Corrosion behavior of tinplate in NaCl solution

The corrosion process of tinplate in 0.5 mol/L NaCl solution was investigated using the electrochemical impedance spectroscopy（EIS）,and the morphology and structure of the corrosion products were characterized by scanning electron microscope（SEM）,scanning probe microscopy（SPM）,X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）.The results showed that the resistance of tin coating,Rc,was essentially constant but the charge transfer resistance,Rct,decreased by 2 orders of magnitude,which indicated that the tin coating was not seriously corroded while the carbon steel substrate was corroded continuously.The corrosion of tinplate in 0.5 mol/L NaCl solution was mainly the dissolution of carbon steel substrate because of the defects in the tin layer and the corrosion product was mainly γ-FeOOH.

Effects of reflowing temperature and time on alloy layer of tinplate and its electrochemical behavior in 3.5%NaCl solution

Effects of reflowing temperature and time on the alloy layer of tinplate and its electrochemical behavior in 3.5%NaCl solution were investigated by electrochemical measurements and surface characterization.It is found that the amount of alloy layer increases with the increase of reflowing temperature and time.Then the corrosion potential of detinned tinplate shifts positively and the corrosion rate decreases.After being coupled with tin,the detinned tinplate acts as cathode and tin acts as anode initially.However,after being exposed for some time,the potential shifts of both detinned tinplate and tin reverse the polarity of the coupling system.The galvanic current density decreases with the increase of reflowing temperature and time.

Effect of Black Plate on Corrosion Resistance of T5 Tinplate

The effect of black plate on corrosion resistance of T5 tinplate was studied by glow discharge spectrograph, X-ray diffractometer （XRD）, stress tester, roughness tester and metallographic microscope. The result shows that black plate influences corrosion resistance of T5 tinplate intensely. It also indicates that the increase of content of manganese, phosphorus, silicon and aluminum in black plate would reduce the corrosion resistance of T5 tinplate and the increase of degree of crystal orientation on （200） crystal face, ｜X-Y｜ value （internal stress difference within two orientation）, roughness and exposure degree of iron grain after the same acid wash of black plate would enhance the corrosion resistance of T5 tinplate and the grain number of black plate has small effect on corrosion resistance of T5 tinplate.

Degradation Mechanism of Lacquered Tinplate in Energy Drink by in-situ EIS and EN

The corrosion process of phenolic epoxy coated tinplate in energy drink was investigated by in-situ electrochemical impedance spectroscopy（EIS） and electrochemical noise（EN） techniques. The experimental results indicate that the degradation process of novolac epoxy coated tinplate in energy drink can be divided into three main stages： organic coating wetted by the beverage; corrosion initiation beneath the organic coating; and corrosion extension process. It was proposed that the tin coating and carbon steel were mainly corroded by organic acids in energy drink through the pores of the organic coating. After the tin coating was corroded, the carbon steel started to corrode due to its higher electrochemical activity and became to be the dominated corrosion reaction.

Crystallographic texture and earing behavior analysis for different second cold reductions of double-reduction tinplate

Since the production of tinplate with non-earing properties is difficult, especially when it is produced via the double-reduction process, the optimal degree of second cold reduction is particularly important for achieving desirable drawing properties. The evolution of texture and the earing propensity of double-reduction tinplate with different extents of second reduction were investigated in this study. Optical microscopy and scanning electron microscopy were used to observe the changes in the microstructure at various extents of reduction. Two common testing methods, X-ray diffraction（XRD） and electron backscatter diffraction, were used to investigate the texture of the specimens, which revealed the effects of deformation percentage on the final texture development and the change in the grain boundary. The earing rate was determined via earing tests involving measurement of the height of any ear. The results obtained from both XRD analyses and earing tests revealed the same ideal value for the second cold reduction on the basis of the relationship between crystallographic texture and the degree of earing.

Influence of reflow processing conditions on the uniformity of the chromium passivation film on tinplate

This study aims to systematically analyze the key parameters of the reflow process that influence the uniformity of the chromium passivation film coated on tinplate. The distribution characteristics of the chromium passivation film coated on the tinplate surface under different treatment conditions were systematically characterized using the scanning Kelvin probe technique, X-ray photoelectron spectroscopy, and X-ray diffraction. Results indicate that the use of flux reduces the porosity of tin coating, thereby favoring the uniform growth of the passivation film. Furthermore, an increase in the reflow power and quenching temperature facilitates the homogeneous distribution of the passivation film on the tinplate surface,particularly when treated with electrolytic cathodic sodium dichromate.

Corrosion detection of tinplate cans containing coffee using EIS/EN sensor

The corrosion behavior of tinplate cans containing coffee was investigated using novel electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) sensors.The contents of iron and tin dissolved in cans were detected by inductively coupled plasma mass spectrometer(ICP-MS),and the morphology of corroded surface was observed by optical microscopy and scanning probe microscopy(SPM).The results reveal that the coating resistance,charge transfer resistance and noise resistance decrease with the prolongation of storage time.The iron and tin contents in cans increase with the storage time,while the bump height of coating surface increases from 30 nm to 80 nm during the corrosion of twelve months.The existence of deformation would enhance the corrosion process of tinplate cans.Finally,the corrosion mechanism of tinplate cans in coffee was proposed.

