Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência e Engenharia de Materiais. / Made available in DSpace on 2012-10-19T17:48:52Z (GMT). No. of bitstreams: 1 184887.pdf: 2819877 bytes, checksum: 04a2991640edceae6bf782317218fff5 (MD5) / Este trabalho teve por objetivos (a) determinar a temperabilidade Jominy de diversos aços estruturais nacionais, de grande uso na indústria mecânica; (b) avaliar a influência do revenido sob condições variadas de tempo e de temperatura sobre a dureza pós-têmpera e (c) buscar uma correlação entre as variáveis do processo de revenido (parâmetro de revenido) capaz de servir como ferramenta quando da otimização do processo. O levantamento das curvas de temperabilidade (ou endurecibilidade) busca orientar a engenharia de projetos na seleção de aços para as mais diversas aplicações de manufatura de componentes mecânicos. Um estudo que não foi contemplado no ensaio original desenvolvido por Walter Jominy e seus colaboradores é o levantamento destas curvas na condição de uso da liga de aço, que associa os tratamentos térmicos de têmpera e revenido. Portanto, é de extremo interesse também, o levantamento destas curvas, relacionando as durezas obtidas no revenido para diferentes tempos e temperaturas de tratamento.

[pt] Aços de alta resistência contendo frações significativas de austenita retida têm alcançado grande interesse comercial principalmente quando associados ao fenômeno TRIP durante o processo de conformação final. Recentemente, um novo conceito de tratamento térmico, denominado Têmpera e Partição, vem sendo estudado como mais uma alternativa no desenvolvimento de aços multifásicos. Neste processo, o controle da fração volumétrica da austenita retida é possível uma vez que durante o tratamento de partição, a supersaturação de carbono na martensita temperada é utilizada para estabilizar a austenita não transformada, evitando assim transformações futuras que poderiam ocorrer em temperaturas mais baixas. A seqüência de processamento térmico envolve o tratamento de têmpera numa faixa de temperatura entre Ms e Mf, seguido de partição numa temperatura igual ou superior à temperatura de têmpera. A partição do carbono da martenista para a austenita é possível caso reações competitivas, como por exemplo, a precipitação de carbetos, sejam suprimidas pela adição de elementos de liga tais como Si e/ou Al. Uma condição básica para o modelo está relacionada à restrição de movimentação da interface martensita/austenita, uma vez que a difusão em temperaturas baixas está limitada aos átomos interticiais. Essa restrição leva a um novo conceito de equilíbrio denominado Equilíbrio Constrito de Carbono, que é caracterizado pela igualdade do potencial químico na interface austenita-martensita apenas para o carbono. Nesse trabalho foram desenvolvidos quatro aços, contendo diferentes percentuais de C e Ni e com a presença dos elementos Si, Mn, Mo e Cr. A adição desses elementos teve finalidade reduzir a temperatura Bs, visando desacoplar o tratamento de têmpera e partição de uma eventual transformação bainítica. Um conjunto de condições para o tratamento de têmpera e partição foi então desenhado, envolvendo diferentes temperaturas de têmpera e diferentes temperaturas e tempos de partição. A avaliação microestrutural foi realizada utilizando recursos de microscopia ótica e microscopia eletrônica de varredura e de transmissão. A técnica de difração de raios-X foi empregada para quantificar a fração de austenita retida e seu enriquecimento em carbono. Foi modelado o processo de partição do carbono utilizando o programa DICTRATM. Os resultados dessas simulações foram analisados em termos dos parâmetros microestruturais, do tempo e da temperatura, e como essa combinação influência a cinética de partição do carbono. Os resultados obtidos para as amostras ensaiadas em tração indicaram uma vasta combinação de resistência e ductilidade, confirmando o potencial do processo na otimização das propriedades mecânicas. / [en] High strength steels containing significant fractions of retained austenite have been developed in recent years and are the subject of growing commercial interest when associated with the TRIP phenomenon during deformation. A new process concept, Quenching and Partitioning, has been recently proposed for production of steel microstructures containing carbon-enriched austenite. The heat treatment sequence involves quenching to a temperature between the martensite-start (Ms) and martensite-finish (Mf) temperatures, followed by a partitioning treatment, above or at the initial quench temperature, designed to enrich the remaining untransformed austenite with the carbon escaping from the supersaturated martensite phase, thereby stabilizing the retained austenite phase during the subsequent quench to room temperature. To enable the austenite enrichment, competing reactions, principally carbide precipitation, must be suppressed by appropriate alloying elements, such as Si and/or Al. The concept assumes a stationary martensite/austenite interface and the absence of shortrange movements of iron and substitutionals elements. The condition under which partitioning occur has been called Constrained Carbon Equilibrium (ECC), due to the restriction in movement of the interface and the assumption that only carbon equilibrates its chemical potencial at the interface. In this work, a group of four alloys was investigated, containing different additions of C and Ni and containing Si, Mn, Mo e Cr. These alloys were designed to preclude bainite formation at the partitioning temperatures of interest. Several heat-treatments, were performed in