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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Desenvolvimento de insertos sinterizados autolubrificantes para uso em matrizes de conformação a frio

Cóser, Marcelo Salvador January 2016 (has links)
Este trabalho avalia o uso de insertos autolubrificantes de pó de aço ferramenta sinterizado para aplicação em ferramentas dos processos de Conformação a Frio. São apresentadas a preparação e a análise de diferentes composições de misturas de pós de aço ferramenta H 13. A Metalurgia do Pó convencional foi utilizada como processo para a obtenção dos insertos do estudo. Foram compactadas e sinterizadas misturas de pó de aço H13 com a adição de percentuais variados do lubrificante sólido Bissulfeto de Molibdênio – MoS2, também em pó, com o objetivo de atribuir propriedades de autolubrificação ao composto. O percentual de lubrificante sólido empregado nas amostras variou de 1% a 5%, com posterior sinterização. Os resultados obtidos no Ensaio de Atrito com anéis de Alumínio AA6351 recozido apresentaram nos insertos autolubrificantes do estudo coeficientes de atrito μ entre 0,10 e 015, menores que os valores μ entre 0,20 e 0,30 obtidos com aço H13 laminado convencional. Também o desgaste abrasivo do ferramental proposto avaliado no Ensaio de Abrasão com Roda de Borracha foi 12% menor quando comparado com o aço ferramenta H13 laminado exposto ao mesmo ensaio. / This study evaluates the use of self-lubricating tool steel powder sintered inserts for use in tools of Cold Forming processes. Preparation and analysis of various compositions of H13 tool steel powder mixtures are presented. The conventional Powder Metallurgy was used as a process for obtaining the study inserts. Were compacted and sintered mixtures of H13 steel powder with the addition of varying percentages of the solid lubricant Molybdenum Disulphide - MoS2, also in powder form, with the purpose of giving self-lubricating properties to the composite. The percentage of solid lubricant used in the samples varied from 1% to 5%, with subsequent sintering. The results of the friction test on AA6351 aluminum rings had friction coefficients μ between 0.10 and 015 with self-lubricating inserts in study, smaller than μ values between 0.20 and 0.30 obtained with the conventional steel H13 laminate. Also, the abrasive wear of the tooling proposed evaluated in the abrasion test with rubber wheel was 12% lower when compared to the H13 tool steel laminate exposed to the same test.
42

Utilização de insertos com agregado sólido de lubrificantes confeccionados por metalurgia do pó convencional

Bueno, Alex Fabiano January 2016 (has links)
O presente trabalho apresenta o desenvolvimento de um inserto em aço ferramenta AISI H13 obtido por meio do processo de Metalurgia do Pó com a adição de lubrificante sólido na sua composição, que tem a finalidade de conferir propriedades autolubrificantes ao mesmo. Foram utilizados os pós de MoS2 e de h- BN para promover a redução do coeficiente de atrito. Adicionou-se o lubrificante MoS2 ao pó de aço ferramenta na etapa de mistura dos pós, em concentrações que variaram de 1% a 5%. Da mesma forma, foram confeccionados corpos de prova substituindo o MoS2 por h-BN. Após a compactação de todos os corpos de prova eles foram sinterizados. A mistura com h-BN apresentou grande formação de óxido durante os processos de sinterização e de tratamento térmico, sendo descartada sua utilização para os ensaios de abrasão para verificar desgaste e para os ensaios do anel que determinam o coeficiente de atrito. Conforme as análises realizadas, pode-se observar a formação de fases distintas, com ilhas de lubrificante MoS2 em matriz ferrítica. Utilizou-se o ensaio do anel para determinação do coeficiente de atrito de Coulomb – μ, e anéis de Alumínio como corpos de prova para este ensaio. Os insertos de MoS2 apresentaram ótimos resultados neste ensaio, e foram similares a experimentos realizados por outros pesquisadores que utilizaram o mesmo sistema tribológico deste trabalho - H13 como ferramenta, MoS2 como lubrificante e anéis de Alumínio para conformação. A diferença satisfatória obtida pelo material confeccionado neste estudo em relação aos obtidos da literatura pesquisada está na forma de utilização do lubrificante, que neste caso foi adicionado à matriz pelo processo de Metalurgia do Pó, enquanto que nos trabalhos analisados o lubrificante foi borrifado sobre a matriz. / The present work describes the development of an insert of tool steel AISI H13 obtained by powder metallurgy process with the addition of solid lubricant in the composition, in order to impart self-lubricating properties. MoS2 and h-BN powder were used to promote the reduction of the friction coefficient. It was added MoS2 lubricant with the tool steel powder in the mixing step at concentrations ranging from 1% to 5%. Similarly were prepared specimens replacing MoS2 for h- BN. After compression of the samples they were also sintered. The mixture with h- BN showed extensive formation of oxide during the sintering process and heat treatment, and discarded their use for the abrasion test for wear and ring assays for the determination of the friction coefficient. Through the analysis carried out, were observed the formation of distinct phases with lubricant MoS2 islands in ferritic matrix. The tests for friction in samples with MoS2 showed good results, similar to experiments by other researchers who used the same tribological system of this work - H13 as a tool, MoS2 as a lubricant and aluminum rings for conformation. Satisfactory difference obtained by the material made in this study compared to those obtained from the literature is in the form of use of the lubricant, which in this case was added to the matrix by the powder metallurgy process, whereas in the studies analyzed the lubricant was sprayed onto the matrix.
43

