جستجوی مقالات مرتبط با کلیدواژه « Brass Alloy » در نشریات گروه « شیمی »

In the present study, the Schiff base was synthesized [1,1'-((1E,1'E)-((4,5-dimethyl-1,2-phenylene)bis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol) ] derived from the reaction of 2-hydroxy-1-naphtha-aldehyde with, 4,5-Dimetyl-1,2-penylenediamine for 4hr. and yield was 90.09%. The prepared compound was identified by C.H.N, UV-Vis, FT-IR 1H–NMR, and mass spectroscopy and was studied also theoretically using Gaussian 09 software based on the DFT method at B3LYP/6-31G (d,p). Quantum chemical calculations were performed to provide further insight into the inhibition efficiencies that were conducted experimentally. The weight loss method was used to measure the efficiency of the prepared compound as a corrosion inhibitor in an acid medium. It was found that the inhibition efficiency was increased with decreasing temperature and the concentration increase of synthesized Schiff base and the highest inhibition efficiency was obtained at an optimum concentration of (1×10-3 M) for inhibitor at 298 K. Moreover, it was found that the adsorption process of the inhibitor on the surface of the brass is obeyed by the Langmuir isotherm of adsorption. The value of the free energy change was found to be -28.28 kJ/mol, which indicates that the prepared compound adsorbed on the surface of the metal. The antioxidant activity of the prepared Schiff base was investigated on the basis of the radical scavenging effect of 1,1-diphenyl-2-picryl-hydrazyl (DPPH)-free radical activity was also studied. The ligand (S1) exhibited excellent activity.

This paper describes the kinetics of the electropolymerization of 4-amino-3-methyl-1,2,4-triazole-5-thiol (MTSNH) on a brass substrate in alkaline solution containing methanol. Our laboratory has developed a new synthesis strategy for MTSNH. This compound was purified and characterized by 1HNMR and 13CNMR spectroscopies. The electrochemical study was investigated using cyclic polarization, chronoamperometry, electrochemical impedance techniques and scanning electronic microscopy. The polymeric film was achieved by successive cyclic voltammetry sweep between 0 and 2.2 V at the scan rate of 10mV/s. The effect of the scan rate for 10-3 M of MTSNH in a basic solution of potassium hydroxide 0.1 M containing methanol shows that the increase of the scan rate is accompanied by the increase of the intensity of the first oxidation peak, which indicates the acceleration of the studied process. We have also shown that the monomer oxidation reaction is essentially irreversible and controlled by a diffusion process. The protective effect of the film formed on brass has been studied in a 3% NaCl. The results showed important inhibition efficiency, about 83% for 1 h of testing time.

In this study, the weld nugget zone (WNZ) electrochemical behavior in copperbrass plates, welded using friction stir lap welding, in 0.015 M borate-buffered(Borax) (pH 9.3) and 1 M NaCl (pH 7.2) solutions are investigated. Therefore, dissimilar copper/ brass plates welded with welding conditions of welding speed of 25 mm/min and rotation speed of 710 rpm. Features of specimen welded nugget zone under open circuit potential; potentiodynamic polarizations are compered and then the morphology of the products corrosion formed in polarization experiment are analyzed using SEM. Electrochemical impedance spectroscopy (EIS) is used for the characterization of surface films formed on the welded specimens during 3600s immersion at Eocp in the two test solutions. Results showed that the welding process reduced the welded NZ corrosion resistance and offered lower corrosion resistance than copper and higher corrosion resistance than brass in 1 M NaCl (pH 7.2) solution. On the other hand, polarization plots showed that welding process results in current densities decreases from 0.512 for copper and 0.711 for brass to 0.213 µAcm−2 for the WNZ and significant shifts toward positive for corrosion potential in Borax solution. Indeed, the welded NZ corrosion rate in Borax solution was less than that in 1 M NaCl. The oxide film formed on the welded joints of NZ surface was more porous in borate buffer solution than in the NaCl solution. The hardness of welded joints was higher than copper and brass, and the highest hardness observed in the welded specimen nugget zone with low heat input during the welding process, because the grain refined most meaningfully in the welded joints NZ during welding process.