Na Ficha Catalogr?fica consta o t?tulo: "Monitoramento qu?mico da composi??o e da a??o do biodiesel do ?leo de am?ndoa da maca?ba no contato direto com a?o carbono e a?o carbono galvanizado". / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2018-11-01T18:00:34Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-11-10T11:52:57Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) / Made available in DSpace on 2018-11-10T11:52:57Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) Previous issue date: 2018 / O biodiesel ? uma importante fonte alternativa de energia, pois ? derivado da biomassa fotossint?tica de plantas oleaginosas. ?leos de muitas esp?cies de plantas t?m sido investigados por serem material precursor para a produ??o de biodiesel. Maca?ba (Acrocomia aculeata) ? uma palmeira nativa do Brasil, cuja fruta tem uma propor??o significativa de ?leo, com potencial real para a produ??o industrial de biodiesel. Existe uma ampla gama de quest?es ainda a serem sistematicamente exploradas, a fim de se obter uma vis?o adequada do manejo racional da cultura da palma, extra??o e processamento do ?leo para a produ??o e armazenamento comercial do biodiesel. O comportamento qu?mico dos ?steres met?licos de ?cidos graxos do ?leo da am?ndoa de maca?ba e a lixivia??o de elementos met?licos por contato dos a?os carbono usados na constru??o de tanques e dutos s?o o foco principal deste trabalho experimental. A composi??o em ?steres met?licos do biodiesel obtido da rea??o de transesterifica??o de triacilglicer?is do ?leo de am?ndoa da maca?ba com metanol, em contato direto com os a?os carbono ASTM A283 grau C e API X65 galvanizados e n?o galvanizados foi monitorada. A lixivia??o de elementos qu?micos da estrutura dos a?os carbono foi tamb?m investigada. Os resultados obtidos por espectroscopia M?ssbauer neste trabalho tamb?m mostraram que o contato com o biodiesel de maca?ba confere prote??o aos a?os n?o galvanizados contra a corros?o oxidativa no contato direto com o ar. Al?m disso, observou-se ainda a forma??o de esp?cies qu?micas contendo ferro, nomeadamente magnetita (Fe3O4) e w?stita (Fe1-xO), na superf?cie das barras de a?o n?o galvanizado quando em contato direto com o ar, mas sem contato com o biodiesel; nenhum ?xido de ferro foi detectado nas barras de a?o usadas no biodiesel, monitoradas at? 105 dias de armazenamento. As taxas de corros?o s?o baixas, de acordo com a norma NACE-RP0775, Standard Recommended Practice: Preparation, Installation, Analysis, and Interpretation of Corrosion Coupons in Oilfield Operations. O biodiesel do ?leo da am?ndoa da maca?ba tem 63,44 massa% de ?steres de ?cidos graxos saturados. Uma condi??o que assegura relativamente alta estabilidade oxidativa do combust?vel, mesmo em contato (na presente experi?ncia, por imers?o) com o a?o carbono API ou ASTM, galvanizado ou n?o. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2018. / Biodiesel is an important alternative source of energy, as it is derived from the photosynthetic biomass of oleaginous plants. Oils of many plant species have been investigated for being precursor material for the production of biodiesel. Maca?ba (Acrocomia aculeata) is a native palm in Brazil, whose fruit has a significant proportion of oil, with real potential for the industrial production of biodiesel. There is a wide range of issues still to be systematically explored, in order to achieve an adequate view of the rational crop management of the palm, extraction and processing of the oil for the production and the commercial storage of biodiesel. The chemical behavior of the fatty acid methyl esters from the maca?ba oil and the leaching of metal elements put directly in contact with carbon steels used in the construction of tanks and pipelines are the main focus of the present experimental work. The composition in methyl esters of the biodiesel obtained from the transesterification reaction of triacylglycerols of the maca?ba fruit kernel oil with methanol, in direct contact with the galvanized and non-galvanized carbon steels ASTM A283 grade C and API X65. The M?ssbauer spectroscopy results obtained in this work also showed that the contact with the maca?ba biodiesel gives protection to the non - galvanized steels against the oxidative corrosion in direct contact with air. Also the formation of iron-bearing chemical species, namely magnetite (Fe3O4) and w?stite (Fe1-xO), on the surface of the non-galvanized bar steels when in direct contact with air; no such iron oxide was detected on the steel bars used in the biodiesel, by monitoring up to 105 days of storage. But the corrosion rates are low, according to the NACE-RP0775, Standard Recommended Practice: Preparation, Installation, Analysis, and Interpretation of Corrosion Coupons in Oilfield Operations. These results allow better evaluate and more adequately specify conditions of storage and transportation of biodiesel obtained from the maca?ba oil. The biodiesel of the maca?ba almond oil has 63.44 mass% of esters of saturated fatty acids. A condition that ensures relatively high oxidative stability of the fuel, even in contact (in the present experiment, by immersion) with API or ASTM carbon steel, galvanized or not.