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Previous issue date: 2017-07-10 / Materiais particulados inferiores a 10 e 2,5 ?m, PM10 e PM2,5, respectivamente; emitidos por motores diesel se inalados por seres humanos podem causar disfun??es endoteliais, inflama??es e estresse oxidativo. Em ambientes onde h? uso intenso de motores de combust?o interna, uma parcela do PM ? composta por debris, part?culas met?licas provenientes do desgaste do motor, portanto caracter?sticas tribol?gicas da origem e do padr?o estoc?stico do PM s?o de fundamental import?ncia na preven??o e controle dos problemas associados. Esse trabalho investigou e modelou segundo uma cadeia de Markov os mecanismos de desgaste e o PM emitido por dois motores do ciclo diesel: o primeiro utilizando B6 e o segundo B6 microemulsionado com tensoativo e ?gua. Utilizou-se uma bancada dinamom?trica acoplada a um motor e o PM foi coletado utilizando um novo dispositivo desenvolvido por integrantes do Grupo de Estudos de Tribologia e Integridade Estrutural da UFRN para captura de part?culas. As coletas foram feitas a cada 20 horas dentro de um total de 140 horas, n?o cont?nuas, de funcionamento para cada combust?vel. Posteriormente, realizou-se a an?lise dos debris atrav?s de microscopia eletr?nica de varredura (MEV) e microan?lise qu?mica por energia diepersiva de Raios-x (EDS), os principais mecanismos de desgaste identificados foram fadiga, tribo-corros?o, dano por altas temperaturas e delamina??o; a transi??o entre os mecanismos foi modelada segundo uma cadeia de Markov. A cadeia mostrou que as probabilidades de transi??o entre os mecanismos de desgaste possuem uma distribui??o de equil?brio para longos per?odos e que o dano por fadiga possui o dobro da probabilidade de ocorr?ncia que os demais. A distribui??o de equil?brio ? atingida ap?s 300 horas de funcionamento. / Particulate matter less than 10 and 2.5 ?m, PM10 and PM2,5, respectively; emitted by diesel engines if inhaled by humans can cause endothelial disorders, inflammation and oxidative stress. In environments where there is heavy use of internal combustion engines, a portion of PM is composed of debris, metal particles of engine wear, therefore, tribological characteristics of PM origin and behavior are of fundamental importance in the prevention and control of associated problems. This work investigated the wear mechanisms and PM emitted by two diesel engines: the first use B6 and the second B6 microemulsified with tensoactive and water. A dynamometer coupled to a motor was used and the PM was collected using a new device developed by the Tribology Study Group for capture particles. The collections were done every 20 hours within a total of 140 hours, not continuous, operating for each fuel. Subsequently, an analysis of the debris was carried out by scanning electron microscopy (SEM) and chemical microanalysis by X-ray dispersive energy (EDS) spectroscopy. The main wear mechanisms identified were fatigue, tribo-corrosion, damage by high temperatures and delamination; A transition between the mechanisms was modeled by a Markov chain. The chain showns transition probabilities between wear mechanisms, an equilibrium distribution for long periods and that the fatigue damage has twice the probability of occurrence. An equilibrium distribution is active after 300 hours of operation.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24730 |
| Date | 10 July 2017 |
| Creators | Oliveira, F?bio C?sar Miranda de |
| Contributors | 10973370491, Matamoros, Efrain Pantaleon, 21896458831, Souza, Juliana Ricardo de, 05844998413, Silva, Luciano Rodrigues da, 07416407400, Medeiros, Jo?o Tel?sforo N?brega de |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA MEC?NICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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