The elastohydrodynamic lubrication regime (EHD) is found in many machine elements, such as rolling element bearings, gears, cam/tappet, where a combination of hydrodynamic effect, elastic deformation of the surfaces and an increase of the lubricant’s viscosity with pressure create a continuous lubricant film which is capable of supporting pressures of the order of tens of thousands of atmospheres. One of the most important features of these films is their thickness, as this determines whether the bounding surfaces are completely separated, thus avoiding premature wear and failure of the contact. Consequently for many years scientists were interested in finding methods for measuring the lubricant film thickness in elastohydrodynamic conditions. One of the most versatile and widely used techniques for measuring lubricant film thickness in EHD contacts is the optical interferometry method. Apart from numerous advantages, this method has the limitation in the fact that one of the contacting surfaces must be transparent, usually glass or sapphire, thus it does not replicate real conditions found in machine elements contacts. On the other hand, the other group of methods used for studying the behaviour of elastohydrodynamic films includes a variety of electrical methods. Historically, these appeared before the optical methods, but gradually lost importance with the success of the later. Most capacitive, resistive, inductance methods developed so far use specially designed sensors for monitoring the lubricant film thickness. In the case of electrical techniques, both elements of the contact are metallic, which means that these can be used for measuring film thickness in real machine elements. One of the main disadvantages of electrical methods though, is the difficulty with which the calibration of various electrical quantities, against lubricant film thickness is obtained. This thesis describes the work carried out by the author on the application of a capacitive method for studying lubrication of elastohydrodynamic contacts. The novelty of the method used consists in the calibration of the capacitance of the contact with optical interferometry. This project started from the premises that a thicker Chromium layer will supply the phase change needed to precisely measure the lubricant film thickness by eliminating the fragile silica layer, and it has been shown that an increase in Cr thickness results in a increase in reflection of the glass–Cr interface making the resulting images hard to process. Modifications to the existing experimental rig were carried out in order to apply/collect an electrical signal from both the disc and the ball. Signal collection from the disc was quite straightforward and a graphite brush paired with a copper nut was used, as this is the oldest method of collecting/applying and electrical signal from a rotating element. Collecting an electrical signal from the ball presented quite a challenge as the ball is submerged in oil. A number of brushes was designed, made and tested and the one that provided the most stable results chosen. For calibration purposes a base oil and two additives were chosen, the additives were chosen in such a way that the improvement made to the lubrication process to be very different from one additive to the other. The chosen additives were a Viscosity Index Improver [VII] and an Organic Friction Modifier [OFM]. The VII is used by many researchers in order to obtain multigrade lubricants using the same base oil by varying its percentage in the mix. The OFM is used to provide protection between the two contacting bodies when EHD film fails and EHD lubrication is replaced by mixed lubrication by forming a boundary layer on the contacting surfaces. Optical measurements were carried out on the base oil and the two resulting lubricants from the additive mixes using the Ultra Thin Film Interferometry [UTFI] method. The measurements were used as a benchmark against which the capacitive measurements were calibrated. Tests were conducted in a number of controlled conditions for speed, temperature, load and sliding conditions. Results showed that the highest influence on the lubrication process was given by the speed, an increase in speed results in an increase in optically measured film thickness and a decrease in electrically measured film thickness. Phenomenon explained by a large amount of lubricant pushed into the contact. Another parameter that influenced the results quite significantly was temperature, a rise in temperature supplies a decrease in optically measured film thickness and an increase in capacitive measured film thickness which was explained by lubricant viscosity dropping with a rise in temperature. Three different sliding conditions were employed and a small drop in optically measured film thickness followed by a small rise in electrically measured film thickness was recorded due to a local increase in contact temperature when sliding was employed. The capacitive method developed in this project is precise enough to accurately measure lubricant film thickness down to 100nm; a model for thicknesses lower that 100nm was proposed Results from the optical and capacitive methods were compared and a good correlation was found, indicating that the developed capacitive method can be used as a tool for measuring metal on metal contacts without further calibration.

