Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (31권6호 371-378)

A study on removing impurities in the zind bate for hot dip galvannealed coatings

합금화 용융아연 도금욕의 불순물 제거에 관한 연구

진영구;

포항제철(주) 기술연구소 광양압연연구소;

Abstract

The zind bate contaminated in the hot dip galvannealed operation was successfully by appling the dross formation mechanism ; the Fe content was lowered from 0.028% to 0.011% and the dress size was decreased from 15~20$mu extrm{m}$ to under 3$mu extrm{m}$. The cooled metal from CGL zinc bath during operation of the galvannealed steel strip was remelted in graphite crucible at the lab and agitated after increasing Al content from 0.14% to 0.16% with decreasing the molten metal temperature from $470^{circ}C$to $445^{circ}C$. The agitating was done by agitator and nitrogen. The molten was analyed by SEM and EDS. It was considered that the Fe and the bottom dross($FeZN_7$) could react with aluminium to from the float dress($Fe_2Al_5$) according to the molten metal temperature down and the float dress rise to the surface of the zine bath. So the Fe and dross in the bath could be romoved out of the bath. It was confirmed that the proper purication conditions of GA zine bath is 0.02% of Al increasing, bath temperature down from $460^{circ}C$ to $450^{circ}C$and agitator and nitrogen.

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