Made available in DSpace on 2015-04-14T13:58:50Z (GMT). No. of bitstreams: 1 438728.pdf: 2369501 bytes, checksum: 5a95c750cd0b1991376d6d6391c90d40 (MD5) Previous issue date: 2012-04-13 / This work presents a numerical-experimental correlation of the factors that may influence the hardenability of SAE 1045 steel subjected to the Jominy end quench test at austenitizing temperature of 850 ?C. This correlation was made by calculating the heat transfer coefficient and its phase‟s presents during the cooling of the specimen. These calculations were obtained based on thermal analysis of the test, through the cooling rates. A thermocouple was installed near from the edge of the specimen to obtain the cooling temperature curves. Based on these informations were estimated uncertainties of measurement temperature ? 23 ?C for an evaluation of the reproducibility of the process, even an error of ? 10.3 ?C. During the Jominy test, should be considered parameters such as hydraulic pressure suitable austenitizing temperature with a tolerance of ? 6 ?C, temperature and water flow. These parameters change the phase heat transfer, and also the flux density and therefore the heat transfer coefficient of heat. It was determined the variation of the heat transfer coefficient versus time h=f(t), and the average value is close to theorycal value, which is approximately 15.3 kW/m2.K / O trabalho aborda uma correla??o num?rico-experimental dos fatores que podem influenciar a temperabilidade de um a?o SAE 1045 submetido ao Ensaio Jominy em uma temperatura de austenitiza??o de 850?C. Tal correla??o foi feita a partir do c?lculo do coeficiente de transfer?ncia de calor e os modos presentes durante o resfriamento do corpo de prova. Estes c?lculos foram obtidos com base na an?lise t?rmica do ensaio, atrav?s das taxas de resfriamento. Para isso, um termopar foi instalado em uma dist?ncia pr?xima da extremidade do corpo de prova a fim de obter as curvas de resfriamento. Com base nestes dados foi calculada a incerteza de medi??o de temperatura de ? 23 ?C, para uma avalia??o da repetibilidade do processo, chegando ao erro de ? 10,3 ?C. Devem ser levados em considera??o durante o ensaio Jominy par?metros significativos como: press?o hidr?ulica adequada, temperatura de austenitiza??o com toler?ncia de at? ? 6?C, temperatura e vaz?o da ?gua. Estes par?metros alteram as condi??es de transfer?ncia de calor, e tamb?m a densidade de fluxo de calor e por conseq??ncia o coeficiente de transfer?ncia de calor. Foi determinada a varia??o do coeficiente de transfer?ncia de calor em rela??o ao tempo h = f(t), e seu valor m?dio est? de acordo com o valor informado na teoria, que ? de aproximadamente 15,3 kW/m?K

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-05-22T12:17:06Z No. of bitstreams: 1 469254 - Texto Completo.pdf: 3137412 bytes, checksum: e261817a0c99d0108e10ccd039c62c92 (MD5) / Made available in DSpace on 2015-05-22T12:17:06Z (GMT). No. of bitstreams: 1 469254 - Texto Completo.pdf: 3137412 bytes, checksum: e261817a0c99d0108e10ccd039c62c92 (MD5) Previous issue date: 2015-03-23 / The objective of this work is to analyze the influence of annealing and austempering heat treatments on the machinability with constant pressure of an austempered ductile cast iron. The results were correlated to microstructural formation and mechanical properties. It was used the turning process varying the depth of cut, the speed of cut, the angle of tool and the use of cut fluid. The samples (18 initially annealed) were heated at 910?C for 90 minutes for austenitization and cooled in salt bath in one-step at temperatures 300?C, 360?C and 420?C for 30, 60 and 90 minutes. Other 16 samples (8 previously annealed) were austempered in two-step process at 245oC and 300oC for 5 and 30 minutes, respectively. The samples were analyzed initially by optical microscopy and mechanical tests (Brinell hardness and Vickers microhardness), and after were machined in an universal lathe for machinability tests. The mechanical lathe was instrumented in relation to active power and cutting time, and the machinability evaluation was made with reference to cutting force, cutting pressure and material removal index criteria. The samples austempered at 300oC for 30 minutes (with annealing) showed the best machinability, impact resistance and lowest hardness in the one-step process. However, the samples in the same temperature and time (with annealing) showed the worst machinability, highest hardness and lowest impact resistance. The two-step austempering was performed in 8 samples that showed the best machinability and 8 samples that showed the worst machinability in one-step process. In these samples, the machinability test were performed with and without fluid cut and cut angle of 90o and 60o. The results showed the highest performance for the condition austempered at 300oC for 30 minute in two-step process, with previous annealing, when machined with fluid cut and angle of tool of 60o. The microstructure was composed by ausferrite, graphite and retained austenite. / Neste trabalho foi investigado atrav?s da t?cnica de aplica??o de press?o constante, a usinabilidade do ferro fundido nodular austemperado em fun??o de tratamentos t?rmicos de recozimento e aust?mpera. Os resultados foram correlacionados com a forma??o microestrutural e com as propriedades mec?nicas. Para tanto foi utilizado o processo de torneamento, variando a profundidade de corte, a velocidade de corte, o ?ngulo de posi??o da ferramenta de corte e utiliza??o e n?o utiliza??o de fluido de corte. Para este fim, 36 amostras (18 recozidas previamente) foram austemperadas em etapa ?nica nas temperaturas de 300 ?C, 360 ?C e 420 ?C nos tempos de 30 min, 60 min e 90 min. e 16 pe?as (8 com recozimento pr?vio) em duas etapas ? 