Effect of Fluoride Conversion Coating on the Corrosion Resistance and Adhesion of E-painted AZ31 Magnesium Alloy

Fazal, Basit Raza; Moon, Sungmo

doi:10.5695/jkise.2016.49.5.395

Cited by 4 publications

(4 citation statements)

References 12 publications

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“…The UHF-coated alloys showed significantly elevated OCP values after one hour; the standard PDP curves for both the uncoated and coated alloys can be seen in Figure 9(a); the anodic curves indicate the dissolution of magnesium, whereas the cathode polarization curves represent the evolution of cathode hydrogen through water reduction. The increased corrosion rate is shown by the increased density of corrosion currents and lower corrosion potential [21,30]. The anodic and cathodic sections in the three specimens vary significantly from one another, depending on Tafel plots of corrosion potential and current density of corrosion for the uncoated and UHF-coated alloys.…”

Section: Potent Dynamic Polarization (Pdp) Testmentioning

confidence: 99%

Control Degradation of New Magnesium Alloy by MgF2 Coating for Cardiovascular Applications

2024

jjmie

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The deployment of permanent biomaterials has significantly modified in the last few decades. Magnesium (Mg) and its alloys' inherent ability to break down without producing harmful products has opened up a wide range of biomedical applications, including musculoskeletal, orthopedic, and cardiovascular stent applications. This work investigated the control of the degradation rate and also improved the corrosion resistance of novel magnesium biodegradable alloy via fluoride chemical conversion coating. However, the surface roughness, corrosion resistance, and degradation rate of the chemical conversion film (MgF2) with various physiological solutions have been investigated in this study. We established the rules that the MgF2 film with a greater thickness of 14.21μm and better corrosion resistance were produced under longer preparation times through in vitro hydrogen evolution volume 0.037 ml/cm 2 change P.H. of solutions, composition and structure analysis, and roughness of surface 27.8 nm. Comparing the variations of various classification techniques, addition of the MgF2 film can have high bonding strength with substrate greater than 50 MPa as the corrosion rate with PDP reduced from 3.37 mm/y to 0.62mm/y for Alloy with coating MgF2 in simulated blood plasma, respectively while decreasing the corrosion rate in phosphate buffer saline from 17.07 mm/y to 1.55 mm/y. At the same time, we showed that the MgF2 film was highly cytocompatible and that osteoblasts attached to and formed satisfactorily on its surface. These findings significantly affect how the MgF2 film is used in cardiac stents.

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Section: Potent Dynamic Polarization (Pdp) Testmentioning

confidence: 99%

Control Degradation of New Magnesium Alloy by MgF2 Coating for Cardiovascular Applications

2024

jjmie

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“…Some researchers [31,32] have performed studies on properties of the surface films formed on Mg alloys in acidic or alkaline solutions containing PO 4 3and Fions, reporting that these anions can form a uniform layer of magnesium phosphate (Mg 3 (PO 4 ) 2 ) and magnesium fluoride (MgF 2 ). However, their studies include combined effect of anions together with H + or OHions, they could not provide the information on the contribution of anions only to the electrochemical behavior of Mg alloys.…”

Section: -mentioning

confidence: 99%

Electrochemical Behavior of AZ31 Mg Alloy in Neutral Aqueous Solutions Containing Various Anions

Kwon¹,

Pham²,

Song³

et al. 2023

J. Electrochem. Sci. Technol

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This work was performed to characterize the electrochemical behavior of AZ31 Mg alloy in neutral aqueous solutions where Cl−, SO42−, PO43−, and F− ions were present and pH was adjusted to 6 to exclude the contribution of H+ and OH− ions. Open-circuit potential (OCP) transient, electrochemical impedance spectroscopy (EIS) and potnetiodynamic polarization curves were employed. The OCP value appeared to decrease in the order of F− > Cl− > SO42− > PO43− ions while corrosion current density increased in the same order. Electrochemical impedance spectroscopy (EIS) data showed two capacitive arcs in all the solutions and one more inductive arc appeared in PO43−-containing solution. By fitting of two capacitive arcs, capacitance of dense film (Cdf), resistance of porous film (Rpf) and double layer capacitance (Cdl) and charge transfer resistance (Rct) beneath the porous films were obtained. A simplified model in which various thicknesses and coverages of dense and porous films are assumed to be present on the AZ31 Mg alloy surface, is suggested to explain the effects of four different anions on the electrochemical behavior of AZ31 Mg alloy.

