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Search Results: 1 - 10 of 554608 matches for " E. J. R. Davim "
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Valoriza??o das escórias da celulose do caima por técnicas de vitrifica??o
Ribeiro,A. S. M.; Davim,E. J. R.; Monteiro,R. C.; Fernandes,M. H. V.;
Ciência & Tecnologia dos Materiais , 2007,
Abstract: one of the most serious environmental problems of the developed countries is related with the difficulty in finding alternative treatments for the produced industrial wastes. slag produced by biomass boilers is an example of these industrial wastes and is usually used for road wadding, land corrective mixtures, sludge inertization or landfilling. however, these undesirable wastes can offer interesting valorisation capabilities. the main purpose of this work was to try an alternative way of recycling industrial wastes from a biomass boiler. the slag was produced in a portuguese plant ?celulose do caima?, located in constancia-sul, and producing about 70 tons of slag per month. vitrification of the slag was the tested procedure as suggested by its chemical and mineralogical composition. physical, chemical, mineralogical and thermal characterisation of the slag indicated a high proportion of sio2 (>81%) and a particle size distribution in the range 0,06-53 mm. in order to produce a melt of suitable viscosity for casting and aiming to favour vitrification, na2o was used as fluxing agent, which was provided by soda solvay. the mixture was heated at 1450 oc and gave rise to a castable melt and a homogeneous green coloured glass on cooling. characterisation of the obtained glass by differential thermal analysis and dilatometry showed thermal properties similar to the ones of other glasses obtained from waste vitrification. the results also indicated that these glasses are capable of being further heat treated to obtain structural materials to be used in building applications, such as floor and wall cladding panels.
Valoriza o das escórias da celulose do caima por técnicas de vitrifica o
A. S. M. Ribeiro,E. J. R. Davim,R. C. Monteiro,M. H. V. Fernandes
Ciência & Tecnologia dos Materiais , 2007,
Abstract: Um dos mais graves problemas ambientais com que se debatem actualmente os países civilizados está relacionado com a dificuldade de encontrar o destino certo para os resíduos industriais. Um exemplo destes resíduos s o as escórias produzidas pelas caldeiras de biomassa, as quais s o habitualmente reutilizadas em misturas com lamas para correctivo de solos, no enchimento de estradas, na inertiza o de lamas de etares ou s o simplesmente depositadas em aterros. S o estes resíduos, sem utiliza o ou indesejáveis pelo seu detentor, que podem apresentar potencialidades para valoriza o. O objectivo deste trabalho foi testar uma forma de valorizar este tipo de resíduos. Foram utilizadas escórias provenientes do leito da caldeira de biomassa da Celulose do Caima, indústria produtora de papel situada em Constancia-Sul que origina cerca de 70 toneladas de escórias por mês. A vitrifica o destas escórias foi o processo testado, tendo em conta a sua composi o química e mineralógica. As escórias foram caracterizadas física, química, mineralógica e termicamente, sendo notório o seu elevado teor em SiO2 (> 81%) e o reduzido tamanho médio de partículas (entre 0,06 e 53 mm). Para favorecer a forma o de um fundido com viscosidade adequada ao vazamento utilizou-se Na2O, como agente fundente, proveniente da soda Solvay. A mistura fundida a 1450 oC deu origem a um vidro de cor verde, homogéneo e trabalhável. Os resultados da caracteriza o deste vidro por Análise Térmica Diferencial e por Análise Dilatométrica sugeriram que o material obtido tem propriedades térmicas idênticas à de outros materiais obtidos por vitrifica o de resíduos e tem potencialidades para ser submetido a tratamentos térmicos posteriores que conduzam à obten o de materiais estruturais com aplica o na constru o civil tais como revestimento e pavimento. One of the most serious environmental problems of the developed countries is related with the difficulty in finding alternative treatments for the produced industrial wastes. Slag produced by biomass boilers is an example of these industrial wastes and is usually used for road wadding, land corrective mixtures, sludge inertization or landfilling. However, these undesirable wastes can offer interesting valorisation capabilities. The main purpose of this work was to try an alternative way of recycling industrial wastes from a biomass boiler. The slag was produced in a Portuguese plant “Celulose do Caima”, located in Constancia-Sul, and producing about 70 tons of slag per month. Vitrification of the slag was the tested procedure as suggested by its chem
Fura??o com alta velocidade de corte em compósitos poliméricos refor?ados com fibras de vidro
Rubio,Juan C. Campos; Silva,Leonardo R; Abr?o,Alexandre M.; Faria,Paulo E.; Correia,A. Esteves; Davim,J. Paulo;
Ciência & Tecnologia dos Materiais , 2007,
Abstract: high speed machining is an outstanding technology which allows increasing competitiveness with regard to both the quality of the machined component and machining costs. this work is concerned with high speed drilling of fiber reinforced polymeric composites. in spite of the advantages offered by this category of materials generally associated to their specific strength, fiber reinforced composites are considered difficult to machine materials owing to the accelerated tool wear rates resulting from abrasion, in addition to the fact that the fibers anisotropy affects chip formation. therefore, the knowledge related to the machinability of metallic alloys cannot be directly applied to polymeric composite.
