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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Micro-arc oxidation (MAO) vs. plasma electrolytic oxidation (PEO)
Q. Hello:
I am a university student. I am searching some information about a method to protect aluminium named PEO (Plasma Electrolytic Oxidation). If there is any help available, it will be gratefully appreciated.
Thanks.
seckin tohumcustudent - bursa, turkey
2003
April 2, 2009
A. Hi,
PEO means plasma electrolytic oxidation.
This process is applied on light metals like aluminium, titanium, magnesium, ...
This process needs a nice power supply with min. 600 volt output in bipolar and constant current mode.
This process has 2 issues:
1- electronics hardware (how to apply voltage and current applied) that are needed.
2- electrolytic chemicals
- tehran, iran
2007
I am helping my boss search for surface treatment technology on Mg for bike frames,
what is the difference between MAO and patented chrome-free technology by Keronite UK.
Anyone know where I can get this patent .
folding bikes - Shenzhen, China
2007
A. Micro-arc oxidation and plasma electrolytic oxidation are both chrome-free. I don't know the differences.
According to Keronite's website, a semi-automatic Keronite PEO surface treatment line is being installed in partnership with Chongqing Meridian BoAo Magnesium Co. Ltd (CMBM) in Chongqing, China. Keronite already has a production line in Kunshan near Shanghai. Contact them for more information and perhaps have some sample frames coated for testing. The coating is possibly too rigid to withstand much flexing. Let us know if you find out.
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
A. There is no difference between "MAO" (Micro Arc Oxidation) and "PEO" (Plasma Electrolytic Oxidation). The former was a more widely used name before academics such as Dr Yerokhin (see Journal of Surface and Coatings Technology, issue 222, p.73-93) began to question the true scale and nature of the "arcs" (discharges) and proposed what was supposed to be a less controversial name.
I should point out, however, that there are very wide performance variations within the field. A lot of older MAO technologies cannot match the performance of newer, more advanced, technologies (which tend to be referred to by the newer name "PEO"!).
As far as rigidity is concerned, some PEO coatings are in very compliant. They have a global modulus of ~30 GPa and as such, they are actually less stiff than aluminum substrates. This low modulus means they can tolerate high strains without experiencing high stresses.
For more technical detail, have a look at this paper:
"Thermo-physical Properties of Plasma Electrolytic Oxide Coatings on Aluminium", Curran, J.A. and Clyne, T.W., Surface and Coatings Technology, v.199(2-3), pp.168-176 2005.
- Cambridge, United Kingdom
2007
A. Corbin,
Your first respondent was correct about the Keronite facilities in China.
There should be no problem with flexibility of the Keronite layer on this application, assuming the flexions are within the elastic limit of the frame.
Regards,
- Cambridge, UK
2007
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Ed. note: For more discussions on PEO/MAO, please see also letter 685 "Microarc Oxidation Q&A's"
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