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Ultra-low friction W–S–N solid lubricant coating

Gustavsson, Fredrik; Jacobson, Staffan; Cavaleiro, Albano; Polcar, Tomas
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.12%
W–S–N films were deposited by reactive magnetron sputtering from WS2 target in Ar/N2 atmosphere. Besides the standard evaluation of composition, structure, morphology, hardness and cohesion/adhesion, the core objective of this paper was to analyze coating tribological behavior. The chemical composition was 34 at.% N, 12 at.% O, 29 at.% W and 25 at.% S, and the as-deposited films were completely amorphous. The film thickness was 2.3 μm, including the approximately 300-nm thick adhesion improving titanium interlayer. The friction coefficient was lower than 0.003 when sliding in dry nitrogen. The coating showed remarkable wear resistance surviving more than 2 million laps on pin-on-dics. The excellent friction properties were attributed to the formation of a thin tungsten disulfide tribofilm on the top of the wear track of the coating and on the counterpart surface. Moreover, the coating showed ability to replenish damaged areas with solid lubricant. We demonstrated that a structural transformation of the coating from an amorphous-like to a gradient quasi-ordered structure and an ordered transfer layer formation improved mechanical properties and radically decreased friction and wear.

Geophysical investigation using resistivity and GPR methods: a case study of a lubricant oil waste disposal area in the city of Ribeiro Preto, So Paulo, Brazil

LAGO, Alexandre Lisboa; ELIS, Vagner Roberto; BORGES, Welitom Rodrigues; PENNER, Giovanni Chaves
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.4%
Geophysics has been shown to be effective in identifying areas contaminated by waste disposal, contributing to the greater efficiency of soundings programs and the installation of monitoring wells. In the study area, four trenches were constructed with a total volume of about 25,000 m(3). They were almost totally filled with re-refined lubricating oil waste for approximately 25 years. No protection liners were used in the bottoms and laterals of the disposal trenches. The purpose of this work is to evaluate the potential of the resistivity and ground penetrating radar (GPR) methods in characterizing the contamination of this lubricant oil waste disposal area in Ribeiro Preto, SP, situated on the geological domain of the basalt spills of the Serra Geral Formation and the sandstones of the Botucatu Formation. Geophysical results were shown in 2D profiles. The geophysical methods used enabled the identification of geophysical anomalies, which characterized the contamination produced by the trenches filled with lubricant oil waste. Conductive anomalies (smaller than 185 Omega m) immediately below the trenches suggest the action of bacteria in the hydrocarbons, as has been observed in several sites contaminated by hydrocarbons in previously reported cases in the literature. It was also possible to define the geometry of the trenches...

Desenvolvimento e avaliação de um lubrificante, com partículas magnéticas, destinado à redução de atrito em motores de combustão interna; Development and evaluation of a lubricant, using magnetic particles, in order to reduce friction in internal combustion engines

Oliveira, Adelci Menezes de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 14/09/2009 PT
Relevância na Pesquisa
37.59%
Os motores de combustão interna (MCI) têm sido usados pela humanidade há mais de 100 anos e ainda continuarão por muito tempo em virtude da sua alta confiabilidade e baixo custo de produção. No entanto, eles apresentam grande impacto ambiental em relação à emissão de 'CO IND.2'. Atualmente, diversos trabalhos têm sido realizados com o objetivo de reduzir o consumo de combustíveis, o que conseqüentemente resulta em redução de emissões. Esses trabalhos englobam melhoramentos de projeto, desenvolvimento de novos materiais e lubrificantes de maior desempenho. No presente trabalho desenvolveu-se um lubrificante que contém partículas magnéticas constituídas de Compostos Intermetálicos Lubrificantes (CIL), que foi avaliado em tribômetro do tipo quatro esferas. Este lubrificante foi testado nas temperaturas de 60 ºC, 100 ºC e 150 ºC, sob perfil de carga específico e rotação de 1.500 rpm. Comparado com outro óleo de mesmo grau SAE de viscosidade, apresentou desempenho friccional superior, exceto para a temperatura de 150 ºC. Constatou-se que as partículas de CIL atuavam através da combinação da atividade superficial e atração magnética provocada pelo processo friccional das superfícies. Também se realizou um estudo de simulação computacional...

