Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403

공학

한국표면공학회지 (52권4호 233-238)

Effect of Fe(NO3)2 Concentration on Electrochemical Behavior of SCM430 in Zinc Phosphate Conversion Coating Solution

아연계 인산염 피막용액에서 Fe(NO3)2 농도가 SCM430 합금의 전기화학적 거동에 미치는 영향

권두영;송풍근;문성모;
Kwon, Duyoung;Song, Pung-Keun;Moon, Sungmo;

재료연구소 표면기술연구본부 전기화학 연구실;부산대학교 재료공학부;
Surface Technology Division, Korea Institute of Materials Science;Department of Materials Science and Engineering, Pusan National University;

DOI : 10.5695/JKISE.2019.52.4.233

Abstract

The formation behavior of zinc phosphate conversion coating (ZPCC) on SCM430 alloy was investigated in 25 vol.% of 1M ZnO + 170 ml/L solution containing various $Fe(NO_3)_2$ concentrations, using open-circuit potential(OCP), electrochemical impedance spectroscopy(EIS), cyclic polarization(CP) curve and tape peel test. OCP of SCM430 alloy and corrosion current density increased with increasing $Fe(NO_3)_3$ concentration. Resistance of films formed on SCM430 alloy by chemical conversion treatment decreased with increasing $Fe(NO_3)_3$ concentration. Color and adhesion of chemical conversion coatings became darker and worse, respectively, with increasing $Fe(NO_3)_3$ concentration. It is concluded that addition of $Fe(NO_3)_3$ into a zinc phosphating bath leads to faster reaction to form porous surface coatings with poor adhesion and corrosion resistance.

Keywords

Chemical Conversion Coating;SCM430 Alloy;phosphating;$Fe(NO_3)_2$ concentration;