OX-W – Hard White Anodizing

OX-W is a special hard anodizing treatment of aluminium in conformity with MIL-A-8625 Type III, ISO 10074 and UNI 7796 standards. Compared to traditional hard anodizing treatment, the OX-W treatment has been developed to increase hard anodizing characteristics and obtain a more compact and uniform aluminium oxide layer, with less roughness and greater corrosion resistance.

Main properties of hard white anodizing


High corrosion resistance
The compact OX-W layer protects the base material from corrosion and brilliantly withstands 336 hours of exposure to salt mist without any corrosive attack.

High wear resistance and hardness
The hardness and compactness of the aluminium oxide layer permits obtaining high abrasive and adhesive wear resistance comparable to that of hard chrome.

Compact and smooth layer
The OX-W treatment creates a more compact and uniform layer of aluminium oxides with less roughness compared to traditional hard anodizing treatment.

Light colour
The OX-W treatment has a light grey colour with shades that depend on the treated aluminium alloy.

Low friction OX-W-PTFE variant
To lower the friction coefficient and give non-adhesion properties, the OX-W treatment can be impregnated with PTFE nanoparticles.

Technical specifications

Composition and applicable standards

Composition
The OX-W treatment transforms the base aluminium into a compact layer of aluminium oxide. The composition therefore largely depends on the initial alloy.
Al O S Impurities
20÷40% 50÷70% 3÷5% Depending on the alloy

Product technical standards
ISO 10074
UNI 7796
MIL-A-8625 | Type III

RoHS Conformity
RoHS conform. No restricted-use substances beyond maximum tolerated concentrations.

REACh Conformity
REACh conform. No SVHC in quantities greater than 0.1% by weight.

Anodizable alloys

Anodizable alloys
Wrought alloys Hardness Wear resistance Corrosion resistance Max thickness
Series 2000 ★★★☆☆ ★★★☆☆ ★★★☆☆ ★★★☆☆
Series 5000 (with >2% Mg) and 7000 ★★★★☆ ★★★★☆ ★★★★☆ ★★★★★
Series 6000 (except 6082, 6061) ★★★★★ ★★★★★ ★★★★★ ★★★★★
6082, 6061 ★★★★★ ★★★★★ ★★★★★ ★★★★☆
Casting alloys Hardness Wear resistance Corrosion resistance Max thickness
Alloys with Si>8% or Cu>2% ★☆☆☆☆ ★☆☆☆☆ ★☆☆☆☆ ★☆☆☆☆
Die-casts with Si<8% or Cu<2% ★★☆☆☆ ★★☆☆☆ ★★☆☆☆ ★☆☆☆☆
Other alloys ★★☆☆☆ ★★☆☆☆ ★★★☆☆ ★★★☆☆

Coating thickness and aesthetic appearance

Coating thickness
Standard thickness Tolerance
30µm ±10µm
Treatment thickness grows 50% outside and 50% inside the surface of the aluminium piece. The radial dimensional increase is therefore equal to half the treatment thickness. Hard anodizing thickness
Uniform thickness over the entire external surface. Reduced thickness in holes.

Aesthetic appearance
Slightly matt appearance with light grey colour. The colour tone depends on the base alloy and treatment thickness. Morphology similar to machined piece.

Tribological properties

Hardness
The OX-W treatment has a high layer hardness. It varies depending on the treated alloy.
Hardness value Alloy
>280HV Series 2000
>330HV Series 5000 (with >2% Mg) and 7000
>400HV Other wrought alloys

Wear resistance
OX-W has a very high resistance to adhesive and abrasive wear. It varies depending on the treated alloy.
Wear value, TWI-CS17 Alloy
A low number indicates a better performance - MIL-A-8625F 3.7.2.2 and ISO 10074 C.3 - Taber Abraser wear test - abrasive wheels CS 17 - load 1 kg
<35 mg / 10000 cycles Series 2000
<25 mg / 10000 cycles Series 5000 (with >2% Mg) and 7000
<15 mg / 10000 cycles Other wrought alloys

Friction coefficient
The OX-W-PTFE variant consists of an impregnation treatment of the anodizing layer with PTFE nanometric particles. This impregnation permits obtaining a non-adhesion, self-lubricating surface with low friction coefficient.

Chemical properties

Corrosion resistance
The OX-W treatment permits obtaining high corrosion and oxidisation resistance. Brilliantly withstands 336 hours of exposure to salt mist without any sign of corrosion.
Corrosion resistance value Base material
NSS according to ISO 9227 and ISO 10074 10
≥336 hours without corrosion Alloy 6000

Chemical resistance
Approximate values of compatibility with the coating environment. The actual resistance to the environment must in any case be tested in the field.
Hydrocarbons (e.g. petrol, diesel fuel, mineral oil, toluene)
Alcohols, ketones (e.g. ethanol, methanol, acetone)
Neutral saline solutions (e.g. sodium chloride, magnesium chloride, brine)
Diluted reducing acids (e.g. citric acid, oxalic acid)
Oxidizing acids (e.g. nitric acid)
Concentrated acids (e.g. sulphuric acid, hydrochloric acid)
Diluted bases (e.g. diluted sodium hydroxide)
Oxidizing bases (e.g. sodium hypochlorite)
Concentrated bases (e.g. concentrated sodium hydroxide)

Production facility