these alloys, using the Q&P concept, to evaluate its effect on the resulting microstructure and mechanical properties. Each alloy was quenched at selected temperatures and partitioned from 350 to 450°C for times ranging from 10 to 1000s. Microstructural characterization was performed by optical microcoscopy, scanning and transmission electron microscopy, while X-ray diffraction was used to determine both the fraction and the carbon content of the retained austenite. Partitioning kinetics were simulated with DICTRATM. The results were analyzed taking into consideration the scale of the microstructure, as well as the partitioning temperature. Tensile test results indicated that very high levels of strength with moderate toughness can be achieved confirming the potential of the Q&P to produce a superior combination of mechanical properties.

Orientador: Valdemar Silva Leal / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T02:09:31Z (GMT). No. of bitstreams: 1 Carvalho_AntonioRogerioTorres_M.pdf: 2108495 bytes, checksum: 57b748cffef6835e43201549b90022af (MD5) Previous issue date: 2004 / Resumo: Estuda-se a influência da variação da agitação e da severidade de têmpera do meio de resfriamento sobre as curvas e taxas de resfriamento durante o processo de têmpera do aço. Os ensaios foram realizados com amostras dos aços 1045, 8620 e 8640, temperadas em água e salmoura, promovendo-se a variação do estado de agitação do refrigerante. Os dados apontam para variação da taxa de resfriamento máxima de 27,65% a 110,09% e uma diminuição nos tempos de resfriamento de 7,83% a 63,25%, para os três materiais estudados, com o aumento da agitação do meio. Verificam-se ainda, ganhos nas taxas e tempos de resfriamento com a variação da severidade de têmpera pela troca do meio, água por salmoura, da ordem de 73,27%, sem agitação do meio, e diminuição do tempo de resfriamento em aproximadamente 20%. Os dados ainda demonstram ganhos no tempo e nas taxas de resfriamento devido ao aumento do percentual de carbono no aço, quando se compara os dados obtidos para as amostras dos aços 8620 e 8640 / Abstract: Study about the influence of the agitation range and quench severity of the quenchant on cooling times and rates during the quench. The assays were accomplished with samples of steel 1045, 8620 and 8640, water and brine quenched, by increasing the agitation of the quenchant. The data show a rise in the maximum cooling rates of the 27.65% - 110%, and a reduction in the times of cooling of the 7.83% - 63.25%, on the three materials studied, with the increase of the agitation of the quenchant. They were verified too, a gain in the cooling rates and times with the variation of the quenchant severity, water to brine, of 73.27%, without agitation, and reduction of cooling time in approximately 20%. The data still show a gain in the cooling time and rates caused by the percentage of carbon increase on the steel, when be compared with the data scored in the samples of steel 8620 and 8640 / Mestrado / Instrumentação e Controle Industrial / Mestre Profissional em Engenharia Mecanica

Drop impact on a surface has an effect on nearly every industry and this impact may have adverse effects if not controlled. Superhydrophobic (SH) surfaces have been created with the extreme ability to repel water. These surfaces exist in nature but may also be fabricated using modern techniques. This thesis explores heat transfer from these SH surfaces to drops impacting them. This thesis is devoted to increasing the breadth of knowledge of thermal atomization during drop impingement on superheated SH surfaces. When a water drop impinges vertically on a horizontal superheated surface, intense atomization can occur. The atomization is caused by rapid vapor generation at the surface and the corresponding formation and collapse of vapor bubble cavities. This thesis is divided into two main works, experimental quantification of thermal atomization and analytical prediction of vapor generation. An experimental exploration, comprising chapter 3 contains experimental work done on drop impingement on nanostructured surfaces. of this thesis, presents results of experiments meant to quantify the amount of thermal atomization during drop impingement on superheated superhydrophobic surfaces. Effects of time, surface temperature, and surface geometry are investigated. Superhydrophobic surface geometries explored in this work included post, rib, and carbon nanotube (CNT) structures. Each surface is characterized by its temperature jump length. It is shown that, in general, atomization intensity decreases with increasing temperature jump length. It is also shown that atomization is completely suppressed on surfaces with nanoscale surface features and high cavity fraction (e.g. CNT structures). This work also relates the effect of temperature jump length on the maximum atomization temperature and the maximum atomization time. Both quantities show a systematic relationship with temperature jump length. The analytical portion, comprising chapter 4 of this thesis, presents an analytical model used to predict the amount vapor generated during drop impingement on superheated SH surfaces. This vapor generation is then correlated to experimental values of atomization. Atomization is caused by vapor generation so their magnitudes are thought to be proportional. Two existing analytical models for drop contact area of impinging drops are combined to predict drop spread for all impact scenarios. An analytical model for heat flux is used to find heat transfer to impinging drops and mass flow rate of vapor generated from boiling.