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2016-08-03T18:24:29Z No. of bitstreams: 1 DIS_LOANI_BASSANI_DE_OLIVEIRA_COMPLETO.pdf: 4322519 bytes, checksum: e01558dfcb88bb2ce1765983c4cd249e (MD5) / Made available in DSpace on 2016-08-03T18:24:29Z (GMT). No. of bitstreams: 1 DIS_LOANI_BASSANI_DE_OLIVEIRA_COMPLETO.pdf: 4322519 bytes, checksum: e01558dfcb88bb2ce1765983c4cd249e (MD5) Previous issue date: 2016-03-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The present study analyzes the influence of the presence of Ca2+, by the addition of CaCO3 in water saturated with CO2, on the corrosion of SAE 1045 steel tempered and quenched under conditions of 80? C, 15 MPa and 168 hours (7 days) andon the properties of the corrosion scales formed on the steel surface. The corrosion rates of the steel were determined by weight loss tests according to ASTM G1-03 (2010). The techniques of electron scanning microscopy by field emission (FEG/MEV), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and potentiodynamic polarization were used to obtain information about the properties of corrosion scales. Uniform corrosion was observed and the results indicated that by adding calcium carbonate, with concentrations of 10 ppm, 100 ppm, 1000 ppm and 10000 ppm of Ca2+ in solution, the corrosion rates by weight loss and the thicknesses of the corrosion product films decreased. However, the addition of calcium carbonate decreased the corrosion rate for all concentrations, probably due to its property of increasing the pH of the solution. The highest corrosion rate determined by weight loss was observed when corrosion was induced without the presence of calcium carbonate and with concentration of 100 ppm of Ca2+. The corrosion rate did not changed linearly with Ca+ concentrations, the highest corrosion rate was observed for 100 ppm of Ca2+. The EDS analyzes provide information that a mixed carbonate is formed in presence of Ca+2 in solution, probably FexCa1-xCO3, with increasing of Ca incorporation in the crystalline lattice of FeCO3, with increasing of calcium content and a respective reduction of Fe amounts. The XRD analyzes also indicated that the corrosion product films formed in the presence of calcium are composed by FeCO3 enriched with Ca besides oxides and iron hydroxides as goethite - FeO(OH) and Fe3O4 - magnetite. Based on the electrochemical tests, the film that had the more negative potential (Ecorr) and higher corrosion current density (icorr) was the one formed in the presence of 100 ppm Ca2+, and this film showed electrochemical properties very similar to the bare steel. / O presente trabalho analisa a influ?ncia da presen?a de Ca2+, por meio da adi??o de CaCO3 em ?gua saturada com CO2, na corros?o do a?o SAE 1045, temperado e revenido, sob condi??es de 80 ?C, 15 MPa e 168 horas (7 dias) e nas propriedades dos filmes de produtos de corros?o formados na superf?cie do a?o. As taxas de corros?o do a?o foram determinadas por testes de perda de massa segundo ASTM G1-03 (2010). As t?cnicas de microscopia eletr?nica de varredura por emiss?o de campo (FEG/MEV), espectroscopia de energia dispersiva (EDS), difra??o de raios X (DRX) e polariza??o potenciodin?mica foram utilizadas para obter informa??es sobre as propriedades dos filmes de produtos de corros?o. Observou-se corros?o uniforme e os resultados mostraram que ao adicionar carbonato de c?lcio, com concentra??es de 10 ppm, 100 ppm, 1000 ppm e 10000 ppm de Ca2+ na solu??o, as taxas de corros?o por perda de massa e as espessuras dos filmes de produtos de corros?o diminuiram. A adi??o de carbonato de c?lcio reduziu as taxas de corros?o para todas as concentra??es de Ca2+, provavelmente, devido sua propriedade de aumentar o pH da solu??o. A taxa de corros?o n?o variou linearmente com a concentra??o de Ca2+ em solu??o, sendo que a maior taxa de corros?o foi observada para a concentra??o de 100 ppm de Ca2+.As an?lises de EDS indicaram a forma??o de carbonato misto, provavelmente FexCa1-xCO3, com o aumento da incorpara??o de Ca na rede cristalina do FeCO3, visto que com o aumento da adi??o de carbonato de c?lcio observou-se um aumento no teor de Ca e uma respectiva redu??o nos teores de Fe. As an?lises de DRX indicaram que os filmes de produtos de corros?o formados em presen?a de c?lcio s?o compostos de FeCO3 enriquecido com Ca, de ?xidos e hidr?xidos de ferro como goetita - FeO(OH) e Fe3O4 - magnetita. De acordo com os ensaios eletroqu?micos, o filme que apresentou o potencial de corros?o menos nobre (Ecorr) e maior densidade de corrente de corros?o (icorr) foi o formado na presen?a de 100 ppm Ca2+, sendo que este filme apresentou propriedades eletroqu?micas muito similares ao do a?o refer?ncia (sem produto de corros?o na superf?cie).