245 ?C e 300 ?C nos respectivos tempos de 5 min e 30 min.. Para aust?mpera em etapa ?nica, amostras austemperadas ? 300 ?C por 30 minutos (sem recozimento pr?vio) obtiveram melhor usinabilidade, resist?ncia ao impacto e menor dureza. J?, as austemperadas no mesmo tempo e temperatura (com recozimento pr?vio) obtiveram pior usinabilidade, maior dureza e menor resist?ncia ao impacto. A aust?mpera em duas etapas foi realizada em 8 pe?as que obtiveram melhor usinabilidade e em 8 pe?as de pior usinabilidade nos testes de aust?mpera em ?nica etapa. Estes testes de usinabilidade foram executados com e sem o uso de fluido de corte utilizando-se os ?ngulos de posi??o da ferramenta de corte de 90? e 60?. Os resultados apontam para melhor usinabilidade ?s amostras austemperadas pelo processo de duas etapas e que foram previamente recozidas e austemperadas ? 300 ?C durante 30 minutos, quando usinadas com fluido de corte e ?ngulo de posi??o da ferramenta de corte de 60?. A microestrutura foi composta por matriz ausferr?tica, grafita e austenita n?o transformada.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-07-17T20:14:00Z No. of bitstreams: 1 472389 - Texto Completo.pdf: 3567307 bytes, checksum: 701ea7ad45fd2a973390e2755f3d5161 (MD5) / Made available in DSpace on 2015-07-17T20:14:00Z (GMT). No. of bitstreams: 1 472389 - Texto Completo.pdf: 3567307 bytes, checksum: 701ea7ad45fd2a973390e2755f3d5161 (MD5) Previous issue date: 2015-03-30 / This work presents the influence of the heat treatment parameters of austempering carried out in a zinc aluminum bath on the mechanical properties of a ductile cast iron (ADI). Samples were extracted from as-cast standard blocks for the austempering heat treatment. The material was heated to 900?C for 60 minutes for austenitization and cooled in a zinc-aluminum bath, to a temperature of 400?C, for 30 minutes, 60 minutes and 90 minutes. The samples were analyzed by optical microscopy, scanning electron microscopy, and mechanical tests (Brinell hardness, Micro Vickers hardness, Izod Impact Test and Tensile Test). The results, comparing the mechanical properties and microstructural characteristics in all cycles, present results compatible with the two stages of the material process window, confirming the effectiveness of the zinc-aluminum bath in getting the ADI. / O presente trabalho apresenta a influ?ncia da varia??o de par?metros do tratamento t?rmico de aust?mpera realizado usando um banho de zinco fundido, e os efeitos nas propriedades mec?nicas do ferro fundido austemperado (ADI). Corpos de prova foram extra?dos de blocos fundidos padronizados para aplica??o dos tratamentos t?rmicos de aust?mpera. O material foi aquecido a 900oC durante 60 minutos para austenitiza??o, e ent?o resfriado em um banho de zinco-alum?nio fundido a 400oC por 30 minutos, 60 minutos e 90 minutos. Os corpos de prova foram analisados por microscopia ?ptica, microscopia eletr?nica de varredura e ensaios mec?nicos (dureza Brinnell, microdureza Vickers, testes de Impacto Charpy e Resist?ncia ? Tra??o). Os resultados, comparadas as propriedades mec?nicas e caracter?sticas microestruturais em todos os ciclos, apresentam resultados compat?veis com os dois est?gios previstos pela janela de processo do material, confirmando a efetividade do banho de Zinco-Alum?nio na obten??o do ADI.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2016-09-27T12:28:48Z No. of bitstreams: 1 TES_CESAR_ROLANDO_NUNURA_NUNURA_COMPLETO.pdf: 7025675 bytes, checksum: fe9a9c1bc68c18e3f29d77b89573af7b (MD5) / Made available in DSpace on 2016-09-27T12:28:48Z (GMT). No. of bitstreams: 1 TES_CESAR_ROLANDO_NUNURA_NUNURA_COMPLETO.pdf: 7025675 bytes, checksum: fe9a9c1bc68c18e3f29d77b89573af7b (MD5) Previous issue date: 2016-03-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / His work considers the numerical simulation of the Jominy test, which evaluates the hardenability of steels, using as a solution the Finite Difference Method. Taking the initial and boundary conditions of the test and considering the heat transfer by conduction and forced convection, is solved numerically explicitly the differential equation that modeling the test, to obtain simulations of the thermal evolution or cooling curves at the specimen. Using the thermal profile obtained by the