Do you know anything about anodizing（anodic oxidation）

Jan 28,21

Do you know anything about anodizing（anodic oxidation）

****What is anodizing？

anodizing of aluminum and aluminum alloy is a process in which aluminum or aluminum alloy products are used as anodes and put into electrolyte solution for electrifying treatment, and aluminum anodizing film is formed on the surface by electrolysis. After anodizing, several micrometers to hundreds of micrometers of oxide film can be formed on the surface of aluminum. Compared with the natural oxide film of aluminum alloy, the corrosion resistance, wear resistance and decoration of the film are obviously improved.

****What is the anodizing standard？

1. Black anodizing as per Mil-A-8625 Type2 Class2 Thickness 12-18um;

1.2 Clear anodizing as per Mil-A-8625 Type2 Class1 Thickness 8-12um
1.3 Hard anodizng as per Mil-A-8625 Type3 Class1 Thickness 30-80um
1.4 Black hard anodizing as per Mil-A-8625 Type3 Class2 Thickness 30-80um
1.5 Yellow chromate(Gold Iridite) as per Mil-C-5541 Class 2 Thickness 1-3 um;
1.6 Clear chromat(Iridite) as per Mil-C-5541 Class1 Thickness 1-3 um
1.7 Dyed anodizing as per Mil-A-8625 Color according to customer’s requirements;

1. 1.8 Sand blasting

****Types of hard anodizing

1. 1.1.1.1.1
2. PAA (phosphoric acid anodizing) is mainly used to increase the adhesion of coating substrate
3. 1.1.1.1.2
4. CAA (chromic acid anodizing) mil 8625f type I or IB, AMS 2470k, ISO 8076, ISO 8077, BAC 5019, BAC 5884, and HP 4-35 is a common anodizing technology for high dimensional precision spacecraft parts. The thickness of CAA oxidation film is less than 5um, which has high environmental performance and can avoid the disadvantages of hard oxidation which reduces the fatigue life of materials. It is widely used in aerospace.
5. 1.1.1.1.3
6. BSAA (boric sulfuric acid anodizing) is used to produce thin oxide film instead of CAA to avoid hexavalent chromium pollution
7. 1.1.1.1.4
8. SAA (sulfuric acid anodizing, mil 8625 type II, AMS 2471, AMS 2472) is the most common anodizing technology, which is widely used in aerospace and other fields
9. 1.1.1.1.5
10. Tfsaa (thin film sulfuric acid anodizing mil 8625 type IIB) thin sulfuric acid anodizing can also be obtained by BSAA. While maintaining the dimensional accuracy, it can provide good performance as saa-yang'w and provide the base for the coating.
11. 1.1.1.1.6
12. HCA (hard coat anodizing: hard anodizing, mil 8625f type III, AMS 2469) hard anodizing, wear-resistant and high hardness anodizing. Due to the influence on the fatigue life of materials, the application of HCA in aerospace field is relatively cautious.
13. 1.1.1.1.7
14. THCA (Teflon hard coat anodize + Teflon permeation composite anodizing, mil-a-63576a type II type III, AMS 2482)
15. 1.1.1.1.8
16. Passivation & chemfilm (passivation and chemical conversion coating, mil-c-5541, class 1a, class 3, type II, mil-dtl-81706b, AMS 2473, alodine, surtec), chemical conversion coating.

****MIL-DTL-5541F

1. MIL-DTL-5541F chemical protective coatings on aluminum and aluminum alloys
2. MIL-DTL-5541F
3. Superseeding instead
4. MIL-C-5541E
5. Chemical coating on aluminum and aluminum alloy
6. 1. Scope
7. 1.1 this specification is applicable to the protective coating formed on the surface of aluminum products and aluminum alloy due to chemical material reaction.
8. 1.2 chemical conversion coatings are of the following types and grades.
9. 1.31. Chemical conversion coatings are classified into the following types (see 3.1):
10. 1.4 model I - contains hexavalent chromium.
11. Type II - composition does not contain hexavalent chromium
12. 1.2.2 grade. The materials of protective coating formed by chemical reaction for aluminum products and aluminum alloy products are divided into the following grades (see 6.1 and 6.4)
13. Class 1A - for maximum corrosion protection, painted or unpainted protective coatings
14. Class 3 - anti corrosion coatings for low resistance requirements

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Do you know anything about anodizing（anodic oxidation）