The metallic alloys employed in oxidizing environment at high temperature rely on the development of a protective oxide scale to sustain the long-term aggressive exposition. However, the oxide scale growth is most of the time coupled with stress and morphological developments limiting its lifetime and then jeopardizing the metallic component reliability. In this study, a mechanism of local stress effect on the oxidation kinetics at the metal/oxide interface is investigated. The objective is to improve the understanding on the possible interactions between stress generation and non-uniform oxide scale growth, which might result in a precipitated mechanical failure of the system. Two different oxides are studied, alumina and chromia, in two different industrial systems, thermal barrier coatings and solid oxide fuel cell interconnects. A specific thermodynamic treatment of local oxide phase growth coupled with stress generation is developed. The formulation is completed with a phenomenological macroscopic framework and a numerical simulation tool is developed allowing for realistic analyses. Two practical situations are simulated and analyzed, concerning an SOFC interconnect and a thermal barrier coating system, for which oxide scale growth and associated stress and morphological developments are critical. The consequence of the non-uniform oxide growth on the system resistance to mechanical failure is investigated. Finally, the influences of material-related properties are studied, providing optimization directions for the design of metallic alloys which would improve the mechanical lifetime of the considered systems.

Orientadores: Rubens Caram Junior, Conrado Ramos Moreira Afonso / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T17:14:04Z (GMT). No. of bitstreams: 1 Aleixo_GiorgiaTaiacol_M.pdf: 13698827 bytes, checksum: 10117398b384c5a1eda6c62fbfc74507 (MD5) Previous issue date: 2006 / Resumo: Ligas de titânio formam a classe mais versátil de materiais metálicos utilizados para aplicações biomédicas. As ligas de Ti tipo ß usadas em dispositivos ortopédicos envolve, além de excelentes propriedades como baixa densidade, elevada resistência mecânica e excepcional resistência à corrosão, a biocompatibilidade com elementos de liga, tais como Nb, Ta, Zr e Mo. O objetivo deste trabalho foi analisar a estabilidade e metaestabilidade de fases em ligas tipo ß no sistema Ti-Nb através da verificação da influência do teor de nióbio sob diversas condições de tratamento térmico. Para tanto variou-se a adição de Nb de 5% a 30% em peso na liga, obtendo amostras que foram submetidas a condições distintas de resfriamento a partir do campo ß. Amostras obtidas foram caracterizadas no tocante à microestrutura via microscopia ótica, eletrônica de varredura e de transmissão, difração de raios-X, enquanto o comportamento mecânico foi preliminarmente avaliado através de ensaios de dureza Vickers e de medidas de módulo de elasticidade através de técnicas acústicas. Os resultados obtidos indicam que baixas taxas de resfriamento conduzem à microestrutura de equilíbrio (a+ß) enquanto que altas taxas de resfriamento levaram à formação de estruturas metaestáveis. À medida que o teor de Nb foi incrementado e sob altas taxas de resfriamento, obteve-se, respectivamente, martensita a¿ (hexagonal compacta), martensita a¿ (ortorrômbica), fase ? (trigonal) e finalmente, fase ß metaestável. Em relação ao módulo de elasticidade, observou-se que esse parâmetro decresce entre 0 e 15% de Nb e após este último valor, tal constante elástica se eleva como resultado da precipitação de fase ? bem como da possível alteração de dimensões da estrutura cristalina. As ligas Ti-Nb apresentaram uma variabilidade de microestruturas e propriedades que dependem fortemente da composição e condição de resfriamento / Abstract: Titanium alloys form one of the most versatile classes of metallic materials used for biomedical applications. ß Ti alloys for orthopaedic devices involves, besides excellent properties like low density, high mechanical strength and good corrosion resistance, great biocompatibility with alloying elements, such as Nb, Ta, Zr and Mo. The objective of this work was to analyze the stability and metastability of phases in ß Ti-Nb alloys through the evaluation of the influence of percentage of Nb obtained in different heat treatment conditions. In this way, Nb addition was varied from 5 to 30wt% in Ti-Nb system. Samples were obtained and microstructural characterization was made through optical microscopy, scanning and transmission electron microscopy and X-ray diffraction, while mechanical behavior was primarily evaluated by Vickers hardness and elasticity modulus through acoustic techniques. The results obtained indicate that lower cooling rates resulted in the equilibrium microstructures (a+ß), otherwise higher cooling rates led to formation of