Ti를 첨가한 유/무기 하이브리드 코팅 용액의 경화 조건에 따른 냉간 압연 강판의 코팅 특성 평가

Abstract

Chromate treatment, which is primarily used on galvanized steel sheets, is the method that restrains the corrosion of a galvanized steel sheet and it is low in price. However, Cr+6 which are included in chromium sulfate conversion coating are now restricted due to current environment protection legislation. Thus, many researcher developed a coating solution that replaces Cr+6 coating in galvanized steel sheets and also researched adhesive properties, stability and corrosion resistance. Namely, They drew the optimum condition of coating of Cr-free coating solutions. Meanwhile the demand of cold rolled carbon(CR) steel for structural member is gradually increasing. If surface treatment(coating for corrosion resistance) of CR steel is not conducted, the use is very limited. Because, CR steel is vulnerable to corrosion. Therefore we need the development of coating solution of high corrosion resistance about CR steel. In this study, I researched corrosion resistance according to the hardening conditions of coated CR steel with organic/inorganic hybrid coating solutions. I used LR-0727(1) (urethane 13 wt.% + Si polysilicate 7 wt.% + Ti amorphous 0.5 wt.%) and LR-0727(2) (urethane 7 wt.% + Si polysilicate 7 wt.% + Ti amorphous 0.5 wt.% + epoxy 6 wt.%) coating solutions. When hardening time is fixed, the resistance corrosion of LR-0727(1) and LR-0727(2) was improved as hardening temperature increased and the optimum minimum temperature was decreased as hardening time. And at the optimum hardening condition of two coating solutions, hardening time of LR-0727(1) solutions was shorter than the thing of LR-0727(2) in same hardening temperature. LR-0727(1) coated specimens did not have desquamation and all of the specimens had good adhesive property. But, in case of LR-0727(2) coated specimens, the desquamation occurred. Therefore the adhesive property of LR-0727(1) is superior. Pencil hardness is average 3H without reference to the type of coating solutions and hardening conditions. At boiling water resistance test, LR-0727(1) coated specimens were discolored, but LR-0727(2) coated specimens were not. So, moisture proof of LR-0727(2) is superior.