CORROSION IMPACT AND COMPATIBILITY STUDY OF METALLIC MATERIALS WITH BIODIESEL FUEL

Biodiesel has been generally known nowadays as an alternative source for fossil fuel. Many countries including Malaysia have implemented the usage of biodiesel in order to promote the usage of alternative fuel. However, there has been a concern regarding the compatibility of biodiesel especially in automotive components such as engine fuel system. It was reported that higher percentages of the blended biodiesel can affect the properties of the metallic materials. Thus, the compatibility of biodiesel was studied in this project, focusing on the metallic material which are typically used in the engine fuel system.
This project studied on the effect toward the physical appearance and mechanical properties of the materials with different percentage of blended palm biodiesel. The specimens used are aluminium, copper and mild steel which are machined into a dog-bone as per ASTM E8 using a wire-cut machine. The immersion test as per ASTM G1 was conducted for 14 and 42 days in this study with different percentage of blended palm biodiesel ranging 5% to 20%. Next, the corrosion rate was measured by weight loss measurement and color changes while tensile test as per ASTM E8 and hardness test as per ASTM E18 were done for mechanical properties. Besides, microstructural change of the materials was also examined using optical microscope. Results show that the extent of corrosion rate upon exposure to metals are more in biodiesel than in diesel. Copper was more susceptible to corrosion in biodiesel as compared to aluminium and mild steel. The presence of biodiesel in the fuel mixture also caused the tensile strength and yield strength of the materials to slightly change and decreases. The changes was observed up to 13% and 29% decrement in the tensile strength and yield strength respectively. The same goes with the hardness of the materials where there are some changes occurred and the highest decrement percentages recorded is only 17%. In term of microstructural change, the sample surface appeared to have deposited corrosion product and oxide layer. However, there were no localized damage on the surface topology.