What is hard anodizing for aluminum finishing?
Developed more than forty years ago hard anodizing is an electrochemical process. It involves placing an aluminum part into an electrolytic bath and applying electrical current through the bath. This process forms an oxide coating (sapphire-hard) on the aluminum part. This oxide coating can be harder than casehardened steel and provide excellent abrasion resistance; it is protective to the aluminum part and can be very durable. However, a number of factors can affect the quality, durability and density of the coating. This electrochemical process generally creates polarization of the cathode and anode in the electro-chemical process. This normally generates large amounts of oxygen at the anode and hydrogen at the cathode. This polarization fills the pores of the oxide coating and builds resistance to the electrical current. As a result, progressively more voltage has to be applied in order to maintain adequate current densities. These high voltages generate dangerously high temperature
