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  Vacuum Systems >> Micro-arc Oxidation MAO System >> Micro-arc Oxidation / Plasma Electrolytic Oxidation System

Micro-arc Oxidation / Plasma Electrolytic Oxidation System




Micro-arc oxidation (MAO) or Plasma Electrolytic Oxidation (PEO) is a plasma-chemical and electrochemical process.  The process combines electrochemical oxidation with a high voltage spark treatment in an alkaline electrolyte, resulting in the formation of a physically protectiveoxide film on the metal surface to enhance wear and corrosion resistance as well as prolonging component lifetime. It is especially suitable for the surface oxidation and pigmentation of aluminum, titanium, niobium, zirconium, magnesium and their alloys. The treated components are used in buildings, mechanics, transportations and energy sectors.  The technology is simple and energy saving and offers high throughput, low cost, high film quality, wide range of color pigmentation  as well as environmental friendliness.






Widely used to enhance the wear, thermal, and corrosion resistance as well as
visual appearance of industrial
 components used in the defense, aerospace,
mechanics, transportation, building, chemical, and biomedical industry.


MAO Colors 


Main specifications:


Oxidation bath:

can be designed and constructed according to the processes

Power supply: 

biopolar pulse mode, Solid-state IGBT switching

Positive polar: 

100 - 800 V

Negative polar: 

20 - 200 V

Mode of output:

constant current, constant voltage and constant power
Frequency:   30Hz - 2kHz
(+)/(-) ratio:    1:1 - 15:1 
Duty cycle: 10% - 80%
Output power:  20kW, 30kW, 50kW, 100kW, 200kW, 400kW
Input power: 3 phases, 380V 50/60Hz




Micro-arc Oxidation MAO treatment Video


Practical Reference:

           Degrease - Rinse - Oxidation - Rinse - Dry up

Terms                   Parameters                   Remarks
Applicable Materials : Al, Ti, Mg and their alloys /
Electrolyte Composition : Main Salt with additive

Main Salt: Sodium Silicate or Sodium Phosphate; Different additives can result in different colors and properties

Electrolyte Concentration : 5 - 50 g/litre for main salt The higher the concentration, the faster the oxidation rate and lower rise-up temperature
Electrolyte pH value : 8 - 13, Alkaline /
Working Voltage : 200 V - 700 V Different alloy and recipe can use different discharge voltage; The surface morphology and oxide properties can be different under different voltage
Current Density : 0.1 - 15 A/dm2 /
Oxidation Rate : 30 -150 um/h /
Power Consumption : 0.008 - 0.1 kWh/um.dm2 /
Temperature : < 50 degree C Cooling system is needed as large amount of heat will be released during the oxidation process
Oxidation Time : 10 - 60 minutes Longer time with denser layer but with rougher surface
Thickness : 10 um  - 200 um /
Reaction Tank : Reinforced Polypropylene /
Anode Fixator : Aluminium alloy /
Cathode Materials : Stainless steel /
Process Procedures : Degrease - Rinse - Oxidation - Rinse - Shielding - Dry up /
Hardness : 500 HV - 3000 HV /
Electrical Isolation : > 100 MegaOhm /
Corrosion Resistance : > 500h salt fog test /
Microstructure : Crystalline /
Surface Status : Rough surface sample can become relatively smooth while smooth surface will become relatively rough after MAO treatment /

Related Scientific Articles:

  1. F. Y. Jin, H. H. Tong, L. R. Shen, K. Wang, and P. K. Chu, "Micro-structural and Dielectric Properties of Porous TiO2 Films Synthesized on Titanium Alloys by Micro-Arc Discharge Oxidization", Materials Chemistry and Physics, vol. 100, no. 1, pp. 31 - 33 (2006).
  2. F. Y. Jin, P. K. Chu, G. D. Xu, J. Zhao, D. L. Tang, H. H. Tong, "Structure and Mechanical Properties of Magnesium Alloy Treated by Micro-Arc Discharge Oxidation Using Direct-Current and High-Frequency Bipolar Pulsing Modes", Materials Science and Engineering A, vol. 435 - 436, no. 1 -  2, pp. 123 - 126 (2006).
  3. F. Y. Jin, P. K. Chu, H. H. Tong, and J. Zhao, "Improvement of Surface Porosity and Properties of Alumina Films by Incorporation of Fe Micrograins in Micro-Arc Oxidation", Applied Surface Science, vol. 253, no. 2, pp. 863 - 868 (2006).
  4. C. B. Wei, X. B. Tian, S. Q. Yang, X. B. Wang, R. K. Y. Fu, and P. K. Chu, "Anode Current Effects in Plasma Electrolytic Oxidation", Surface and Coatings Technology, vol. 201, no. 9 - 11, pp. 5021 - 5024 (2007).
  5. T. Qiu, X. L. Wu, F. Y. Jin, A. P. Huang, and P. K. Chu, "Self-Assembled Growth of MgO Nanosheet Arrays via a Micro-Arc Oxidation Technique", Applied Surface Science, vol. 253, no. 8, pp. 3987 - 3990 (2007).








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