Product Information (Sulfuric Acid Alumite)

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Sulfuric Acid Anodic Oxide Coating(Sulfuric Acid Alumite)
NODIZE(Anodic Coatings for Aluminum and Aluminum Alloys)________________________________________
Sulfuric acid alumite is the most popular type of alumite, which is a coating produced by anodizing ofaluminum in a sulfuric acid aqueous solution. Since sulfuric acid alumite is produced with a simple
technique, even small-scale facilities can produce sulfuric acid alumite having a reasonable finish
without applying any special quality control. Nonetheless, as a matter of course, quality control isessential in supplying products of stable quality. You can rest assured in this respect. Our company has
supplied products of stable quality through ensuring solution management and temperature control
and utilizing the know-how we have accumulated until now. We have applied not only pure water(deionized water) for preparation of treatment solution but also reverse osmosis (RO) water for rinsing
which is produced by removing salt from water with a reverse osmosis technique. We have one of thelargest processing lines among specialized manufacturers, allowing us to handle large-sizedcomponents. Regarding pore-sealing treatment, we offer various types of sealing such as dichromate,steam, hot water, and cold sealings in addition to nickel acetate sealing. It is possible to select the mostappropriate sealing according to the product’s intended application.
*Other types of sealing besides the above-mentioned sealings are also available. Please contact oursales staff for more information.

図中語句
日本語

英語

アルマイト皮膜

Anodic oxide coating (alumite)

アルミ素地

Aluminum substrate

孔の数Number of pores

孔壁厚さ

Pore wall thickness

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Product Information (Sulfuric Acid Alumite)

孔径Pore size

バリアー層厚さ

Barrier layer thickness

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Pore wall thickness = 16 nm
Pore size = 12 nm
Barrier layer thickness= 20 nm
Features - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ◎Appearance: For corrosion-resistant alloys, the transparent coating of sulfuric acid alumite provides
a silver-white appearance while maximizing the metallic texture of aluminum. Integral colors may besometimes observed depending on the type of alloy and the thickness of coating (refer to Table 1).
Table 1: Major types of aluminum alloy and their spontaneousType of Alloy
Color ofType of Alloy(Wrought Alloy)
Coating(Casting/Die Casting)
1000
Pure aluminum
Al-Cu
Silver white
AC1A/AC1B
Seriesfor industrial useseries
2000
Al-Cu series
Gray white
SeriesAC2A/B
3000
Al-Mg series
Silver white
AC4A/B/C/D
Al-Si series
Series
AC8A/B
4000
Grayish
Al-Si series
Seriesblack5000
Al-Mg
Al-Mg series
Silver white
AC7A
Seriesseries6000
Al-Mg-Si series
Silver white ADC10/ADC12
Si series
SeriesSilver white
7000
Al-Zn-Mg(-Cu)
or light
ADC5/ADC6Mg series
Seriesseriesyellow

Color ofCoating
Gray white

Gray

Silver white
Brown orcharcoal graySilver white◎Dye-affinity: Sulfuric acid anodic oxide coating allows colorful dyeing because of its clearness andgood adsorption property. Abrasion resistance: Sulfuric acid anodic oxide coating is especially
excellent in sliding wear resistance with a good galling resistance.
◎Corrosion resistance: In general, the thicker the coating, the better the corrosion resistance. However,when used without painting, excessively thick coating may develop cracks leading to reduction incorrosion resistance. The optimum coating thickness to prevent corrosion is 15 to 20μm. Dependingon the type of alloy, coating of 30μm or greater in thickness is also available.
◎Protection of products: Sulfuric acid alumite protects products from scratch, abrasion, and corrosion
in general applications. For products used under harsh environments, please consider applying hardalumite or oxalic acid alumite .

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Table 2: Performance of anodic oxide coating by aluminum material
Wrought
Alloy
1000
Series
3000
Series
3000
Series
4000
Series
5052
5056
5083
60616063
7000
SeriesPerformance of Anodic Oxide Coating
AbrasionCorrosion Colori Luste
ResistancProtectionngre

Casting/Die
Casting

Performance of Anodic Oxide Coating
AbrasionCorrosion Colorin Luste
ResistancProtection
gre

A

A

A

A

AC2A

△××△

CB

DC

AC4C

○××△

A

B

CA

AC7A

○○○○B

C to DDB

AC8A△××△◎◎◎◎◎◎◎○◎◎○○△△○◎◎◎◎◎△××△○○○○△○△v

ADC10ADC12ADC5ADC6Riken Alumite Industry Co., LTD.