Orientador: Marcos Fernando de Souza Teixeira / Banca: Ana Maria Pires / Banca: Antonio Carlos Dias Angelo / Resumo: A formação de filmes poliméricos contendo azobenzeno tem recebido atenção especial devido à sua aplicação em dispositivos fotônicos. Neste trabalho estudamos a eletropolimerização de Bismarck Brown R (4-3- (2,4-diamin-5-metilfenil)- 4-metilfenildiazenil]diazenil-6-metilbenzeno-1,3-diamindiclorohidrato), filmes ultra-finos sobre substratos de ITO. Foi realizado o estudo do comportamento do filme polimérico variando-se parâmetros durante a etapa de eletropolimerização para a otimização do poliBBR, visando o desenvolvimento de eletrodos modificados para serem utilizados como sensores químicos. O uso da técnica eletroquímica na preparação de filmes poliméricos tem diversas vantagens, tais como a formação do filme diretamente sobre diferentes substratos, controle de espessura do filme, alta reprodutibilidade, geração de polímeros dopados e possibilidade de imobilização de espécies durante a fase de polimerização. Os filmes ultra-finos depositados nos substratos condutores por eletropolimerização foram caracterizados eletroquimicamente (voltametria cíclica e pulso diferencial), espectroscopia de ultravioleta-visível e microscopia de força atômica (AFM). O trabalho se destaca por possuir pouco ou nenhum relato na literatura sobre os dados obtidos dos estudos eletroquímicos e ópticos do comportamento do polímero de Bismarck Brown R. Foram obtidos dados interessantes no comportamento óptico no estudo da imobilização de íons metálicos na estrutura polimérica do BBR, destacando-se as diferentes geometrias e conformações (cis e trans) investigadas no trabalho / Abstract: The formation of azobenzeno containing polymeric films have been special attention due to its application in photonic devices. In this work we studied the electropolymerization of Bismarck Brown R (4-3-(2,4-diamin-5-methylphenyl)-4-methylphenyldiazenyl]diazenyl-6-methilbenzene-1,3-diamindiclorohidrato), ultra thin films on substrates of ITO. Was carried out study the behavior of the polymer film varying the parameters during the step for the electropolymerization polyBBR optimization, in order to develop modified electrodes to be used as chemical sensors. The use of electrochemical technique for preparing polymer films have several advantages, such as film formation directly on different substrates, film thickness control, high reproducibility, generating doped polymers and possible immobilization of species during the polymerization. The ultra-thin films deposited in conductive substrates were characterized electrochemically (cyclic voltammetry and differential pulse), UV-Vis spectroscopy and atomic force microscopy (AFM). The work stands out due to little or no reports in the literature on data obtained from studies of the electrochemical and optical behavior of polymer Bismarck Brown R. We obtained interesting data on optical behavior in the study immobilization of metal ion in the polymeric structure of the BBR, highlighting the different geometries and conformations (cis and trans) investigated in the work / Mestre

Visando determinar os valores ótimos para o processo de serramento de anéis bobinados de filme metalizado ultrafino de alumínio com dielétrico de poliéster a partir das condições atuais do processo de fabricação de capacitores pela empresa Epcos do Brasil, realizou-se a avaliação de diferentes tipos de serras circulares variando-se a velocidade de rotação (n) e o tempo de corte (tc). Desenvolvido projeto de experimento desses três fatores a fim de obter o resultado das interações entre eles quanto à resistência de isolamento (Riso) das peças cortadas. A serra de 160 dentes de metal-duro com revestimento de filme de carbono tipo diamante (DLC) apresentou os melhores resultados quanto à “Riso” acima de 0,378 G e quanto ao número de peças com valor abaixo deste. Constatou-se que “n” não influencia significativamente para a distribuição de “Riso”; porém, gera menos peças abaixo do especificado. Já “tc” não influencia significativamente o processo. Quanto ao tipo de dente, o perfil reto obteve melhor resultado para lâminas de serra com 80 dentes e perfil curvo para lâminas com 160 dentes. Já a espessura da lâmina não influenciou de forma expressiva o processo. A lâmina de aço-rápido apresentou adesão de alumínio na lateral do corpo da serra e, consequentemente, adesão de material na superfície de