Abstract:The influence of processing parameters on the coating surface roughness of LD10 aluminum alloy treated by the power source with positive and negative pulse in the alkaline electrolyte was discussed. Lots of experiments were done with different processing parameters including the positive final voltage, the negative final voltage, the frequency, the duty ratio, the processing time and electrolyte temperature. And the surface roughness tester TR200 was used to measure the coating surface roughness. The influence of the processing time on the surface roughness is the smallest, less than 0.2 μm. The surface roughness decreases gradually with the duty ratio decreasing or the frequency increasing; it decreases gradually with each of the other parameters increasing, and then increases gradually after achieving the minimum value. Appropriately by selecting processing parameters, the coating with R_a 0.6 can be obtained.

Key words: micro-arc oxidation; processing parameter; surface roughness; aluminum alloy