Product Information (Sulfuric Acid Alumite)

4 / 6Standard performance and quality assurance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ◎Meets the performance requirements of the U.S. military specification MIL-A-8625 Type II(Guaranteed by salt spray test (ASTM B117) for 336 hours using material 2024-T3 with a coating
thickness of 10 to 15μm; coating weight 1000mg or greater/ft2 [10.75g or greater/m2])◎Meets JIS H8601:1999 Class A (With the exception of the coating thickness test, any of thefollowing coating performance tests, when required, will be outsourced.)
Table 3: Coating thickness grade and coating performance (JIS H8603:1999 Anodic Oxide Coatings
for Aluminum and Aluminum Alloys)
Coating Thickness (μm)
Minimum
Local
Thickness

Average
Minimum
Thickness

AA3
AA5

2.4
4.0

3.0
5.0

AA6

4.8

6.0

AA10

8.0

10.0

AA15

12.0

15.0

AA20

16.0

20.0

AA25

20.0

25.0

GradeCorrosion ResistanceAlkaline Corrosion
CASSResistance
TestJIS H8681-1
JISH8681-2
Class AClass B
30 sec orlonger
50 sec orlonger
75 sec orlonger
100 sec
or longer
125 sec
or longer

90 sec orlonger
150 sec
or longer
225 sec
or longer
300 sec
or longer
375 sec
or longer

8h
16 h
32 h
56 h
72 h

Abrasion Resistance JIS H8682
SandAbrasive
FallingAbrasive
Wheel
Abrasion
Jet Test
WearResistance
Test
Test
150 sec or
longer
30 cycles
500 sec or 24 sec oror more
longerlonger--------750 sec or 36 sec or
Coatinglonger
longerwear
1000 sec
48 sec or(μm)
or longerlonger1250 sec60 sec oror longerlonger(RN9.0 or greater)
Note: When high-pressure steam sealing treatment is applied, the conditions shown for Class B in thetable above are also applicable. The conditions shown in the above table are exclusively applicable toquality assurance of corrosion-resistant wrought alloys.
Applicable Standards - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - MIL-A-8625 Type II Classes 1 and 2 (the latest version: F Amendment 1)
SAE-AMS 2471&2472, and other aeronautical standards
Sealing - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Hot water sealing and steam sealing are pore-sealing treatments utilizing hydration reactions of anodicoxide coating. With the hydration reactions, microscopic pores of anodic oxide coating are sealed off,
while the coating becomes chemically inactivated. The sealing treatment improves corrosion
resistance and stain resistance of coating, which is also applied to dye fixing for dyed products. Innickel acetate sealing, orifices of microscopic pores are filled with deposits, thus preventing dyebleeding and providing excellent corrosion resistance and surface smoothness. The MIL-A-8625
specifies that pores of non-dyed coating should be completely sealed off in 5% sodium dichromate,
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potassium dichromate, acetate, or other suitable solutions. The high-pressure steam sealing developedby the Institute of Physical and Chemical Research (RIKEN) allows the maximum-level hydration
sealing treatment and provides outstanding corrosion resistance. At the Riken Alumite Industry, weoffer nickel acetate sealing treatment, dichromate sealing treatment, deionized water (hot water)
sealing treatment, and high-pressure steam sealing treatment.
In cold sealing treatment also called pseudo-sealing treatment, chemical reactions at around ambient
temperature between nickel fluoride or other chemicals and the inner surface of pores chemicallyinactivate anodic oxide coatings leading to improvement of corrosion resistance.
Design Information - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ◎Size change: Depending on the material of products and the coating thickness, after coating, thesurface of a product generally increases in thickness by approximately one third the coating layer
thickness, leading to an increase in product size. Meanwhile, reduction in size during pretreatment
must also be considered. Products with strict requirements for their finished size therefore needadjustment before coating.
◎Products with complex shapes and assembled products: Sulfuric acid alumite is produced by using
sulfuric acid which is a strong acid as the electrolytic solution. Concerning the objects whereelectrolytic solution is highly likely to remain such as products with complex shapes, components withdeep blind holes, and products assembled by using welding, riveting and other methods, the residual
electrolytic solution may cause problems including corrosion and discoloration. When sulfuric acidanodization is applied to those types of object, the problems mentioned above may be prevented fromoccurring with post-processing, coating applied separately for individual components, and masking ofany gaps.
◎Electrical insulation: The anodic oxide coating has electrical insulation properties.
For the sites requiring electrical contacts, electrical contacts can be secured by removing the coating
through post-processing or leaving the conductive substrate uncoated with prior masking. Note thatthe insulation resistance may vary depending on use environment. Please be careful when using ananodic oxide coated-product as an insulator.
◎Precautions pertaining to chemical substances: Since containing sulfate, the coating elutes sulfate
ions in water and releases SOx and water vapor in a low-pressure or high-temperature environment.
Sulfuric acid alumite sealed by nickel acetate may elute very small quantity of nickel.
Table 4: Coating thickness grade and major applications (JIS H8601:1999)
Coating Thickness GradeMajor Application

AA3

Reflectors, electrical parts (internal parts), etc.

AA5

Kitchen utensils, household products, home appliance parts,

AA6

decorative products, furniture components, vehicle interiors,

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Product Information (Sulfuric Acid Alumite)

AA10

building components (indoors)

AA15Kitchen utensils, vehicle exteriors, civil engineering andAA20

architectural materials, ship parts

AA25

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