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2018-04-11T16:46:38Z No. of bitstreams: 1 2017 - Mariana Falc?o Lopes Princisval Carlos.pdf: 3027874 bytes, checksum: f7dd2c459e8918f917f701198c97f955 (MD5) / Made available in DSpace on 2018-04-11T16:46:38Z (GMT). No. of bitstreams: 1 2017 - Mariana Falc?o Lopes Princisval Carlos.pdf: 3027874 bytes, checksum: f7dd2c459e8918f917f701198c97f955 (MD5) Previous issue date: 2017-08-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / In this work, seven enaminoesters were synthesized, divided into three series depending on the starting amine, the series A is derived from phenethylamine, the series B of aniline and, finally, the series C derived from benzylamine. The synthesis occurred in two ways, the first being through the reaction of the ethyl acetoacetate in the presence of the corresponding amine in ethanol as solvent in the presence of p-toluenesulfonic acid and the second the amine in the presence of triethylamine and methanol as solvent, both in magnetic stirring at room temperature. The compounds were obtained as oil, with a high purity, and for some compounds separation via flash chromatography in ethyl acetate / hexane was required, yields ranging from 70-93%. The compounds were characterized by spectroscopic techniques such as Infrared and Nuclear Magnetic Resonance 1H and 13C, in addition to the refractive index. Six of the seven compounds synthesized were evaluated using electrochemical techniques of Impedance Spectroscopy Electrochemistry, Potentiodynamic Polarization and Resistance to Linear Polarization and the mass loss technique, as to the action as inhibitors of corrosion against AISI 1020 carbon steel in 0.5 mol L-1 HCl. The Molecular Modeling technique was used to better visualize the structures of the synthesized enaminoesters and, later, correlation of the inhibition efficiencies found. The theoretical parameters such as the energy of the orbitals of symmetrical boundaries and dipole moment with the results corrosion efficiency were also evaluated. In general, the enaminoesters showed good corrosion efficiency, excess by the compound derived from hydroxylaniline. All presented corrosion inhibition efficiency with mixed inhibitor characteristics. However, the compounds that did not present substituents and those that contain electron donor group (OCH3) stood out as inhibitors, highlighting the compound EN1, which presented efficiency of 92% of inhibition of the corrosion by the technique of Resistance to Polarization Potentiodynamics and 98% by the technique of mass loss after 24h of immersion. The efficiency was shown to be dependent on the concentration in the synthesized compounds, that is, the corrosion inhibition efficiency increases with XXIII increasing inhibitor concentration, and that the adsorption phenomena of the compounds studied obey the Langmuir isotherm. Thus, the synthesized, especially the not substituted, enaminoesters can be considered as promising corrosion inhibiting agents for acidic AISI 1020 carbon steel. / Nesta disserta??o, foram sintetizados sete enamino?steres, divididos em tr?s s?ries de acordo com a amina de partida, sendo a s?rie A derivada da fenetilamina, a s?rie B da anilina e, por ?ltimo, a s?rie C derivada da benzilamina. A s?ntese ocorreu de duas formas, sendo a primeira atrav?s da rea??o do acetoacetato de etila na presen?a da amina correspondente em etanol como solvente, na presen?a de ?cido p-toluenossulf?nico e, a segunda, a amina na presen?a de trietilamina e metanol como solvente, ambas em agita??o magn?tica ? temperatura ambiente. Os compostos foram obtidos em forma de ?leo, com alto grau de pureza, sendo necess?ria para alguns compostos a separa??o via cromatografia flash em acetato de etila/hexano, os rendimentos variaram na faixa de 70-93%. Os compostos foram caracterizados por t?cnicas espectrosc?picas de Infravermelho e Resson?ncia Magn?tica Nuclear 1H e 13C, al?m de ?ndice de refra??o. Seis dos sete compostos sintetizados foram avaliados por t?cnicas eletroqu?micas de Espectroscopia de Imped?ncia Eletroqu?mica, Polariza??o Potenciodin?mica e Resist?ncia a Polariza??o Linear e, por ensaio de perda de massa, quanto ? a??o como inibidores de corros?o frente a a?o carbono AISI 1020 em solu??o de HCl 0,5 mol L-1 . Modelagem Molecular foi utilizada para melhor visualiza??o das estruturas moleculares dos enamino?steres sintetizados e, posterior, correla??o das efici?ncias de inibi??o encontradas. Os par?metros te?ricos como a energia dos orbitais de fronteiras sim?tricos e momento dipolar foram calculados e, apenas os valores de momento dipolar correlacionaram com os resultados experimentais da efici?ncia anticorrosiva. De forma geral, os enamino?steres apresentaram boa