numerical solution is proposed a method for obtain the cooling rates and expressions that correlate hardness profile after the test [HRC = f (Cooling Rate)], and the numerical prediction of the final microstructures [Microstructure% = f (Cooling Rate)]. To validate the simulations were tested 02 steels: SAE 1060 and SAE 52100 according to ASTM A 255-07. These tests were instrumented with thermocouples for obtain the experimental thermal profile and compare with the simulated results. Hardness tests (HRC) were applied at the specimens for obtain the Jominy profile. Finally, analysis microscopy was applied to the specimens revealed the amounts of martensite, bainite, pearlite and ferrite present in the microstructure of the steel in function to the cooling rates. These microstructures validate the numerical results of [HRC = f (Cooling Rate)] and [% Microstructure = f (Cooling Rate)]. / Este trabalho prop?e a simulacao numerica do Ensaio Jominy, que avalia a temperabilidade dos a?os, usando como solu??o o M?todo das Diferen?as Finitas. Tomando as condi??es iniciais e de contorno do ensaio e considerando os mecanismos de transfer?ncia de calor de condu??o e convec??o for?ada, resolve-se numericamente de forma expl?cita a equa??o diferencial que modela o ensaio para realizar simula??es da evolu??o t?rmica ou curvas de resfriamento no corpo de prova. Utilizando o perfil t?rmico obtido pela solu??o num?rica prop?e-se um m?todo de c?lculo das taxas de resfriamento, para poder obter express?es que correlacionam perfil de dureza ap?s o ensaio [HRC = f(Taxas)], bem como a previs?o num?rica das microestruturas finais [%Microestrutura = f(Taxas)]. Para validar as simula??es foram ensaiados 02 a?os: SAE 1060 e SAE 52100 conforme a norma ASTM A 255-07. Estes ensaios foram instrumentados com termopares para obter um perfil t?rmico experimental para poder confrontar os resultados simulados. Ensaios de dureza HRC foram aplicados para obter a curva Jominy que avalia a profundidade de t?mpera nos a?os em quest?o. Finalmente, an?lises de microscopia aplicados nos corpos de prova revelaram as quantidades de martensita, bainita, perlita e ferrita presentes na microestrutura do a?o em fun??o das taxas de resfriamento. Estas microestruturas validam os resultados num?ricos de [HRC = f (Taxas)] e [%Microestrutura = f (Taxas)].

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-05-12T13:19:40Z No. of bitstreams: 1 1976 - Gabriel de Ara?jo Santos.PDF: 424018 bytes, checksum: 842e6f799add21cdd867e8159b9ae5c8 (MD5) / Made available in DSpace on 2017-05-12T13:19:40Z (GMT). No. of bitstreams: 1 1976 - Gabriel de Ara?jo Santos.PDF: 424018 bytes, checksum: 842e6f799add21cdd867e8159b9ae5c8 (MD5) Previous issue date: 1976-07-14 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The purpose of the present work was to study the efect of heat treatments on three different oxisols and to follow the changes in free Al by chenical determinations and pot experiments with plants. Soil samples were treated in laboratory conditions for one hour at temperatures from room temperature up to 300?C. Changes in the soil chemical properties and mineralogical composition were followed in the heat treatcd samples in order to detect any modifications in the following properties: pH taken in H KCl suspensions, organic carbon content, Fe and Al extracted with KCl and XH4 Ac pH 4.8. A compelemtary experiment was carried in order to defect any effcct of the treatment at 400?C for 15 minutes, on dry matter production of sorgo plants grown76 on one of the oxisols. One hour heat treatment on these soils at temperatures below 100?C caused little to no change in the above listed soil properties, where as deep changes occured when the soil was heated above 100?C. Carbon content decreased slightly at 200?C and dropped to half its value at 300?C. Fe(III) was sensibly reduced to Fe(II) at the expenses of carbon oxidation. This reduction caused an increase in Fe extraction in NH 4 AC reaching a maximum at 200?C. At higher temperatures a fast dropin extratable Fe was observed with a tendency to reach zero. This observations seen to indicate that in the process of burning the vegetation cover of tropical soils, fhe heat itself can cause a benefic effect decrasing Al toxity. This effect is enhanced by the neutralixing action of the ash produced. / No presente trabalho estudou-se o efeito do tratamento t?rmico em tr?s latossolos com o objetivo de detectar-se modifica??es nos teores de Al livre, e conseq?ente elimina??o de toxides desse elemento para as plantas. Nos solos, tratados em laborat?rio ? temperaturas que variavam do ambiente at? 300?C, foram estudadas as modifica??es causadas pelo calor sobre: a composi??o mineral?gica, o teor de carbono, o pH determinado em suspens?o aquosa e em KCl, o Al e o Fe extra?dos em KCl 1N e AcNH4 pH 4,8. Foi ainda estudado o efeito do tratamento t?rmico a 200?C e 400?C sobre o crescimento de plantas sorgo em um dos solos que apresentava toxides. Com um per?odo de aquecimento de uma hora, poucas