metastable structures. As the Nb content was increased and under greater cooling rates, it was obtained, respectively, martensite a¿ (hexagonal closed packed), martensite a¿ (orthorhombic), ? phase (trigonal) and finally, metastable ß phase. Regarding modulus of elasticity it was observed that it decreases as the %Nb increases up to 15% and beyond this percentage the modulus increases due the precipitation of ? phase as well as possible variation of crystalline structure dimensions. Ti-Nb alloys presented a great variety of combinations between microstructures and properties that strongly depends on composition and cooling conditions / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Orientadores: Rubens Caram Junior, Conrado Ramos Moreira Afonso / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-15T14:37:29Z (GMT). No. of bitstreams: 1 Aleixo_GiorgiaTaiacol_D.pdf: 25669452 bytes, checksum: 43f10d141f1b3e5a6d696930ee2f86ec (MD5) Previous issue date: 2009 / Resumo: Este trabalho trata da preparação, processamento e caracterização microestrutral e mecânica de ligas Ti-Nb-Sn tipo ß visando a fabricação de dispositivos ortopédicos para implante. Amostras contendo Ti com teores de 25, 30 e 35% em peso de Nb e 2, 4 e 8% em peso de Sn foram preparadas por fusão a arco, homogeneizadas a 1000ºC/8 h e deformadas plasticamente por forjamento rotativo. Tais amostras foram submetidas a ensaios de resfriamento contínuo objetivando avaliar condições de obtenção de fases metaestáveis. Em seguida, amostras aquecidas a 1000ºC foram resfriadas rapidamente e submetidas a ensaios de calorimetria diferencial de varredura e de raios-X com aquecimento até médias temperaturas, o que permitiu avaliar a decomposição martensítica. Em seguida, amostras aquecidas no campo ß foram resfriadas ao ar, o que resultou em microestruturas com a fase a precipitada na matriz ß. Tais amostras foram caracterizadas no tocante à microestrutura via microscopia ótica, eletrônica de varredura e de transmissão e difração de raios X, enquanto que o comportamento mecânico foi avaliado por meio de testes de dureza Vickers, de medidas de módulo de elasticidade usando técnicas acústicas, ensaios de tração e ensaios de fadiga. Os resultados obtidos indicam que a decomposição da martensita resulta nas fases ß, ? e finalmente, a e também, que a fase ? atua como substrato na nucleação da fase a. O comportamento mecânico das amostras depende diretamente das fases presentes na microestrutura, bem como de suas frações volumétricas. Constatou-se também que o módulo de elasticidade, a dureza e o limite de resistência à tração de amostras resfriadas ao ar exibem valores superiores aos valores obtidos com as amostras resfriadas rapidamente, enquanto que a ductilidade se reduz. Finalmente, observou-se que o limite de fadiga de amostras resfriadas ao ar é máximo para baixos teores de Nb e se reduz com a adição de Sn / Abstract: This work deals with preparation, processing and microstructural and mechanical characterization of ß type Ti-Nb-Sn alloys aiming the manufacturing of orthopedic devices for implants. Ti samples containing Nb at levels of 25, 30 and 35 wt % and Sn at levels of 2, 4 and 8 wt % were prepared by arc melting, homogenized at 1000ºC/8 h and plastically deformed by swaging. These samples were submitted to continuous cooling experiments to evaluate conditions for obtaining metastable phase. Then, samples heated to 1000ºC were rapidly cooled and analyzed by using differential scanning calorimetry and X-ray diffraction at medium temperatures, which allowed the evaluation of martensite decomposition. Next, samples in the ß field were air-cooled, which resulted in microstructures with a phase precipitated into ß matrix. These samples were characterized concerning the microstructure by applying optical, scanning electron and transmission electron microscopies and X-ray diffraction, while the mechanical behavior was evaluated by Vickers hardness test, elastic modulus measurement using acoustic techniques, tensile and fatigue tests. The results obtained indicate that martensite decomposition results in ß, ? and finally a phases. It was also found that ? phase acts as substrate for a phase nucleation. The sample mechanical behavior directly depends on the phases present in the microstructure, as well as their volumetric fraction. It was also observed that elastic modulus, hardness and tensile strength of air cooled samples show higher values than those of rapidly quenched samples, while ductility decreases. Finally, it was observed that fatigue resistance of air cooled samples is higher for low Nb content alloys, however, it decreases with Sn addition / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

