Study on Flex Fuel Compatible Coatings for Automotive Fuel Tank

<div class="section abstract"><div class="htmlview paragraph">Reducing CO<sub>2</sub> emissions is now a major focus in India heading towards net zero emissions by 2070. India is the 3rd largest automobile market in the world and the transportation sector is the 3rd largest CO<sub>2</sub> emitter. In this direction, it is necessary to reduce the carbon footprint from the automobile sector to combat climate change. The adoption of sustainable biofuels such as ethanol will enable us to reduce emissions, as ethanol is carbon neutral fuel. However, vehicle manufacturers are facing challenges in manufacturing flex fuel compatible parts in the vehicle mainly fuel systems.</div><div class="htmlview paragraph">Ethanol has both nonpolar and polar bonds, making it miscible to both gasoline and water, thereby water contamination is inevitable in ethanol blend fuels. In addition, control of ethanol contamination by sulfates and chlorides during ethanol production is challenging. Thus, ethanol blend fuels are considered more corrosive and tendency towards deposit formation than normal gasoline fuels.</div><div class="htmlview paragraph">Design and development of corrosion resistant and flex fuel compatible materials for fuel systems are important without compromising the functional requirements. In fuel systems, fuel tank is one of the major parts, which acts as a reservoir for fuel supply and needs to have good chemical and corrosion resistance. This paper describes the comparative study of three different coating systems of single layer coating with and without topcoat on top of steel sheet to withstand up to 85% ethanol fuel blends. In all these coated samples, base metal used is low carbon steel sheet which is commonly used for automotive fuel tank application. The fuel tank internal corrosion study is conducted using test fuel as aggressive ethanol blend fuel at coupon level as per SAE J1747. The test fuel has been selected to simulate the effect of possible contamination in the real usage condition and to provide accelerated corrosion test. The selection criteria used for the evaluation are base material corrosion, pitting, weight loss, formation of reaction products and its elution behavior into the test fuel.</div><div class="htmlview paragraph">No pitting, perforation and weight loss were observed in all the coating systems after the test. Base material corrosion was encountered in only 2 coating systems and reaction products were observed as deposits in all coating systems for higher ethanol blend test fuels. The reaction products were analyzed in SEM-EDS and their elution effect into the fuel was studied under both static and dynamic fluid conditions.</div></div>