efici?ncia anticorrosiva, com exce??o do composto derivado da hidr?xianilina (EN6). Todos apresentaram efici?ncia de inibi??o ? corros?o com caracter?sticas de inibidores mistos. Por?m, os compostos que n?o apresentaram substituintes e os que cont?m grupo doador de el?trons (OCH3) se destacaram como inibidores mais eficientes, dando destaque ao composto EN1, que apresentou efici?ncia de 92% de inibi??o da corros?o, pela t?cnica de Resist?ncia a Polariza??o Potenciodin?mica e 98% pela t?cnica de perda de massa ap?s 24 h de imers?o. XXI A efici?ncia se mostrou dependente da concentra??o nos compostos sintetizados, ou seja, a efici?ncia de inibi??o da corros?o aumentou com o aumento da concentra??o dos inibidores. Os fen?menos de adsor??o dos compostos estudados, apenas o EN1 obedece ? isoterma de Langmuir e os restantes a Langmuir modificada. Com isso, os enamino?steres sintetizados, especialmente os n?o substitu?dos, podem ser considerados como promissores agentes inibidores da corros?o para o a?o carbono AISI 1020 em meio ?cido.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-10T20:59:53Z No. of bitstreams: 1 GleidsonLimaPinheiro_DISSERT.pdf: 2590622 bytes, checksum: 06de3b4091ef1d22ceaba6df4aead4d0 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-12T19:33:54Z (GMT) No. of bitstreams: 1 GleidsonLimaPinheiro_DISSERT.pdf: 2590622 bytes, checksum: 06de3b4091ef1d22ceaba6df4aead4d0 (MD5) / Made available in DSpace on 2016-05-12T19:33:54Z (GMT). No. of bitstreams: 1 GleidsonLimaPinheiro_DISSERT.pdf: 2590622 bytes, checksum: 06de3b4091ef1d22ceaba6df4aead4d0 (MD5) Previous issue date: 2014-08-15 / Oleodutos sofrem corros?o do tipo qu?mica, devido a tens?o, entre outros mecanismos, e eletroqu?mica devido a grande quantidade de salmoura (?gua e cloretos), presentes nos fluidos produzidos na forma??o. Este trabalho tem como objetivo estudar a efici?ncia de um inibidor de corros?o comercial, usado na ind?stria do petr?leo, na inibi??o de corros?o agindo isoladamente e em mistura com microemuls?o (ME) na propor??o [1:1]. A ME foi obtida a partir dos seguintes constituintes: ?gua de torneira (fase aquosa), querosene (fase oleosa), n-butanol (cotensoativo) e UNT L90 (tensoativo). O inibidor possui mecanismo de prote??o tipo f?lmico, na prote??o do a?o carbono API 5L A210, muito usado na constru??o de oleodutos terrestres. Os experimentos foram formulados em solu??es salinas com 3% de NaCl que funcionam como meio agressivo, na presen?a e aus?ncia de borbulhamento do g?s (CO2), em temperatura ambiente (25?C). O inibidor estudado apresenta em sua fase ativa compostos de am?nio quatern?rio e derivados de imidazolina, e foi caracterizado como um inibidor formador de filme. Os resultados de efici?ncia de inibi??o foram avaliados por dados experimentais de densidades de corrente de corros?o atrav?s da t?cnica eletroqu?mica polariza??o linear, com extrapola??o de Tafel. O inibidor comercial agindo isoladamente mostrou-se mais eficiente no combate ? corros?o do que em microemuls?o quando n?o houve borbulhamento de CO2. Quando ocorreu a satura??o da solu??o de trabalho com CO2, observou-se uma eleva??o da inibi??o ao misturar-se o aditivo comercial com a microemuls?o. Tamb?m se constatou que o excesso de CO2 dissolvido na solu??o de trabalho implicou em uma eleva??o da taxa de corros?o, comparado aos ensaios an?logos realizados na aus?ncia do borbulhamento cont?nuo de CO2. Os ensaios foram realizados em concentra??es de inibidores de 10, 20, 40, 100, 200 e 400 ppm. As melhores efici?ncias foram observadas nos ensaios com concentra??o de 40 ppm, na aus?ncia do borbulhamento, e 200 ppm, quando o ensaio foi realizado na presen?a de borbulhamento com CO2. Os dados experimentais se ajustaram ao modelo de Langmuir, sugerindo a forma??o de um filme de monocamadas. / Pipelines suffer from chemical, under tension, and other kinds of corrosion mechanisms, as well as electrochemica l corrosion caused by the existing large amount of brine (water and chlorides) in the produced fluids. The goal of this work is to research the efficiency of a commercial corrosion inhibitor, used in pipelines on the oil industry, on the corrosion inhibition of the API 5L A210 iron, which is widely used on the overland pipelines constructions, acting alone and in a mixture with micro emulsion (ME) on a [1:1] ratio. The ME was obtained from the following constituents: tap water (aqueous phase), kerosene (oily phase), n-butanol (co-surfactant), and UNT L90 (surfactant). We observed the formation of protective film on the steel surface as an inhibitor?s protection mechanism. The experiments were formulated in saline solutions with 3% of NaCl that functioned as aggressive environment, on the presence and absence of gas bubbling (CO2), in