Preparation and characterization of Nd-doped double-layer silane anticorrosion coating on AZ91D magnesium alloy surface

Abstract Magnesium alloys have found widespread application as engineering and functional materials in automobile, aerospace, electronics, and biomedical industries. However, these alloys are susceptible to corrosion, and the development of new anticorrosion coatings on Mg alloys surface is urgently needed. In this work, pristine and doped double-layer silane coatings were applied to the AZ91D Mg alloy surface in order to improve its corrosion resistance properties in a 3.5% NaCl solution. The doped silane coatings consisted of KH-550 as the bottom layer and Nd(NO3)3-doped bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) as the top layer. The effect of Nd(NO3)3 concentration on the corrosion inhibition properties of silane coatings was studied, and the highest corrosion resistance was achieved when the Nd(NO3)3 concentration was 5 × 10−3 mol/L. Compared to the pristine coating, the doped coating had enhanced hydrophobicity with a water contact angle of 108° and, to the best of our knowledge, one of the lowest corrosion current densities (1.51 × 10−2 μA/cm2) reported to date for treated AZ91D. These significant improvements were attributed to the presence of the Si-O-Nd network in the doped coating, leading to the uniform and homogeneous nature and excellent anticorrosion properties of Nd-doped silane coating.

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Influence of digene tablet juice orally taken in on the corrosion resistance of orthodontic wire made of SS 18/8 in presence of artificial saliva

Zastita materijala ◽

10.5937/zasmat2103220p ◽

2021 ◽

Vol 62 (3) ◽

pp. 220-227

Author(s):

Chandrasekaran Priya ◽

Antony Regis ◽

Susai Rajendran

Keyword(s):

Corrosion Resistance ◽

Charge Transfer ◽

Double Layer ◽

Artificial Saliva ◽

Corrosion Current ◽

Charge Transfer Resistance ◽

Double Layer Capacitance ◽

Orthodontic Wires ◽

Transfer Resistance ◽

Orthodontic Wire

Dentists make use of orthodontic wires such as SS 18/8, SS 316, Ni-Cr etc., to regulate the growth of teeth. In the saliva environment these wires undergo corrosion. Aside from this, they undergo corrosion by the food items, juices and Tablets orally in taken. Corrosion resistance of SS 18/8 alloy in artificial saliva (AS) , in the absence and presence of Digene Tablet juice, has been investigated by polarization and AC impendance techniques. It is inferred that corrosion resistance of SS 18/8 alloy in artificial saliva decreases in presence of Digene Tablet. This is exposed by decrease in Linear Polarization Resistance (LPR) value, Charge transfer resistance (Rt) value, in impedance value, and increase in corrosion current and double layer capacitance value(Cdl). In presence of Digene Tablet, the LPR value decreases from 3488228 to 1629535 Ohmcm2. The corrosion current value increases from 1.447 x10-8 to 2.637x10-8A/cm2 . The Charge transfer resistance (Rt) value decreases from 37796 to 10481Ohmcm2 . The double layer capacitance value increases from 1.349x10-10 F/cm2 to 4.866x10-10F/cm2. The impedance value decreases from 4.857 to 4.428. Hence it implies that people with orthodontic wire made of SS 18/8 alloy should avoid taking Digene Tablet juice orally.

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Investigation on Microstructure, Hardness, and Corrosion Resistance of Mo–Ni–B Coatings Prepared by Laser Cladding Technique

Coatings ◽

10.3390/coatings9120856 ◽

2019 ◽

Vol 9 (12) ◽

pp. 856 ◽

Cited By ~ 1

Author(s):

Xiaojie Ni ◽

Shengze Wang ◽

Yuantao Zhao ◽

Wenge Li ◽

Xiong Jiao

Keyword(s):

Corrosion Resistance ◽

Laser Cladding ◽

Laser Scanning ◽

Bottom Layer ◽

Scanning Speed ◽

Corrosion Current ◽

Corrosion Resistant ◽

Cermet Coatings ◽

Laser Scanning Speed ◽

Corrosion Resistant Coatings

The hard and corrosion resistant coatings of Mo2NiB2 cermet were prepared by the laser cladding technique. The influences of the Mo:B ratio and the laser scanning speed on the microstructure and property of the Mo2NiB2 cermet coatings were investigated. The results showed that the laser scanning speed of 1.5 mm/s and the Mo:B ratio of 1 were more beneficial to the formation of Mo2NiB2 cermet than 2.0 mm/s and 0.8, 1.2, respectively. The amount of the Mo2NiB2 ceramic phases were decreased from the top layer to the bottom layer of the coating. The changes of microstructure and composition led to the changes of hardness and corrosion resistance of the Mo2NiB2 cermet coatings. The coating prepared at the Mo:B ratio of 1 and the scanning speed of 1.5 mm/s possessed the highest hardness, and the hardness gradually decreased from the top layer to the bottom layer of the coating. The formation of Mo2NiB2 and {FeM} phases led to the enhanced corrosion resistance of the Mo2NiB2 cermet coatings, and the coating prepared at the Mo:B ratio of 0.8 possessed the best corrosion resistance and the minimum corrosion current.