Egg (the whole, the yolk or the white) is a natural product used since ancient times as tempera painting medium mainly in Europe and the Mediterranean Basin countries. In addition, egg is a complex multicomponent microstructured system susceptible of being influenced by the pigments that compose the paints, as well as a source of nutrient susceptible of biodeterioration. Modifying effect of artists' pigments on the binding medium as well as, the microbial biodeterioration are responsible for changes in the structure and composition of the binding medium and, consequently, on the physico-chemical properties of the paint. For this purpose, analytical techniques such as Fourier transform infrared spectroscopy - attenuated total reflection (FTIR-ATR) was used for the chemical characterization, Field emission scanning microscopy (FESEM) and Atomic force microscopy - nanoindentation (AFM-nanoindentation) were run for morphological and mechanical characterization of the deterioration processes resulted from the pigment-binder interactions involved in tempera painting. On the other hand, the current research report the application of the voltammetry of microparticles (VMP), complemented with FTIR-ATR, FESEM and AFM-nanoindentation techniques to monitor the deterioration of a series of tempera reconstructed model paint specimens under the action of different biological agents. This methodology would be of application for identifying the type of biological agent causing deterioration of painting, which is an important problem affecting cultural heritage. The analysis of biodeterioration processes is complicated by the fact that the action of microorganisms can affect both pigment and binding media. The deterioration of pictorial specimens by Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum and Trichoderma pseudokoningii fungi and Arthrobacter oxydans, Bacillus amyloliquefaciens and Streptomyces cellulofans bacteria was tested using sample-modified graphite electrodes immersed into aqueous electrolytes. Finally, the study carried out by means of FTIR-ATR, FESEM and AFM-nanoindentation confirms that egg proteins attached to the pigment grains changes their secondary structures. The results obtained also confirm that proteins and phospholipids are prevalently established linkages with the solid particles of pigment whereas triglycerides should be integrated in the complex binding network responsible for the cohesion of the paint film. Interactions between egg components with solid pigment particles are described and correlated with micromorphology and mechanical properties determined at micro- and nano-scale on the reconstructed model paint specimens. As a result of the crossing of VMP data with the results obtained by means of FTIR, FESEM and AFM-nanoindentation, the voltammetric signals obtained were associated to the electrochemical reduction of pigments and different complexes associated to the binding media. These results were particularly relevant in the study of biodeterioration, to allowing the electrochemical monitoring of biological attack. / El huevo (entero, yema o clara) es un producto natural utilizado desde la antigüedad como medio aglutinante en la pintura al temple, principalmente en Europa y los países de la cuenca mediterránea. Además, el huevo es un complejo sistema multicomponente microestructurado susceptible de ser alterado por los pigmentos que componen las pinturas, así como fuente de nutrientes susceptible de biodeterioro. El efecto de los pigmentos sobre el medio aglutinante, así como el biodeterioro microbiano son responsables de cambios en la estructura y composición del medio aglutinante y, por consiguiente, en las propiedades fisicoquímicas de la pintura. Es por esto que, se utilizaron técnicas analíticas como la Espectroscopía Infrarroja por Transformada de Fourier en modo Reflexión Total Atenuada (FTIR-ATR), para la caracterización química de los procesos de deterioro resultantes de las interacciones pigmento-aglutinante en la pintura al temple. Así mismo, se utilizó Microscopía Electrónica de Emisión de Barrido (FESEM) para el estudio morfológico de las muestras, y para el estudio de las propiedades mecánicas Microscopía de Fuerza Atómica en modo Nanoindentación (AFM-nanoindentación). Por otro lado, la presente investigación propone el uso de la Voltamperometría de Micropartículas (VMP), en conjunto con otras técnicas de análisis como FTIR-ATR, FESEM y AFM-nanoindentación para el estudio del biodeterioro producido por hongos y bacterias sobre una serie muestras pictóricas sometidas. El estudio de las alteraciones causadas por el biodeterioro es complicado por el hecho de que la acción de los microorganismos puede afectar tanto al pigmento como al medio aglutinante. Para esto, se prepararon una serie de muestras de pinturas al temple y emulsión que fueron inoculadas con los hongos Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum, y Trichoderma pseudokoningii, y las bacterias Arthrobacter oxydans, Bacillus amyloliquefaciens y Streptomyces