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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

Representative FE-SEM images of the samples treated hydrothermally at 120 °C for (a,b) 8 h and (c,d) 12 h at a pH of 12 and (e) 120 °C for 12 h in DI Water; (f) EDS spectrum acquired from different areas on sample (e): (f1) Flat and (f2) Flower-like zones.
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f1: Representative FE-SEM images of the samples treated hydrothermally at 120 °C for (a,b) 8 h and (c,d) 12 h at a pH of 12 and (e) 120 °C for 12 h in DI Water; (f) EDS spectrum acquired from different areas on sample (e): (f1) Flat and (f2) Flower-like zones.

Mentions: Figure 1 shows the low- and high-resolution FE-SEM images of the Mg alloy after the hydrothermal treatment at 120 °C for 8 h (a–b) and 12 h (c–d) at a pH of 12 in aqueous solutions and for 12 h in DI water (pH ≈ 6.5) (e). A uniform film is formed after the hydrothermal treatment at a high pH. Microsheets with a morphology showing a vertical shape about 1 μm in width to a tilted one about 2 μm in width are produced by increasing the reaction time from 8 h to 12 h (Fig. 1b,d). The inset image in Fig. 1d discloses that the hydrothermal coating comprises two different layers composed of an inner compact layer about 4 μm thick and another 1 μm thick microsheet layer on top. If the hydrothermal time is prolonged, the thickness of the layer increases only slightly but the top uniform microsheet layer is partially damaged (Figures S1 and S2). At a high pH (13 and 14), the microsheets become scarce and even disappear resulting in deteriorated corrosion resistance (Figure S2). On the other hand, in DI water, many flower-like structures integrated with many big microsheets are dispersed on the surface in addition to the flat microsheet coating (Fig. 1e). Selected-area EDS shows strong Al and Mn signals from the flower-like structure (Figs 1f1, 2).


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)

Representative FE-SEM images of the samples treated hydrothermally at 120 °C for (a,b) 8 h and (c,d) 12 h at a pH of 12 and (e) 120 °C for 12 h in DI Water; (f) EDS spectrum acquired from different areas on sample (e): (f1) Flat and (f2) Flower-like zones.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Representative FE-SEM images of the samples treated hydrothermally at 120 °C for (a,b) 8 h and (c,d) 12 h at a pH of 12 and (e) 120 °C for 12 h in DI Water; (f) EDS spectrum acquired from different areas on sample (e): (f1) Flat and (f2) Flower-like zones.
Mentions: Figure 1 shows the low- and high-resolution FE-SEM images of the Mg alloy after the hydrothermal treatment at 120 °C for 8 h (a–b) and 12 h (c–d) at a pH of 12 in aqueous solutions and for 12 h in DI water (pH ≈ 6.5) (e). A uniform film is formed after the hydrothermal treatment at a high pH. Microsheets with a morphology showing a vertical shape about 1 μm in width to a tilted one about 2 μm in width are produced by increasing the reaction time from 8 h to 12 h (Fig. 1b,d). The inset image in Fig. 1d discloses that the hydrothermal coating comprises two different layers composed of an inner compact layer about 4 μm thick and another 1 μm thick microsheet layer on top. If the hydrothermal time is prolonged, the thickness of the layer increases only slightly but the top uniform microsheet layer is partially damaged (Figures S1 and S2). At a high pH (13 and 14), the microsheets become scarce and even disappear resulting in deteriorated corrosion resistance (Figure S2). On the other hand, in DI water, many flower-like structures integrated with many big microsheets are dispersed on the surface in addition to the flat microsheet coating (Fig. 1e). Selected-area EDS shows strong Al and Mn signals from the flower-like structure (Figs 1f1, 2).

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