The use of natural additives in biodiesel has been investigated, however, there is limited information in the literature in relation to their influence on corrosion resistance and oxidative stability. This work aims to investigate the oxidative stability of biodiesel and the corrosion resistance of carbon steel (AISI 1020) in contact with soybean biodiesel solutions (B100) in the presence and absence of natural additives such as: rosmarinic acid, curcumin, gingerol, eugenol, thymol and quercetin. Corrosion and microscopy tests were used to assess corrosion resistance. The Rancimat technique was used to study oxidative stability. The results obtained indicate that curcumin was the best additive in relation to oxidative stability, while rosmarinic acid showed better performance in inhibiting corrosion. The effect of these substances is related to the presence of phenolic compounds or the existence of oxygen in its molecular structure.

This work investigates the effect of the addition of glycerol on the microstructure, corrosion resistance, and efficiency of the electrodeposition process of Cu coating in an acid sulphate solution. The morphology and microstructures of electrodeposits were analyzed using Scanning Electron Microscopy (SEM), Spectrometry X-Ray Diffraction (XRD) and laser scanning confocal microscopy (LSCM). Evaluation of the corrosion resistance was performed in 2.0 mol⋅L −1 NaCl by means of weight loss tests and electrochemical techniques. The addition of glycerol resulted in a decrease in grain and crystallite sizes, a decrease in roughness and an increase in the tensile strain of the coating. The deposition efficiency and the corrosion resistance increased with the addition of glycerol exhibiting a maximum value at the concentration of 0.42 mol⋅L −1 , increasing the efficiency of electrodeposition by approximately 96%. This is related to the roughness of the coating, which is minimal at this concentration.