room temperature (25?C). The studied inhibitor exhibits in its active phase quaternary ammonium compounds and imidazoline derivatives, which means it is a film-forming inhibitor. The inhibition efficiency results are evaluated by experimental data of corrosion current density by the electrochemical technique of linear polarization with Talef extrapolation. The inhibitor exhibit two distinct behaviors: in medium of saturation with CO2 we observed an increase of inhibition by blending the commercial additive with the micro-emulsion, and in medium without saturation of CO2 we observed a higher efficiency when the inhibitor was acting singly. We also could find that the excess of dissolved CO2 in the working solution resulted in an increase of the corrosion rate, compared to similar experiments in the absence of continuous bubbling of CO2. The best efficiencies were observed in the experiments with concentration of 40ppm without bubbling, and 200ppm when the experiments were performed in the presence of bubbling with CO2. The experimental data fitted to the Langmuir model, suggesting the formation of a film made of monolayers.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-08-26T12:43:16Z No. of bitstreams: 1 474158 - Texto Completo.pdf: 30740052 bytes, checksum: 0b50c4fe801d696f16180d6fa641a96c (MD5) / Made available in DSpace on 2015-08-26T12:43:16Z (GMT). No. of bitstreams: 1 474158 - Texto Completo.pdf: 30740052 bytes, checksum: 0b50c4fe801d696f16180d6fa641a96c (MD5) Previous issue date: 2015-03-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / In this work, it was evaluated the possibility of using bark of black wattle (Acacia mearnsii) as a corrosion inhibitor in environments with presence of CO2 under high pressure. SAE 1010 carbon steel samples were exposed to two corrosive situations (with and without oxygen) under the conditions of 15 MPa and 70 ?C, with distinct tannin concentrations for different exposure times (168, 360 and 2160 hours). In order to characterize the specimens it was used infrared spectroscopy analysis, Xray diffraction, scanning electron microscopy by field emission, energy dispersive spectroscopy, mass loss and potentiodynamic polarization tests, determining the rate of corrosion and the efficiency tannin as of tannin as inhibitor. The results indicated that the tannin in deaerated environmental has no potential for use as an inhibitor once there was no significant reduction in corrosion rates and, also the formation of ferric-tannates film. Was not observed corrosion rates values, due mass loss, and were classified as severe corrosion, according to values of NACE RP-07-75 and was not inhibition efficiency values higher than 21 % obtained. Nevertheless, in aerated environmental, tannin worked as a barrier to diffusion of O2 and/or complexation of Fe2+ and Fe3+, providing favorable conditions to the formation of FeCO3 film with protective features. The corrosion rates were classified as moderate for 2160 hours, while 168 h and 360 h, as severe, also according to the values of NACE-RP-07-75, reaching values of up to 72% inhibition efficiency. / Neste trabalho, avaliou-se a possibilidade de utiliza??o do tanino vegetal da ac?cia negra (Acacia mearnsii) como inibidor de corros?o em ambientes com a presen?a de CO2 a alta press?o. Corpos de prova de a?o SAE 1010 foram expostos a dois meios corrosivos (sem e com O2) sob condi??es de 15 MPa e 70?C, com diferentes concentra??es de tanino para diferentes tempos de exposi??o (168, 360 e 2160 h). Para caracteriza??o foram realizadas an?lises de espectroscopia de infravermelho, difra??o de raios X, microscopia eletr?nica de varredura por emiss?o de campo, espectroscopia de energia dispersiva, perda de massa e ensaios de polariza??o potenciodin?mica, determinando-se a taxa de corros?o e a efici?ncia do tanino como inibidor. Os resultados indicaram que o tanino, em meio desaerado, n?o apresenta potencial para utiliza??o como inibidor, pois n?o houve redu??o significativa nas taxas de corros?o e tamb?m n?o se observou a forma??o do filme de ferrotanatos. Todos os valores de taxas de corros?o, por perda de massa, foram classificados como corros?o severa, segundo valores da NACE-RP-07-75 e n?o se obteve valores de efici?ncia de inibi??o maiores que 21 %. No entanto, em meio aerado, o tanino atuou como barreira para a difus?o de O2 e/ou na complexa??o dos ?xidos de Fe2+ e Fe3+, formando filmes de ferrotanatos, propiciando condi??es favor?veis para a forma??o do filme de FeCO3 com caracter?sticas protetoras. As taxas de corros?o foram classificadas como moderada para 2160 h, enquanto que para 168 h e 360 h, como severa, tamb?m segundo valores da NACE-RP-07-75, atingindo-se valores de at? 72 % de efici?ncia de inibi??o.