Graxa de poliuréia - estudo da compatibilidade da poliuréia, polialfaolefina e politetrafluoretileno irradiado para melhoria da lubricidade e estabilidade; Development of high performance lubricant through the compatibility of polyalphaolefin, polyurea and irradiated polytetrafluoroethylene

Ratão, Natalia Torres
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/12/2013 PT
Relevância na Pesquisa
37.4%
Lubrificantes são produtos gasosos, líquidos, semi sólidos ou sólidos (pó) que formam um filme entre duas partes evitando o atrito. Lubrificantes de alto desempenho são designados para trabalharem em condições severas de temperatura, pressão e contaminação. Os mais utilizados são os líquidos (óleos) e semi sólidos (graxas). As graxas são aplicadas aonde o óleo pode escorrer e em pontos de difícil acesso e são divididas basicamente em duas classes, sabão e não sabão. A graxa não sabão mais utilizada é a poliuréia, obtida pela reação entre aminas e isocianato, possui elevada tixotropia, alta rigidez dielétrica e excelente poder anticorrosivo, por isso é amplamente utilizada para lubrificação de motores elétricos e maquinário naval. Para obter uma graxa com altíssimo desempenho, nesse estudo foi utilizado o fluido lubrificante sintético polialfaolefina e também foi empregado o aditivo lubrificante sólido politetrafluoroetileno (PTFE) por apresentar o menor coeficiente de atrito conhecido, é comercialmente encontrado irradiado em ar para obter partículas menores e produzir grupos terminais oxigenados que são mais compatíveis com a superfície metálica. Os ensaios foram realizados de forma comparativa usando a graxa de poliuréia pura e aditivada com PTFE. As caracterizações foram feitas por espectroscopia de infravermelho...

Analysis of surface integrity for minimum quantity lubricant - MQL in grinding

da Silva, Leonardo Roberto; Bianchi, Eduardo Carlos; Fusse, Ronaldo Yoshinobu; Catai, Rodrigo Eduardo; Franca, Thiago Valle; Aguiar, Paulo Roberto
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 412-418
ENG
Relevância na Pesquisa
37.12%
The quality of machined components is currently of high interest, for the market demands mechanical components of increasingly high performance, not only from the standpoint of functionality but also from that of safety. Components produced through operations involving the removal of material display surface irregularities resulting not only from the action of the tool itself, but also from other factors that contribute to their superficial texture. This texture can exert a decisive influence on the application and performance of the machined component. This article analyzes the behavior of the minimum quantity lubricant (MQL) technique and compares it with the conventional cooling method. To this end, an optimized fluid application method was devised using a specially designed nozzle, by the authors, through which a minimum amount of oil is sprayed in a compressed air flow, thus meeting environmental requirements. This paper, therefore, explores and discusses the concept of the MQL in the grinding process. The performance of the MQL technique in the grinding process was evaluated based on an analysis of the surface integrity (roughness, residual stress, microstructure and microhardness). The results presented here are expected to lead to technological and ecological gains in the grinding process using MQL. (c) 2006 Elsevier Ltd. All rights reserved.

Evaluation of the biodegradation of different types of lubricant oils in liquid medium

Lopes, Paulo Renato Matos; Bidoia, Ederio Dino
Fonte: Brazilian Archives of Biology and Technology Publicador: Brazilian Archives of Biology and Technology
Tipo: Artigo de Revista Científica Formato: 1285-1290
ENG
Relevância na Pesquisa
37.4%
Avaliação da Biodegradação de Diferentes Tipos de Óleo Lubrificante em Meio Aquoso pela Norma Técnica L6.350 (CETESB, 1990), utiliza-se o processo respirométrico de Bartha e Pramer para acompanhar a biodegradação de diferentes tipos de óleo lubrificante automotivo adaptado ao meio aquoso. Para realização do experimento foram preparados um inóculo base e, posteriormente, um inóculo aquoso. Quatro tratamentos foram realizados em dois experimentos consecutivos: T1 (controle); T2 (óleo semi-sintético); T3 (óleo mineral); T4 (óleo usado). Dentre os resultados, obteve-se a seguinte ordem decrescente na produção de CO2 nos respirômetros: T4 > T2 > T3 > T1. Assim, o óleo lubrificante usado surgiu com maior biodegradabilidade, seguido do semisintético e do óleo mineral. Observou-se também que o lubrificante mineral apresentou maior período de adaptação comparado ao semisintético.; The aim of this work was to study the biodegradation of different types of automotive lubricant oils adapted to the aqueous medium using a base inoculum and an aqueous inoculum. Four treatments were carried out in two consecutive and similar experiments: T1 (control); T2 (half-synthetic oil); T3 (mineral oil); T4 (used oil). The results showed the following decreasing order of CO2 production in the Bartha and Pramer respirometers: T4 > T2 > T3 > T1. Thus...