[pt] DETERMINAÇÃO ELEMENTAR EM ÓLEO LUBRIFICANTE, ÓLEO COMBUSTÍVEL E BIODIESEL POR ICP OES E DRC-ICP-MS / [en] ELEMENTAL DETERMINATION IN LUBRIFICANT OIL AND FUEL OIL BY ICP OES AND DRC-ICP-MS

JEFFERSON RODRIGUES DE SOUZA 13 September 2011 (has links)
[pt] Neste trabalho, são propostas duas metodologias para análise elementar em óleo lubrificante, óleo combustível e biodiesel, através das técnicas de espectrometria de emissão óptica com plasma indutivamente acoplado e espectrometria de massa com plasma indutivamente acoplado com célula de reação dinâmica. Foram combinadas a facilidade e a rapidez na preparação de amostras através da diluição direta em solventes orgânicos, sem tratamento prévio, com a capacidade multielementar das técnicas espectrométricas em estudo. Em ICP OES, foram avaliados os resultados analáticos para os micronebulizadores PFA-100 e Miramist através da análise de dois materiais de referência certificados, a saber, NIST 1634c (óleo combustível) e NIST 1085b (óleo lubrificante). Um planejamento experimental de alta resolução foi realizado para otimização das vazões de Ar e O2 no fluxo de nebulização, com experimentos em duplicata e triplicata no ponto central. Aumentos na razão sinal-ruído foram observados para Ag, Al, B, Ba, Ca, Cr, Cu, Fe, Mn, Si, Ti e V e as maiores razões foram observadas para o micronebulizador PFA-100. As vazões de Ar e O2 foram escolhidas de forma a maximizar essas razões. Para o Miramist, 0,50 L min(-1) (Ar) e 0,020 L min(-1) (O2) foram usados, enquanto para o PFA-100, 0,45 L min(-1) (Ar) e 0,025 L min(-1) (O2). Os materiais de referência NIST 1634c e NIST 1085b foram empregados para validação do método e as melhores recuperações foram obtidas para o micronebulizador PFA-100, com resultados entre 93% e 110%. Os limites de detecção para os dois micronebulizadores não variaram significativamente entre si, estando entre 0,48 ng g(-1) (Mn) e 15,8 ng g(-1) (Al). Em DRC-ICP-MS, foi realizado um planejamento composto central para otimização das condições operacionais do plasma. As vazõoes de argônio de nebulização e auxiliar apresentaram uma influência relevante sobre o teor de Ba++, LaO+ e sobre a intensidade do elemento índio. Uma condição de compromisso foi empregada, sendo 0,42 L min(-1) (Ar de nebulização) e 1,2 L min(-1) (Ar auxiliar). Para redução das interferências espectrais, o metano foi adotado como gás de reação. Os parâmetros operacionais, como a vazão do gás de reação e o parâmetro de rejeição q (Rpq), foram otimizados, visando a menor incidência de interferências sobre isótopos como 52Cr e 56Fe. Os materiais de referência NIST 1634c e NIST 1085b foram empregados para validação do método e as recuperações estiveram entre 90% e 110% para a maioria dos elementos, enquanto os limites de detecção estiveram entre 0,02 ng g(-1) (52Cr) e 7,4 ng g(-1) (40Ca). Os resultados obtidos para o material de referência NIST 1085b foram comparados entre os dois métodos propostos e os mesmos foram considerados concordantes, não diferindo entre eles em mais de 10% para a maioria dos elementos. Os resultados obtidos na análise elementar das amostras de óleo lubrificante mostram que realmente é possível avaliar o desgaste de equipamentos através da metodologia proposta, pois o aumento significativo de alguns