Miomir Pavlovic

Protection of Copper and its Alloys Using Corrosion Inhibitor-Literature Review

A review of the literature dealing with the electrochemical corrosion of copper and its alloys with purpose to find the most suitable inhibitor for its protection has been done. According to their chemical composition of corrosion inhibitors are divided into inorganic and organic inhibitors. Inhibition of alloying metals are possible (such as the addition of arsenic alloy components in brass, preventing its unzincanization). The paper reviews the theoretical basis of application of inhibitors to protect metals from corrosion as well as an overview of current research application of inhibitors to protect copper and copper alloys. Benzotriazole (BTA) is most often used corrosion inhibitor for copper and its alloys in acidic and alkaline solution, because of its high inhibition efficiency. The lowest concentration of inhibitor for protection of copper in various solutions was 0.05%, and for the protection of copper in contact with steel is 0.1%. On the surface of copper and brass BTA forms a protective Cu-BTA film. However, BTA is like many other synthesized organic inhibitors is very toxic and if used in very small concentrations. It turned out that the AETD, AETDA and PTAT good corrosion inhibitors of copper mixed type with the efficiency of inhibition increases with concentration. Due to the adverse effects on the environment, health and other bodies in recent times the focus of research is transferred to the inhibiting action of biological molecules or mixtures of natural compounds called „Green inhibitors“.

New Technology for the Synthesis of New Materials Based on Cellulose and Sorption of Noble Metals

Cellulose is continuously updated biopolymer through photosynthesis and, hence, it is inexhaustible raw material for new materials and new technology (Bojanic et al., 1988a; Granja et al., 2006; Hubbe et al., 2008, 2011; Jovanovic et al., 2002; Kamel, 2007; Puoci et al., 2008; Schwanninger et al., 2004; Vainio, 2007; Wu et al., 2007; Zhang et al., 2010). Modification of biopolymers has been given scientific and practical importance. Grafting is one of the best methods making the synthesis of new materials and their applications virtually unlimited (Achilleos & Vamvakaki, 2010; Bhattacharya & Mirsa, 2004; Cohen Stuart et al., 2010; Crini, 2005; Gandini, 2008; Li et al., 2011; Lu et al., 2008; Roy et al., 2009; Petrovic et al., 2010; Sharma et al., 2010; Xin et al., 2011). Cellulose is, due to its chemical and submolecular structure, mechanically resistant and chemically stable. Such properties are of great importance for the chemical and electrochemical modification and represent a subject to numerous studies aimed at obtaining new materials with special properties for specific applications (Anderson, 2000; Bonne, 2008; Chmielewska et al., 2010; Cao et al., 2007; Hu et al., 2009; Kim et al., 2010; Pinto & Maaroufi, 2005; Spiridon et al., 2011; Vitz et al., 2010; Wang, 2008; Zhou et al., 2011). Grafting reactions represent possible solutions for changing chemical, physical and mechanical properties of the cellulose molecules in desired direction. Modification of cellulose leads to formation of the new ionic polymers (Heinze, 1998) and grafting of N-vinyl pyrrolidone (Gupta & Sahoo, 2001; Chauhan et al., 2005), styrene, methyl methacrylate, methyl acrylamide (Coshun & Temuz, 2005; Sharma & Chauhan, 2009) acrylamide and acrylic acid (Chauhan & Lal, 2003), grafting of acrylamide (Chauhan et al., 2003) and 4-vinylpyridine (Chauhan et al., 2000; Kaur & Dhiman, 2011), and ethyl acrylate (Kalia et al., 2011) on cellulose have been studied. New materials based on biopolymers and, especially, modification of cellulose and lignin, have been used as semipermeable membranes, ion-exchangers and matrices for medicaments (Bilba, 1998; Hubicki et al., 2008; Maliyekkal et al., 2010; Nada et al., 2007; Ozdemir et al., 2006; Parajuli, 2006; Rodriguez et al., 2009; Saarinen, 2008; Vlasankova & Sommer, 1999; Wang, 2005; Xu, 2005). In order to obtain grafted cellulose copolymers with 4-vinylpyridine, vinylimidazole, 1-vinyl-2-pyrrolidone, 9-vinylkarbazole and other vinyl monomers containing double bonds capable for copolymerization with vinyl monomers have been introducted in cellulose. For

Impact of roughness of Zn-Mn coatings on corrosive stability

This paper involves electrochemical deposition of Zn-Mn coatings from four solutions. We measured their roughness and corrosion stability. We used cathodes made of steel of unknown composition that were licensed under the chemical preparation before the electrochemical deposition of dual-Zn-Mn coatings, and we also used the anode of zinc, purity of 99.99%. Dual Zn- Mn coatings were electrodeposited for 15 minutes from all of the solutions at a current densities of 1 A/dm2, 2 A/dm2 and 4 A/dm2. All experiments were carried out galvanostatialy (at constant current) in an electrochemical cell, volume of 500 cm3 and at room temperature. The roughness of electrochemically deposited Zn-Mn coatings was measured by a TR200 device and corrosion stability of deposited coatings by determining the Electrochemical Impedance Spectroscopy (EIS). The results show that the coatings with the smallest roughness are coatings deposited at a current density of 2 A/dm2 from all of the solutions. The exception is solution 3 with the relation [Mn2+]:[Zn2+]=1:2 where the roughness is at the lowest level in comparison to all solutions, ranging from 0.71 to 0.875 μm, and the roughness is lowest at the current density of 4 A/dm2 and is 0.71 μm. Based on electrochemical measurements, the corrosive most stable Zn-Mn coating is deposited at a current density of 2 A/dm2 from all the solutions and at the current density of 4 A/dm2 from solution 3 with a ratio of [Mn2+]:[Zn2+]=1:2. This suggests that the corrosion stability is related directly to the roughness and compactness of Zn-Mn coatings. When it comes to corrosion, the most stable coatings are those with the lowest roughness.