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Biodiesel Resistance of Thin Resin Cr-free Steel Sheets for Fuel Tank. Dong-Joo Yoon , Kyung-Hwan Lee, Jong-Geun Choi Sunchon National University, Korea Sangkeol Noh, Jae-Ryung Lee POSCO Technical Research Lab, Korea. Introduction. Experimental Procedures. Contents.
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Biodiesel Resistance of Thin Resin Cr-free Steel Sheets for Fuel Tank Dong-Joo Yoon , Kyung-Hwan Lee, Jong-Geun Choi Sunchon National University, Korea Sangkeol Noh, Jae-Ryung Lee POSCO Technical Research Lab, Korea
Introduction Experimental Procedures Contents Results & Discussion Conclusions
Introduction • Higher corrosion rate of biodiesel in fuel tank than petroleum based fuels due to acidic contents(formic acid, acetic acid, oleic acid, etc) • Difficulties in quantitative evaluation of corrosiveness due to the variety in biodiesel, chemical substances in preparation phase, and corrosion environment, etc. • Since the actual testing on fuel resistance of fuel tank for biodiesel will take more than 10 years, various ways to evaluate assurance period for corrosion have been studied. • Generally cyclic corrosion test (CCT) is applied to determine relative corrosion resistance.
Objectives • To analyze and evaluate the corresponding corrosion behavior for the degree of corrosiveness of biodiesel. • To determine the fuel resistance of thin resin Cr-free steel sheets, which is widely used as the steel sheets of automobile fuel tank • To investigate the effect of contents ratio between biodiesel and diesel fuel, water, and possible by-products during preparation of biodiesel
Experimental Procedures Fig. 1 Schematic diagram of the double -layered Cr-free specimen Fig. 2 Shape & size of cup specimen
Experimental Procedures Fig. 3 Shaking tester for corrosiveness of fuel and material
Experimental Procedures Table 1. Specification of shaking tester
Experimental Procedures Test conditions • Fuel : Diesel, Biodiesel(Soybean) • Agitation frequency : 1 Hz • agitation : 8hrs, 80℃ • 1 Cycle(1day) • stoppage : 16hrs, ambient temperature • Fuel replacement : every 14 cycles(2 weeks) • Total cycles : 56 cycles(8 weeks)
Experimental Procedures Fig. 4 Cell size for comparison of corrosiveness in cup specimens
Results & Discussion Fig. 5 Corrosion behaviour of cup specimens with increased contents of biodiesel containing H2O(10%)
Results & Discussion (a) Time of corrosion occurrence (b) Corroded cell area Fig. 6 Corrosion test result for the case of containing H2O(10%)
Results & Discussion Fig. 7 Corrosion behaviour of cup specimens with increased contents of biodiesel containing H2O(10%)+formic acid(20ppm)
Results & Discussion (a) Time of corrosion occurrence (b) Corroded cell area Fig. 8 Corrosion test result for the case of containing H2O(10%)+formic acid(20ppm)
Results & Discussion Fig. 9 Corrosion behaviour of cup specimens with increased contents of biodieselcontaining H2O(10%)+formic acid(20ppm) +methanol(10%)
Results & Discussion 90 (a) Time of corrosion occurrence (b) Corroded cell area Fig. 10 Corrosion test result for the case of containing H2O(10%)+formic acid(20ppm) +methanol(10%)
Results & Discussion Fig. 11 Corrosion behaviour of cup specimens with increased contents of biodiesel containing H2O(10%)+formic acid(20ppm) +methanol(10%) + peroxide(0.3%)
Results & Discussion 90 (a) Time of corrosion occurrence (b) Corroded cell area Fig. 12 Corrosion test result for the case of containing H2O(10%) +formic acid(20ppm) +methanol(10%) + peroxide(0.3%).
Results & Discussion Fig. 13 SEM image of corroded area in the case of containing H2O(10%)+formic acid(20ppm)+methanol(10%) + peroxide(0.3%) (a) corroded debris (b) substrate (c)Zn-Ni layer
Results & Discussion Fig. 14 EPMA curves for the case of containingH2O(10%) +formic acid(20ppm)+methanol(10%) + peroxide(0.3%)
Results & Discussion Table. 2 EPMA results of corrosive area in Fig 13(a), (b)
Results & Discussion (a) Time of corrosion occurrence Fig. 15 Corrosion test result for allcases
Results & Discussion (b) Corroded cell area Fig. 15 Corrosion test result for all cases
Results & Discussion Fig. 17 SEM image of corroded area in the case of containing H2O+ H2S
Results & Discussion Fig. 18 EPMA curves for the case of containing of H2O+ H2S
Results & Discussion Table. 3 EPMA results of corrosive area in Fig. 15
Conclusions • Peroxide additive has the strongest corrosiveness. Coating and plating layer are delaminated, and even substrate material is corroded. • For methanol, mixing with blended fuel shows the reduction in corroded area by reduction in the additive concentration. • Formic acid has weaker corrosiveness than peroxide, but corrosion is occurred throughout all the specimen. • Water is not mixed with fuel, and does not impact on corrosion significantly. However, water is easily mixed with other additives, and is considered to facilitate the corrosion by other additives.