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Study on Preparation of Superhydrophobic Ni-Co Coating and Corrosion Resistance by Sandblasting–Electrodeposition

Coatings ◽

10.3390/coatings10121164 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1164

Author(s):

Zhengwei Zhang ◽

Zhenyu Shen ◽

Hongbin Wu ◽

Lingquan Li ◽

Xiuqing Fu

Keyword(s):

Contact Angle ◽

Corrosion Resistance ◽

Laser Scanning ◽

Three Dimensional ◽

Electrochemical Corrosion ◽

Corrosion Current ◽

X Ray Diffraction ◽

Water Contact ◽

Angle Measuring ◽

Surface Contact Angle

To enhance the corrosion resistance of type C45E4 substrates, a superhydrophobic Ni-Co coating was prepared on a C45E4 surface by sandblasting pretreatment and electrodeposition. The surface microstructure, three-dimensional surface roughness, and crystal structure of the coating was characterized by scanning electron microscope, laser scanning confocal microscope, and X-ray diffraction. An optical surface contact angle measuring instrument and an electrochemical workstation was used to characterize the wettability and corrosion resistance of the surface. The results showed that the water contact angle reached 151.2 degrees on the Ni-Co coating surface. The surface was superhydrophobic and still had stable hydrophobicity after four months. In electrochemical corrosion experiments. Compared with polishing pretreatment, the corrosion current density of superhydrophobic Ni-Co coating prepared by sandblasting pretreatment reached Icorr = 5.05 × 10−7 A·cm−2, and the corrosion potential reached Ecorr = −0.33 V. The superhydrophobic Ni-Co coating had excellent corrosion resistance.

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Reinforced Superhydrophobic Anti-Corrosion Epoxy Resin Coating by Fluorine–Silicon–Carbide Composites

Coatings ◽

10.3390/coatings10121244 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1244

Author(s):

Zhicai Zhang ◽

Nie Zhao ◽

Fugang Qi ◽

Biao Zhang ◽

Bin Liao ◽

...

Keyword(s):

Corrosion Resistance ◽

Epoxy Resin ◽

Composite Coating ◽

Salt Spray ◽

Corrosion Current ◽

Water Contact ◽

Sic Nanoparticles ◽

Ep Matrix ◽

Overall Performance ◽

Different Content

SiC was modified by fluorine-containing organic substance 1H,1H,2H,2H-trifluoro-noctyltriethoxysilane (FAS) to change its hydrophilicity from hydrophilic to superhydrophobic nanoparticles, and the optimum conditions for hydrophobicity were effectively explored. Then, different content of fluorine-modified SiC (F–SiC) nanoparticles were added to the epoxy resin (EP) matrix to prepare composite coating samples. The results showed that the surface of SiC was modified by FAS to show superhydrophobicity, and the dispersion in EP was significantly improved. After adding F–SiC, the hydrophobicity, wear resistance and corrosion resistance of the coating were significantly improved. In addition, the corrosion resistance of the composite coating containing different contents of F–SiC was analyzed through electrochemical and salt spray tests. The results showed that the corrosion resistance of the coating was the best when the addition amount was 3 wt %. In general, the composite coating with 3 wt % F–SiC had the best overall performance. Compared with the EP coating, the water contact angle of 3 wt % F–SiC/EP composite coating was increased by 62.9%, the friction coefficient was reduced by 73.5%, and the corrosion current was reduced by three orders of magnitude. This study provides a new idea for the development of ultra-wear-resistant and anti-fouling heavy-duty coatings.

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Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.3.2020.14.0618 ◽

2020 ◽

Vol 17 (3) ◽

pp. 8206-8213

Author(s):

J. Alias

Keyword(s):

Corrosion Resistance ◽

Powder Metallurgy ◽

Corrosion Behaviour ◽

Corrosion Current ◽

Optical Microscope ◽

High Reactivity ◽

Aluminium Content ◽

Powder Metallurgy Method ◽

X Ray Diffraction ◽

Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

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Corrosion Behavior and Osteogenic Activity of a Biodegradable Orthopedic Implant Mg–Si Alloy with a Gradient Structure

Metals ◽

10.3390/met11050781 ◽

2021 ◽

Vol 11 (5) ◽

pp. 781

Author(s):

Weiyan Jiang ◽

Wenzhou Yu

Keyword(s):

