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Anodizing/Type II anodizing
Usually, anodizing refers to aluminum anodizing or aluminum alloy anodizing.
Aluminum anodizing is a process that uses aluminum products or aluminum alloy products as anodes, places them in an electrolyte for charging, and forms an aluminum oxide film on the surface of the product through electrolysis.
After anodizing treatment, the oxide film generated on the surface of aluminum can reach several micrometers to several hundred micrometers. If anodizing is not specified, it usually refers to sulfuric acid anodizing.
In general, the film thickness of Type II anodizing for aluminum alloys is 5-8 ¦Ì m.
Ordinary aluminum alloy anodizing (Type II Anodizing) is not suitable for cast aluminum. Because the anodizing effect of cast aluminum is not good, the surface has no luster, and the color can only be black.
The principle of aluminum anodizing is essentially the principle of water electrolysis.
When current passes through, the following reactions occur:
On the cathode, H2 is released according to the following reaction:
2H + + 2e ¡ú H2
On the anode,
4OH-4e ¡ú 2H2O + O2
The precipitated oxygen is not only molecular oxygen (O2), but also atomic oxygen (O) and ionic oxygen (O-2). Usually, they are represented by molecular oxygen in the reaction.
Aluminum used as an anode will be oxidized by the oxygen released from it, forming an anhydrous Al2O3 film:
2Al + 3[O] = Al2O3 + 1675.7KJ.
It should be pointed out that not all generated oxygen interacts with aluminum, and some of it precipitates in gaseous form.
cathodic reaction
H2£º2H + + 2e ¡ú H2
anode reaction
4OH - 4e ¡ú 2H2O + O2
Al2O3 coating:
2Al + 3[O] = Al2O3 + 1675.7KJ
Available types: Black anodizing, Sandblasting Black anodizing, Sandblasting Bright Black anodizing. B. Blast bright black anodized. Black anodized (without sandblasting). Remove anodizing.
Red anodizing
Black anodizing
Transparent anodizing