Made available in DSpace on 2014-12-17T15:41:49Z (GMT). No. of bitstreams: 1 DanyelleMA_DISSERT.pdf: 886887 bytes, checksum: bdfc465050e9656b4d629363ccd362a0 (MD5) Previous issue date: 2010-07-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Corrosion inhibitors in solution are utilized to minimize processes from corrosion in steel. Of the present dissertation was evaluated the efficiency by inhibition from the surfactant saponified coconut oil (OCS) in the carbon steel 1020 through in linear polarization electrochemistry technique, well as, studied the process from adsorption through from the isotherms from Langmuir, Frumkin and Temkin. The corrosion current was determined through in Tafel extrapolation from the curves in the polarization, and then, was calculated the efficiency in the inhibitor to each concentration and temperature. Were studied four concentrations (12,5 ppm, 25 ppm, 50 ppm, and 75 ppm) in the inhibitor OCS and one in the NaCl salt (10.000 ppm) in six temperatures (301 K, 308 K, 313 K, 318 K, 323 K, and 328 K) in triplicate. By the results obtained observed that the technique applied can evaluated with rapidity and efficiency corrosion inhibitors. In relation to the isotherms, the than best appropriated was the in Langmuir and in the concentrations studied, the that obtained the best efficiency was the concentration of 75 ppm / Inibidores de corros?o em solu??o s?o utilizados para minimizar processos de corros?o em a?o. Na presente disserta??o foi avaliada a efici?ncia de inibi??o do tensoativo ?leo de coco saponificado (OCS) no a?o carbono 1020, atrav?s da t?cnica eletroqu?mica polariza??o linear, bem como, estudado o processo de adsor??o atrav?s das isotermas de Langmuir, Frumkin e Temkin. A corrente de corros?o foi determinada atrav?s da extrapola??o de Tafel nas curvas de polariza??o e, ent?o, foi calculada a efici?ncia do inibidor para cada concentra??o e temperatura. Foram estudadas quatro concentra??es (12,5, 25,0, 50,0 e 75,0 ppm) do inibidor OCS e uma do sal NaCl (10.000 ppm) em seis temperaturas (301, 308, 313, 318, 323 e 328 K) em triplicata. Pelos resultados obtidos, observou-se que a t?cnica utilizada pode avaliar com rapidez e efici?ncia inibidores de corros?o. Em rela??o ?s isotermas, a que melhor se adequou foi a de Langmuir e dentre as concentra??es estudadas a que obteve a melhor efici?ncia foi ? concentra??o de 75 ppm

Made available in DSpace on 2014-12-17T15:41:43Z (GMT). No. of bitstreams: 1 ThiagoRR.pdf: 1895833 bytes, checksum: 59d0cd6d03df2b5c8165e3ae0bf39a80 (MD5) Previous issue date: 2008-04-25 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / An interesting development in surfactants science and technology is their application as corrosion inhibitors, since they act as protective films over anodic and cathodic surfaces. This work aims to investigate the efficiency of saponified coconut oil (SCO) as corrosion inhibitor and of microemulsified system (SCO + butanol + kerosene oil + distilled water), in saline medium, using an adapted instrumented cell, via techniques involving linear polarization resistance (LPR) and mass loss coupons (MLC). For this, curves of efficiency versus SCO concentration (ranging between 0 and 75 ppm) have been constructed. According to the obtained results, the following efficiency levels were reached with OCS: 98% at a 75 ppm concentration via the LPR method and 95% at 75 ppm via the MLC method. The microemulsified system, for a concentration of 15 ppm of SCO, obtained maximum inhibition of 97% (LPR) and 93% (MLC). These data indicate that it is possible to optimize the use of SCO in similar applications. Previous works have demonstrated that maximal efficiencies below 90% are attained, typically 65% as free molecules and 77% in microemulsified medium, via the LPR method in a different type of cell. Therefore, it can be concluded that the adapted instrumented cell (in those used methods) showed to be an important tool in this kind of study and the SCO was shown effective in the inhibition of the metal / Tensoativos v?m sendo alvo de interesse como inibidores de corros?o, pois funcionam como pel?culas protetoras sobre ?reas an?dicas e cat?dicas. Este trabalho teve como objetivo avaliar a efici?ncia de inibi??o ? corros?o do tensoativo ?leo de coco saponificado (OCS) e do sistema icroemulsionado (OCS + butanol + querosene + ?gua destilada), em meio salino, utilizando-se uma c?lula instrumentada adaptada. A efic?cia do OCS foi avaliada utilizando-se os m?todos de resist?ncia de polariza??o linear (LPR) e cupons de perda de massa (CPM), tendo sido constru?das curvas de efici?ncia versus concentra??o de OCS (variando de 0 a 75 ppm). De acordo com os resultados obtidos, verificou-se que este tensoativo apresenta a seguinte ordem de efici?ncia de inibi??o ? corros?o: para uma concentra??o de 75 ppm, 98% pelo m?todo LPR e 95% pelo m?todo CPM. O sistema microemulsionado, para uma concentra??o de 15 ppm de OCS, obteve inibi??o m?xima de 97% (LPR) e 93% (CPM). Atrav?s deste trabalho foi poss?vel otimizar o uso do tensoativo OCS, que em trabalhos anteriores mostrou efic?cia m?xima inferior a 90% (63% na sua forma livre e 77% na sua forma microemulsionada, pelo m?todo LPR, em um outro tipo de c?lula). Conclusivamente, pode-se dizer que a c?lula instrumentada adaptada (nos m?todos utilizados) provou ser uma ferramenta importante neste tipo de estudo e o OCS mostrou-se efetivo na inibi??o do metal

