Anodization of AZ91 magnesium alloy in alkaline solution containing silicate and corrosion properties of anodized films

The corrosion behavior of duplex Ni-P coatings deposited on AZ91 magnesium alloy was studied. The electroless deposition process of duplex Ni-P coating consisted in the preparation of low-phosphorus Ni-P coating (5.7 wt.% of P), which served as a bond coating and high-phosphorus Ni-P coating (11.5 wt.% of P) deposited on it. The duplex Ni-P coatings with the thickness of 25, 50, 75 and 100 µm were deposited on AZ91 magnesium alloy. The electrochemical corrosion behavior of coated AZ91 magnesium alloy was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization method in 0.1 M NaCl. Obtained results showed a significant improvement in the corrosion resistance of coated specimens when compared to uncoated AZ91 magnesium alloy. From the results of the immersion tests in 3.5 wt.% NaCl, 10% solution of HCl and NaOH and 5% neutral salt spray, a noticeable increase in the corrosion resistance with the increasing thickness of the Ni-P coating was observed.

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Effect of Sc on Microstructures and Corrosion Properties of AZ91

Materials Science Forum ◽

10.4028/www.scientific.net/msf.546-549.139 ◽

2007 ◽

Vol 546-549 ◽

pp. 139-142 ◽

Cited By ~ 9

Author(s):

Su Juan Yao ◽

Dan Qing Yi ◽

Sheng Yang ◽

X.H. Cang ◽

W.X. Li

Keyword(s):

Magnesium Alloy ◽

Electrochemical Technique ◽

Second Phase ◽

Az91 Magnesium Alloy ◽

Corrosion Properties ◽

Corrosion Resistant ◽

Az91 Magnesium

The microstructures and corrosion properties of AZ91 magnesium alloy with trace additions of Sc were investigated. The microstructures were observed by OM and SEM, and the corrosion properties were studied by electrochemical technique. The results show that the alloys with Sc form a second-phase Al3Sc, the grains become finer with the increasing content of Sc and the microstructure is the finest when Sc content up to 0.6%, the corrosion resistant of alloy combining with Sc is improved.

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Microstructural, Mechanical and Corrosion Properties of AZ91 Magnesium Alloy Processed by a Severe Plastic Deformation Method of Hydrostatic Cyclic Expansion Extrusion

Metals and Materials International ◽

10.1007/s12540-020-00828-0 ◽

2020 ◽

Author(s):

Armin Siahsarani ◽

Farshad Samadpour ◽

Mohammad Hossein Mortazavi ◽

Ghader Faraji

Keyword(s):

Plastic Deformation ◽

Magnesium Alloy ◽

Severe Plastic Deformation ◽

Az91 Magnesium Alloy ◽

Deformation Method ◽

Corrosion Properties ◽

Az91 Magnesium ◽

Mechanical And Corrosion Properties

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Effect of Strontium on Corrosion Properties of AZ91 Magnesium Alloy

Electrochemical and Solid-State Letters ◽

10.1149/2.021111esl ◽

2011 ◽

Vol 14 (11) ◽

pp. C21 ◽

Cited By ~ 15

Author(s):

W. C. Kim ◽

N. D. Nam ◽

J. G. Kim ◽

J. I. Lee

Keyword(s):

Magnesium Alloy ◽

Az91 Magnesium Alloy ◽

Corrosion Properties ◽

Az91 Magnesium

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Sealing of PEO Coated AZ91 Magnesium Alloy Using La-Based Solutions

International Journal of Corrosion ◽

10.1155/2017/5305218 ◽

2017 ◽

Vol 2017 ◽

pp. 1-13 ◽

Cited By ~ 12

Author(s):

Luca Pezzato ◽

Katya Brunelli ◽

Riccardo Babbolin ◽

Paolo Dolcet ◽

Manuele Dabalà

Keyword(s):

Corrosion Resistance ◽

Magnesium Alloy ◽

Photoelectron Spectroscopy ◽

Az91 Alloy ◽

Az91 Magnesium Alloy ◽

Corrosion Properties ◽

X Ray ◽

Different Temperatures ◽

Az91 Magnesium ◽

Sealing Treatment

In this work, solutions containing lanthanum salts were used for a post-treatment of sealing to increase the corrosion resistance of PEO coated AZ91 alloy. PEO coatings were produced on samples of AZ91 magnesium alloy using an alkaline solution containing sodium hydroxide, sodium phosphates, and sodium silicates. The sealing treatment was performed in a solution containing 12 g/L of La(NO3)3at pH 4 at different temperatures and for different treatment times. Potentiodynamic polarization test, an EIS test, showed that the sealing treatment with solution containing lanthanum nitrate caused a remarkable increase in the corrosion resistance. The corrosion behavior was correlated with the surface morphology and elemental composition evaluated with scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In particular, the sealing treatment at 50°C for 30 min resulted in being the most promising to increase the corrosion properties of PEO treated samples because of the formation of a homogeneous sealing layer, mainly composed of La(OH)3.

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