Performance of Nozzle Steels in Biofuel

Blanco Estupiñan, David Leonardo | 2022

To evaluate the corrosion resistance of stainless-steel injection nozzles under immersion test in biodiesel and perform electrochemical characterization under HNO3 solutions. Methods and materials: Chemical characterization of biofuel was performed to analyze its stability. Immersion tests were carried out for 4 months, evaluating 304 stainless steel under 3 different diesel/biofuel mixtures concentrations. Additionally, polarization tests were done using NOx concentrations above the levels measured from engine emissions. Results and discussion: The use of biofuels in Colombia has been largely driven by ethanol production from vegetable sources. Their use brings some advantages related to reducing emissions of particles and toxic gases (mainly aromatic groups, NOx, and CO2). However, degradation of materials can occur when they are in direct contact with biodiesel. Furthermore, solidification into waxes, which leads to plugging of nozzles, has been reported. However, it is unknown whether this influences oxygen diffusion in the solution and, in turn, affects the corrosion resistance of stainless steel. Conclusions: The corrosion resistance of the 304 stainless steel changed under immersion conditions, even though its protective layer was not affected by the NOx concentrations registered in the biofuel mixtures.