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Opis: The electroanalytical and surface characterization of copper immersed in 3 wt.% NaCl solution containing 1 mM of 2-phenylimidazole (2PhI) is presented. It was proven that 2PhI can be employed as corrosion inhibitor for copper using various electrochemical analyses, such as cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy, and potentiodynamic curve measurements. The adsorption of 2PhI on copper was further analyzed by 3D-profilometry, attenuated total reflectance Fourier transform infrared spectroscopy, contact angle measurements, and scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. This system was therefore comprehensively described by various analytical approaches.
Ključne besede: corrosion inhibitor, copper, electrochemical impedance spectroscopy, EIS, cyclic voltammetry, attenuated total reflectance Fourier transform infrared, ATR-FTIR
Objavljeno v DKUM: 17.01.2019; Ogledov: 1402; Prenosov: 341
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Opis: In this paper the visioplasticity method is used to find the complete velocity and strain rate distributions from the experimental data, using the finite-difference method. The data about values of strain rates in plastic re- gion of the material is very important for calculating stresses and the prediction of product quality. Specimens of copper alloy were extruded with different lubricants and different coefficients of friction and then the strain rate distributions were analysed and compared. Significant differences in velocity and strain rate distributions were obtained in some regions at the exit of the deformed zone.
Ključne besede: forward extrusion, copper alloy, visioplasticity, strain rate, lubrication
Objavljeno v DKUM: 03.07.2017; Ogledov: 588; Prenosov: 112
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Opis: Copper and its alloys are soft and malleable metals and are often used for fabricating structures and monuments open to the atmosphere where they are subject to corrosion attack. There are many ways to protect metal against corrosion: corrosion inhibitors, protective layers, hydrophobic layers. He aim was to develop a simple technological process for forming hydrophobic, protective coatings for protection of Cu, Cu10Zn, Cu40Zn and Zn under conditions of atmospheric corrosion as tested in simulated urban rain. Carboxylic acids form self-assembled hydrophobic layers by adsorption to the positively charged metal surfaces via their carboxylic group. Corrosion inhibitors are often used to protect metals against corrosion in closed system. Most used corrosion inhibitors to protect Cu and its alloys is benzotriazole (BTAH) which showed good results in different environments. 2-mercaptobenzimidazole (2-MBI) is a derivative of BTAH with stronger affinity to adsorb on the Cu surface and showed good corrosion protection results in acidic solutions. Corrosion protection properties of the layers were tested with the use of electrochemical methods: potentiodynamic polarization and electrochemical impedance spectroscopy. The results were complement with immersion test where the weight loss was obtained. The properties of the layers were explored with surface-analytical methods: measurement of the contact angles, X-ray photoelectron spectroscopy, scanning electron microscopy with a chemical analysis and glow discharge optical emission spectroscopy. First the optimal conditions to produce hydrophobic coatings with the use of carboxylic acids were explored. The inhibition efficiency increased with increasing carbon chain length, longer preparation time in ethanol solution and increasing concentration of carboxylic acid. The inhibition of corrosion of Cu, Cu10Zn, Cu40Zn and Zn in simulated urban rain was further studied using the self-assembly of BTAH, 2-MBI and SA in ethanol solution, as individual inhibitors and in combinations. The morphology of layers differed greatly. The results of electrochemical measurements and weight loss immersion test ruled out BTAH as a possible inhibitor, unless combined with stearic acid. In the cases of Cu40Zn and Zn it even promoted corrosion. In contrast, 2-MBI gave good results, and even better in combination with stearic acid. SA layers provided the best long term corrosion protection of all tested inhibitors and exhibited the highest contact angles. 2-MBI provided less protection than SA. Combining organic inhibitor and stearic acid improves the corrosion protection properties of the self-assembled layers compare to individual layers. To make the procedure of layer preparation more appropriate for industrial application the time of immersion was decreased. Layers prepared on Cu with 1 min immersion time showed adequate corrosion protection of Cu in simulated urban rain. We also studied the possibility of combining SA with vitamin E in the layer preparation procedure. The modified layers formed with combination of Vitamin E and SA showed better corrosion inhibition properties for Cu and Cu40Zn in simulated urban rain as individual layers. Combining inhibitor and carboxylic acid together to prepare corrosion protective layers has a positive effect on the corrosion properties of the layers. Layers made combining corrosion inhibitor and carboxylic acid showed better corrosion protection than individual layers. The self-assembling process is a fast process shown by the tests made on the Cu layers with shorter immersion time. The addition of Vitamin E in the preparation of layers with carboxylic acids shows a positive effect on the corrosion properties of layers.
Ključne besede: copper, brass, corrosion, simulated urban rain, inhibitors, carboxylic acid, benzotriazole, 2-mercaptobenzimidazole
Objavljeno v DKUM: 30.11.2015; Ogledov: 1296; Prenosov: 148
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Ključne besede: vineyard, soil, copper, zinc, phytopharmaceuticals
Objavljeno v DKUM: 10.07.2015; Ogledov: 957; Prenosov: 30
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Ključne besede: copper fungicides, copper fertilizers, apple scab, disease control
Objavljeno v DKUM: 10.07.2015; Ogledov: 1057; Prenosov: 40
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