corte. As lâminas de metal-duro sem revestimento apresentaram falhas no filme metalizado por causa do atrito gerado entre a superfície de corte e a lateral da lâmina; esse inconveniente é eliminado quando ela é revestida com filme DLC apresentando melhorias quanto à “Riso” das peças para “n” menores. Também houve adesão de alumínio na parte inferior do dente devido a uma delaminação da camada de filme DLC. / In order to determine the optimal values for the sawing process of wound rings of metalized ultra-thin film with dielectric of polyester from current conditions of capacitor manufacturing process by Epcos company in Brazil, it was performed the evaluation of different types of circular saws varying the rotational speed (n) and the cutting time (tc). Developed experiment design methodology for these three factors in order to get the result of the interactions between them regarding to the insulation resistance (Riso) of cut parts. Through the analysis of the main effects, the cemented carbide saw with 160 teeth and diamond-like carbon (DLC) film coating showed the best results in terms of "Riso" above 0,378 G and regarding to the number of parts with value below the specified. It was found that "n" does not influence significantly the distribution of "Riso"; however, generates fewer parts below the specified. Now "tc" does not significantly influence the process. Regarding the tooth type, straight profile obtained better results for saw blades with 80 teeth and curved profile for blades with 160 teeth. However the thickness of the blade did not influence significantly the process. The high speed steel blade presented adhesion of aluminum on the side of the saw body and, consequently, adhesion of material on the cutting surface. The cemented carbide blades uncoated presented failures on metalized film because of the friction generated between the cutting surface and the side of the blade; this drawback is eliminated when it is coated with DLC film presenting improvements to the parts "Riso" for lower "n". There was also aluminum adhesion on the bottom of the tooth due to a delamination of the DLC film layer.

Made available in DSpace on 2014-06-11T19:29:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-04-13Bitstream added on 2014-06-13T19:38:01Z : No. of bitstreams: 1 cincotto_fh_me_sjrp.pdf: 789637 bytes, checksum: 23f32cf9d8279cacf5618ee5020c1dc6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A formação de filmes poliméricos contendo azobenzeno tem recebido atenção especial devido à sua aplicação em dispositivos fotônicos. Neste trabalho estudamos a eletropolimerização de Bismarck Brown R (4-3- (2,4-diamin-5-metilfenil)- 4-metilfenildiazenil]diazenil-6-metilbenzeno-1,3-diamindiclorohidrato), filmes ultra-finos sobre substratos de ITO. Foi realizado o estudo do comportamento do filme polimérico variando-se parâmetros durante a etapa de eletropolimerização para a otimização do poliBBR, visando o desenvolvimento de eletrodos modificados para serem utilizados como sensores químicos. O uso da técnica eletroquímica na preparação de filmes poliméricos tem diversas vantagens, tais como a formação do filme diretamente sobre diferentes substratos, controle de espessura do filme, alta reprodutibilidade, geração de polímeros dopados e possibilidade de imobilização de espécies durante a fase de polimerização. Os filmes ultra-finos depositados nos substratos condutores por eletropolimerização foram caracterizados eletroquimicamente (voltametria cíclica e pulso diferencial), espectroscopia de ultravioleta-visível e microscopia de força atômica (AFM). O trabalho se destaca por possuir pouco ou nenhum relato na literatura sobre os dados obtidos dos estudos eletroquímicos e ópticos do comportamento do polímero de Bismarck Brown R. Foram obtidos dados interessantes no comportamento óptico no estudo da imobilização de íons metálicos na estrutura polimérica do BBR, destacando-se as diferentes geometrias e conformações (cis e trans) investigadas no trabalho / The formation of azobenzeno containing polymeric films have been special attention due to its application in photonic devices. In this work we studied the electropolymerization of Bismarck Brown R (4-3-(2,4-diamin-5-methylphenyl)-4-methylphenyldiazenyl]diazenyl-6-methilbenzene-1,3-diamindiclorohidrato), ultra thin films on substrates of ITO. Was carried out study the behavior of the polymer film varying the parameters during the