cellulofans. El estudio voltamperometrico se realizó utilizando electrodos de grafito modificados con las muestras inmersos en un electrolito acuoso. Las conclusiones obtenidas de manera general, apuntan a que las proteínas presentes en el huevo cambian su estructura secundaria al adherirse a los granos de pigmento. La información química, morfológica y mecánica obtenida por las diferentes técnicas de análisis instrumental es consistente. Finalmente, como resultado del cruce de los datos VMP con los resultados obtenidos mediante FTIR, FESEM y AFM-nanoindentación, las señales voltamperometricas obtenidas se asociaron a la reducción electroquímica de los pigmentos y a los complejos formados con el medio aglutinante. Estos resultados fueron particularmente relevantes en el estudio del biodeterioro de las películas pictóricas inoculadas, para permitir la monitorización electroquímica del ataque microbiológico. / L'ou (sencer, rovell o clara) és un producte natural utilitzat des de l'antiguitat com a mitjà aglutinant en la pintura al tremp, principalment a Europa i els països de la conca mediterrània. A més, l'ou és un complex sistema multicomponent MICROESTRUCTURAT susceptible de ser alterat pels pigments que componen les pintures, així com a font de nutrients susceptible de biodeterioració. L'efecte dels pigments sobre el medi aglutinant, així com el BIODETERIORI microbià són responsables de canvis en l'estructura i composició del medi aglutinant i, per tant, en les propietats fisicoquímiques de la pintura. És per això que, es van utilitzar tècniques analítiques com l'Espectroscòpia Infraroja per Transformada de Fourier en mode Reflexió Total Atenuada (FTIR-ATR), per a la caracterització química dels processos de deteriorament resultants de les interaccions pigment-aglutinant en la pintura al tremp. Així mateix, es va utilitzar Microscòpia Electrònica d'emissió de Rastreig (FESEM) per a l'estudi morfològic de les mostres, i per a l'estudi de les propietats mecàniques Microscòpia de Força Atòmica en mode Nanoindentació (AFM-nanoindentació). D'altra banda, la present investigació proposa l'ús de la Voltamperometría de Micropartícules (VMP), en conjunt amb altres tècniques d'anàlisi, com FTIR-ATR, FESEM i AFM-nanoindentació per a l'estudi de l'biodeterioració produït per fongs i bacteris sobre una sèrie de mostres pictòriques sotmeses. L'estudi de les alteracions causades pel biodeteriori és complicat pel fet que l'acció dels microorganismes pot afectar tant el pigment com al medi aglutinant. Per això, es van preparar una sèrie de mostres de pintures al tremp i emulsió que van ser inoculades amb els fongs Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum, i Trichoderma pseudokoningii i els bacteris Arthrobacter oxydans, Bacillus amyloliquefaciens i Streptomyces cellulofans. L'estudi voltamperomètric es va realitzar utilitzant electrodes de grafit modificats amb les mostres immersos en un electròlit aquós. Les conclusions obtingudes de manera general, apunten que les proteïnes presents en l'ou canvien la seva estructura secundària al adherir-se als grans de pigment. La informació química, morfològica i mecànica obtinguda per les diferents tècniques d'anàlisi instrumental és consistent. Finalment, com a resultat de l'encreuament de les dades VMP amb els resultats obtinguts mitjançant FTIR, FESEM i AFM-nanoindentació, els senyals voltamperomètrics obtinguts es van associar a la reducció electroquímica dels pigments i als complexos formats amb el medi aglutinant. Aquests resultats van ser particularment rellevants en l'estudi del biodeteriori de les pel·lícules pictòriques inoculades, per tal de permetre la monitorització electroquímica de l'atac microbiològic. / Ortiz Miranda, A. (2017). Development of analytical methods for the characterization of tempera paintings at micro- and nano-scale and their deterioration and biodeterioration processes [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90571 / TESIS

The first part of the final thesis is focused on the use of thermovision for diagnosing defects and failures in building industry. Documented history, physical principles and conditions for the measuring of thermographic camera are described in this part. Thermal images of the object described below were used for demonstrating the defects. The second part is dedicated to the elaborated energy assessment for a nine-storey slab block building. In total, there are five energy economic measures developed for the building. Three of those are of structural character and two of those are for building equipment. There are two variants designed based on the measures, one of which is recommended and evalu-ated. The final section is focused on the measurement of slab block building indoor environment (CO2, air temperature, relative humidity, dew point) and its assessment in concern with the current legislation.

