scholarly journals Improved Corrosion Resistance of Magnesium Alloy AZ31 in Ringer Lactate by Bilayer Anodic Film/Beeswax–Colophony

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 564
Author(s):  
Anawati Anawati ◽  
Medio Febby Fitriana ◽  
Muhammad Dikdik Gumelar
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Az31 Alloy ◽  
Dip Coating ◽  
Anodic Film ◽  
Ringer Lactate ◽  
Strong Attachment ◽  
Electrochemical Corrosion Resistance

A bilayer anodic film/beeswax–colophony is proposed for improving the corrosion resistance of magnesium alloy surface. The bilayer was synthesized on the AZ31 alloy by anodization and subsequent dip coating, and the corrosion behavior was investigated by electrochemical measurements and weight loss test in Ringer lactate at 37 °C. The bilayer improved the electrochemical corrosion resistance by four orders of magnitude, as demonstrated by ~104 times lower corrosion current density in the polarization curves and ~104 higher film resistance in the impedance spectra. The tremendous surface area of the porous anodic film led to a strong attachment of the topcoat beeswax–colophony. Most of the coating remained attached to the surface after 14 days soaking in Ringer lactate. A few small blisters developed under the bilayer contributed to the low mass loss of 0.07 mg/cm2/day compared to the bare substrate, with an average loss rate of 0.25 mg/cm2/day. Local detachment of topcoat layer exposed the underlying anodic film that triggered the deposition of Ca and further nucleation of the Ca–P compound on the surface. The existence of a Ca−P compound with a Ca/P ratio of 1.68 indicated the ability of the bilayer to promote the formation of bone mineral apatite.

Ceria Coatings Prepared by Sol-Gel Approach on AZ91 Magnesium Alloy

2017 ◽  
Vol 898 ◽  
pp. 1369-1380 ◽  
Author(s):  
Hui Min Han ◽  
Dan Tong Wang ◽  
Hua Qian Yu ◽  
Min Zuo ◽  
Li Hong Wang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Sol Gel ◽  
Electrochemical Corrosion ◽  
Chemical Conversion ◽  
Corrosion Current ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

The ceria coatings on AZ91 substrates were successfully synthesized by chemical conversion and the corrosion resistance of AZ91 samples with and without ceria coatings were evaluated by means of electrochemical corrosion in 3.5 wt.% NaCl solution. According to the parameters derived from the polarization date, the Icorr (the corrosion current density) values of the coated samples are smaller than that of bare one, indicating that the corrosion resistance of AZ91 alloys has been improved to some extent. The influence of fluoridated pretreatment, inter-layer heat treatment, sintering temperature and the layer of films on the performance of ceria coatings were also investigated. It was found that the inter-layer heat treatment has no influence on improving the anticorrosion resistance of AZ91 alloy. In comparison with the bare one, the Icorr of optimal sample is about 0.0219mA/cm2, which decreases by two orders of magnitude, indicating that the ceria coatings could significantly improve the corrosion resistance of AZ91 magnesium alloy.

scholarly journals Effect of Current Density on the Performance of Ni–P–ZrO2–CeO2 Composite Coatings Prepared by Jet-Electrodeposition

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 616
Author(s):  
Zhaoyang Song ◽  
Hongwen Zhang ◽  
Xiuqing Fu ◽  
Jinran Lin ◽  
Moqi Shen ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Current Density ◽  
Composite Coatings ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
X Ray Diffraction ◽  
X Ray ◽  
Jet Electrodeposition ◽  
Electrochemical Corrosion Resistance

The objective of this study was to improve the surface properties, hardness, wear resistance and electrochemical corrosion resistance of #45 steel. To this end, Ni–P–ZrO2–CeO2 composite coatings were prepared on the surface of #45 steel using the jet-electrodeposition technique by varying the current density from 20 to 60 A/dm2. The effect of current density on the performance of the composite coatings was evaluated. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were applied to explore the surface topography, elemental composition, hardness and electrochemical corrosion resistance of the composite coatings. The results showed that with the increase in the current density, the hardness, wear resistance, and electrochemical corrosion resistance tends to increase first and then decrease. At a current density of 40 A/dm2, the hardness reached a maximum of 688.9 HV0.1, the corrosion current reached a minimum of 8.2501 × 10−5 A·cm−2, and the corrosion potential reached a maximum of −0.45957 V. At these values, the performance of the composite coatings was optimal.