step for the electropolymerization polyBBR optimization, in order to develop modified electrodes to be used as chemical sensors. The use of electrochemical technique for preparing polymer films have several advantages, such as film formation directly on different substrates, film thickness control, high reproducibility, generating doped polymers and possible immobilization of species during the polymerization. The ultra-thin films deposited in conductive substrates were characterized electrochemically (cyclic voltammetry and differential pulse), UV-Vis spectroscopy and atomic force microscopy (AFM). The work stands out due to little or no reports in the literature on data obtained from studies of the electrochemical and optical behavior of polymer Bismarck Brown R. We obtained interesting data on optical behavior in the study immobilization of metal ion in the polymeric structure of the BBR, highlighting the different geometries and conformations (cis and trans) investigated in the work

Visando determinar os valores ótimos para o processo de serramento de anéis bobinados de filme metalizado ultrafino de alumínio com dielétrico de poliéster a partir das condições atuais do processo de fabricação de capacitores pela empresa Epcos do Brasil, realizou-se a avaliação de diferentes tipos de serras circulares variando-se a velocidade de rotação (n) e o tempo de corte (tc). Desenvolvido projeto de experimento desses três fatores a fim de obter o resultado das interações entre eles quanto à resistência de isolamento (Riso) das peças cortadas. A serra de 160 dentes de metal-duro com revestimento de filme de carbono tipo diamante (DLC) apresentou os melhores resultados quanto à “Riso” acima de 0,378 G e quanto ao número de peças com valor abaixo deste. Constatou-se que “n” não influencia significativamente para a distribuição de “Riso”; porém, gera menos peças abaixo do especificado. Já “tc” não influencia significativamente o processo. Quanto ao tipo de dente, o perfil reto obteve melhor resultado para lâminas de serra com 80 dentes e perfil curvo para lâminas com 160 dentes. Já a espessura da lâmina não influenciou de forma expressiva o processo. A lâmina de aço-rápido apresentou adesão de alumínio na lateral do corpo da serra e, consequentemente, adesão de material na superfície de corte. As lâminas de metal-duro sem revestimento apresentaram falhas no filme metalizado por causa do atrito gerado entre a superfície de corte e a lateral da lâmina; esse inconveniente é eliminado quando ela é revestida com filme DLC apresentando melhorias quanto à “Riso” das peças para “n” menores. Também houve adesão de alumínio na parte inferior do dente devido a uma delaminação da camada de filme DLC. / In order to determine the optimal values for the sawing process of wound rings of metalized ultra-thin film with dielectric of polyester from current conditions of capacitor manufacturing process by Epcos company in Brazil, it was performed the evaluation of different types of circular saws varying the rotational speed (n) and the cutting time (tc). Developed experiment design methodology for these three factors in order to get the result of the interactions between them regarding to the insulation resistance (Riso) of cut parts. Through the analysis of the main effects, the cemented carbide saw with 160 teeth and diamond-like carbon (DLC) film coating showed the best results in terms of "Riso" above 0,378 G and regarding to the number of parts with value below the specified. It was found that "n" does not influence significantly the distribution of "Riso"; however, generates fewer parts below the specified. Now "tc" does not significantly influence the process. Regarding the tooth type, straight profile obtained better results for saw blades with 80 teeth and curved profile for blades with 160 teeth. However the thickness of the blade did not influence significantly the process. The high speed steel blade presented adhesion of aluminum on the side of the saw body and, consequently, adhesion of material on the cutting surface. The cemented carbide blades uncoated presented failures on metalized film because of the friction generated between the cutting surface and the side of the blade; this drawback is eliminated when it is coated with DLC film presenting improvements to the parts "Riso" for lower "n". There was also aluminum adhesion on the bottom of the tooth due to a delamination of the DLC film layer.