Corrosion Resistance ◽

Corrosion Behavior ◽

Polarization Resistance ◽

Corrosion Current Density ◽

Corrosion Current ◽

Gradient Structure ◽

Orthopedic Implant ◽

Biological Functions ◽

Alloy Matrix ◽

Osteogenic Activity

A gradient Mg-8 wt % Si alloy, which was composed of the agglomerated Mg2Si crystals coating (GMS8-1) and the eutectic Mg–Si alloy matrix (GMS8-2), was designed for biodegradable orthopedic implant materials. The bio-corrosion behavior was evaluated by the electrochemical measurements and the immersion tests. The results show that a significant improvement of bio-corrosion resistance was achieved by using the gradient Mg–Si alloy, as compared with the traditional Mg-8 wt % Si alloy (MS8), which should be attributed to the compact and insoluble Mg2Si phase distributed on the surface of the material. Especially, GMS8-1 exhibits the highest polarization resistance of 1610 Ω, the lowest corrosion current density of 1.7 × 10−6 A.cm−2, and the slowest corrosion rate of 0.10 mm/year. In addition, GMS8-1 and GMS8-2 show better osteogenic activity than MS8, with no cytotoxicity to MC3T3-E1 cells. This work provides a new way to design a gradient biodegradable Mg alloys with some certain biological functions.

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Using Graphene-Based Composite Materials to Boost Anti-Corrosion and Infrared-Stealth Performance of Epoxy Coatings

Nanomaterials ◽

10.3390/nano11061603 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1603

Author(s):

Meng-Jey Youh ◽

Yu-Ren Huang ◽

Cheng-Hsiung Peng ◽

Ming-Hsien Lin ◽

Ting-Yu Chen ◽

...

Keyword(s):

Electrochemical Impedance ◽

Graphene Nanosheets ◽

Salt Spray ◽

Corrosion Current ◽

Filler Concentration ◽

Epoxy Coatings ◽

Corrosion Properties ◽

Water Contact ◽

Different Temperatures ◽

Thermal Signature

Corrosion prevention and infrared (IR) stealth are conflicting goals. While graphene nanosheets (GN) provide an excellent physical barrier against corrosive agent diffusion, thus lowering the permeability of anti-corrosion coatings, they have the side-effect of decreasing IR stealth. In this work, the anti-corrosion properties of 100-μm-thick composite epoxy coatings with various concentrations (0.01–1 wt.%) of GN fillers thermally reduced at different temperatures (300 °C, 700 °C, 1100 °C) are first compared. The performance was characterized by potentiodynamic polarization scanning, electrochemical impedance spectroscopy, water contact angle and salt spray tests. The corrosion resistance for coatings was found to be optimum at a very low filler concentration (0.05 wt.%). The corrosion current density was 4.57 × 10−11 A/cm2 for GN reduced at 1100 °C, showing no degradation after 500 h of salt-spray testing: a significant improvement over the anti-corrosion behavior of epoxy coatings. Further, to suppress the high IR thermal signature of GN and epoxy, Al was added to the optimized composite at different concentrations. The increased IR emissivity due to GN was not only eliminated but was in fact reduced relative to the pure epoxy. These optimized coatings of Al-GN-epoxy not only exhibited greatly reduced IR emissivity but also showed no sign of corrosion after 500 h of salt spray test.

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PVD Coated Bipolar Plates for PEM Fuel Cells

Journal of Fuel Cell Science and Technology ◽

10.1115/1.2041671 ◽

2005 ◽

Vol 2 (4) ◽

pp. 290-294 ◽

Cited By ~ 17

Author(s):

Shuo-Jen Lee ◽

Ching-Han Huang ◽

Yu-Pang Chen ◽

Chen-Te Hsu

Keyword(s):

Corrosion Resistance ◽

Fuel Cells ◽

Fuel Cell ◽

Physical Vapor Deposition ◽

Corrosion Current ◽

Pem Fuel Cells ◽

Bipolar Plates ◽

Coating Materials ◽

Pvd Coating ◽

Simulated Fuel

Aluminum was considered a good candidate material for bipolar plates of the polymer electrolyte membrane (PEM) fuel cells due to its low cost, light weight, high strength and good manufacturability. But there were problems of both chemical and electrochemical corrosions in the PEM fuel cell operating environment. The major goals of this research are to find proper physical vapor deposition (PVD) coating materials which would enhance surface properties by making significant improvements on corrosion resistance and electrical conductivity at a reasonable cost. Several coating materials had been studied to analyze their corrosion resistance improvement. The corrosion rates of all materials were tested in a simulated fuel cell environment. The linear polarization curve of electrochemical method measured by potentiostat instrument was employed to determine the corrosion current. Results of the corrosion tests indicated that all of the coating materials had good corrosion resistance and were stable in the simulated fuel cell environment. The conductivities of the coated layers were better and the resistances changed very little after the corrosion test. At last, single fuel cells were made by each PVD coating material. Fuel cell tests were conducted to determine their performance w.r.t. that was made of graphite. The results of fuel cell tests indicated that metallic bipolar plates with PVD coating could be used in PEM fuel cells.

