Research Of Corrosion Performance Of Tin Free Steel And It’s Improving Strategy

Food packaging industry is commonly use tin plate as packaging material,along with its use continues to expand,metaltin resource is becoming scarce,so chrome plate is the future development direction of packaging industry.However,due to the lack of chrome plating technology knowledge,the production of TFS exposed the problem of poor corrosion resistance.The factors that affacts the corrosion resistance of chrome plate and the measures to improve it were studied systematically by SEM、EDS、metalloscope and electrochemical workstation.During the pretreatment process,the longer time the base plate was degreased and pickled,the better corrosion resistance of chromium layer would be.In the process of electrotinning,the effects of current density、bath temperature and bath composition on corrosion resistance were studied by orthogonal experiment.Their influence degree was in the following order:current density is the first,chromic acid concentration is the second,NH4F concentration is the third and bath temperature is the last one.The results also showed that,the optimize process condition is that chromic acid concentration is150g/L,NH4F concentration is4.5g/L, current density is50A/dm2, bath temperature is35℃.In addition,impurity ions will also influence on corrosion resistance of TFS,so the impurity ion content should be control strictly.