電流反転電解による高力及び快削アルミニウム合金の陽極酸化

抄録

The purpose of this study is to improve the characteristics of the anodic coatings on aluminum alloys, 2014, 2017, 2024 and KS-21 (free cutting alloy) by ‘Current inversion method’. Anodic oxidation was carried out with DC-rectangle inverter (cycle: 0.033-500Hz) in a bath of 35wt% H₂SO₄ containing 10g/l H₂C₂O₄ 2H₂O. The peak current density was fixed at 4A/dm² and the duty was varied from 50 to 100%. It was found that the hardness, coating ratio and thickness of coatings were improved remarkably by current inversion method with 10-20Hz and higher duty. The hardness of coatings obtained from the electrolyte of 35wt% H₂SO₄ were larger than that from 15wt% H₂SO₄, and the addition of oxalic acid to sulfuric acid baths improved the properties of coatings. The hardness of coatings on high strength and free cutting alloys decreased with increasing Cu content in alloys.