mo-7 3 difica??es se fizeram sentir at? a temperatura de 100?C. A partir da? houve profundas modifica??es na composic?o mineral?gica que culminaram com o desaparecimento da gibsita e da goetita. O teor de carbono reduziu-se apreciavelmente com o aquecimento ? temperatura de 200?C e acima desta, tendo produzido a redu??o do Fe3+ a Fe2+ . Com a redu??o do Fe3+, houve um aumento progressivo da extra??o desse elemento, tanto em KCl como AcNH4 pH 4,8, que atingiu um m?ximo a temperatura de 200?C, diminuindo rapidamente a temperatura mais altas. O Al troc?vel, extra?do em KCl, sofreu uma diminui- ??o progressiva e acentuada, a propor??o que a temperatura do tratamento aumentava, reduzindo-se a zero a temperatura de 300?C. O Al extra?do em AcAG14 pH 4,8 aumentou a propor??o que a temperatura do tratamento crescia acima de 100?C. Esse aumento ? provavelmente devido a solubiliza??o de estruturas do alum?nio mais sujeitas ao ataque da solu??o de pH 4,8 proveniente de estruturas cristalinas ou semi-cristalinas, pr?- existentes que foram fragmentadas pela desidrata??o consequete do tratamento t?rmico. O pH do solo tamb?m aumentou consideravelmente com ostratamentos acima de 100?C, chegando a valores que se situavam a mais de uma unidade acima do seu valor inicial. Da mesma forma o alum?nio "n?o troc?vel", representado pela diferen-74 ?a entre os dois m?todos de extra??o aumentou com a temperatura. Um experimento com sorgo usando como substrato o solo aquecido a 200?C e 400?C por 15 minutos confirmou as observa??es qu?micas de laborat?rio sobre a redu??o da toxides do alum?nio por efeito do calor. Fica portanto provado que independentemente do efeito neutralizante da cinza proveniente das queimadas, o pr?prio calor do fogo atua sobre o alum?nio livre do solo, reduzindo-o a n?veis menos t?xicos para as plantas.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-10-14T12:07:35Z No. of bitstreams: 1 CarlosRenerDoNascimento_DISSERT.pdf: 10760871 bytes, checksum: 485a7679240639021e896c02d64ad53a (MD5) / Approved for entry into archive by Maria Maia (aniolly@bczm.ufrn.br) on 2015-10-14T12:39:56Z (GMT) No. of bitstreams: 1 CarlosRenerDoNascimento_DISSERT.pdf: 10760871 bytes, checksum: 485a7679240639021e896c02d64ad53a (MD5) / Made available in DSpace on 2015-10-14T12:39:56Z (GMT). No. of bitstreams: 1 CarlosRenerDoNascimento_DISSERT.pdf: 10760871 bytes, checksum: 485a7679240639021e896c02d64ad53a (MD5) Previous issue date: 2013-12-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / A diatomita ? um material natural que possui in?meras aplica??es devido ?s mudan?as nas suas propriedades f?sica e qu?mica ap?s processamento. Atualmente, ? utilizada na ind?stria como isolante ac?stico, auxiliar de filtra??o e carga industrial. O material filtrante deve apresentar composi??o qu?mica de material inerte, o que confere ? diatomita um alto valor comercial e desempenho, n?o encontrados em outros materiais particulados, para esta aplica??o. A diatomita sofre altera??es superficiais ap?s tratamento t?rmico em altas temperaturas, a partir de 800?C, apresentando propriedades que permitem sua aplica??o nas ind?strias aliment?cias, de bebidas, farmac?uticas, t?xteis e cosm?ticas. Neste trabalho, desenvolveu-se um estudo sobre tratamento t?rmico em diatomita natural a fim de adequar suas propriedades ? aplica??o como auxiliar de filtra??o. Os tratamentos t?rmicos foram realizados em forno aberto nas temperaturas de 800?C, 1000?C e 1200?C, por um tempo de 24 horas. Foram adicionados tamb?m reagentes na constitui??o das amostras em an?lise. Os reagentes usados foram, o carbonato de s?dio (Na2CO3) e o cloreto de s?dio (NaCl). As amostras foram caracterizadas por difra??o de raios-x, fluoresc?ncia de raios-x, microscopia eletr?nica de varredura, an?lise de distribui??o e tamanho de part?culas, ?rea superficial especifica pelo m?todo BET, e volume de poros pelo m?todo BJH. Os resultados mostraram uma redu??o na porosidade do material bem como um incremento significativo da ?rea superficial especifica ap?s tratamento t?rmico e com os reagentes na propor??o de 3% em peso. As diatomitas, ap?s tratamento t?rmico, sofreram altera??es na sua colora??o, variando nas cores branca, creme e bege, que interferem diretamente na velocidade do processo de filtra??o de materiais. Todos os resultados obtidos antes e ap?s tratamento t?rmico do material foram comparados aos valores obtidos para as amostras j?a usadas industrialmente, da ind?stria brasileira e americana, que foram caracterizadas atrav?s dos mesmos m?todos experimentais realizados com as amostras em estudo, e indicaram uma efici?ncia promissora ao material estudado da regi?o de Puna? - RN, ap?s seu processamento; adi??o de reagentes e tratamento t?rmico, como elemento na composi??o de filtrante. / The diatomite is a natural material that has numerous applications due to changes in their physical and chemical properties after processing. It is currently used in the industry as a sound insulator , filter aid and industrial load . The filter material shall be