Biodegradation and toxicological evaluation of lubricant oils

Tamada, Ivo Shodji; Lopes, Paulo Renato Matos; Montagnolli, Renato Nallin; Bidoia, Ederio Dino
Fonte: Brazilian Archives of Biology and Technology Publicador: Brazilian Archives of Biology and Technology
Tipo: Artigo de Revista Científica Formato: 951-956
ENG
Relevância na Pesquisa
37.54%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); The aim of this work was to compare different toxicity levels of lubricant oils. The tests were performed using the earthworm (Eisenia andrei), arugula seeds (Eruca sativa) and lettuce seeds (Lactuca sativa), with three types of contaminants (mineral lubricant oil, synthetic lubricant oil and used lubricant oil) for various biodegradation periods in the soil. The toxicity tests indirectly measured the biodegradation of the contaminants. The samples were analyzed at t0, t60, t120 and t180 days of biodegradation. The used lubricant oil was proved very toxic in all the tests and even after biodegradation its toxicity was high. The mineral and synthetic oils were biodegraded efficiently in the soil although their toxicity did not disappear completely after 180 days.

Applied models to biodegradation kinetics of lubricant and vegetable oils in wastewater

Montagnolli, Renato N.; Lopes, Paulo R. M.; Bidoia, Ederio Dino
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 297-305
ENG
Relevância na Pesquisa
37.48%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Bioremediation technologies are used in order to remove pollutants from the environment in a safe, economical and harmless way during the treatment of waste, especially with the use of techniques such as biodegradation. A lubricant and vegetable oil contaminated water sample was studied in order to evaluate the biodegradability of different types of oils, considering the relevance of the obtained data in the bioremediation procedures. The objective of this paper is to use respirometry technique as a biodegradation process data source, and then apply to the obtained data the experimental design of mathematical models to characterize and determinate how the different types of oils are capable of affecting the parameters in biodegradation kinetics. The kinetics was then evaluated through selected models with a reasonable fit to experimental data. The Bartha and Pramer respirometer is used as a method to accurately measure the CO(2) formation in the organic compounds degradation by microorganisms. Therefore, the difference in biodegradation efficiency process is compared in the different groups of oils using mathematical models fitting the obtained data for the kinetics of biodegradation. The results demonstrated that used lubricant automotive oils are more susceptible to the biodegradation process...

DETERMINATION of SILICON IN LUBRICANT OIL BY HIGH-RESOLUTION CONTINUUM SOURCE FLAME ATOMIC ABSORPTION SPECTROMETRY USING LEAST-SQUARE BACKGROUND CORRECTION and INTERNAL STANDARDIZATION

Raposo, Jorge Luiz; Oliveira, Silvana Ruella; Gomes Neto, Jose Anchieta; Nobrega, Joaquim Araujo; Jones, Bradley Todd
Fonte: Taylor & Francis Inc Publicador: Taylor & Francis Inc
Tipo: Artigo de Revista Científica Formato: 2150-2161
ENG
Relevância na Pesquisa
37.29%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); The least-squares background correction (LSBC) and internal standardization procedures were combined to eliminate spectral interferences caused by the CS molecular band (251.602 nm) and transport effects for determining Si in sulfuric acid digests of lubricant oil by high-resolution continuum source flame atomic absorption spectrometry. Aluminum, Ba, Ti, V, and W were tested as internal standard (IS) candidates, and W provided the best results. For absorbance measurements of solutions containing 0.5-5.0 mg L-1 Si in the presence of 25 mg L-1 W (at the wavelength integrated absorbance equivalent to 3 pixels), the correlation coefficient for the ratio of absorbance of Si to absorbance of W vs. analyte concentration was 0.9978. Fluctuations in analytical signals due to variations in sulfuric acid concentrations or acetylene/nitrous oxide flow-rate ratios were corrected by using this calibration plot. Relative standard deviations varied from 1.9 to 7.2% and 2.1 to 5.4% (n=12) with and without LSBC/IS, respectively. Recoveries for samples spiked with 2.0 mg L-1 Si in 5.0% (v/v) sulfuric acid were within the 72.5-82.5% and 94.0-99.0% ranges without correction and by LSBC associated with internal standardization procedure...

