Browse > Article

Corrosion Behavior of Cathodic Electrodeposited Epoxy Based Coating for Automotive Primer  

Lee, Soung-Youb (Dongju Industiral Co.)
Lee, Jung-Mu (Department of Industrial Chemistry, Division of Applied Chemical Engineering Pukyong National University)
Kwag, Sam-Tag (Department of Industrial Chemistry, Division of Applied Chemical Engineering Pukyong National University)
Moon, Myung-Jun (Department of Industrial Chemistry, Division of Applied Chemical Engineering Pukyong National University)
Suh, Cha-Soo (Department of Industrial Chemistry, Division of Applied Chemical Engineering Pukyong National University)
Publication Information
Applied Chemistry for Engineering / v.16, no.2, 2005 , pp. 250-256 More about this Journal
Abstract
Coating appearance is the most important problem in automotive industry. To increase the coating appearance quality, the corrosion resistance and the coating adhesion on metal substrates must be basically solved. The phosphating film made by the pretreatment of metal substrate is important factor to increase the coating adhesion. During the cathodic electrodeposition, the pH at the cathode surface increases up to about 12. In such a highly alkaline condition, the dissolution of metal substrate and phosphate film occurs. These phenomena result in the decrease of the bonding strength between the phosphating film and the substrate. Generally, the structure of zinc phosphating film is hopeite or phosphophyllite. It has been known that the phosphophyllite film contains better corrosion resistance and paint adhesion for hot water immersion test because of the decrease of dissolving amount of both metal substrate and phosphating film during the cathodic electrodeposition. It is found that the addition of Ni and Mn composition increase P-ratio and then can improve the paint adhesion on metal surface and the corrosion resistance.
Keywords
cathodic electrodeposition; phosphophyllite; zinc phosphating; corrosion behavior; automotive primer;
Citations & Related Records
연도 인용수 순위
  • Reference
1 P. E. Pierce, J. Coat. Tech., 53, 52 (1981)
2 C. K. Schoff, Electrodeposion Training Manual, PPG Industries (1993)
3 N. Sumie, Japan Finish., 10, 81 (1982)
4 J. A. Kargol and D. L. Jordan, Corrosion, 38, 201 (1982)   DOI   ScienceOn
5 W. Machu, Handbook of Electropainting Technology, Electrochemical publication Ltd. (1978)
6 A. Takashi, J. Iron Steel Inst. Jpn., 77, 861 (1991)
7 D. B. Freeman, Phosphating and metal pre-treatment, Woodhead-Faulkner Ltd. (1986)
8 H. Okada, T. Miyawaki, and M. Miyaji, Bosei Kanri, 26, 254 (1982)
9 T. Watanabe and Y. Ishida, J. Met. Finish. Soc. Jpn., 29, 682 (1988)
10 GM Test Method, GM M9301
11 N. Sato and T. Minami, Surf. Coat. Technol., 34, 331 (1988)   DOI   ScienceOn
12 M. Wismer and J. F. Bosso, Chem. Engin., June 14, 114 (1971)
13 G. Lorin, Phosphating of metal, Finishing publication Ltd. (1974)
14 G. W. Lee, The Paint Finish, 22, 50 (1981)
15 O. Pawling and R. Trettin, Mater. Res. Bull., 34, 1959 (1999)   DOI   ScienceOn
16 O. Hurushi, Japan Finish. 10, 149 (1982)
17 R. D. Wyvill and T. Cape, Prod. Finish., 52, 68 (1987)
18 N. Sato, T. minami, and H. Kono, J. Mat. Finish. Soc. Japan, 38, 571 (1987)   DOI
19 S. Maeda, T. Asai, and H. Okada, Corros. Engin., 31, 268 (1982)