Material compatibility of SI engine components towards corrosive effects on methanol-gasoline blends for flex fuel applications

The experimental study is conducted through static immersion of engine components to evaluate the material compatibility against the corrosive nature of methanol. The investigation is performed at room temperature along with different fractions of methanol in gasoline (M0, M20, M50, and M100) for varied durations of 60, 120, and 180 days. Further, the surface characterization of metal samples and fuel properties are examined in previous and post-immersion test duration in order to comprehend the penetration of corrosion. Also, the impact of corrosion on morphological changes, composition and engender of oxide layers on the engine components are inspected by SEM/EDX and XRD. Similarly, the changes brought by corrosion products on the physical (density and viscosity) and chemical properties (calorific value and TAN) are investigated and compared before immersion. The result of the study demonstrates that increasing the methanol percentage intensifies the corrosiveness of fuel samples when exposed to metal samples. Additionally, it has been found that the presence of oxygen in methanol significantly contributes to an increase in metal corrosion. Based on the investigational outcomes, comparatively the piston exhibits lesser resistance towards corrosion than the piston ring and valve. On the other hand, corrosion attack on the engine component surfaces disclosed to M100 is higher relative to that of M50, M20 and M0. Consequently, the characteristics of fuels are changed with respect to corrosion intensity and M100 has a higher variation among fuel samples. Therefore, the application of methanol in a lower concentration is suitable for SI engines in accordance with material compatibility since the corrosiveness of methanol is minimal on the engine components. Finally, this work reports some proposals based on the experimental outcomes to exalt the performance of engine components against the corrosive nature of methanol for flex-fuel engines (FFE).