Corrosion Process Detection of Tinplate in Deaerated Functional Beverage by EIS

The corrosion process of tinplate in deaerated functional beverage was investigated by using electrochemical impedance spectroscopy (EIS) combined with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. The results reveal that the uncoated tinplate shows a poor corrosion resistance and the corrosion type is detinning. During the initial stage of immersion, EIS spectrum consisted of two capacitance arcs with obvious time-constant dispersion effect, which was attributed to the two-dimensional and three-dimensional inhomogeneous distribution of the electrode surface. With the increase of immersion time, the capacitance arc of high frequency shrunk and degenerated, due to the corrosion of tin coating. The pore resistance of tin coating and the charger transfer resistance of substrate, which are determined from the electrochemical equivalent circuit, can be used as the indicators of tinplate corrosion process. The decrease of the pore resistance of tin coating indicates that the corrosion degree of tin layer becomes more severe, whereas the decrease of the charger transfer resistance of substrate implies that the corrosion degree of steel substrate also becomes more severe as the immersion time prolongs.

Smudge on tinplate steel sheets and the effects of cathodic dichromate treatment

Smudge is black granules that scatter on tinplate sheet; it was formed during the process of plating and storing, and seriously affected the function and appearance of tinplate sheet. Reflowing and cathodic dichromate treatment (CDC) are two major phases in which smudge is produced. In this paper, the appearance and component of smudge was analyzed by means of whiteness meter, SEM and EDS quantitatively. Factors of CDC conditions was studied. Results of tests showed that whiteness measurement is convenient to evaluation of the degree of smudge and the effects of CDC on it , quantitatively.

Generation reason and corrosion characteristicof cavity of tinplate alloy layer

The surface morphology of alloy layer of tinplate was studied by means of scanning electron microscopy. By using the layer on layer debonding technology of glow discharge spectrum, the contents of C and O at the boundary of alloy layer and black plate were analyzed. And the corrosion characteristic of cavity of tinplate alloy layer was studied on-line and in-situ by means of electrochemical atomic force microscope. The corrosion depth of cavity of alloy layer in-situ after different corrosion time was measured. The results show that the cavity of alloy layer is a critical factor causing rapid decline of corrosion resistance of tinplate, and the formation of cavity of alloy layer is due to incorrect pretreatment of black plate before electrotinning. The cavity of alloy layer is the internal factor causing pitting corrosion of tinplate when the tinplate is applied to food packaging material. And the dynamic equation of pitting corrosion generated in the cavity of alloy layer conforms to logarithm law.

Evaluation on the contribution of steel products to environmental improvement from LCA perspectives

High functionality given to steel products results in an increase of environmental loads in the steelmaking stage. However, at the stage of their utilization, the high-functional steel products prove to be more environmentally friendly than their conventional counterparts in many cases. In view of this contradiction, the evaluation on the contribution of steel products to environmental improvement requires a more integrated approach--Life Cycle Assessment （ LCA ）, which incorporates the effects over the products＇ entire life cycles. This paper discusses the relationship between the improvement of steel products＇ performance and the according environmental impact from the entire life cycle perspectives. How to evaluate and assess the contribution of high-functional steel products to environmental improvement using LCA method is explained in detail. Two case studies of Baosteel are given to substantiate the effectiveness of LCA as a scientific and systematic method for eco-material evaluation or eco-design： @ For a power transformer, by replacing silicon steel B30G130 with B30Pll0,the carbon dioxide emissions were reduced by 15.1% over the life cycle of the transformer. @ Tinplate steel of Baosteel used for two-piece steel cans experienced six reductions in thickness from 0.28 mm to 0.225 mm,which results in a 14.5% emission reduction over the life cycle of two-piece steel cans.

Evaluation on Contribution of Steel Products to Environmental Improvement from Life Cycle Assessment Perspectives

High functionality given to steel products results in incremental environment loads at the steelmaking stage.However,at the stage of utilization,high-functional steel products prove more environment friendly than their conventional counterparts in many cases.Therefore,evaluation on contribution of steel products to environmental improvement requires an integrated approach that considers the product over its entire life cycle - life cycle assessment(LCA).This paper discusses the relationship between the improvement of steel products performance and environmental impact from the entire life cycle perspectives.The LCA method to calculate and assess contribution of high-functional steel products during the life cycle to environmental improvement is explained.Two case studies of Baoshan Iron & Steel Co.,Ltd.(Baosteel for short) are given to show that LCA is a scientific and systematic method for eco-materials evaluation or eco-design:in a power transformer,using silicon steel B30P110 to replace B30G130 can reduce carbon dioxide emissions in the region of 15.1% over the life cycle of the power transformer;tinplate steel of Baosteel for two-piece steel cans experienced six times thickness reduction from 0.280 to 0.225 mm,which results in 14.5% emission reduction over the life cycle of two-piece steel cans.It is a systematic and scientific method for evaluating on products environmental performance from life cycle perspective.