inert chemical composition , which will diatomite confers a high commercial value and performance not found in other particulate materials , for this application. The diatomite surface undergoes changes after thermal treatment at high temperatures , from 800?C , with properties that enable its application in the food , beverage , pharmaceutical , cosmetic and textiles . In this work , we developed a study on thermal treatment on natural diatomite to adapt their properties to the application as a filter aid . The heat treatments were performed in an open oven at temperatures of 800?C , 1000?C and 1200?C for a time of 24 hours. Reagents were added in the constitution of the samples analyzed. The reagents used were sodium carbonate (Na2CO3 ) and sodium chloride (NaCl) . The samples were characterized by x - ray diffraction , x -ray fluorescence , scanning electron microscopy , analysis and particle size distribution , specific surface area by the BET method , and pore volume by BJH method. The results showed a reduction in porosity of the material as well as a significant increase in specific surface area after heat treatment and the reactants in the ratio of 3 wt%. The diatomaceous earth , after heat treatment , undergone changes in its coloration , varying in white, cream and beige , which directly interferes with the speed of filtration materials process. All results obtained before and after heat treatment of the material with the values obtained for samples already used industrially , Brazilian and American industry , which were characterized using the same test methods performed with the samples in the study were compared and showed promising efficiency when material studied in the region of Puna? - RN , after processing , reagent addition and heat treatment, as an element in the composition of filter .

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-22T20:06:45Z No. of bitstreams: 1 IgorUcellaDantasDeMedeiros_DISSERT.pdf: 1809666 bytes, checksum: b32680e5684b3244bc1d041e70803d4f (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-08T21:32:59Z (GMT) No. of bitstreams: 1 IgorUcellaDantasDeMedeiros_DISSERT.pdf: 1809666 bytes, checksum: b32680e5684b3244bc1d041e70803d4f (MD5) / Made available in DSpace on 2017-03-08T21:32:59Z (GMT). No. of bitstreams: 1 IgorUcellaDantasDeMedeiros_DISSERT.pdf: 1809666 bytes, checksum: b32680e5684b3244bc1d041e70803d4f (MD5) Previous issue date: 2016-11-11 / O consumo de frutas est? associado ao seu efeito ben?fico ? sa?de pela presen?a de fibras, vitaminas e compostos bioativos, sobretudo compostos fen?licos (CF) e vitaminas com atividade antioxidante. O Brasil possui produ??o diversificada de frutas tropicais, como a acerola, goiaba e caju, normalmente processadas formando grandes volumes de res?duos agroindustriais. Assim, o presente trabalho objetivou caracterizar res?duos liofilizados de acerola (RLA), goiaba (RLG) e caju (RLC) quanto aos aspectos nutricionais, tecnol?gicos e funcionais associados ao estudo do conte?do bioativo ap?s tratamento t?rmico. Os res?duos apresentaram elevado teor de fibras diet?ticas, com destaque para as insol?veis no RLG (40,6%) e sol?veis no RLA (14,2%). O RLG apresentou maior valor prot?ico (13,8%) e de lip?dios (9,2%), por?m de forma geral, todos os res?duos apresentaram valor cal?rico reduzido. Os minerais em destaque foram pot?ssio, c?lcio e magn?sio, especialmente no RLC (K: 83,5 mg/g) e o RLA (Ca:31,9 mg/g e Mg: 2,8 mg/g). Quanto aos aspectos tecnol?gicos, todos os res?duos apresentaram baixa higroscopicidade e valores promissores de reten??o de ?gua (4,4 ? 12,0 g/g) e ?leo (3,0 ? 5,4 g/g). O RLA foi o mais rico em CF totais (5331,7 mg eqAG/100g), flavonoides totais (760,9 mg eqC/100g) e atividade antioxidante (688,1 ?mol eqTrolox/g no ORAC) e o RLG apresentou mais proantocianidinas (217,8 mgEqPAC2/100g). O RLA obteve melhor perfil fen?lico com ?cido salic?lico (3503,4 mg/100g), miricetina (929,4 mg/100g) e catequina (498,2 mg/100g). Nenhum res?duo apresentou atividade antibacteriana frente aos micro-organismos Salmonella typhimurium, Shigella sonneie, Staphylococcus aureus, Bacillus cereus e Listeria monocytogenes. O RLA apresentou-se mais sens?vel ao tratamento t?rmico, com baixa reten??o de CF totais atingindo 29% aos 150?C. Por?m a atividade antioxidante apresentou melhor reten??o em todos os res?duos e temperaturas (superiores a 70%). No caso do RLC, um aumento de at? 133% aos 150?C foi detectado, relacionando-se com a forma??o de melanoidinas em todos os res?duos (com varia??es de at? 582%). Com os dados obtidos, conclui-se que o RLA, RLG e RLC apresentam alto potencial nutricional, tecnol?gico e biotivo, inclusive para fortifica??o de outras matrizes alimentares. / The dietary consumption of fruit is linked to beneficial health effects due the presence of fiber, vitamins and bioactive compounds, especially antioxidant phenolic compounds (PC) and vitamins. Brazil has a diversified of tropical fruits production such as acerola, guava and cashew, which are usually processed and transformed into large amounts of agro-industrial pomaces. Thus, this study aimed to characterize freeze-dried acerola pomace (ACE), guava (GUA) and cashew (CAS) in regard to their nutritional, technological and functional aspects, in addition to evaluate the impact of the thermal-treatment. These residues are high in dietary fiber, especially insoluble for GUA (40.6%) and soluble for ACE (14.2%). The GUA residue has higher protein (13.8%) and lipids (9.2%), but overall, all pomaces have reduced caloric content. Minerals such as potassium, calcium and magnesium were found in CAS (K: 83.5 mg/g) and ACE (Ca: 31.9 mg/ g and Mg: 2.8 mg/g). Moreover, all dried residues had low hygroscopicity and satisfactory water (4,4 ? 