Visando determinar os valores ótimos para o processo de serramento de anéis bobinados de filme metalizado ultrafino de alumínio com dielétrico de poliéster a partir das condições atuais do processo de fabricação de capacitores pela empresa Epcos do Brasil, realizou-se a avaliação de diferentes tipos de serras circulares variando-se a velocidade de rotação (n) e o tempo de corte (tc). Desenvolvido projeto de experimento desses três fatores a fim de obter o resultado das interações entre eles quanto à resistência de isolamento (Riso) das peças cortadas. A serra de 160 dentes de metal-duro com revestimento de filme de carbono tipo diamante (DLC) apresentou os melhores resultados quanto à “Riso” acima de 0,378 G e quanto ao número de peças com valor abaixo deste. Constatou-se que “n” não influencia significativamente para a distribuição de “Riso”; porém, gera menos peças abaixo do especificado. Já “tc” não influencia significativamente o processo. Quanto ao tipo de dente, o perfil reto obteve melhor resultado para lâminas de serra com 80 dentes e perfil curvo para lâminas com 160 dentes. Já a espessura da lâmina não influenciou de forma expressiva o processo. A lâmina de aço-rápido apresentou adesão de alumínio na lateral do corpo da serra e, consequentemente, adesão de material na superfície de corte. As lâminas de metal-duro sem revestimento apresentaram falhas no filme metalizado por causa do atrito gerado entre a superfície de corte e a lateral da lâmina; esse inconveniente é eliminado quando ela é revestida com filme DLC apresentando melhorias quanto à “Riso” das peças para “n” menores. Também houve adesão de alumínio na parte inferior do dente devido a uma delaminação da camada de filme DLC. / In order to determine the optimal values for the sawing process of wound rings of metalized ultra-thin film with dielectric of polyester from current conditions of capacitor manufacturing process by Epcos company in Brazil, it was performed the evaluation of different types of circular saws varying the rotational speed (n) and the cutting time (tc). Developed experiment design methodology for these three factors in order to get the result of the interactions between them regarding to the insulation resistance (Riso) of cut parts. Through the analysis of the main effects, the cemented carbide saw with 160 teeth and diamond-like carbon (DLC) film coating showed the best results in terms of "Riso" above 0,378 G and regarding to the number of parts with value below the specified. It was found that "n" does not influence significantly the distribution of "Riso"; however, generates fewer parts below the specified. Now "tc" does not significantly influence the process. Regarding the tooth type, straight profile obtained better results for saw blades with 80 teeth and curved profile for blades with 160 teeth. However the thickness of the blade did not influence significantly the process. The high speed steel blade presented adhesion of aluminum on the side of the saw body and, consequently, adhesion of material on the cutting surface. The cemented carbide blades uncoated presented failures on metalized film because of the friction generated between the cutting surface and the side of the blade; this drawback is eliminated when it is coated with DLC film presenting improvements to the parts "Riso" for lower "n". There was also aluminum adhesion on the bottom of the tooth due to a delamination of the DLC film layer.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14871号 / 工博第3139号 / 新制||工||1470(附属図書館) / 27293 / UT51-2009-K667 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 伊藤 紳三郎, 教授 長谷川 博一, 教授 金谷 利治 / 学位規則第4条第1項該当

No description available.

