DEDICATÓRIA Dedico este trabalho ao meu grande amigo, meu mestre, meu espelho, meu herói. Meu querido e amado pai, DINECIO DOS SANTOS. AGRADECIMENTOS Agradeço a Deus, aos meus pais, meus avós, minha família e meus antepassados. Ao professor Doutor Hélio Goldenstein pela preciosa orientação, amizade, confiança e apoio em todos os momentos. Aos professores Doutor Amilton Sinatora e Doutor Jan Vatavuk, pelas importantes e essenciais contribuições. Aos amigos do laboratório de transformação de fases do departamento de engenharia metalúrgica da escola politécnica da USP. Aos amigos integrantes do grupo de engenharia de desenvolvimento de motores e do laboratório metalúrgico da General Motors. A todos que contribuíram direta ou indiretamente para a realização deste trabalho, que é o resultado do esforço de incontáveis e importantes pessoas. RESUMO O presente estudo descreve as alterações metalúrgicas e topográficas do cilindro de blocos de motor de combustão interna fabricados em ferro fundido cinzento, após a realização de testes de durabilidade em dinamômetro. O motor testado tem tecnologia "Flex-Fuel", e pode ser operado com qualquer proporção de mistura gasolina comum/etanol. Um motor foi testado com combustível etanol e o outro com gasolina comum, buscando-se assim representar duas condições extremas de trabalho em termos de combustível. A pesquisa constituiu-se da revisão bibliográfica e da parte prática que envolveu: a realização de testes de durabilidade de motor em dinamômetro; a caracterização metalúrgica e topográfica do cilindro após teste com ambos os combustíveis, utilizando técnicas de microscopia eletrônica de varredura, metalografia por microscopia óptica, perfilometria e quantificação de parâmetros de rugosidade, entre outros; a análise crítica, discussão dos resultados e apresentação da conclusão. Palavras chave: Motor de combustão interna. Bloco de motor. Cilindro. Flex-Fuel. Desgaste. Tribologia. Ferro fundido. Anéis de pistão. ABSTRACTThe present study approaches the metallurgical and topographical alterations on the cylinder of an internal combustion engine block made of gray cast iron, after durability dynamometer tests. The tested engine has flexible fuel technology (Flex-Fuel), and is capable to work with both gasoline/ethanol fuels, in any mixture proportion. One engine has been tested with ethanol and another one tested with gasoline, and so representing two extreme conditions on which the engine may work in terms of fuel.The research has been developed basically through the conceptual approach by the bibliographic review and the experimental steps that involved: general engine durability test at dynamometer bench; metallurgical and topographic characterization analysis at laboratory, after the test with both fuels, applying Scanning Electronic Microscopy SEM, optical microscopy metallography, profilometer and roughness parameters quantification, and so forth; critical analysis on the results, discussion and final conclusion.
A concept of plasma treatment for enhancing pre-textured surfaces of components made in pearlitic gray cast iron is proposed. It consists of a plasma nitriding at low temperatures and short times, in order to increase the hardness of the surface by means of a shallow depth nitride formation in the surface of the iron. As a result, the roughness pattern of a previously textured surface is preserved after the treatment. A review on the wear of internal combustion engine cylinders along with background research was conducted, which consisted in the description of cylinder bore wear features observed experimentally. The background research substantiated the significance of initiatives to enhance wear and friction response of pre-textured surfaces made of cast iron, such as the internal combustion engine cylinders. A series of plasma nitriding experiments was run on specimens extracted from engine cylinders. Flat specimens, obtained from blanks extracted from the cylinder wall of an engine cylinder block, were textured in laboratory in order to emulate the typical roughness distribution of an ordinary cylinder bore plateau honing process. Complementarily, a case-study experiment was performed in a honed sample of an internal combustion engine cylinder, whose surface in its original form (cylindrical) has been textured through industrial honing operations. Therefore, one among the potential applications of the research has been assessed. 3-D interference roughness measurements were performed before and after the plasma treatment to assess topographic stability of the textured surfaces. ε-Iron nitride (Fe 3 N) formation was identified via X-ray diffraction analysis. In addition, nitrogen concentration profile was quantitatively evaluated using wavelength-dispersive (X-ray) spectroscopy microanalysis, substantiating the nitride formation at shallow depth. Microhardness measurements and instrumented linear sclerometry test ('scratch test') results indicated that ε-iron nitride formation and solid solution hardening could provide enhanced properties to the surface of general pearlitic cast iron components, such as increase of wear resistance, and decrease of apparent coefficient of friction, in the assessed conditions. The results demonstrated that the roughness texture pattern was satisfactorily preserved after the treatment, which was supported by direct observation of the surfaces via scanning electronic microscopy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
334 Leonard St
Brooklyn, NY 11211
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.