12,0 g/g) and oil holding capacity (3,0 ? 5,4 g/g). ACE presented the highest phenolic content (5331.7 mg AGE/ 100g), total flavonoid (760.9 mg CE/ 100g) and antioxidant activity (688.1 ?mol TE/g in ORAC) and GUA presented higher proanthocyanidins (217.8 mg PA2/ 100g). ACE also presented outstanding phenolic profile, and salicylic acid (3503.4 mg/ 100g), myricetin (929.4mg / 100g) and catechin (498.2 mg/ 100g) were identified. No antibacterial activity against Salmonella typhimurium, Shigella sonneie, Staphylococcus aureus, Bacillus cereus e Listeria monocytogenes was detected. Severe reduction of total phenolic content was observed for ACE sample, reaching 29% at 150 ?C. However, higher antioxidant activity retention (above 70 %) was observed to all pomaces and temperatures. Interestingly, an increased TPC of up to 133% at 150 ?C was detected, which may be related to the formation of melanoidins in all pomaces (with variations up to 582%). Based on these results, we conclude that freeze dried pomaces have high nutritional, technological and bioactive potential, and might be used as phytochemical-rich ingredients to different food matrices.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-03-20T23:06:42Z No. of bitstreams: 1 WesleyFeuDosSantos_DISSERT.pdf: 2488767 bytes, checksum: 54fa9201753bfbbe0b0ff0a295b2a4ac (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-24T21:53:11Z (GMT) No. of bitstreams: 1 WesleyFeuDosSantos_DISSERT.pdf: 2488767 bytes, checksum: 54fa9201753bfbbe0b0ff0a295b2a4ac (MD5) / Made available in DSpace on 2017-03-24T21:53:11Z (GMT). No. of bitstreams: 1 WesleyFeuDosSantos_DISSERT.pdf: 2488767 bytes, checksum: 54fa9201753bfbbe0b0ff0a295b2a4ac (MD5) Previous issue date: 2016-09-09 / A fabrica??o do Cimento Portland ? uma atividade que causa grande impacto ambiental devido ? sua elevada taxa de emiss?o de CO2 na atmosfera. Visando reduzir esse impacto, a viabilidade t?cnica de materiais alternativos em substitui??o ao Cimento Portland tem sido cada vez mais analisada. J? s?o conhecidos os benef?cios que as adi??es minerais infere ao concreto convencional (CV), no entanto, existe a necessidade de compreender melhor seus benef?cios quando utilizadas em CAA e verificar o comportamento deste quando curado termicamente. Assim, este trabalho avalia os efeitos da incorpora??o de f?ler calc?rio (Fc) e metacaulim (Mk) na hidrata??o do concreto autoadens?vel, quando submetido ? cura t?rmica. Para tanto, foram produzidos seis composi??es de CAA, sendo uma de refer?ncia, sem adi??o mineral, quatro misturas bin?rias com substitui??o do cimento por 10% de Mk, 10% Fc, 20% de Mk e 20% Fc e uma terci?ria com substitui??o do cimento por 10% de Mk e 10% de Fc. Os concretos foram dosados e realizados os ensaios realizados para os concretos dosados foram: slump flow, T500, L-box, V-test e J-ring para caracteriza??o do CAA no estado fresco. Ap?s iniciada a pega (aproximadamente 3 horas), intervalo chamado de pr?-cura, os corpos de prova moldados foram curados atrav?s de imers?o total em banho aquecido. A taxa de aquecimento utilizada foi de 20 ?C/h, chegando ?s temperaturas m?ximas de 50, 60 e 70 ?C, com posterior resfriamento de 10 ?C/h. O tempo total do ciclo (pr?-cura, aquecimento, patamar isot?rmico e resfriamento), foi de 18 a 20 horas. Tamb?m foram confeccionados corpos de prova de CAA que foram curados por imers?o em ?gua a temperatura ambiente. As propriedades analisadas no estado endurecido de todas as composi??es foram: resist?ncia ? compress?o nas idades de 1, 3, 7 e 28 dias, com m?dulo de elasticidade din?mico, absor??o de ?gua por capilaridade, massa espec?fica e absor??o total aos 28 dias de idade. A an?lise da microestrutura dos diferentes concretos se deu por microscopia eletr?nica de varredura e difra??o de raios X aos 3 e 28 dias de idade. As adi??es de metacaulim e filer calc?rio podem substituir o cimento Portland, nos percentuais de 10% e 20%, de maneira satisfat?ria em misturas bin?rias e terci?rias. Aos 28 dias de idade, os CAA curados termicamente em geral n?o apresentaram resist?ncias ? compress?o inferiores aos curados a 28 ?C. A cura t?rmica ?mida por imers?o propicia um aumento na resist?ncia ? compress?o nas primeiras idades, exceto para os concretos contendo 20% de f?ler calc?rio em substitui??o ao cimento Portland. Para cada tra?o