elementos, como Fe, foi detectado nas amostras de lubrificante usado, enquanto a análise de amostras de biodiesel mostrou através da técnica de espectrometria de massa, que há nesse biocombustível a presença de elementos que não são contemplados na legislação brasileira. / [en] Two methodologies for elemental analysis of lubrificant oil, fuel oil and biodiesel are proposed, employing inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry with dynamic reaction cell. The methodologies combine the facility and fastness of sample preparation through direct dilution in organic solvents, without any pretreatment, with the multielemental capability of these spectrometric techniques. In ICP OES, the analytical results for the micronebulizers PFA-100 and Miramist were evaluated using two certified reference materials, NIST 1634c (residual fuel oil) and NIST 1085b (wear metals in lubrificant oil). Ar and O2 flow rates were optimized employing a high resolution experimental design was realized, with replicate experiments and triplicate at the central point. Improvement in the signal-to-noise ratio were observed for Ag, Al, B, Ba, Ca, Cr, Cu, Fe, Mn, Si, Ti and V and the highest ratios were obtained with the PFA-100 micronebulizer. The Ar and O2 flow rates were optimized in order to improve these ratios. For Miramist, 0.50 L min(-1) (Ar) e 0.020 L min(-1) (O2) were used and, for PFA-100, 0.45 L min(-1) (Ar) e 0.025 L min(-1) (O2). The reference materials (NIST 1634c and NIST 1085b) were analyzed for validation of the method and the highest recoveries were obtained for the PFA-100 micronebulizer, with results between 93% and 110%. The limits of detection for both micronebulizers were very similar, between a range of 0.48 kg(-1) (Mn) and 15.8 ug kg-1 (Al). In DRC-ICP- MS, a central composite design was realized for the optimization of the plasma operational conditions. The nebulizer and auxiliary flow rates showed a relevant influence on Ba++ and LaO+ content and In intensity. A compromising condition was employed, being 0.42 L min(-1)(Ar nebulizer flow rate), 0.1 L min(-1) (O2 flow rate) and 1.2 L min(-1) (auxiliary flow rate). In order to minimize spectral interference, methane was adopted in this work as reaction gas. The operational conditions of the reaction gas flow rate and rejection parameter q (Rpq), were optimized to minimize the interferences on isotopes, such as 52Cr and 56Fe. Two reference materials (NIST 1634c and NIST 1085b) were employed for method validation and the recoveries were between 90% and 110% for most elements, being the limits of detection between 0.02 ng g(-1) (52Cr) and 7.4 ng g(-1) (40Ca). The results obtained for the reference material NIST 1085b by the two proposed methods were in agreement at a 95% confidence level and did not show difference higher than 10% for most elements. The results obtained by elemental analysis of lubricant oils using the ICP OES methodology showed that it is possible to evaluate equipment wear through the analysis of its oil by the proposed methodology, since a significant increase of some elements concentrations, such as Fe, was detected in used lubricant oil samples. The analysis of biodiesel samples by ICP-MS indicated the presence of elements that are not controlled by the Brazilian legislation.
44