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Structure, Corrosion Resistance, Mechanical and Tribological Properties of ZrB2 and Zr-B-N Coatings

Metals ◽

10.3390/met11081194 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1194

Author(s):

Philipp Kiryukhantsev-Korneev ◽

Alina Sytchenko ◽

Yuriy Kaplanskii ◽

Alexander Sheveyko ◽

Stepan Vorotilo ◽

...

Keyword(s):

Corrosion Resistance ◽

Tribological Properties ◽

Current Density ◽

Corrosion Current Density ◽

Elastic Recovery ◽

Optical Emission ◽

Corrosion Current ◽

Impact Testing ◽

Total Oxidation ◽

Mechanical And Tribological Properties

The coatings ZrB2 and Zr-B-N were deposited by magnetron sputtering of ZrB2 target in Ar and Ar–15%N2 atmospheres. The structure and properties of the coatings were investigated via scanning and transmission electron microscopy, energy dispersion analysis, optical profilometry, glowing discharge optical emission spectroscopy and X-ray diffraction analysis. Mechanical and tribological properties of the coatings were investigated using nanoindentation, “pin-on-disc” tribological testing and “ball-on-plate” impact testing. Free corrosion potential and corrosion current density were measured by electrochemical testing in 1N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °С temperature interval. The coatings deposited in Ar contained 4–11 nm grains of the h-ZrB2 phase along with free boron. Nitrogen-containing coatings consisted of finer crystals (1–4 nm) of h-ZrB2, separated by interlayers of amorphous a-BN. Both types of coatings featured hardness of 22–23 GPa; however, the introduction of nitrogen decreased the coating’s elastic modulus from 342 to 266 GPa and increased the elastic recovery from 62 to 72%, which enhanced the wear resistance of the coatings. N-doped coatings demonstrated a relatively low friction coefficient of 0.4 and a specific wear rate of ~1.3 × 10−6 mm3N−1m−1. Electrochemical investigations revealed that the introduction of nitrogen into the coatings resulted in the decrease of corrosion current density in 3.5% NaCl and 1N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-В-N coatings was related to the finer grains size and increased volume of the BN phase. The samples ZrB2 and Zr-B-N resisted oxidation at 600 °C. N-free coatings resisted oxidation (up to 800 °С) and the diffusion of metallic elements from the substrate better. In contrast, Zr-B-N coatings experienced total oxidation and formed loose oxide layers, which could be easily removed from the substrate.

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The Potential of Calcium/Phosphate Containing MAO Implanted in Bone Tissue Regeneration and Biological Characteristics

International Journal of Molecular Sciences ◽

10.3390/ijms22094706 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4706

Author(s):

Shun-Yi Jian ◽

Salim Levent Aktug ◽

Hsuan-Ti Huang ◽

Cheng-Jung Ho ◽

Sung-Yen Lin ◽

...

Keyword(s):

Corrosion Resistance ◽

Calcium Phosphate ◽

Soft Tissues ◽

Salt Spray ◽

Surface Characteristics ◽

Corrosion Current ◽

Biological Properties ◽

Bone Tissue Regeneration ◽

Additional Surgery

Micro arc oxidation (MAO) is a prominent surface treatment to form bioceramic coating layers with beneficial physical, chemical, and biological properties on the metal substrates for biomaterial applications. In this study, MAO treatment has been performed to modify the surface characteristics of AZ31 Mg alloy to enhance the biocompatibility and corrosion resistance for implant applications by using an electrolytic mixture of Ca3(PO4)2 and C10H16N2O8 (EDTA) in the solutions. For this purpose, the calcium phosphate (Ca-P) containing thin film was successfully fabricated on the surface of the implant material. After in-vivo implantation into the rabbit bone for four weeks, the apparent growth of soft tissues and bone healing effects have been documented. The morphology, microstructure, chemical composition, and phase structures of the coating were identified by SEM, XPS, and XRD. The corrosion resistance of the coating was analyzed by polarization and salt spray test. The coatings consist of Ca-P compounds continuously have proliferation activity and show better corrosion resistance and lower roughness in comparison to mere MAO coated AZ31. The corrosion current density decreased to approximately 2.81 × 10−7 A/cm2 and roughness was reduced to 0.622 μm. Thus, based on the results, it was anticipated that the development of degradable materials and implants would be feasible using this method. This study aims to fabricate MAO coatings for orthopedic magnesium implants that can enhance bioactivity, biocompatibility, and prevent additional surgery and implant-related infections to be used in clinical applications.

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