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Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion.

Zhang X, Wu G, Peng X, Li L, Feng H, Gao B, Huo K, Chu PK - Sci Rep (2015)

Bottom Line: A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions.Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane.The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.

ABSTRACT
Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions. Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane. As a result of the trapped air pockets in the microstructure, the super-hydrophobic surface with the Cassie state shows better corrosion resistance in the immersion tests. The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys.

No MeSH data available.


Related in: MedlinePlus

(a) Polarization curves of the Wenzel-like (HR 120 °C-12 h at a pH of 12) and Cassie state (HR 120 °C-8 h at a pH of 12) superhydrophobic samples, (b) Corresponding Nyquist plots, and (c,d) Bode plots. (e) Corresponding equivalent circuit model based on the PTES modified samples. The measurement is carried out in a 3.5 wt% NaCl aqueous solution.
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f7: (a) Polarization curves of the Wenzel-like (HR 120 °C-12 h at a pH of 12) and Cassie state (HR 120 °C-8 h at a pH of 12) superhydrophobic samples, (b) Corresponding Nyquist plots, and (c,d) Bode plots. (e) Corresponding equivalent circuit model based on the PTES modified samples. The measurement is carried out in a 3.5 wt% NaCl aqueous solution.

Mentions: Polarization is adopted to determine the instantaneous corrosion rate. As shown in Fig. 7, a smaller corrosion current density and bigger corrosion potential difference (∆E) correspond to a lower corrosion rate and better corrosion resistance thereby providing indication of better corrosion resistance. Notably, Icorr [(3.35–9.23) × 10−9 A.cm−2] obtained from the both superhydrophobic states samples is 10–20 times smaller than that of hydrothermal samples [Icorr = (0.55–1.35) × 10−7 A.cm−2] and ∆E is about three times larger. The corrosion current density of the sample in Cassie-Baxter model is about three times smaller than that in Wenzel-like state in NaCl aqueous solution, and far lower than that of most irregularly rough superhydrophobic surfaces on Mg alloy18313241424344, the excellent corrosion resistance performance is due to the regular roughness and orientation of microsheets which extremely decrease the chance of contact between the substrate and solution23.


Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion.

Zhang X, Wu G, Peng X, Li L, Feng H, Gao B, Huo K, Chu PK - Sci Rep (2015)

(a) Polarization curves of the Wenzel-like (HR 120 °C-12 h at a pH of 12) and Cassie state (HR 120 °C-8 h at a pH of 12) superhydrophobic samples, (b) Corresponding Nyquist plots, and (c,d) Bode plots. (e) Corresponding equivalent circuit model based on the PTES modified samples. The measurement is carried out in a 3.5 wt% NaCl aqueous solution.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663789&req=5

f7: (a) Polarization curves of the Wenzel-like (HR 120 °C-12 h at a pH of 12) and Cassie state (HR 120 °C-8 h at a pH of 12) superhydrophobic samples, (b) Corresponding Nyquist plots, and (c,d) Bode plots. (e) Corresponding equivalent circuit model based on the PTES modified samples. The measurement is carried out in a 3.5 wt% NaCl aqueous solution.
Mentions: Polarization is adopted to determine the instantaneous corrosion rate. As shown in Fig. 7, a smaller corrosion current density and bigger corrosion potential difference (∆E) correspond to a lower corrosion rate and better corrosion resistance thereby providing indication of better corrosion resistance. Notably, Icorr [(3.35–9.23) × 10−9 A.cm−2] obtained from the both superhydrophobic states samples is 10–20 times smaller than that of hydrothermal samples [Icorr = (0.55–1.35) × 10−7 A.cm−2] and ∆E is about three times larger. The corrosion current density of the sample in Cassie-Baxter model is about three times smaller than that in Wenzel-like state in NaCl aqueous solution, and far lower than that of most irregularly rough superhydrophobic surfaces on Mg alloy18313241424344, the excellent corrosion resistance performance is due to the regular roughness and orientation of microsheets which extremely decrease the chance of contact between the substrate and solution23.

Bottom Line: A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions.Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane.The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.

ABSTRACT
Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions. Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane. As a result of the trapped air pockets in the microstructure, the super-hydrophobic surface with the Cassie state shows better corrosion resistance in the immersion tests. The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys.

No MeSH data available.


Related in: MedlinePlus