The results showed that the applied voltage is the most significant factor affecting the corrosion resistance of the coatings.

关键词： Nanocrystalline plasma electrolytic nitrocarburising 316L austenitic stainlesssteel Corrosion resistance Potentiodynamic polarization Analysis of variance

Effect of Temperature on Pitting Corrosion Resistance of 316 Stainless Steel Coated by Cerium Oxide Film in 3.5% NaCl Solution

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Journal of materials Science & Technology 2008年第5期24卷 715-717页

作者： H.Hasannejad T.Shahrabi A.Sabour Rouhaghdam m.aliofkhazraei Department of materials Engineering Faculty of EngineeringTarbiat Modares University

One of the main problems of stainless steel is its poor pitting corrosion resistance in the aggressive environment containing Cl-, such as seawater. In this paper we investigated the corrosion behavior of the 316 stainless steel coated by cerium oxide nanocoating prepared by sol-gel process. Potentiodynamic polarization and electrochemical impedance spectroscopy （EIS） were used to study the corrosion behavior of cerium oxide nanocoatings in 3.5% NaCl solution. The microstructure of the cerium oxide was examined by scanning electron microscopy （SEm） and the formed phases was identified by X-ray diffraction （XRD）. The pitting corrosion resistance of the cerium oxide nanocoating was found to be improved after heat treatment of the cerium oxide nanocoating at 300℃ for 30 min.

关键词： Cerium oxide nanocoating Sol-gel Pitting corrosion resistance 316 stainless steel

Plasma electrolytic oxidation of magnesium and its alloys:mechanism,properties and applications

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Journal of magnesium and Alloys 2017年第1期5卷 74-132页

作者： Gh.Barati Darband m.aliofkhazraei P.Hamghalam N.Valizade Department of materials Engineering Faculty of EngineeringTarbiat Modares UniversityP.O.Box:14115-143TehranIran

Plasma Electrolyte Oxidation(PEO)process has increasingly been employed to improve magnesium surface properties by fabrication of an mgO-based coating.Originating from conventional anodizing procedures,this high-voltage process produces an adhesive ceramic film on the surface.The present article provides a comprehensive review around mechanisms of PEO coatings fabrication and their different properties.Due to complexity of PEO coatings formation,a complete explanation regarding fabrication mechanisms of PEO coatings has not yet been proposed;however,the most important advancements in the field of fabrication mechanisms of PEO coatings were gathered in this work.mechanisms of PEO coatings fabrication on magnesium were reviewed considering voltage–time plots,optical spectrometry,acoustic emission spectrometry and electronic properties of the ceramic film.Afterwards,the coatings properties,affecting parameters and improvement strategies were discussed.In addition,corrosion resistance of coatings,important factors in corrosion resistance and methods for corrosion resistance improvement were considered.Tribological properties(important factors and improvement methods)of coatings were also studied.Since magnesium and its alloys are broadly used in biological applications,the biological properties of PEO coatings,important factors in their biological performance and existing methods for improvement of coatings were explained.Addition of ceramic based nanoparticles and formation of nanocomposite coatings may considerably influence properties of plasma electrolyte oxidation coatings.Nanocomposite coatings properties and nanoparticles adsorption mechanisms were included in a separate sector.Another method to improve coatings properties is formation of hybrid coatings on PEO coatings which was discussed in the end.

关键词： Plasma electrolytic oxidation magnesium Tribological properties Biomedical properties Nanocomposite coatings

Corrosion and wettability of PEO coatings on magnesium by addition of potassium stearate

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Journal of magnesium and Alloys 2017年第2期5卷 210-216页

作者： S.S.Farhadi m.aliofkhazraei Gh.Barati Darband A.Abolhasani A.Sabour Rouhaghdam Department of materials Science Faculty of EngineeringTarbiat Modares UniversityP.O.Box:14115-143TehranIran

Hydrophobic PEO coatings were fabricated in an electrolyte containing potassium stearate.The wetting behaviour of coated samples was studied using dynamic and static contact angle.Also,the corrosion behaviour of the samples was evaluated by polarization method.The dynamic contact angle and hysteresis of the contact angle for PEO coating were evaluated by Wilhelmy plate method.There was an increase in the contact angle of the nanocomposite and traditional PEO coatings when potassium stearate was added to the electrolyte up to 130°.The more hydrophobic coatings,showed more corrosion resistance in 3.5 wt.%NaCl solution.The synergistic effect of potassium stearate and nanoparticles increased the hydrophobicity because of assembling of fatty acid on ceramic powder.

