The paper presents an examination of the possibility of applying raspberry flower extract (Rubus idaeus L.) as a green inhibitor of general corrosion of copper in 3% NaCl. Raspberry flowers (Rubus idaeus L.) sort Polka were collected from the Moševac near Maglaj city, Bosnia and Herzegovina. Raspberry flower extract in ethanol was obtained by ultrasonic extraction. A significant content of polyphenol was found in the raspberry flower extract by UV/VIS spectrophotometry analysis. Results obtained by DC techniques (by the methods of Tafel extrapolation, potentiodynamic polarization and linear polarization) prove that the corrosion rate decreases in the presence of the raspberry flower extract. Tests performed by the method of electrochemical impedance spectroscopy prove that the tested extracts slow down the kinetics of the corrosion process, which is visible through the increase in resistance. The results of the conducted tests prove that in an aggressive medium, such as 3% NaCl solution, Polka raspberry flower extract can be used as an inhibitor of copper's corrosion.

Austenitic stainless steel is mostly used at high temperatures. It is known that during heating of the austenitic stainless steel with increasing temperature and time of annealing a microstructure is changed i.e. there is the precipitation of carbides followed by precipitation of secondary phases as a sigma phase. The presence of the delta ferrite in austenitic stainless steel enhances the formation of the sigma phase. This study represents the influence of delta ferrite on the sigma phase formation and the effect of the sigma phase on general corrosion. Corrosion tests were conducted in the corrosion cell according to Standard ASTM G5, on instrument potentiostat/galvanostat, Princeton Applied Research, model 263A-2, with the software PowerCORR® (Standard, ASTM G5-94). Examinations were carried out in 1% HCl and 10% FeCl3 solutions. The Tafel extrapolation method was used for the investigation of general corrosion. The results of corrosion testing indicated that the intensity of the general corrosion increases with the increase of the delta ferrite and sigma phase contents.

Gallic acid is a phenolic acid widely spread in various plants, where it is present either in free form or as part of tannins, called gallotannins. It shows several positive effects on human health. It has different biological effects: antibacterial, antiviral, and anti-inflammatory. Many scientists are showing great interest in gallic acid precisely because of its antitumor effect. The content of gallic acid was determined in (Rubus idaeus L.) Polka raspberry by applying reverse-phase high-resolution liquid chromatography on reverse phases on Shimadzu Prominence Modular HPLC with UV/Vis detector, mobile phase degasser, pump, autosampler, and column oven. The analysis was performed in ethanolic extracts of Polka raspberry flower obtained by the Soxhlet extraction and the ultrasonic methods. Raspberry flowers (Rubus idaeus L.) Polka varieties were collected from two different localities in Bosnia and Herzegovina, namely: Starposle near Kakanj and Moševac near Maglaj. Gallic acid was determined in all analyzed samples of Polka raspberry. The highest gallic acid content was determined in the extract of Polka raspberry flower from the Maglaj-Moševac site, using the ultrasonic method (0.1789%), and the smallest in the Polka raspberry flower from the Kakanj Starposle site, using Soxhlet extraction (0.0995%). The proportion of gallic acid was higher in the extract of Polka raspberry flower from the Maglaj-Moševac site, which suggests that these flowers of Polka variety are recommended as better natural sources of this phenolic acid and that ultrasonic extraction has proven to be a more efficient method for extraction of gallic acid in ethanolic extracts, which is the goal of research.