Mestrado em Química
URI Permanente para esta coleção
Nível: Mestrado Acadêmico
Ano de início: 2006
Conceito atual na CAPES: 5
Ato normativo: Homologação da 85ª Reunião do CTC-ES, Parecer CNE/CES nº 163/2005.
Processo nº 23001.000081/2005-56 do Ministério da Educação.
Publicado no DOU 28/07/2005, seção 1, página 11)
Periodicidade de seleção: Anual
Área(s) de concentração: Química
Url do curso: https://quimica.vitoria.ufes.br/pt-br/pos-graduacao/PPGQ/detalhes-do-curso?id=954
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- ItemAnálise de petróleo por espectroscopia de impedância eletroquímica e da corrosão do aço AISI 1005 em soluções contendo íons sulfeto(Universidade Federal do Espírito Santo, 2011-02-11) Perini, Nickson; Freitas, Marcos Benedito José Geraldo de; Souza, Ernesto Chaves Pereira de; Castro, Eustaquio Vinicius Ribeiro deThe electrochemical impedance spectroscopy is technique that allowtomonitoring ofcrude oil, blends,emulsions, and the interaction between these multiphase fluids and steel, allowing the evaluation of corrosion resistance. Crude oils are dielectric and has low conductivity. Therefore it is difficult to conduct measurements in conventional electrochemical cells with three electrodes, which under these conditionsrequired the use of only two parallel electrodes and validation of the impedance measurements. The behavior of the blends and crudeoil is framed for the characterization in the Nyquist diagram for a homogeneous distribution in constant relaxationtime, represented by undistorted semicircle in high frequency. At low frequencies, presents a distorted semicircle assigned to the interface metal/oil. The Nyquist diagram for water in oil emulsions showstwo semicircles in high and medium frequency attributed, respectively, to oil phase and emulsion. The thirddistorted semicircle at low frequency indicates the value of the corrosion resistance of carbon steel in contact with the emulsion. Multivariate analysis (PCA) is used to correlate oil properties with the values obtained by equivalent circuit of the impedance spectra. The corrosion of carbon steel, followed by film formation in aqueous solutions containing H2S in low concentration, is measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), SEM, XRD and Mossbauer. The films of iron sulfide formed under these conditions are corrosive and it increases the rate of corrosion. In CV are detected two peaks of anodic current density, attributed to film formation of iron sulfide and its subsequent oxidation. The irregular and compact morphology was observed by SEM and the composition of the film by EDX, with the majority consisting of Fe, S and O. The crystalline phases were detected by XRD, containing Mackenawite, Marcasite, Pyrite,Troilite, iron hydroxide and hydrate iron sulfate. The effect Mossbauer characterization indicatedthat the film is 85,3% as FeS2, mainly Pyrite. The impedance of the films in solution0.1 mol.L-1Na2SO4reveals that the films of iron sulfide formed under these conditions are corrosive and it increases the rate of corrosion
- ItemSíntese de híbridos moleculares contendo os núcleos morfolínico, 1,4-naftoquinônico, 7-cloroquinolínico e 1,3,5-triazínico com atividade inibidora de corrosão no aço AISI 316 em meio de água de produção simulada(Universidade Federal do Espírito Santo, 2019-02-15) Westphal, Regina; Greco, Sandro José; Kuster, Ricardo Machado; Filomeno, Claudinei AndradeCorrosion is a recurring and troubling problem in many sectors of industry and society. The petroleum and petrochemical industries are the most affected by the phenomenon of corrosion, which is present throughout the production chain, causing operational delay, increased production costs, oil contamination and other serious damages to the environment and health or even to the life of employees. This is due to the presence of corrosive substances, such as Cl-, H2S, CO2 and O2, dissolved in the production water and oil. One way to mitigate the problems caused by corrosion is by injecting chemical inhibitors into the production line. The organic inhibitors (focus of this work) are substances that adsorb chemically to the surface of the steel, coordinating to the metal and, thus, forming a protective film. Therefore, it is interesting that these inhibitors have in their structures strongly polar insaturations and / or clusters such as nitrogen, sulfur or oxygen atoms, which have pairs of electrons available to be donated to metals. In this sense, the molecular hybrids 70, 71 and 72, containing the morpholine, naphthoquinone, quinoline and triazine cores (which have a recognized corrosion inhibitory activity) were synthesized, with yields ranging from 32% to 35%, characterized and evaluated for their anticorrosion activities in AISI 316 steel in simulated water medium containing 150,000 mg.L-1 of Cl- and 5 mg.L-1 of S2-. The potentiodynamic polarization study revealed that the three compounds synthesized showed corrosion inhibiting activity, with inhibition efficiency ranging from 66% to 85%, being the best result obtained for compound 70. The study of electrochemical impedance corroborated with the study of polarization, pointing to compound 70 as the best inhibitor and further indicated that the compounds studied act by forming a protective film on the surface of the AISI 316 steel. A fourth molecular hybrid 98containing only the triazine and naphthoquinone cores was also synthesized, however its structural characterization still requires some more analysis.