Study on the behavior of the Minimum quantity lubricant - MQL technique under different lubricating and cooling conditions when grinding ABNT 4340 steel

Silva, L. R.; Bianchi, E. C.; Catai, R. E.; Fusse, R. Y.; França, T. V.; Aguiar, P. R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 192-199
ENG
Relevância na Pesquisa
37.4%
The behavior of the minimum quantity lubricant (MQL) technique was analyzed under different lubricating and cooling conditions when grinding ABNT 4340 steel. The comparative analysis of the residual stress values showed that residual compressive stresses were obtained under all the lubrication/cooling conditions and types of abrasive tools employed. The highest residual compressive stress obtained with the aluminum oxide grinding wheel with MQL under the condition of V= 30m/s for air and V= 40ml/h for lubricant was -376MPa against the -160MPa attained with conventional cooling, representing a 135% increase in residual compressive stress. The results show that method and quantity of lubricant and cooling are factors that influence the grinding process.

Sistema de medição de consumo de oleo lubrificante por nivel em motores de combustão interna; Measurement system for lubricant oil consumption by oil pan level in internal combustion engines

Omar Hildinger
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/12/2009 PT
Relevância na Pesquisa
37.12%
medição de consumo de óleo lubrificante em motores de combustão interna tem a característica de ser impreciso e demorado quando se fala no procedimento tradicional de drenar e pesar, ainda muito utilizado pela maioria das empresas de autopeças no desenvolvimento de motores e componentes. Neste trabalho mapeamos os fatores que influenciam na medição e estudamos a possibilidade de mensurar o consumo pelo nível de óleo do motor. Tivemos ótimos resultados quando utilizamos um transdutor de pressão para inferir o nível de óleo no cárter, onde se mediu a altura manométrica que o óleo exerce obtendo boa repetibilidade nos resultados, quando trabalhamos com o amortecimento numérico das medições. O tempo de teste para medição de consumo pôde ser reduzido de 60 para 20 horas de teste com a mesma precisão e, o tempo total dos testes de durabilidade pôde ser reduzido de 6 a 13% em função das paradas para pesagem do óleo que não precisam mais ser realizadas. Com o controle correto dos parâmetros que influenciam a medição, podemos considerar que a complexidade do sistema de medição melhorou em relação ao método de drenar e pesar. Também se diminuiu o manuseio de grandes quantidades de óleo com ganhos em segurança e ergonomia para o operador...

Flowsheet optimization of a lubricant base oil hydrotreatment process

Medeiros,J. L.; Barbosa,L. C.; Vargas,F. M.; Araújo,O. Q. F.; Silva,R. M. F.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2004 EN
Relevância na Pesquisa
37.29%
Unsaturated, nitrogenated and sulfured compounds may reach undesirable levels in lubricant base oils, requiring hydrotreatment (HDT) at high temperatures and pressures. HDT processes are well known for their high capital and operational costs due to the use of hydrogen, compressors and multistage heterogeneous reactors. Process costs are thus highly dependent on the applied conditions. An oversized process entails unnecessary costs and capital investment. On the other hand, mild reaction conditions lead to unspecified products. This work analyzes the process using a compositional modeling and a kinetic framework developed previously (Barbosa et al., 2002) for the HDT of lubricant base oils. The industrial reactor is rigorously modeled on an adiabatic and multistage configuration. For the remaining equipment in the flowsheet, we adopt shortcut models for compressors and exchangers. The process is then optimized in terms of its variables subject to product specification constraints.