Vibrating CPD Chemical Degradation Oil Sensor

Tsiareshka, Siarhei G. 23 May 2006 (has links)
Oil analysis is a broad field comprised of hundreds of individual tests that provide meaningful benefit by assessing one or more properties of lubricants or machines. Many tests are performed on new types of oil during research and development. The lubricants chemical, physical, or lubricating properties are validated for quality control purposes and product performance classification. Much of the research in this area is devoted to the online oil degradation systems which allow getting a prompt response about the condition of lubricant. This thesis investigates the concept for monitoring oil degradation with a vibrating Kelvin probe technique. The Vibrating Kelvin probe method for measuring the work function of metals has been used since 1932. Among the applications of this technique are adsorption, corrosion, friction and other studies. A novel application of this method is proposed in this thesis. The vibrating Kelvin system was created with one static surface acting as a sampling surface and the other one electrically isolated. The interaction of the oil with one of the surfaces of a capacitor results in a signal which is synchronously measured. The oil molecules adsorb on the surface of one of the plates and form a space charge layer which changes the work function of that surface. Oil prepared by intentional oxidation was used to evaluate and to monitor the ability to see changes in oil.
45

Electrochemical studies of the automotive lubricant additive zinc n-dibutyldithiophosphate

Jacob, Sarah R. January 1998 (has links)
Zinc dialkyldithiophosphates (ZDTPs) are widely incorporated in lubricant formulations as anti-oxidant and anti-wear additives. Recent years have seen the emergence of considerable research aimed at defining the mode of action of these compounds. Despite this, the mechanistic action of ZDTPs in their capacity as both anti-wear and anti-oxidant agents remains ill defined. Previous investigations have used a wide variety of techniques, however, electrochemical methods have been poorly exploited. This thesis describes application of electrochemical techniques to the study of zinc ndibutyldithiophosphate (Bu<sup>n</sup>-ZDTP) in an investigation of the value of such methods as a tool for ZDTP analysis. A comprehensive study of Bun-ZDTP redox activity under standard electrochemical conditions has been implemented. Using cyclic voltammetry, Bu<sup>n</sup>-ZDTP has been shown to be oxidised in an irreversible 2 electron transfer process. The diffusion coefficient of this species in DMF has been calculated via rotating disc electrode (RDE) voltammetry. Bu<sup>n</sup>-ZDTP reduction proceeds via nucleation of zinc at the electrode surface. The limiting current of the 2 electron reduction process is lower than previously observed for Bu<sup>n</sup>- ZDTP oxidation. This occurs since zinc deposition is confined to growth centres which effectively limit the electroactive area of the electrode. A more thorough investigation of zinc nucleation at the electrode surface was undertaken using chronoamperometry. Transients plotted in dimensionless form were compared to theoretical models of nuclear growth. The potential of atomic force microscopy as a promising technique for the imaging of ZDTP filming action has been demonstrated. Ex-situ atomic force microscopy was conducted of electrode surfaces following reduction in Bu<sup>n</sup>-ZDTP solution under cyclic and RDE voltammetric conditions. Development of a variable elevated temperature apparatus for the study of Bu<sup>n</sup>-ZDTP under conditions more typical of an engine environment has been described. Application of the system to a wide range of electrochemical problems was demonstrated as an illustration of the advantages of this novel experimental approach. Studies of N, N, N/, N/-tetramethyl-p-phenylenediamine and tris(4-bromophenyl)amine oxidation yielded diffusion co-efficients (D) at elevated temperatures from which activation parameters for diffusion were obtained. Variation of D with temperature was compared to predicted theory according to the Stokes-Einstein and Wilke-Chang relationships. Studies of ortho-bromonitrobenzene and 9-chloroanthracene reduction demonstrated the elevated temperature apparatus to be a viable method for the interrogation of rapid kinetic processes. Both compounds are reduced according to an ECE mechanistic scheme where halide bond cleavage constitutes the chemical step. Since the use of microelectrodes permits "outrunning" of bond cleavage kinetics to give an n<sub>eff</sub> of less than two, rate constants at varying temperatures were evaluated. Arrhenius plots were used to deduce activation parameters of halide bond cleavage in both compounds. Preliminary studies of Bu<sup>n</sup>-ZDTP redox activity under conditions more typical of an engine environment are discussed. Application of the novel microelectrode apparatus to an elevated temperature study of Bu<sup>n</sup>-ZDTP is described. Voltammetric investigations in toluene, a resistive solvent which serves as a convenient model for oil, are discussed.
46