estudado, houve um temperatura que se mostrou mais eficaz, ou seja, uma temperatura patamar mais adequada. Na an?lise da microestrutura dos CAA pode se observar que a elevada resist?ncia obtida a 1 dia de idade, deve-se a r?pida forma??o de CSH para os CAA tratados termicamente. / The manufacture of Portland cement is an activity that causes great environmental impact due to its high CO2 emission rate in the atmosphere. In order to reduce this impact, technical feasibility of alternative materials to replace Portland cement has been increasingly analyzed. It is already known the benefits that mineral additions infers to conventional concrete (CV), however, little is known of their use in self-compacting concrete (SCC) subjected to heat treatment. This work evaluates the effects of the incorporation of limestone fillers (LP) and metakaolin (MK) in the hydration of self-compacting concrete, when subjected to thermal curing. For this purpose six SCC compositions were produced, as a reference without mineral addition, four binary mixtures with replacement of cement with 10% MK, 10% LP, 20% MK and 20% LP and a tertiary with substitution of cement by 10% MK and 10% LP. The concrete were measured and made the tests slump flow, T500, L-box, V-test and J-ring to characterize the SCC fresh. After started the crystallization reactions (about 3 hours), range called pre-curing, the molded specimens were cured through total immersion in a warm bath. The heating rate used was 20 ?C/hr, reaching the maximum temperatures 50, 60 and 70 ?C, with subsequent cooling 10 ?C/hr. The total cycle time (pre-curing, heating, cooling and isothermal level) was 18 to 20 hours. Also, specimens were prepared which were cured by immersion in water at room temperature. The analyzed properties in the hardened state of all compositions were compressive strength at ages of 1, 3, 7 and 28 days at modulus, water absorption by capillarity, density, and total absorption to 28 days of age. The analysis of the microstructure of different concrete was given by scanning electron microscopy and X-ray diffraction at 1 and 28 days of age. The CAA thermally cured obtained a high increase in compressive strength at 1 day old, when compared to CAA cured at room temperature. For each dosage analyzed, there is a maximum temperature within the thermal cycle, which provides better mechanical performance to the CAA. The thermal curing causes changes in the microstructure, including, promote the rapid formation of calcium silicate hydrate (CSH). The additions of metakaolin and lime filer can replace Portland cement in percentages of 10% and 20%, satisfactorily in binary and tertiary mixtures. After 28 days the CAA cured thermally groups showed no resistance to compression to lower cured at 28 ? C. The wet thermal curing dip provides an increase in compressive strength at early ages, except for the concrete containing 20% filler limestone to replace Portland cement. For each studied trait, there was a temperature that was more effective, i.e., a temperature most suitable level. The analysis of the microstructure of the CAA can be seen that the high strength obtained at 1 day old, due to rapid formation of the CSH to the heat-treated CAA.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-06-02T19:15:13Z No. of bitstreams: 1 EvertonHenriqueAndradeDeAraujo_DISSERT.pdf: 3778917 bytes, checksum: 0afcf798e13e94301cdf0341c3e0e55d (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-06-05T19:24:51Z (GMT) No. of bitstreams: 1 EvertonHenriqueAndradeDeAraujo_DISSERT.pdf: 3778917 bytes, checksum: 0afcf798e13e94301cdf0341c3e0e55d (MD5) / Made available in DSpace on 2017-06-05T19:24:51Z (GMT). No. of bitstreams: 1 EvertonHenriqueAndradeDeAraujo_DISSERT.pdf: 3778917 bytes, checksum: 0afcf798e13e94301cdf0341c3e0e55d (MD5) Previous issue date: 2016-09-02 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Dentre os argilominerais largamente estudados e aplicados na grande ?rea dos materiais cer?micos e outras ?reas, a caulinita se destaca, devido as suas caracter?sticas e desempenho tecnol?gico. O Estado do Rio Grande do Norte, possui um grande potencial na explora??o deste mineral, onde a principal forma de extra??o ? a lavra. O caulim desta regi?o, caracteriza-se como de origem prim?ria interperizada, devido a sua forma??o e caracter?sticas locais, diferenciando-o dos caulins de outras regi?es. Para isso, o caulim obtido foi submetido a um tratamento t?rmico, onde foi constatada uma gradativa amorfiza??o da estrutura cristalina caracter?stica do material. Com a obten??o da forma amorfa em laborat?rio, tamb?m denominada metacaulinita, foi poss?vel a realiza??o de uma investiga??o sobre as caracter?sticas pozol?nicas frente a outro material j? consolidado no mercado. Dessa forma o objetivo deste trabalho ? investigar a amorfiza??o do caulim industrial, oriundo da regi?o pegmat?tica do Serid? do RN, e comparar a sua atividade pozol?nica com um metacaulim comercial amplamente utilizado. Para isto, foram usadas as t?cnicas de Fluoresc?ncia