Liquid-liquid extraction and adsorption on solid surfaces applied to used lubricant oils recovery

Assunção Filho,J. L.; Moura,L. G. M.; Ramos,A. C. S.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
Relevância na Pesquisa
37.29%
In this work, the recovery of base oils from waste lubricants following the steps of solvent extraction, adsorption on solids and solvent removal by evaporation was evaluated. In the step of solvent extraction, the most efficient was 1-butanol, followed by tert-butanol, 2-propanol and ethanol; for the step of adsorption, activated carbon was the most effective solid for PAH removal, confirming the similarity of these compounds with petroleum aromatic fractions. Thus, the optimum solvent-adsorbent pair for the recovery of used lubricant oils through the proposed methodology was 1-butanol/activated carbon. At the end of the process, it was possible to establish a set of steps that permit the recovery of lubricant base oils with lower content of contaminants.

Evaluation of the biodegradation of different types of lubricant oils in liquid medium

Lopes,Paulo Renato Matos; Bidoia,Ederio Dino
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2009 EN
Relevância na Pesquisa
37.4%
The aim of this work was to study the biodegradation of different types of automotive lubricant oils adapted to the aqueous medium using a base inoculum and an aqueous inoculum. Four treatments were carried out in two consecutive and similar experiments: T1 (control); T2 (half-synthetic oil); T3 (mineral oil); T4 (used oil). The results showed the following decreasing order of CO2 production in the Bartha and Pramer respirometers: T4 > T2 > T3 > T1. Thus, the used lubricant oil showed with highest biodegradability, followed by the half-synthetic one and the mineral oil. It was also observed that the mineral lubricant presented a longer period of adaptation compared to the half-synthetic one.

Biodegradation and toxicological evaluation of lubricant oils

Tamada,Ivo Shodji; Lopes,Paulo Renato Matos; Montagnolli,Renato Nallin; Bidoia,Ederio Dino
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
Relevância na Pesquisa
37.54%
The aim of this work was to compare different toxicity levels of lubricant oils. The tests were performed using the earthworm (Eisenia andrei), arugula seeds (Eruca sativa) and lettuce seeds (Lactuca sativa), with three types of contaminants (mineral lubricant oil, synthetic lubricant oil and used lubricant oil) for various biodegradation periods in the soil. The toxicity tests indirectly measured the biodegradation of the contaminants. The samples were analyzed at t0, t60, t120 and t180 days of biodegradation. The used lubricant oil was proved very toxic in all the tests and even after biodegradation its toxicity was high. The mineral and synthetic oils were biodegraded efficiently in the soil although their toxicity did not disappear completely after 180 days.

Performance profiling of boric acid as lubricant in machining

Damera,Nageswara Rao; Pasam,Vamsi Krishna
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2008 EN
Relevância na Pesquisa
37.12%
Turning is a widely used metal removal process in manufacturing industry that involves generation of high cutting forces and temperature. Lubrication becomes critical to minimize the effects of these forces and temperature on cutting tool and workpiece. The conventional cutting fluids employed in machining have certain limitations with regard to their use for ecological and economic reasons. Development of lubricants that are eco friendly is acquiring importance. In this context, application of solid lubricants has proved to be a feasible alternative to the conventional cutting fluids. In the present work, Boric Acid is used as a lubricant in turning process. Variations in cutting force, tool wear, tool temperature and surface roughness are studied under different machining conditions. The results indicate that there is considerable improvement in the machining performance with Boric Acid assisted machining compared to dry and wet machining.

Viscosity behavior of mixtures of CO2 and lubricant oil

Marcelino Neto,Moisés A; Barbosa, Jr,Jader R
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
Relevância na Pesquisa
37.12%
Experimental data on the viscosity of mixtures of CO2 and lubricant oil were acquired and correlated using an excess-property approach based on the classical Eyring liquid viscosity model. Three oils of different types and viscosity grades (alkylbenzene AB ISO 32, mineral MO ISO 50 and polyol ester POE ISO 68) were evaluated at temperatures ranging from 36.5 to 82ºC. The excess activation energy for viscous flow was successfully correlated as a function of temperature and concentration using Redlich-Kister polynomial expansions with up to three terms. Large departures from the ideal solution viscosity behavior have been identified in all mixtures. The nature of the observed deviations has been explored in the light of their dependence on temperature, refrigerant concentration and oil type. The Katti and Chaudry (1964) model of the activation energy of viscous flow displayed the best correlation of the experimental data, with RMS deviations of 4.6% (AB ISO 32), 3.3% (MO ISO 50) and 2.8% (POE ISO 68).

