Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


한국표면공학회지 (17권3호 78-86)

Hard Anodizing Treatment in Malic Acid Bath mixed with Oxalic Acid

말릭산과 수산혼합욕에서 경질양극 산화처리

Jeong, Yong-Soo;Chang, Do-Yon;Kwon, Sik-Chol;



Hard anodic oxide film was investigated formed on pure aluminium with various temperature (30$^{circ}-60^{circ}C$), current densities (1.5-3.0A/$dm^2$) and concentrations(3-15g/l) of oxalic acid in 0.5M malic acid bath. The resulting characteristic of the anodic oxide film obtained were summarized as follows in the view point of physical and mechanical properties in relation with the above process variables. 1. The film thickness increased with oxalic acid concentration and bath temperature, while the reversed phenomena were obtained at a high concentration of oxalic acid and high temperature due to the severe dissolution of the anodic oxide film. 2. The hardness and the abrasion resistance were improved by lowering the addition of oxalic acid and the bath temperature. This feature was directly dependent on the porosity formed on the anodic oxide film. 3. The maximum hardness of anodic oxide film showed Hv 579 in the temperature of 30$^{circ}C$ with the current density, 2.5A/$dm^2$ in the 0.5M malic acid bath mixed with 5g/l oxalic acid.