Die praktische Arbeit des Monumentalmalers Hermann Prell (1854–1922) wurde zeitlebens von einer intensiven Auseinandersetzung mit Fragen der Maltechnik begleitet, die sich in seinen umfangreichen Aufzeichnungen niederschlug. Aufgrund seiner zahlreichen Kontakte zu Zeitgenossen, wie Hans von Marées und Arnold Böcklin, stellt sein schriftlicher Nachlass eine wichtige Quelle zur kunsttechnischen Entwicklung um 1900 dar. Im Rahmen der vorliegenden Arbeit werden seine Forschungen zur Maltechnik und die Beschreibung der von ihm angewendeten Materialien sowie Techniken das erste Mal tiefgreifend untersucht und umfassend vorgestellt. Die erhaltenen Dokumente bieten die Grundlage für eine Aufschlüsselung der verwendeten Rezepturen und handelsüblichen Künstlermaterialien sowie deren Kontextualisierung. Des Weiteren ergänzen historische Abbildungen und Vorstudien zur Erarbeitung der Komposition und Maltechnik den Blick auf den Werkprozess. Ebenso wird die kunsttechnologische Untersuchung von ausgewählten Werken mit der Auswertung der Quellen kombiniert. Während seiner monumentalen Aufträge galt sein besonderes Interesse der technischen und künstlerischen Umsetzung eines Gesamtkunstwerkes. Hermann Prell widmete sich eingehend kunsttechnologisch relevanter historischer und zeitgenössischer Quellenliteratur, zum Beispiel von Cennino Cennini und Ernst Berger. Die Freskotechnik nahm im breiten technischen Spektrum seines Œuvres einen hohen Stellenwert ein. Daneben spielte die Beschäftigung mit Tempera sowohl für das Staffeleibild als auch für die Wandmalerei eine große Rolle. Insgesamt wird erstmals ein Überblick über Hermann Prells angewendete Kunsttechniken in ihrer Vielfalt sowie deren Genese gegeben. / Throughout his life Hermann Prell (1854–1922) – known for his monumental paintings – accompanied his practical work with intense explorations of questions related to painting technique. This is reflected in his extensive writings. Prell was also engaged in a lively exchange with other artists, such as Hans von Marées and Arnold Böcklin. Hermann Prell’s writings combined with his contemporaries’ present an important source on painting technique around the turn of the 19th century in Germany. This study provides the first in-depth examination and comprehensive presentation of Prell’s research into painting techniques and a description of the materials and techniques he utilised. The preserved documents provide the basis for analysing the recipes the artist used and commercially available artists’ materials as well as their contextualisation with current research. Our view of his working process is further supplemented by historical reproductions and preparatory studies that served Prell to develop his compositions and painting techniques. Furthermore, the results of recent technical examinations of selected artworks are combined with an evaluation of the written sources. For his numerous large commissions for government buildings, Prell was particularly interested in the technical and artistic realisation of a Gesamtkunstwerk. He occupied himself extensively with related historical and contemporary sources, for example, the writings of Cennino Cennini and Ernst Berger. Amongst the broad technical range of his oeuvre the fresco technique assumed particular importance. In addition, his occupation with tempera’s use for easel paintings as well as wall paintings played a major role. In conclusion, for the first time Hermann Prell’s various applied techniques and materials as well as their genesis are given a comprehensive overview.