Made available in DSpace on 2014-12-17T15:41:59Z (GMT). No. of bitstreams: 1 CatiaGFTR.pdf: 919760 bytes, checksum: a600b348289df4c6fa4bb6a54fb4e084 (MD5) Previous issue date: 2007-08-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Corrosion inhibition efficiency of saponified coconut oil (SCO) and sodium dodecilbenzene sulfonate (DBS) surfactants in AISI 1020 carbon steel was evaluated by electrochemical methods. These surfactants were also evaluated as microemulsion systems (SCO-ME and DBS-ME), of O/W type (water-rich microemulsion), in a Winsor IV region. They were obtained according to the following composition: 15% SCO, 15% butanol (30% Co-surfactant/Surfactant C/T), 10% organic phase (FO, kerosene) and 60% aqueous phase (FA). These systems were also used to solubilize the following nitrogenated substances: Diphenylcarbazide (DC), 2,4-dinitro-phenyl-thiosemicarbazide (TSC) and the mesoionic type compound 1,3,4-triazolium-2-thiolate (MI), that were investigated with the purpose of evaluating their anticorrosive effects. Comparative studies of carbon steel corrosion inhibition efficiencies of free DBS and DBS-ME, in brine and acidic media (0.5%), showed that DBS presents better inhibition results in acidic media (free DBS, 89% and DBS-ME, 93%). However, the values obtained for DBS in salted solution (72% free DBS and 77% DBS-ME) were similar to the ones observed for the SCO surfactant in brine (63% free SCO and 74% SCO-ME). Analysis of corrosion inhibition of the nitrogenated substances that were solubilized in the SCO-ME microemulsion system by the linear polarization method in brine (0.5% NaCl) showed that such compounds are very efficient an corrosion inhibitors [DC-ME-SCO (92%), TSC-ME-SCO (93%) and MI-ME-SCO (94%)] / A efici?ncia de inibi??o ? corros?o em a?o AISI 1020 dos tensoativos ?leo de coco saponificado (OCS) e dodecilbenzeno sulfonato de s?dio (DBS), foi avaliada por m?todos eletroqu?micos. Estes tensoativos foram tamb?m avaliados em sistemas microemulsionados (OCS-ME e DBS-ME), do tipo O/A (microemuls?o rica em ?gua) com regi?o de trabalho Winsor IV, e foram obtidos na seguinte composi??o: 15% de OCS, 15% de butanol (30% de Cotensoativo/tensoativo - C/T), 10% de fase org?nica (FO, querosene) e 60% de fase aquosa (FA), tendo sido utilizados, ainda, para a solubiliza??o das subst?ncias nitrogenadas difenilcarbazida (DC), 2,4-dinitro-fenil-tiossemicarbazida (TSC) e do heterociclo do tipo mesoi?nico 1,3,4-triaz?lio-2-tiolato (MI), que foram disponibilizadas para avalia??o dos seus efeitos anticorrosivos. Os estudos comparativos das efici?ncias dos tensoativos DBS livre e DBS-ME na inibi??o da corros?o de a?o carbono, em meios salino e ?cido (0,5%), mostraram que o DBS apresenta melhores resultados de inibi??o em meio ?cido (DBS livre, 89% e DBS-ME, 93%). No entanto, os valores obtidos para o DBS em meio salino (72% DBS livre e 77% DBS-ME) foram semelhantes aos valores observados para o tensoativo OCS em meio salino (63% OCS livre e 74% OCS-ME). A an?lise de inibi??o ? corros?o das subst?ncias nitrogenadas solubilizadas no sistema microemulsionado OCS-ME, pelo m?todo de curvas de polariza??o linear em meio salino (NaCl 0,5%) mostrou que tais compostos s?o muito eficazes na inibi??o ? corros?o [DC-ME-OCS (92%), TSC-ME-OCS (93%) e MI-ME-OCS (94%)]

Made available in DSpace on 2014-12-17T14:06:57Z (GMT). No. of bitstreams: 1 RomuloRMS.pdf: 3055902 bytes, checksum: 75eaf485a85529179129dd468ccfc772 (MD5) Previous issue date: 2007-12-18 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The ionic plasma nitriding is one of the most important plasma assisted treatment technique for surface modification, but it presents some inherent problems mainly in nitriding pieces with complex geometries. In the last four years has appeared a plasma nitriding technique, named ASPN (Active Screen Plasma Nitriding) in which the samples and the workload are surrounded by a metal screen on which the cathodic potential is applied. This new technique makes possible to obtain a perfect uniform nitrided layer apart from the shape of the samples. The present work is based on the development of a new nitriding plasma technique named CCPN (Cathodic Cage Plasma Nitriding) Patent PI 0603213-3 derived from ASPN, but utilizes the hollow cathode effect to increase the nitriding process efficiency. That technique has shown great improvement on the treatment of several types of steels under different process conditions, producing thicker and harder layers when compared with both, ASPN and ionic plasma nitriding, besides eliminating problems associated with the later technique. The best obtained results are due to the hollow cathode effect on the cage holes. Moreover, characteristic problems of ionic plasma nitriding are eliminated due to the fact that the luminescent discharge acts on the cage wall instead of on the samples surface, which remains under a floating potential. In this work the enhancement of the cathodic