Product Information (Hard Alumite)

1 / 5Hard Anodic Oxide Coating(Hard Alumite)
HARD ANODIZE(HARD ANODIC COATINGS)

Riken Alumite Industry’s hard anodizing technology provides reliability and durability for customers.

Meets the U.S. military specification MIL-A-8625F Amendment 1 Type III

Our hard anodic oxide coating has been applied to products in a wide range of fields such as satellite
and aircraft parts and industrial machinery.

Hard alumite is a hard coating which is thicker and has greater abrasion resistance compared tocommon sulfuric acid alumite. In the Japanese Industrial Standards (JIS) H8603:1999 “Hard Anodic
Oxide Coatings on Aluminum and its Alloys” and ISO 10074:1994 (the latest version was issued in2017) “Hard Anodic Oxidation Coatings on Aluminum and its Alloys”, hard alumite is defined as “ananodic oxide coating formed on aluminum materials in a cold electrolytic bath or special electrolyticbaths prepared by applying various types of organic acid. Hard alumite is harder and superior inabrasion resistance compared with coatings treated with conventional methods.” With our establishedtechnologies and know-how, we have offered hard alumite excellent in quality and abrasion resistancecomparable to that for hard chrome plating.

Features◎ Abrasion resistance: Especially excellent in sliding wear resistance with a good galling

resistance.
◎Thickness: A thicker coating compared to conventional coatings compensates for the softness ofaluminum and enhances product strength. This property is best exhibited at a thickness of 30 to 50μm.
◎Hardness: The coating provides a hardness of around 50HV greater than that shown in the JIS-H8603 standard (Table1). (Depending on the type of alloy, hardness sometimes increases by 100HV orgreater.)◎Electrical properties: The specific resistance of hard alumite is reported to be approximately 4 x

Riken Alumite Industry Co., LTD.

Product Information (Hard Alumite)2 / 51015Ω·cm at 20 °C. Its breakdown voltage is so high that 1000 series alloys coated with a thickness of25μm withstand the voltage of DC250V and that with a thickness of 50μm withstand the voltage
ranging from DC800 to 1000V. This property allows hard alumite to be used as an insulating coating
applied to heat sinks and other applications.

Table 1: Performance required by JIS H8603:1999/ISO10074:1994

Riken Alumite Industry Co., LTD.

Product Information (Hard Alumite)

Class

Material

3 / 5

CoatingAbrasive

Abrasive

Taber's

Coating

Test Items (byHardness

Wheel Wear

Jet Test

Abrasion

Massthe agreement

0.05HV

Test

Resistancemg/dm2

between parties

Test
≥ 400

≥ 80 %≥ 80 %≤ 15.0 mg

concerned)≥ 1100ClassWrought1

alloys otherthicknessthan those in

2. Corrosion

Class 2

resistance (For≥ 250≥ 30 %≥ 30 %≤ 35.0 mg≥ 950

1. Coating

sealedClass

2000 series

2-(a)wroughtmaterials, it isalloys

impossible to≥ 300≥ 55 %≥ 55 %≤ 25.0 mg

By theattain both

wrought

agreement

corrosion andalloys

between theabrasion

parties

resistances: No

concerned

corrosion afterClass

7000 series

2-(b)5000 series
wrought

336h of salt

alloysspray test—only

containing

applicable to≥2% of Mg

Class 1)
3. DielectricstrengthClass

Castings

3-(a)containing <≥ 250

By the agreement between the parties concerned

2 % of Cuor < 8% ofSiClass

Castings

By the3-(b)other thanagreement

those inbetweenClass 3-(a)the parties
concerned

Standard performance and quality assurance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - *Note that the following standard performances are inapplicable to alloys containing 5 % or more ofCu or 8% or more of Si. Please contact us for performance and quality assurances for the above-

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Product Information (Hard Alumite)

4 / 5

mentioned alloys.
◎Coating thickness: The thickness is specified based on the agreement between the parties concerned.
*The standard coating thickness for the anodic coating Type III in the MIL-A-8625 is 50.8 ± 10.2 μm(0.002 ± 0.0004"). The thickness generally ranges from 25.4 to 76.2μm with the acceptable coating
thickness tolerance of a specified thickness ±10.2 μm or ± 20 %.
(Please contact our sales department for the details of the possible coating thickness and tolerance
because both values vary depending on the type of alloy. Since it is also possible to finish the productcoating within the specified size tolerance, please feel free to contact us. We will provide the test
results for individual products when required. To measure coating thickness, please note that
depending on the product shape, some products only require non-destructive testing, while otherproducts require destructive testing and cross-sectional observation/measurement. (Cross-sectional
observation/measurement will require a cut-out specimen, time for delivery, and cost.)◎Abrasion resistance: ASTM D4060 Taber® Abrasion Test (with a 1000 g load, CS-17 abrasivewheel, and 10000 cycles)
For alloys with a Cu content of 2% or higher (e.g.

A wear index of 3.5 mg/1000 cycles or2000 series)

lessFor wrought alloys other than the above-mentioned

A wear index of 1.5 mg/1000 cycles oralloys

less(Abrasion resistance is applied only to unsealedalloys.)◎Coating hardness: Refer to Table 1. (Coating hardness shown in the Table 1 is inapplicable to thatspecified by the MIL-A-8625.)◎Corrosion resistance (only applicable when sealing treatment is required): Guaranteed by ASTM
B117 salt spray test for 336 hours

Applicable Standards - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -MIL-A-8625 Type III Classes 1 and 2 (the latest version: F Amendment 1)
SAE-AMS 2469 and other aeronautical standards
Sealing - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Various standards clearly specify that sealing treatment should not be applied in the case whereabrasion resistance is included in the performance requirements for a coating. Sealing treatment is

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Product Information (Hard Alumite)

5 / 5applied when corrosion resistance is required. However, sealing treatment dramatically reduces
abrasion resistance. In the case where sealing treatment is required, therefore, there is a rule thatabrasion resistance should not be pursued. However, unsealed anodic oxide coatings can be easily
stained, which compromises product appearance. For applications requiring superior quality inappearance, therefore sealing treatment should be applied at the expense of abrasion resistance.

At the Riken Alumite Industry, we have offered various types of sealing treatment such as nickel
acetate sealing treatment, dichromate sealing treatment, and steam sealing treatment.

Design Information - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ◎Depending on the type of alloy, the workability varies and the coating performance obtained after
hard alumite coating differs: The type of alloy should be appropriately selected in consideration ofcoating performance to be obtained.
◎After coating, the surface of a product increases in thickness by approximately one half of thecoating layer thickness, leading to an increase in product size: The product size before anodizing
should be determined in consideration of the size change due to coating.
◎Sufficient coating would not be achieved when an object has sharp corners: In order to prevent theloss of coating at the corners, a 0.2 R chamfering is required for a 25 μm coating, and 0.3 R for a 50μm coating.
◎In the coating of a product consisting of assembling components, electrolytic solution is likely toremain on the product surface, leading to erosion of the product. This type of product is recommendedto be assembled after anodizing.
◎Please contact our sales staff for coating of a part with strict size tolerance, such as a mating part.
We will provide a coating plan tailored to each product. It is also possible to mask the parts where
coating is unnecessary.

Riken Alumite Industry Co., LTD.