ANODIZING
Anodizing is an electro-chemical process that modifies the surface structure of Aluminum – accelerating Aluminum’s naturally occurring protective oxide coating.
In the anodizing process, Aluminum is immersed in a sulphuric acid solution. DC current is put through the material with the Aluminum acting as the “anode”. As the anode, the Aluminum reacts with Oxygen in the solution. The result is a layer of Aluminum Oxide that both penetrates the surface of the material and builds up as a chemically bonded surface deposit. In the case of a 1 mil coating, a growth in part size of .5 mil can be measured while the other .5 mil is found below the original surface of the part. This 1:1 ratio of build up to surface penetration holds true for most alloys and provides an extremely durable protective coating for Aluminum.
Standard “architectural” anodizing provides an extremely durable finish that can withstand harsh environmental conditions for many years. Standard Bluewave Yagi and Paragrid™ style antennas are fully anodized. The dipoles and stand-off tubes for our Exposed dipole style antennas are also anodized for durability and long service life.
By maintaining close tolerances to low temperatures in the sulphuric acid solution and through increased DC current levels, most Aluminum alloys can also be “hard” anodized. This hard finish can be harder than 62 RC. This process allows the production of a thicker wear and corrosion resistant coating on a variety of Aluminum alloys. Hard coating allows the use of Aluminum in many design applications formerly restricted to steel.
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