de raios X (FRX); Difra??o de raios X (DRX); An?lise Termogravim?trica (TG); An?lise T?rmica Diferencial (DTA); Microscopia Eletr?nica de Varredura (MEV); Granulometria a Laser; Massa Espec?fica e ?ndice de Atividade Pozol?nica com a Cal. Ap?s as caracteriza??es pode-se observar que o metacaulim oriundo da regi?o em estudo possui boas caracter?sticas qu?micas e mineral?gicas, com a obten??o de um bom grau de amorfiza??o em baixas temperaturas e distribui??o granulom?trica pr?xima do material comercial analisado. A partir do resultado da atividade pozol?nica, o metacaulim obtido em laborat?rio apresentou um grande potencial na forma??o das fases hidratadas, sendo de grande import?ncia na ?rea de cimenta??o, dentre outros. / Among the clay minerals widely studied and applied in the large area of ceramic materials and other areas, kaolinite stands out due to its characteristics and technological performance. The State of Rio Grande do Norte has great potential in the exploration of this mineral, where the main form of extraction is the mining. The kaolin of this region, is characterized as of primary interperizada origin, due to its formation and local characteristics, differentiating it of the Kaolins of other regions. For this, the obtained kaolin was submitted to a thermal treatment, where a was verified a gradual amorphization was found of the crystalline structure characteristic of the material. By obtaining the amorphous form in the laboratory, also called metacaulinite, it was possible to carry out an investigation on the pozolanic characteristics compared to other materials already consolidated in the market. Thus the objective of this work Is to investigate the amorphization of industrial kaolin, coming from the pegmatitic region of Serid? RN, and to compare its pozzolanic activity with a commercially used metakaolin. For this, we used the techniques of fluorescence X-ray (XRF); X-ray diffraction (XRD); Thermogravimetric Analysis (TG); Differential Thermal Analysis (DTA); Scanning Electron Microscopy (SEM); Laser Granulometry; Specific Mass and Pozzolanic Activity Index with Cal. After characterization, it can be observed that metakaolin from the study region It has good chemical and mineralogical characteristics, with a good degree of amorphization at low temperatures and distribution close to the commercial material analyzed. From the result of pozzolanic activity the metakaolin obtained in the laboratory, presented a great potential in the formation of the hydrated phases, being of great importance in the area of cementation, among others.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-01T23:25:13Z No. of bitstreams: 1 ThiagoSouzaViana_DISSERT.pdf: 4828616 bytes, checksum: ee06ed8ff3676ebb8c30b440a888b38d (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-05T20:32:59Z (GMT) No. of bitstreams: 1 ThiagoSouzaViana_DISSERT.pdf: 4828616 bytes, checksum: ee06ed8ff3676ebb8c30b440a888b38d (MD5) / Made available in DSpace on 2017-12-05T20:32:59Z (GMT). No. of bitstreams: 1 ThiagoSouzaViana_DISSERT.pdf: 4828616 bytes, checksum: ee06ed8ff3676ebb8c30b440a888b38d (MD5) Previous issue date: 2017-06-30 / No presente trabalho, estudou-se a influ?ncia de tratamentos t?rmicos nas transforma??es microestruturais de uma liga NiTi com mem?ria de forma de composi??o qu?mica aproximadamente equiat?mica. Um fio de NiTi com 2,5 mm de di?metro, recebido no estado encruado, foi submetido a tratamentos t?rmicos de recozimento em temperaturas de 450 ?C e 500 ?C para observa??o das varia??es microestruturais. As microestruturas predominantes antes e ap?s o recozimento foram observadas, registrando-se um aumento na granulometria da martensita tanto com a temperatura como com a dura??o do tratamento t?rmico entre 30? e 3hs. Foram determinadas as temperaturas de transforma??o, (As, Af, Ms, Mf) de cada amostra, e as altera??es nas temperaturas de transforma??o entre o material no estado encruado e ap?s recozimento. Medidas de microdureza n?o revelaram influ?ncia significativa de tratamentos t?rmicos de recozimento e tampouco de resfriamentos a temperaturas subzero. / In the present work, the influence of heat treatments on the microstructural transformations of an approximately equiatomic NiTi memory form alloy was investigated. A NiTi wire with 2.5 mm in diameter, received in the work hardened state, was submitted to annealing heat treatments at 450 ?C and 500 ?C in order to verify the calorimetric and microstructural changes. The microstructure in the work hardened condition and after the annealing heat treatments was analyzed, which showed a coarsening of the martensite plates for higher temperatures and longer heat treatment times. The determination of the transition temperatures (As, Af, Ms, Mf) and the change in the transformation temperatures between the as received worked hardened and annealed material, were determined. Microhardness measurements did not reveal any significant influence of the annealing or subzero heat treatments on the mechanical behavior of the alloy.