To accelerate environmentally friendly thin film photovoltaic (PV) technologies, copper-based chalcogenides are attractive as absorber materials. Chalcopyrite copper indium gallium selenide (CIGS ≡ CuIn1–xGaxSe2) is today a commercially important PV material, and it is also in many aspects a very interesting material from a scientific point of view. Copper zinc tin sulfide selenide (CZTSSe ≡ Cu2ZnSn(S1–xSex)4) is considered as an emerging alternative thin film absorber material. Ternary Cu2SnS3 (CTS) is a potential absorber material, thus its related alloys Cu2Sn1–xGexS3 (CTGS) and Cu2Sn1–xSixS3 (CTSS) are attractive due to the tunable band gap energies. CuSb(Se1–xTex)2 and CuBi(S1–xSex)2 can be potential as ultra-thin (≤ 100 nm) film absorber materials in the future. In the thesis, analyses of these Cu-based chalcogenides are based on first-principles calculations performed by means of the projector augmented wave method and the full-potential linearized augmented plane wave formalisms within the density functional theory as implemented in the VASP and WIEN2k program packages, respectively. The electronic and optical properties of CIGS (x = 0, 0.5, and 1) are studied, where the lowest conduction band (CB) and the three uppermost valence bands (VBs) are parameterized and analyzed in detail. The parameterization demonstrates that the corresponding energy dispersions of the topmost VBs are strongly anisotropic and non-parabolic even very close to the Γ-point. Moreover, the density-of-states and constant energy surfaces are calculated utilizing the parameterization, and the Fermi energy level and the carrier concentration are modeled for p-type CIGS. We conclude that the parameterization is more accurate than the commonly used parabolic approximation. The calculated dielectric function of CuIn0.5Ga0.5Se2 is also compared with measured dielectric function of CuIn0.7Ga0.3Se2 collaborating with experimentalists. We found that the overall shapes of the calculated and measured dielectric function spectra are in good agreement. The transitions in the Brillouin zone edge from the topmost and the second topmost VBs to the lowest CB are responsible for the main absorption peaks. However, also the energetically lower VBs contribute significantly to the high absorption coefficient. CTS and its related alloys are explored and investigated. For a perfectly crystalline CTS, reported experimental double absorption onset in dielectric function is for the first time confirmed by our calculations. We also found that the band gap energies of CTGS and CTSS vary almost linearly with composition over the entire range of x. Moreover, those alloys have comparable absorption coefficients with CZTSSe. Cu2XSnS4 (X = Be, Mg, Ca, Mn, Fe, Ni, and Zn) are also studied, revealing rather similar crystalline, electronic, and optical properties. Despite difficulties to avoid high concentration of anti-site pairs disordering in all compounds, the concentration is reduced in Cu2BeSnS4 partly due to larger relaxation effects. CuSb(Se1–xTex)2 and CuBi(S1–xSex)2 are suggested as alternative ultra-thin film absorber materials. Their maximum efficiencies considering the Auger effect are ~25% even when the thicknesses of the materials are between 50 and 300 nm. / <p>QC 20170523</p>

Ultra-thin films (UTFs) are important in many applications, seen in the semiconductor industry, in chromatography, in sensing, in microfluidics, in aerospace, and in robotics. They also protect materials from corrosion, change surface energies, limit water intrusion into materials, allow material self-cleaning and self-healing, provide scratch resistance, and impart other specific chemical properties. In many cases, UTFs drastically alter surface properties and therefore their applications. It is imperative that proper and consistent characterization be performed on coatings to confirm and understand their desired properties. In Chapter two, Al oxidation under MgF2 protective layers is studied using real time X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). These tools allowed me to monitor Al oxidation for both short (hours) and long (months) periods of time. XPS revealed the chemical changes that took place in these materials as a function of time, and these changes were verified with SE. These studies help increase an understanding of aluminum changes under MgF2 protective layers. The third chapter demonstrates ab initio calculations guided X-ray photoelectron spectroscopy (XPS) analysis of surfaces functionalized with fluorinated silanes. This study addresses deficiencies in the literature where CF2:CF3 ratios from experimental XPS data do not match theoretical CF2:CF3 ratios. In a systematic approach, I developed semi-empirical models directed both by ab initio calculations and adjustable, empirical parameters. These models were effective in describing the raw data and exceeded fitting methods used in literature. In Chapter four, SiO2 UTFs with variable thicknesses deposited on Eagle XG® glass substrates are characterized. Challenges associated with this work consisted of similar optical functions of the film and substrate as well as backside reflections from the substrate. These obstacles were met using a multi-sample analysis (MSA), a variable angle spectroscopic ellipsometric approach, and mechanical abrasion/roughening of the substrate backside. With these approaches, I developed a model that precisely fit the data collected from all the samples and gave the correct optical function of the material along with thickness values for each film. Surface characterization represents a commitment of resources. It takes time to make measurements, and it takes time to analyze and understand the results. As presented in this work, I increase understanding of ultra-thin films at interfaces using both a multi-tool approach as well as using multiple analytical methods on data collected from each tool.