Performance measurements of rail curve lubricants

Wilson, Lance Jon January 2006 (has links)
Wear of railroad rolling stock and rails costs millions of dollars annually in all rail systems throughout the world. The rail industry has attempted to address flange wear using rail curve lubricants and presently use a variety of lubricants and lubricant applicators. The choice of lubricant and applicator is currently based on considerations that do not address the wear problem directly. This research quantified rail curve lubricant performance through laboratory simulation. The effects of lubricants in the wheel/rail contact were investigated. Rail curve lubricant performance was measured with a laboratory rail/wheel simulator for the purpose of optimising the choice of lubricant. New methods for measurement of rail curve lubricant performance have been presented. These performance measurements are total absorbed energy, the energy absorbed in the lubricant film instead of being utilised for wear processes; total distance slid, the sliding distance or accumulated strain achieved prior to development of a set tractive force limit; half life of lubricant, the time taken for a lubricant to lose half of its sliding performance; and apparent viscosity, a measure of the lubricity presented with respect to accumulated strain. The rail/wheel simulator used in this research consists of two dissimilar wheels (disks) rotating in contact with one another simulating a conformal gauge corner contact. The first wheel, a simulated rail, is driven by an electric motor which then drives the second wheel, a simulated railroad wheel, through the contact. Hydraulic braking on the railroad wheel is used to simulate the rolling/sliding conditions. The variables of the simulated contact that are controlled with this equipment are normal force, input wheel speed, slip ratio between samples, sample geometries and material properties, and lubricant types. Rail curve lubricants were laboratory tested to define their properties using the ASTM and other appropriate standards. The performance differences measured using ASTM standards based tests were susceptible to repeatability problems and did not represent the contact as accurately as the rail/wheel simulator. This laboratory simulator was used to gather data in lubricated and unlubricated conditions for the purpose of providing lubricant performance measurements. These measurements were presented and the tested lubricants were ranked conclusively using three industrially relevant performance criteria. Total sliding distance and total absorbed energy measurements of the rail curve lubricants displayed clear differences in lubricant performance for both of these criteria. Total sliding distance is equivalent to the number of axles in the field situation, while total absorbed energy is the energy unavailable for wear processes of rails and wheels. Lubricants designed using these measurements will increase lubricant performance with respect to these performance criteria which in turn will reduce wear to both rails and wheels. Measurement of the apparent viscosity of rail curve lubricants, using the rail/wheel simulator, displayed changes in rheological characteristics with respect to accumulated strain. Apparent viscosity is a measure of the shear stress transmitted from the wheels to the rails. Designing a rail curve lubricant after analysing measurements taken from the rail/wheel simulator will assist in identifying lubricant properties to reduce the wear producing shear stresses generated in a rail wheel contact. Decay of lubricant performance was measured for three different rail curve lubricants under simulated conditions. The research found appreciable and quantifiable differences between lubricants. Industrial application of the findings will improve positioning of lubrication systems, improve choice of lubricants and predict effective lubrication distance from the lubricant application point. Using the new methods of lubricant performance measurement developed in this thesis, the objective of this research, to quantify rail curve lubricant performance through laboratory simulation, has been achieved.
47

Πειραματική και θεωρητική μελέτη των χαρακτηριστικών αποσβέσεως ενός υγρού λιπαντικού φίλμ

Καραχάλιος, Γ. 22 September 2010 (has links)
- / -
48

Desenvolvimento de insertos sinterizados autolubrificantes para uso em matrizes de conformação a frio

