Rare Earth Conversion Coating of Magnesium Alloy AZ91D

2007 ◽  
Vol 546-549 ◽  
pp. 555-558
Author(s):  
Li Qun Bai ◽  
Di Li ◽  
Min Guo ◽  
Jing Xin
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Magnesium Alloy ◽  
Electrochemical Behavior ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Alloy Az91d ◽  
Chemical Conversion Coating ◽  
Chloride Environment ◽  
Surface Morphologies

Rare earth chemical conversion coating of Mg alloys was studied. Corrosion and electrochemical behavior in chloride environment were investigated with tests of evolution of hydrogen and electrochemical measurements. The surface morphologies and composition of rare earth conversion coating were studied through SEM, EDAX and XPS. The results showed that rare earth conversion coatings could improve corrosion resistance and their corrosion resistance was comparable with that of chromate coatings (HB/Z5078278). This result was further proved by Polarization and EIS.

Effect of Chrome-Free Chemical Conversion Coating on Corrosion Behavior of Magnesium Alloy AZ91D

2006 ◽  
Vol 15-17 ◽  
pp. 473-478
Author(s):  
Li Qun Bai ◽  
Di Li ◽  
Bao Lan Guo ◽  
Min Guo
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Salt Spray ◽  
Chemical Conversion ◽  
Electrochemical Measurement ◽  
Conversion Coating ◽  
Hydrogen Gas ◽  
Az91d Magnesium Alloy ◽  
One Step ◽  
Chemical Conversion Coating

The different chrome-free chemical conversion coatings were prepared on AZ91D magnesium alloy and SEM was used to observe the surface. The corrosion behaviors of die-casting AZ91D magnesium alloy with different coating in chloride environment were investigated by hydrogen gas evolution in immersion test, salt spray test and electrochemical measurement. The results showed that the corrosion resistance of magnesium alloy treated with two-step chemical conversion and sealing was the highest and was comparable with that of chromating, and followed by two-step chemical conversion treatment without sealing. The one-step chemical conversion treatment had the lowest corrosion resistance. Polarization and EIS characteristics in 5% NaCl solution depended on the type of surface treatment and correlated well with the order of corrosion resistance. Contrasted with one-step chemical conversion coating, the coating of two-step chemical conversion with sealing on magnesium alloy had more excellent corrosion resistance because the |Z| increased, the corrosion area was decreased and the time of the first pitting occurrence was prolonged. It is expected that this experiment can provide a foundation for designing more super chemical conversion coating to replacing the chromate conversion.

Cerium-based chemical conversion coating on AZ63 magnesium alloy

2003 ◽  
Vol 172 (2-3) ◽  
pp. 227-232 ◽  
Author(s):  
Manuele Dabalà ◽  
Katya Brunelli ◽  
Enrico Napolitani ◽  
Maurizio Magrini
Keyword(s):  
Magnesium Alloy ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Chemical Conversion Coating

Formation and Properties of Zr/Ti Based Nano-Sized Non-Chromium Chemical Conversion Coating on AA 5083

2019 ◽  
Vol 19 (6) ◽  
pp. 3487-3494 ◽  
Author(s):  
Bin Liu ◽  
Yi Zhao ◽  
Liang Li ◽  
Yafei Feng ◽  
Zhigang Fang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Acidic Solution ◽  
Salt Spray ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Dense Layer ◽  
Environment Friendly ◽  
Chemical Conversion Coating ◽  
Inhibitive Action ◽  
Nano Size

An environment-friendly non-chromium chemical conversion coating was obtained from fluozirconate/fluotitanate acidic solution for the corrosion protection of AA 5083. The surface morphology, composition, electrochemical behavior and corrosion resistance of this coating were investigated. The coating was found to be a homogeneous and dense layer consisting of nano-size particles, of which the major component was compound oxides consisted by Al, Mg, Zr, Ti, F and O. The results of electrochemical measurements, immersion and natural salt spray (NSS) tests demonstrated that the corrosion resistance of the AA 5083 H-116 was improved by the nano-sized non-chromium chemical conversion coating considerably, which was most attributed to the great inhibitive action on the anodic dissolution by acting as a protective barrier layer.

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