Effect of High-Intensity Pulsed Ion Beam Irradiation on the Electrochemical Corrosion Behavior of AZ31 Magnesium Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 571-574
Author(s):  
Peng Li
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Current Density ◽  
Ion Beam ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Open Circuit ◽  
Electrochemical Corrosion Behavior ◽  
Shot Number

HIPIB irradiation experiment is carried out at a specific ion current density of 1.1 J/cm2 with shot number from one to ten in order to explore the effect of shot number on electrochemical corrosion behavior of magnesium alloy. Surface morphologies, microstructure and corrosion resistance of the irradiated samples are examined by scanning electron microscopy (SEM), transmission electron microscope (TEM) and potentiodynamic polarization technique, respectively. It is found that HIPIB irradiation leads to the increase in open circuit potential, corrosion potential and breakdown potential, and the decrease in the corrosion current density and the corrosion rate as compared to the original sample. The improved corrosion resistance is mainly attributed to the grain refinement and surface purification induced by HIPIB irradiation.

Enhancement Corrosion Resistance of (3–Glycidoxylpropyl)- Silsesquioxane Hybrid Films and its Validation by Gas-Molecule Diffusion Coefficients Using MD Simulation

2009 ◽  
Vol 610-613 ◽  
pp. 190-197
Author(s):  
Gang Xie ◽  
Peng Wang ◽  
Li Jiang Hu
Keyword(s):  
Corrosion Resistance ◽  
Diffusion Coefficients ◽  
Md Simulation ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Hybrid Films ◽  
Self Diffusion ◽  
Three Samples ◽  
Unit Cells ◽  
Electrochemical Corrosion Resistance

Based on silsesquioxanes (SSO) derived from hydrolytic condensation of (–glycidoxylpropyl) trimethoxysilane (GPMS) and tetraethoxysilane (TEOS), two hybrid films, f-GPMS-TEOS-SSO (f-GTS) modified with 10 wt-% TEOS and f-GTS modified with 50 wt-% DGEBA (f-GTSD), were prepared. The anticorrosion properties (corrosion potential, Ecorr, and corrosion current density, Icorr) of the bare aluminum alloy (AA) and the two films on AA were tested by electrochemical measurements with typical potentiodynamic polarization curves. The Icorr values of three samples were significantly different with the order of f-GTSD<f-GTS<AA， which implies that the DGEBA addition in the f-GTSD coating indeed enhances the electrochemical corrosion resistance. Two different 3D-amorphous cubic unit cells, cell(f-GTS) and cell(f-GTSD), as models were employed to investigate self-diffusion coefficients by MD simulation for the NO2, SO2 and H2O molecules. All the three self-diffusion coefficients of NO2, SO2 and H2O diffusing in cell(f-GTSD) were less than the coefficients in cell(f-GTS), which validates the corresponding anticorrosion-experiment results. Two reasons that the addition of DGEBA in the system of f-GTS lead to the decrease of the gas self-diffusion coefficient compared to the f-GTS system were discussed.