关键词： magnesium Coatings Wilhelmy plate Plasma electrolytic oxidation Corrosion

Effects of acetic acid on microstructure and electrochemical properties of nano cerium oxide films coated on AA7020-T6 aluminum alloy

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Rare metals 2009年第1期28卷 98-101页

作者： H. Hasannejad T. Shahrabi m. aliofkhazraei materials Engineering Department Faculty of EngineeringTarbiat Modares UniversityTehranIran

Nano cerium oxide films were applied on AA7020-T6 aluminum alloy and the effects of acetic acid concentration on the microstructure and electrochemical properties of the coated samples were investigated by using scanning electron microscopy （SEm）, X-ray diffraction （XRD）, and potentiodynamic polarization methods. It has been found that by increasing the acetic acid/CeCl3·7H2O molar ratio, high uniform and crack-free films with well-developed grains were obtained and grain sizes of the films decreased. Elimination of cracks and decreasing grain size of the nano cerium oxide films caused corrosion resistance to increase.

关键词： nano cerium oxide films acetic acid aluminum alloy electrochemical property microstructure

Effect of electrolyte temperature on the nano-carbonitride layer fabricated by surface nanocrystallization and plasma treatment on a γ-TiAl alloy

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Rare metals 2009年第5期28卷 454-459页

作者： m. aliofkhazraei A. Sabour Rouhaghdam H. Hassannejad Department of materials Engineering Faculty of Engineering Tarbiat Modares University

The distribution of nano-carbonitrides produced by the treatments of surface nanocrystallization and plasma electrolytic carbonitriding on a γ-TiAl was investigated by means of figure analysis. The skewness and kurtosis of Gaussian shape distribution curves were studied and the effect of electrolyte temperature was determined. The usage of lower temperatures of the electrolyte is more suitable for achieving lower sizes of complex nano-carbonitrides. The surface roughness of treated samples was measured and it was observed that there is an optimum level of electrolyte temperature for surface roughness increase （difference between two measured data）.

关键词： carbonitride electrolyte temperature nanostructures plasma electrolytic deposition roughness γ-TiAl

Frequency-dependent viscoelasticity effects on the wave attenuation performance of multi-layered periodic foundations

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Applied mathematics and mechanics(English Edition) 2024年第3期45卷 407-424页

作者： m.SAFI m.VAKILIFARD m.J.mAHmOODI Faculty of Civil Water&Environmental EngineeringShahid Beheshti UniversityTehran ***Iran Faculty of mechanical and Energy Engineering Shahid Beheshti UniversityTehran ***Iran

In this paper,layered periodic foundations(LPFs)are numerically examined for their responses to longitudinal and transverse modes in the time and frequency domains.Three different unit-cells,i.e.,2-layer,4-layer,and 6-layer unit-cells,comprising concrete/rubber,concrete/rubber/steel/rubber,and concrete/rubber/steel/rubber/lead/rubber materials,respectively,are taken into account.Also,the viscoelasticity behavior of the rubber is modeled with two factors,i.e.,a frequency-independent(FI)loss factor and a linear frequency-dependent(FD)loss factor.Following the extraction of the complex dispersion curves and the identification of the band gaps(BGs),the simulations of wave transmission in the time and frequency domains are performed using the COmSOL software.Subsequent parametric studies evaluate the effects of the rubber viscoelasticity models on the dispersion curves and the wave transmission for the longitudinal and transverse modes.The results show that considering the rubber viscoelasticity enhances the wave attenuation performance.moreover,the transverse-mode damping is more sensitive to the viscoelasticity model than its longitudinal counterpart.The 6-layer unit-cell LPF exhibits the lowest BG,ranging from 4.8 Hz to 6.5 Hz.

关键词： layered metamaterial periodic foundation complex dispersion curve wave transmission diagram