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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.
1

Design and analysis of a liquid/gas seal

Rutledge, Joyce 08 1900 (has links)
No description available.
2

Estudo tribol?gico de biolubrificantes com adi??o de nanopart?culas de ?xidos (zinco e cobre) / Tribological study of addition of nano lubricants with oxide particles

Trajano, Marinalva Ferreira 02 August 2013 (has links)
Made available in DSpace on 2014-12-17T14:58:23Z (GMT). No. of bitstreams: 1 MarinalvaFT_DISSERT.pdf: 2645446 bytes, checksum: d4a95fdf4bdc8c40f2876e653a2bb39f (MD5) Previous issue date: 2013-08-02 / Currently, vegetable oils have been studied for bio-lubricants base that fits the new environmental standards. Since, in a world full of finite natural resources, mineral oils bring consequences to the environment due to its low biodegradability and toxicity, also it is important to consider that synthetic oils have a high cost The aim of this work is to obtain a biolubricant additived with oxide nanoparticles (ZnO and CuO) for better resistance to friction and wear, which is not toxic to the environment and have better adherence under boundary lubrication. The methodology consisted in the synthesis of bio-lubricants (soybean and sunflower base) by epoxidation reaction. Then, some physical-chemical analysis in bio-lubricants are made to characterize theses lubricants, such as, density, acidity, iodine value, viscosity, viscosity index. Later, the lubricants were additive with nanoparticles. The tribological performance was evaluated by the equipment HFRR (High Frequency Reciprocating Rig) consisting of a wear test ball-plan type. The characterization of wear analysis was performed by SEM / EDS. The results show that bio-lubricants may be synthesized by reaction of epoxidation with good conversion. Tribological point of view, the epoxidized oils are more effective than lubricant additived with the oxide nanoparticles, they had lower coefficients of friction and better rate of film formation in the study. However, because they are environmentally friendly, bio-lubricants gain the relevant importance in tribological field / Atualmente, os ?leos vegetais tem sido base de estudo para biolubrificantes que se adequem ?s novas normas ambientais. Em um mundo cheio de recursos naturais finitos, os ?leos minerais, provenientes do petr?leo, trazem consequ?ncias ao meio ambiente devido sua baixa biodegradabilidade e toxicidade. Tamb?m deve-se considerar, os ?leos sint?ticos possuem um alto custo. O objetivo deste trabalho ? obter um biolubrificante aditivado com nanopart?culas de ?xido (ZnO e CuO) para uma melhor resist?ncia ao atrito e desgaste, que seja n?o t?xico ao meio ambiente e possua melhor ader?ncia em regime de lubrifica??o limite. Efetuou-se a s?ntese de biolubrificantes (soja e girassol) por rea??o de epoxida??o. Em seguida fizeram-se an?lises f?sico-qu?micas no biolubrificante para caracterizar os ?leos sintetizados, tais como; densidade, acidez, ?ndice de iodo, viscosidade, ?ndice de viscosidade. Posteriormente os mesmos foram aditivados com nanopart?culas. O desempenho tribol?gico foi avaliado pelo equipamento HFRR (High Frequency Reciprocating Rig), que consiste num ensaio de desgaste do tipo esfera-plano. A caracteriza??o do desgaste foi realizada atrav?s de an?lises de MEV/EDS. Os resultados demostraram que os biolubrificantes podem ser sintetizados por rea??o de epoxida??o, com boa convers?o. Do ponto de vista tribol?gico, os ?leos epoxidados puros s?o mais eficazes que os aditivados com nanopart?culas de ?xido, apresentaram menores coeficientes de atritos e melhor percentual de forma??o de filme neste estudo. Por?m, por serem ambientalmente corretos, os biolubrificantes ganham import?ncia relevante no meio tribol?gico

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