Frequency, Patterns and Preferences of Lubricant Use During Anal Intercourse Within Male Sexual Partnerships in Lima, Peru: Implications for a Rectal Microbicide HIV Prevention Intervention

Clark, J; Salvatierra, Hector Javier; Segura, Eddy Roberto; Salazar, Ximena; Konda, Kelika; Galea, Jerome; Klausner, Jeffrey D; Coates, Thomas; Caceres, Carlos Fernando
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.7%
Understanding current practices of lubricant use during anal intercourse can help to assess the contexts for the introduction of topical rectal microbicides as an HIV prevention tool for men who have sex with men (MSM). We used quantitative and qualitative methods to assess: current patterns of lubricant use; preferred characteristics of commercial lubricant formulations; and social and behavioral contexts of lubricant use within male sexual partnerships in Lima, Peru. Between 2007 and 2008, we conducted a quantitative behavioral survey with 547 MSM followed by qualitative individual and group interviews with 36 MSM from Lima, Peru. Approximately half of all participants in the quantitative survey (50.3%) reported using commercial lubricant during intercourse occasionally or consistently during the preceding two months, with lack of availability at the time of intercourse the most commonly reported reason for non-use. No clear preferences regarding the color, smell, taste, or viscosity of commercial lubricants were identified, and all participants who reported using a commercial lubricant used the same product (“Love-Lub”). In the qualitative analysis, participants characterized lubricant use as a sexual practice consistently controlled by the receptive partner...

A Comparison Between Graphene and WS2 as Solid Lubricant Additives to Aluminum for Automobile Applications

Rengifo, Sara
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
37.12%
The purpose of this thesis was to compare graphene nanoplatelets (GNP) and WS2 as solid lubricant additives to aluminum in order to reduce friction and wear. The central hypothesis of this work relied on lubricating properties of 2D materials, which consist layers that slip under a shear force. Two aluminum composites were made (Al-2 vol.% GNP and Al-2 vol.% WS2) by spark plasma sintering. Tribological properties were evaluated by ball-on-disk wear tests at room temperature (RT) and 200°C. WS2 not only presented the lowest COF (0.66) but also improved the wear resistance of aluminum by 54% at RT. Al-2 vol.% GNP composite displayed poor densification (91%) and low hardness resulting in poor wear resistance. The wear rate of Al-2 vol.% GNP composite increased by 233% at RT and 48% at 200°C as compared to pure aluminum. GNP addition also resulted in lower COF (0.79) as compared to pure aluminum (0.87).

Evaluation of Lubricant Viscosity and Base Oil Effects by Form Tapping Test

BIERLA, Aleksandra; FROMENTIN, Guillaume; MARTIN, Jean-Michel; LE MOGNE, Thierry; MINFRAY, Clotilde; GENET, Nicole
Fonte: Technische Akademie Esslingen Publicador: Technische Akademie Esslingen
Relevância na Pesquisa
37.48%
In order to correlate the effect of lubricant viscosity and base oil on the efficiency of a lubricant, we measure the variation of tapping torque according to ASTM D5619 standard. Three fully formulated lubricants containing the same additive package but having different viscosities are tested in the first part of the experiment. The effect of chemically active and chemically non-active paraffinic base oils combined with a sulphur additive is studied in the second part. The nature of the tribofilm created at the bottom of the threads formed during the second part of the study is characterized by X-ray Photoelectron Spectroscopy (XPS). The aim is to associate the surface analysis results with the efficiency obtained during the form tapping tests. The results show that the lubricant viscosity does not have any influence on the tapping torque values whereas physico-chemical interactions between different base oils and a sulphur additive can modify importantly the overall efficiency of lubricant.