What is anodizing?

What is anodizing?

Solar mounting system is for outdoor environment use, sometimes severe weather condition area with humidity, salty. We recommend using anodized aluminum mounting strcuture to withstand weather in 25years design life time of solar system. After 25 years, structure good or nothing.

Anodizing is an electrochemical conversion process in existence since the 1930s.  Several metals are capable of being anodized including aluminum, magnesium, titanium, and tantalum.  Anodized aluminum is used in many applications due to its low cost, aesthetic qualities and ideal mechanical properties. Most familiar is iphone bezel.

Unlike most protective coatings, anodizing permanently changes the outer structure of the metal. When aluminum is exposed to air it naturally develops a thin aluminum oxide film that seals the aluminum from further oxidation.  The anodizing process makes the oxidized surface much thicker, up to several thousandths of an inch thick.  The hardness of the anodized aluminum oxide coating rivals that of a diamond, enhancing the abrasion resistance of the aluminum. The added depth of the oxide layer improves the corrosion resistance of the aluminum, while making cleaning of the surface easier.  The porous nature of particular types of anodizing makes it possible to dye the aluminum a variety of colors, making it more attractive.

Anodizing typically ranges up to 5 mils thickness.   The three most common variations of aluminum anodizing include chromic (type I), sulfuric (type II) and hard (type III).

I   Chromic anodizing utilizes a chromic acid electrolyte and yields the thinnest coatings, only 0.02 to 0.1 mils thick (0.5 to 2.5 microns).  50% penetration into the substrate and 50% growth over original dimensions occurs.  Chromic anodizing has the least effect on fatigue strength and is less corrosive, thus ideal for complex and difficult to rinse parts.  Excellent for coating aluminum castings, most chromic anodized parts are used in military and aerospace applications and are more functional than decorative in nature.

II    Sulfuric anodizing is the most common method of anodizing, utilizing sulfuric acid to yield coatings up to 1 mil (25 microns) thick. 67% penetration into the substrate and 33% growth over original dimensions occurs.  Due to its permeable nature, sulfuric anodizing is excellent for color dyeing and provides a base for primers, bonding agents and organic coatings.  Sulfuric anodizing provides corrosion resistance and is very durable.  Typical applications include architecture, aerospace, manufacturing automotive and computers.

III   Hard anodizing (a.k.a. hardcoating) utilizes a higher concentration sulfuric acid electrolyte at a lower temperature resulting in a tough outer skin with excellent abrasion resistance, corrosion resistance, color fade resistance, dielectric strength and surface hardness (Rockwell C-Scale up to 70).  50% penetration into the substrate and 50% growth over original dimensions occurs for a total thickness of 0.5 to 4 mils.  Hard anodized metals have heightened surface roughness.  Common uses include non-decorative food packing equipment, photocopier paper rolls, and exterior applications such as building storefronts and windows.

We recommend using anodized aluminum mounting strcuture to withstand weather in 25 years design lifetime of the solar system. After 25 years, structure good or nothing.


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