Hot and cold sealing of anodizing
Sealing anodized aluminum closes the pores of the oxide layer and is critical for corrosion resistance, color stability and durability. This page compares hot sealing and cold sealing (nickel salts).
Read MoreAnodizing, also called anodic oxidation, is a surface treatment of aluminum alloys that creates a protective layer of aluminum oxide on the surface of the part. Anodizing is performed by means of an electrolytic process in sulfuric acid solutions. Following a preparation cycle, the aluminum parts are dipped into the anodizing electrolyte. The application of direct current causes a process of controlled oxidation of the surface, which forms a compact layer of aluminum oxide. The main characteristics of anodizing are: The treatment can be divided into two main types: low-thickness clear anodizing and high-thickness hard anodizing. Hard anodizing imparts properties of very high corrosion resistance and exceptional wear resistance to the treated part. This process is employed to extend the lifetime of mechanical components in various sectors, such as automated machinery, textile machines, automotive, cycles and motorcycles, maritime, and many others. MICRON COATINGS Group provides aluminum anodizing through Durox srl
, with proprietary OX processes and facilities for large parts as well.
Free resource Technical Guide to Anodizing Complete technical reference for aluminum anodizing applied to precision engineering Wear and corrosion resistance | ISO 10074 | MIL-PRF-8625 Type III OX-HS is a hard anodizing treatment of aluminium in sulfuric acid in compliance with MIL-PRF-8625 Type III, ISO 10074, and UNI 7796 standards. It imparts excellent corrosion and wear resistance, high hardness and resistance to aggressive environments. The OX-HS treatment can be pigmented in deep black, blue or red. The deep black allows for color uniformity on different aluminium alloys. Wear and corrosion resistance | Low surface roughness | Light color | ISO 10074 | MIL-PRF-8625 Type III OX-W is a special hard anodizing treatment for aluminum in compliance with MIL-PRF-8625 Type III, ISO 10074, and UNI 7796 standards. Compared with conventional hard anodizing, OX-W provides lower surface roughness, higher corrosion resistance and a lighter color. OX-W can be pigmented deep black, blue or red. Deep-black pigmentation provides a uniform color across different aluminum alloys. Corrosion resistance | ISO 7599 | MIL-PRF-8625 Type II OX-A is a clear aluminium anodizing treatment in compliance with MIL-PRF-8625 Type II and ISO 7599. It is used to protect aluminium from environmental oxidation because it has a good level of corrosion resistance and appreciable scratch and wear resistance. The OX-A treatment can be pigmented in deep black, blue or red, thus equalizing the color on all aluminium alloys. The outstanding feature of anodized coatings is their exceptional corrosion resistance.
Corrosion resistance can be improved even further by performing a post-anodization sealing treatment. Sealing is performed in a high temperature solution (approx. 95°C). Hard anodizing provides the best corrosion resistance for aluminum, which can exceed 1000 hours of neutral salt spray without the onset of corrosion. Explore corrosion resistance
and sealing treatments
in the technical guide. The hardness and compactness of the aluminum oxide film makes it possible to achieve high resistance to abrasive and adhesive wear, comparable to that of hard chrome plating. Hard anodizing, which is frequently applied with thicknesses of 40-60 µm, can produce hardness values higher than 450HV. The coating hardness depends on the type of aluminum alloy, because the oxide layer is obtained by converting the substrate material. See hardness and wear resistance
and aluminum alloys
in the technical guide. Anodizing is an eco-friendly treatment. The process does not use hazardous or carcinogenic substances, such as heavy metals or solvents. The coating is mainly composed of aluminum oxide, an inert and non-hazardous material. Thanks to its biocompatibility and high chemical resistance, anodizing is the main coating for aluminum used in the food and medical sectors. Learn more about food contact
and chemical resistance
in the technical guide. Anodizing creates a surface layer of aluminum oxide that reproduces the surface morphology of the part. Thanks to this characteristic, different aluminum surface finishes (polished, satin-finished, brushed, shot-blasted, etc.) are retained after anodizing. The anodizing color changes in accordance with the process type, coating thickness, and the aluminum alloy. It can have a clear, metallic surface appearance with thin coatings or dark grey self-coloration for thick-film hard anodizing. Anodizing can be carried out on all aluminum alloys, whether machined from solid stock, extruded, cast, die cast, or forged.
The final coating characteristics vary depending on the alloy used, especially in terms of color, hardness, and corrosion resistance. Certain alloys, such as those with high silicon content (casting alloys) or high copper content (2000 series), may be difficult to treat. This is why we developed the specific OX-W treatment, which produces improved surface characteristics compared to conventional anodizing treatments.Aluminum anodizing
View guide →OX Anodizing Treatments
OX-HS - Hard anodizing
MORE INFORMATIONVARIANTSOX-HC - Black Pigmented Hard Anodizing
OX-HB - Blue Pigmented Hard Anodizing
OX-HR - Red Pigmented Hard Anodizing
OX-HS-PTFE - Hard Anodizing with PTFE impregnation
OX-W - Hard anodizing
MORE INFORMATIONVARIANTSOX-WN - Black Pigmented Hard Anodizing
OX-WB - Blue Pigmented Hard Anodizing
OX-WR - Red Pigmented Hard Anodizing
OX-W-PTFE - Hard Anodizing with PTFE impregnation
OX-A - Clear anodizing
MORE INFORMATIONVARIANTSOX-AN - Black Pigmented Clear Anodizing
OX-AB - Blue Pigmented Clear Anodizing
OX-AR - Red Pigmented Clear Anodizing
OX-A-PTFE - Clear Anodizing with PTFE impregnationKey features of aluminum anodizing
CORROSION RESISTANCE
WEAR RESISTANCE AND HARDNESS
ENVIRONMENTALLY FRIENDLY
Aesthetic appearance
Anodizable aluminum alloys
Certifications and reference standards
PRODUCT TECHNICAL STANDARDS
CHEMICAL SAFETY
FOOD CONTACT
MANAGEMENT SYSTEMS
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