Cóser, Marcelo Salvador January 2016 (has links)
Este trabalho avalia o uso de insertos autolubrificantes de pó de aço ferramenta sinterizado para aplicação em ferramentas dos processos de Conformação a Frio. São apresentadas a preparação e a análise de diferentes composições de misturas de pós de aço ferramenta H 13. A Metalurgia do Pó convencional foi utilizada como processo para a obtenção dos insertos do estudo. Foram compactadas e sinterizadas misturas de pó de aço H13 com a adição de percentuais variados do lubrificante sólido Bissulfeto de Molibdênio – MoS2, também em pó, com o objetivo de atribuir propriedades de autolubrificação ao composto. O percentual de lubrificante sólido empregado nas amostras variou de 1% a 5%, com posterior sinterização. Os resultados obtidos no Ensaio de Atrito com anéis de Alumínio AA6351 recozido apresentaram nos insertos autolubrificantes do estudo coeficientes de atrito μ entre 0,10 e 015, menores que os valores μ entre 0,20 e 0,30 obtidos com aço H13 laminado convencional. Também o desgaste abrasivo do ferramental proposto avaliado no Ensaio de Abrasão com Roda de Borracha foi 12% menor quando comparado com o aço ferramenta H13 laminado exposto ao mesmo ensaio. / This study evaluates the use of self-lubricating tool steel powder sintered inserts for use in tools of Cold Forming processes. Preparation and analysis of various compositions of H13 tool steel powder mixtures are presented. The conventional Powder Metallurgy was used as a process for obtaining the study inserts. Were compacted and sintered mixtures of H13 steel powder with the addition of varying percentages of the solid lubricant Molybdenum Disulphide - MoS2, also in powder form, with the purpose of giving self-lubricating properties to the composite. The percentage of solid lubricant used in the samples varied from 1% to 5%, with subsequent sintering. The results of the friction test on AA6351 aluminum rings had friction coefficients μ between 0.10 and 015 with self-lubricating inserts in study, smaller than μ values between 0.20 and 0.30 obtained with the conventional steel H13 laminate. Also, the abrasive wear of the tooling proposed evaluated in the abrasion test with rubber wheel was 12% lower when compared to the H13 tool steel laminate exposed to the same test.
49

Utilização de insertos com agregado sólido de lubrificantes confeccionados por metalurgia do pó convencional

Bueno, Alex Fabiano January 2016 (has links)
O presente trabalho apresenta o desenvolvimento de um inserto em aço ferramenta AISI H13 obtido por meio do processo de Metalurgia do Pó com a adição de lubrificante sólido na sua composição, que tem a finalidade de conferir propriedades autolubrificantes ao mesmo. Foram utilizados os pós de MoS2 e de h- BN para promover a redução do coeficiente de atrito. Adicionou-se o lubrificante MoS2 ao pó de aço ferramenta na etapa de mistura dos pós, em concentrações que variaram de 1% a 5%. Da mesma forma, foram confeccionados corpos de prova substituindo o MoS2 por h-BN. Após a compactação de todos os corpos de prova eles foram sinterizados. A mistura com h-BN apresentou grande formação de óxido durante os processos de sinterização e de tratamento térmico, sendo descartada sua utilização para os ensaios de abrasão para verificar desgaste e para os ensaios do anel que determinam o coeficiente de atrito. Conforme as análises realizadas, pode-se observar a formação de fases distintas, com ilhas de lubrificante MoS2 em matriz ferrítica. Utilizou-se o ensaio do anel para determinação do coeficiente de atrito de Coulomb – μ, e anéis de Alumínio como corpos de prova para este ensaio. Os insertos de MoS2 apresentaram ótimos resultados neste ensaio, e foram similares a experimentos realizados por outros pesquisadores que utilizaram o mesmo sistema tribológico deste trabalho - H13 como ferramenta, MoS2 como lubrificante e anéis de Alumínio para conformação. A diferença satisfatória obtida pelo material confeccionado neste estudo em relação aos obtidos da literatura pesquisada está na forma de utilização do lubrificante, que neste caso foi adicionado à matriz pelo processo de Metalurgia do Pó, enquanto que nos trabalhos analisados o lubrificante foi borrifado sobre a matriz. / The present work describes the development of an insert of tool steel AISI H13 obtained by powder metallurgy process with the addition of solid lubricant in the composition, in order to impart self-lubricating properties. MoS2 and h-BN powder were used to promote the reduction of the friction coefficient. It was added MoS2 lubricant with the tool steel powder in the mixing step at concentrations ranging from 1% to 5%. Similarly were prepared specimens replacing MoS2 for h- BN. After compression of the samples they were also sintered. The mixture with h- BN showed extensive formation of oxide during the sintering process and heat treatment, and discarded their use for the abrasion test for wear and ring assays for the determination of the friction coefficient. Through the analysis carried out, were observed the formation of distinct phases with lubricant MoS2 islands in ferritic matrix. The tests for friction in samples with MoS2 showed good results, similar to experiments by other researchers who used the same tribological system of this work - H13 as a tool, MoS2 as a lubricant and aluminum rings for conformation. Satisfactory difference obtained by the material made in this study compared to those obtained from the literature is in the form of use of the lubricant, which in this case was added to the matrix by the powder metallurgy process, whereas in the studies analyzed the lubricant was sprayed onto the matrix.
50

