An Analysis of Burn Defect in Hard Anodized Process of AL 3003

Abstract

The hard anodizing process is performed on aluminum 3003 work-part in order to increase surface hardness and corrosion resistant. Due to the fact that a massive of heat is generated during the process and attributing to burn defect. Burning can be described as an uneven growth and destruction of the oxide layer. The interface between the barrier layer and the aluminum is not smooth on a microscopic scale. Metallic aluminum extends as many small projections into the barrier layer. These intermetallic phases, metallic needles, and/or other impurities transport the electric current easier than the aluminum oxide and as a consequence give rise to a short circuit through the barrier layer in these pores. When the current density concentrates in these pores the temperature will rise at the bottom of the pores and cause burning defect to the work-part. Thus, an analysis of reducing burn defect is implemented using an experimental design technique. It is founded that with an increasing of ramp time, sulfuric acid concentration, and agitation in the hard anodizing process without relaxing current density, burn defects are substantially reduced.