Potentiodynamic Tests of Magnesium Alloy AZ31 with Lithium Additive

2013 ◽  
Vol 211 ◽  
pp. 93-100
Author(s):  
Joanna Przondziono ◽  
Witold Walke ◽  
Eugeniusz Hadasik ◽  
Stanisław Lalik
Keyword(s):  
Magnesium Alloy ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Az31 Alloy ◽  
Chloride Ions ◽  
Molar Concentration ◽  
Lithium Content ◽  
Nacl Solution ◽  
Alloy Az31 ◽  
Magnesium Alloy Az31

The purpose of the study is to assess electrochemical corrosion resistance of magnesium alloy AZ31 with additives of 4.5, 7.5 and 15 % lithium in NaCl solutions. Corrosion tests were performed in solutions with concentration 0.01 2 M NaCl with application of electrochemical testing system VoltaLab®PGP201. Resistance to electrochemical corrosion was evaluated on the ground of registered anodic polarisation curves by means of potentiodynamic method. Results of performed tests show unequivocally deterioration of corrosion characteristics of the alloy together with increase of molar concentration of NaCl solution. As chloride ions concentration increases, decrease of corrosion potential and polarisation resistance, as well as increase of corrosion current density are observed. Deterioration of corrosion characteristics of AZ31 alloy was shown with the increase of lithium content. It must be highlighted that irrespective of molar concentration of NaCl solution, there is also presence of pitting corrosion in the tested alloy. It proves that magnesium alloy AZ31-Li is not resistant to that type of corrosion. Test results prove that it is necessary to apply protective films on elements made of magnesium alloy with lithium additive.

scholarly journals The Corrosion Resistance of Graphene-Modified Oily Epoxy Coating on AZ31 Magnesium Alloys

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhengyuan Gao ◽  
Chengjin Sun ◽  
Lianteng Du ◽  
Dong Yang ◽  
Xiang Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Epoxy Resin ◽  
Current Density ◽  
Corrosion Current Density ◽  
Surface Defects ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Corrosive Media ◽  
Electrochemical Testing

In order to enhance the corrosion resistance of AZ31 magnesium alloy, graphene-modified oily epoxy resin coating (G/OEP) were prepared on the surface of magnesium alloy. SEM observations show that graphene has fewer surface defects, and can significantly improve the surface quality of the coating and reduce defects. FI-TR testing shows that coating are mainly composed of epoxy resin (polyurethane) and its corresponding curing agent. Electrochemical testing shows that the coating can provide good corrosion protection for magnesium alloy. Compared with the corrosion current density of magnesium alloy of 6.20 × 10−7 A/cm2, the G/OEP can significantly reduce the corrosion current density to 6.96 × 10−12 A/cm2. Analysis of the morphology of the coating after electrochemical corrosion found that graphene can improve the shielding ability of the coating to corrosive media, and reduce the damage of corrosion to the coating structure, and enhance the corrosion resistance of the coating. The content of graphene for excellent corrosion resistance of coating during this experiment is 0.6 wt%. The graphene can fill the defects generally in the coating during the curing process to prevent substrate from penetration of corrosive media caused by the density and hydrophobicity of coating are increased.

scholarly journals Corrosion resistance of the microarc oxidation coatings prepared on magnesium alloy

2018 ◽  
Vol 38 ◽  
pp. 02009
Author(s):  
Ying Lv ◽  
Jun Gang Li ◽  
Ming Zhong Wu ◽  
Zhen Ma ◽  
Jing Qiang Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Microarc Oxidation ◽  
Electrochemical Corrosion ◽  
Ceramic Coatings ◽  
Nacl Solution ◽  
Oxide Coatings ◽  
Az91d Magnesium Alloy ◽  
Oxidation Technology ◽  
Electrochemical Corrosion Resistance

Ceramic coatings were prepared on the surface of AZ91D magnesium alloy by microarc oxidation technology. The effects of different voltages on morphology, phase composition and thickness of the coatings were characterized by SEM and XRD. The corrosion resistance of the coatings was measured by electrochemical workstation. Results indicated that the microarc oxidation coatings prepared in sodium silicate electrolyte exhibited porous surface and mainly comprised MgO, Mg2SiO4 and a small amount of MgAl2O4. The thickness of the oxide coatings increased rapidly with the increase of voltage. The coating prepared at 400V voltage had good electrochemical corrosion resistance in 3.5wt% NaCl solution.