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“…Phosphate ions (PO 4 3− ) are known to improve the corrosion resistance of Mg alloys by forming chemical conversion coatings [23]. Fluoride ions (F − ) can improve the corrosion resistance of Mg alloys by forming stable surface films of MgF 2 [24][25][26]. However, since many works [23][24][25][26] have been conducted in acidic or alkaline solutions, the contributions of H + and OH − ions to the formation of surface films cannot be excluded.…”

Section: Introductionmentioning

confidence: 99%

“…Fluoride ions (F − ) can improve the corrosion resistance of Mg alloys by forming stable surface films of MgF 2 [24][25][26]. However, since many works [23][24][25][26] have been conducted in acidic or alkaline solutions, the contributions of H + and OH − ions to the formation of surface films cannot be excluded. When a solution's pH is adjusted to neutral, the contributions of H + and OH − ions can become negligibly small.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behavior of the AZ31 Mg Alloy in Neutral Aqueous Solutions Containing Various Anions

Kwon

Pham

Song

et al. 2023

Metals

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This work demonstrates the corrosion behavior of the AZ31 Mg alloy as a function of an immersion time of 48 h in 0.1 M HCl, H2SO4, H3PO4 and HF solutions, in which pH was adjusted to 6 to exclude the contribution of hydrogen ions (H+) and hydroxide ions (OH−). In situ observations, open circuit potential (OCP), weight changes and AC impedance measurements were performed with an immersion time of 48 h and the morphologies and chemical compositions of the surface products after 48 h of immersion were analyzed by SEM, EDS and XPS. In the chloride ion (Cl−)-containing solution, the corrosion of the AZ31 Mg alloy initiated locally and propagated discontinuously over the surface with immersion time. The OCP value of the AZ31 Mg alloy showed an initial increase from −1.51 VAg/AgCl to −1.47 VAg/AgCl after about 5 h of immersion and then a decrease to −1.51 VAg/AgCl due to corrosion initiation. In the F−-containing solution, after 48 h of immersion, the OCP showed an extremely large value of −0.6 VAg/AgCl, while the relatively lower values of −1.52 VAg/AgCl, −1.59 VAg/AgCl were seen in the solutions containing SO42− and PO43, respectively. In the sulfate ion (SO42−)-containing neutral aqueous solution, needle-like surface films were formed and there were no changes in the weight of the AZ31 Mg alloy with immersion time. In the phosphate ion (PO43−)-containing neutral aqueous solution, a vigorous gas evolution occurred, together with the formation of black surface films with cracks, and a high corrosion rate of −13.8018 × 10−3 g·cm−2·day−1 was obtained. In the fluoride ion (F−)-containing neutral aqueous solution, a surface film with crystalline grains of MgF2 was formed and the weight of the AZ31 Mg alloy increased continuously with immersion time. In conclusion, the corrosion of the AZ31 Mg alloy occurred uniformly in neutral phosphate solution but locally in chloride solution. No corrosion was observed in either the neutral sulfate or fluoride solutions.

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Effect of Fluoride Conversion Coating on the Corrosion Resistance and Adhesion of E-painted AZ31 Magnesium Alloy

Cited by 4 publications

References 12 publications

Control Degradation of New Magnesium Alloy by MgF2 Coating for Cardiovascular Applications

Control Degradation of New Magnesium Alloy by MgF2 Coating for Cardiovascular Applications

Electrochemical Behavior of AZ31 Mg Alloy in Neutral Aqueous Solutions Containing Various Anions

Corrosion Behavior of the AZ31 Mg Alloy in Neutral Aqueous Solutions Containing Various Anions

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