[en] METHOD VALIDATION OF ZDDP QUANTIFICATION IN LUBRICATING OIL BY INFRARED SPECTROMETRY / [pt] VALIDAÇÃO DO MÉTODO DE ENSAIO DE QUANTIFICAÇÃO DO TEOR DE ZDDP EM ÓLEOS LUBRIFICANTES POR ESPECTROFOTOMETRIA DE INFRAVERMELHO

VANESSA BREDER VALENTE ZANATTA 19 January 2010 (has links)
[pt] Este trabalho teve como objetivo desenvolver e validar uma metodologia analítica para a determinação da concentração de ZDDP em óleos lubrificantes por espectrofotometria na região do infravermelho. Optou-se por expressar a concentração de ZDDP baseada no teor de fósforo, devido à necessidade de comparação com técnicas analíticas que determinam o total deste elemento. O método desenvolvido foi capaz de determinar o teor de fósforo por espectrofotometria na região do infravermelho na faixa de 0,0770 a 0,1500 % m/m, o que representa em torno de 0,96 a 1,87 % m/m em termos dos aditivos ZDDP estudados. As leituras foram realizadas com dez varreduras em absorbância, na faixa de número de onda 1100 - 900 cm(-1), resolução 0,5 cm(-1), em célula de selenito de zinco (ZnSe) com caminho óptico 0,10 mm. As curvas analíticas foram construídas utilizando-se regressão linear pelo método dos mínimos quadrados. Amostras reais foram analisadas e os resultados obtidos comparados com os obtidos pela técnica de ICP-OES. A validação foi realizada avaliando-se os seguintes parâmetros: faixa de trabalho, faixa linear de trabalho e linearidade, sensibilidade, especificidade e seletividade, exatidão e tendência (bias), precisão, robustez e incerteza de medição. Com base nos resultados obtidos foi possível utilizar a metodologia no controle de qualidade de produtos cuja formulação seja composta de ZDDP. A análise estatística demonstrou que não existe diferença significativa entre as técnicas estudadas (ICP-OES e IR), considerando-se as faixas e os produtos em questão. Foi aplicado o teste t- Student para comparar o valor certificado da concentração de fósforo de um MRC (NIST 1848) com os valores obtidos utilizando o método proposto. A análise estatística dos resultados apontou que não existe diferença significativa entre o valor da concentração de fósforo certificada e o valor encontrado. / [en] This study aimed to develop and validate an analytical method for determining the concentration of ZDDP in lubricating oils by infrared spectrometry. We chose to express the concentration of ZDDP based on phosphorus content, due to the need for comparison with analytical techniques that determine the total of this element. The method was able to determine the level of phosphorus by spectrometry in the infrared range from 0.0770 to 0.1500% m/m, this represents around 0.96 to 1.87% m/m of the ZDDP additives studied. Date was obtained with ten scans in absorbance in the range of wave number 1100 - 900 cm-1, resolution 0.5 cm-1, using zinc selenite cell (ZnSe) with 0.10 mm optical path. The analytical curves were constructed using a linear regression by the method of least squares. Real samples were analyzed and the results were compared with those obtained by the technique of ICP-OES. Validation was carried out evaluating the following parameters: specificity and selectivity, working range, linear working range and linearity, sensitivity, accuracy and tendency (bias), accuracy, robustness and uncertainty of measurement. Based on the results were possible to use the methodology in quality control of products whose formulation is composed of ZDDP. Statistical analysis showed that no significant difference between the techniques studied (ICP-OES and IR), considering the range and the products in question. We applied the Student t-test to compare the certified value of the concentration of phosphorus of a MRC with the values obtained using the proposed method. Statistical analysis of results showed that no significant difference between the value of the concentration of phosphorus and the certified value found.

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