Optimization of Mild Steel Anodizing using Box-Wilson Experimental Design

Abstract

In this study, a mild steel alloy has been used to determine the influences of voltage, temperature, concentration and time on the film growth, thickness, characteristics and properties of anodic oxide film. A Box–Wilson experimental design method was used to determine effects of parameters and optimum conditions for anodized mild steel alloy. Anodizing of the mild steel alloys in potassium hydroxide solution generates the barrier and porous layers of anodic films according to the conditions used. Mild steel alloy is anodized under different conditions in the KOH solution. Constant voltage technique is used to form oxide films on mild steel alloys in (KOH) electrolyte as a function of the anodization voltage of (1-6V), concentration of (40-70Vol. %), temperature of (20-100°C) and anodization time of (5-75 min). The second order response surface model is given in equations. The model is used in the formulation of objective and constraint functions for the optimization of a optimum conditions of mild steel: T=2.949+0.781X1+0.131X2+1.240X3+0.334X4+0.047X11+0.003X22+0.377X33-0.153X44+0.041X12+0.115X13+0.026X14+0.046X23+0.025X24+0.141X34 Optimum conditions for anodizing mild steel in the alkaline solution were determined by Hook and Jeeves method. The optimum conditions were found as follows: voltage (1V), KOH concentration (40Vol.%), temperature (20°C), and time (5 min). The thickness for mild steel alloy was [0.65µm]. The electrical conductivity characteristic of the oxide was measured; it was found that it has electrical conductivity but with different values depending on anodizationconditions. Different colors of anodic oxide film are formed on carbon steel alloys and change with different conditions. The pores diameter for mild steel was [91.78 nm]. AFM topography shows the roughness values of mild steel is [0.496 nm]. The microhardness of anodic oxide film was [1477.5 Hk].