scholarly journals Electrochemical Corrosion Resistance and Electrical Conductivity of Three-Dimensionally Interconnected Graphene-Reinforced Cu Composites

2021 ◽  
Vol 59 (11) ◽  
pp. 821-828
Author(s):  
Xue Li ◽  
Ateeq Ahmed ◽  
Byung-Sang Choi
Keyword(s):  
Electrical Conductivity ◽  
Corrosion Resistance ◽  
Carbon Content ◽  
Chemical Species ◽  
Electrochemical Corrosion ◽  
Chemical Vapor ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Electrochemical Corrosion Resistance ◽  
Pure Cu

A three-dimensionally interconnected graphene-reinforced Cu (3Di Gr-Cu) composite was synthesized using a simple two-step process technique which involves the mechanical compaction of micronsized Cu particles followed by chemical vapor deposition (CVD) at 995 ℃. The microstructural properties of pure Cu and the 3Di Gr-Cu composite were investigated by optical microscope, scanning electron microscope, and X-ray diffractometer. The electrical and corrosion behaviors of the 3Di Gr-Cu composite and Cu only, prepared by powder metallurgy (PM Cu), were studied and compared. The electrical conductivity (EC) of the 3Di Gr-Cu composites was found to be 38.8 MSm−1 at a carbon content of 73 ppm, and exhibited a 12% higher EC than the PM Cu. Due to the interconnected graphene around the Cu grains, the corrosion current density and corrosion rate of the 3Di Gr-Cu composite decreased by 29% and 40%, respectively, compared to the PM Cu. The EC of the 3Di Gr-Cu composite depended on the carbon content. The improvement in the EC of the 3Di Gr-Cu composite is attributed to the electron-carrying ability of the three-dimensionally interconnected graphene network (3DIGN) formed at the grain boundaries in the composite. The enhancement in corrosion resistance is due to the impermeability of graphene to various chemical species.

Enhancement Corrosion Resistance of Two (Vinyl)Silsesquioxane Hybrid Films and their Validation by Gas-Molecule Diffusion Coefficients Using Molecular Dynamics Simulation

2009 ◽  
Vol 610-613 ◽  
pp. 97-103
Author(s):  
Di Wang ◽  
Xiao Dong Chen ◽  
Yu Liu ◽  
Li Jiang Hu
Keyword(s):  
Molecular Dynamics ◽  
Corrosion Resistance ◽  
Diffusion Coefficients ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Dynamics Simulation ◽  
Hybrid Films ◽  
Self Diffusion ◽  
Electrochemical Corrosion Resistance ◽  
Anticorrosion Properties

Based on silsesquioxanes (SSO) derived from hydrolytic condensation of (vinyl)trimethoxysilane (VMS) and tetraethoxysilane (TEOS), two hybrid films, f-VMS-SSO (f-VS) and f-VMS-TEOS-SSO (f-VTS) modified with 15 wt-% TEOS, were prepared. The anticorrosion properties (corrosion potential, Ecorr, and corrosion current density, Icorr) of the bare aluminum alloy (AA) and the two films on AA were tested by electrochemical measurements with typical potentiodynamic polarization curves. The Icorr values of three samples are significantly different in the order of f-VTS<f-VS<AA which implies that the TEOS addition in the f-VTS coating indeed enhances the electrochemical corrosion resistance. Correlations between the structures of two films and anticorrosion properties were discussed. Four different 3D-amorphous cubic unit cells, two cell(f-VS)s and two cell(f-VTS)s, as models were employed to investigate self-diffusion coefficients by molecular dynamics (MD) simulation for the NO2, SO2 and H2O molecules. All three self-diffusion coefficients of NO2, SO2 and H2O in cell(f-VTS) were less than the corresponding values in cell(f-VS), which validates the anticorrosion experiment results. The reasons why the addition of TEOS in the system of f-VTS leads to a lower gas self-diffusion coefficient compared to the f-VS system, were discussed.

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