cage nitriding layers proprieties, under several conditions for some types of steels was investigated, besides the mechanism for nitrides deposition on glass substrate, concluding that the CCPN is both a diffusion and a deposition process at the same time / A nitreta??o i?nica ? um dos processos de revestimento superficial dos mais importantes, mas apresenta alguns problemas inerentes, principalmente, na nitreta??o de pe?as com geometria complexa. Nos ?ltimos quatro anos surgiu uma nova t?cnica de nitreta??o a plasma, denominada de ASPN (Active Screen Plasma Nitriding), na qual as amostras s?o envolvidas por uma tela polarizada catodicamente e com ela ? poss?vel obter uma camada nitretada, perfeitamente uniforme, independente da forma da amostra. O nosso trabalho baseia-se no desenvolvimento, no ?mbito do LabPlasma, de uma nova t?cnica de nitreta??o em plasma, denominada nitreta??o em gaiola cat?dica (NGC) dep?sito de patente PI 0603213-3 derivada da ASPN, mas que utiliza o efeito de c?todo oco para aumentar a efici?ncia do processo de nitreta??o. Esta t?cnica apresentou bastante efic?cia na nitreta??o de v?rios tipos de a?os, nas mais variadas condi??es de tratamento, proporcionando a obten??o de camadas mais espessas e de maior dureza, quando comparada com a ASPN e com a nitreta??o i?nica convencional, al?m de eliminar problemas de irregularidades associados ? t?cnica convencional. Sua maior efici?ncia deve-se ? utiliza??o do efeito de c?todo oco estabelecido nas paredes dos furos da gaiola, enquanto que a elimina??o dos problemas inerentes ? t?cnica convencional, deve-se ao fato do plasma atuar na gaiola e n?o nas amostras, as quais permanecem em potencial flutuante. Neste trabalho, foram avaliadas as condi??es de otimiza??o da nitreta??o, realizada com esta t?cnica, para diferentes tipos de a?os, al?m de investigarmos os mecanismos que atuam, quando da deposi??o de nitretos em substratos de vidro, observando que a NGC ? um processo misto de difus?o e deposi??o

Made available in DSpace on 2014-12-17T14:07:04Z (GMT). No. of bitstreams: 1 GineideCA_DISSERT.pdf: 4064193 bytes, checksum: e2de6f4f6fcb019525ce377c5625f694 (MD5) Previous issue date: 2012-10-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In the search for products that act as corrosion inhibitors and do not cause environmental, impact the use of plant extracts as corrosion inhibitors is becoming a promising alternative. In this work the efficiency of polar extracts (ethanol extracts) obtained from the plants Anacardium occidentale Linn (AO) and Phyllantus amarus Schum. & Thonn (PA) as corrosion inhibitors were evaluated in different concentrations. For that AO and PA extracts were solubilized in the microemulsion systems (SME) containing saponified coconut oil as surfactant (SME -OCS and SME-OCS-1) in saline (NaCl 3,5 %) solution, which was also used as electrolyte. Both SME-OCS and SME-OCS-1 were characterized by surface tension and viscosity methods showing a Newtonian fluid behavior. The SME-OCS and SME-OCS-1 systems satisfactorily solubilized the polar extracts AO and PA with measurements carried out by ultraviolet spectroscopy. The measurements of corrosion inhibition efficiencies were performed by the electrochemical linear polarization resistance (LPR) technique as well as weight loss, on the surface of AISI 1020 carbon steel. The maximum corrosion inhibition efficiencies were determined by extrapolation of Tafel plots, showing the following values: 95,6 % for the system SME-OCS-AO, 98,9 % for the system SME-OCS-AO-1 and 93,4 % for the system SME-OCS-PA / Na busca por produtos que combatam a corros?o e ao mesmo tempo n?o agridam o meio ambiente, a utiliza??o de extratos vegetais como inibidores de corros?o v?m se tornando uma alternativa promissora. Neste trabalho a efici?ncia de inibi??o ? corros?o foi avaliada em diferentes concentra??es de extratos polares (etan?licos) obtidos das plantas Anacardium occidentale Linn (AO) e Phyllantus amarus Schum. & Thonn (PA). Para tanto, os extratos AO e PA foram solubilizados no sistema microemulsionado (SME) contendo o tensoativo ?leo de coco saponificado (SME-OCS e SME-OCS-1) em solu??o salina (NaCl 3,5 %), que tamb?m foi utilizada como eletr?lito. Estes sistemas microemulsionados foram caracterizados por m?todos que avaliam a tens?o superficial e viscosidade, tendo sido evidenciado que se comportam como fluidos Newtonianos. As medidas de efici?ncia de inibi??o ? corros?o foram realizadas atrav?s da t?cnica eletroqu?mica de resist?ncia ? polariza??o linear (LPR) e perda de massa, na superf?cie de a?o carbono AISI 1020. A corrente aplicada ao eletrodo foi controlada pelo equipamento Potenciostato/Galvanostato possibilitando a medi??o da diferen?a de potencial el?trico entre o eletrodo de trabalho e o de refer?ncia. Os sistemas SME-OCS e SME-OCS-1 solubilizaram os extratos etan?licos AO e PA, com quantifica??es realizadas por espectroscopia na regi?o do ultravioleta. As efici?ncias m?ximas de inibi??o ? corros?o foram determinadas atrav?s da extrapola??o das curvas de Tafel, tendo apresentado os seguintes valores: 95,6 % para o sistema SME-OCS-AO, 98,9 % para o sistema SMEOCS- 1-AO e 93,4 % para o sistema SME-OCS-PA