Análise digital de dano na fura??o de materiais compósitos laminados
Rubio,Juan C. Campos; Abr?o,Alexandre M.; Faria,Paulo E.; Davim,J. Paulo;
Ciência & Tecnologia dos Materiais , 2007,
Abstract: fibre reinforced composites are widely recognized for their superior mechanical properties and advantages for applications in aerospace, defense and transportation sectors. in spite of the fact that, in general, composites are produced to near-net-shape, additional machining operations such as drilling are often required. nevertheless, the cutting tool action during machining may damage the work material surfaces. delamination is the principal damage observed after drilling composite materials. the delamination factor has been used by several investigators to characterize the level damage the drill entrance and exit side of the machined composite material. more frequently, this factor is determined as the ratio of the maximum diameter in the damage zone to the nominal diameter. the aim of this work is to propose a methodology based on digital analysis of the damage in order to assess delamination.
Análise digital de dano na fura o de materiais compósitos laminados
Juan C. Campos Rubio,Alexandre M. Abr?o,Paulo E. Faria,J. Paulo Davim
Ciência & Tecnologia dos Materiais , 2007,
Abstract: Compósitos refor ados com fibras apresentam diversas propriedades que permitem sua utiliza o em aplica es estruturais, particularmente nas indústrias automotiva e aeroespacial, entre outras. Embora sejam fabricados com dimens es e forma próximas das finais, opera es como as de fura o s o freqüentemente necessárias com o objetivo de criar pontos de fixa o. Estas opera es de usinagem provocam danos tanto na entrada como na saída do furo, sendo a delamina o o mais característico destes danos. Diversos autores têm utilizado o fator de delamina o como parametro para carateriza o do nível de dano induzido na fura o de compósitos, no entanto, na maioria dos casos este fator considera a rela o entre o diametro máximo do dano e o diametro nominal do furo. Este trabalho apresenta uma metodologia da análise de imagens digitais para determina o do fator de delamina o e prop e um novo parametro que permita uma melhor caracteriza o do dano ocorrido. Fibre reinforced composites are widely recognized for their superior mechanical properties and advantages for applications in aerospace, defense and transportation sectors. In spite of the fact that, in general, composites are produced to near-net-shape, additional machining operations such as drilling are often required. Nevertheless, the cutting tool action during machining may damage the work material surfaces. Delamination is the principal damage observed after drilling composite materials. The delamination factor has been used by several investigators to characterize the level damage the drill entrance and exit side of the machined composite material. More frequently, this factor is determined as the ratio of the maximum diameter in the damage zone to the nominal diameter. The aim of this work is to propose a methodology based on digital analysis of the damage in order to assess delamination.
Effect of Filler Materials on Dry Sliding Wear Behavior of Polymer Matrix Composites – A Taguchi Approach  [PDF]
S. Basavarajappa, K.V. Arun, J. Paulo Davim
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2009, DOI: 10.4236/jmmce.2009.85034
Abstract: The tribological behaviour of glass epoxy polymer composites with SiC and Graphite particles as secondary fillers was studied using a pin-on-disc wear rig under dry sliding conditions. The influence of wear parameters like, applied load, sliding speed, sliding distance and percentage of secondary fillers, on the wear rate were investigated. A plan of experiments, based on the techniques of Taguchi, was performed to acquire data in a controlled way. An orthogonal array and analysis of variance (ANOVA) were employed to investigate the influence of process parameters on the wear of these composites. The results showed that the inclusion of SiC and Graphite as filler materials in glass epoxy composites will increase the wear resistance of the composite greatly.
Influência da lubrifica??o na maquinabilidade do compósito Tungsténio/Cobre sinterizado (WCu25)
Faustino,M; Davim,J. Paulo;
Ingeniare. Revista chilena de ingeniería , 2012, DOI: 10.4067/S0718-33052012000100011
Abstract: the sintering tungsten/copper composite (wcu25) is a material used in electrodes for electric discharge machining (edm). the current work has as objective study the influence of the lubrication in machinability of sintering tungsten/copper composite (wcu25) using polycrystalline diamond tools (pcd). the present article shows that the lubrication use is fundamental to improve the machinability of the material considering the machining power and force, the workpiece surface finish and tool wear.
Influência da lubrifica o na maquinabilidade do compósito Tungsténio/Cobre sinterizado (WCu25) Influence of lubrication on machinability of sintering Tungsten/Copper composite (WCu25)
M Faustino,J. Paulo Davim
Ingeniare : Revista Chilena de Ingeniería , 2012,
Abstract: O compósito Tungsténio/Cobre sinterizado (WCu25) é um material utilizado em electrodos para electroreros o (EDM). O presente trabalho tem como objectivo estudo da influência da lubrifica o na maquinabilidade do compósito Tungsténio/Cobre sinterizado (WCu25) utilizando ferramentas de diamante policristalino (PCD). O presente artigo mostra que a utiliza o lubrifica o é fundamental para melhorar a maquinabilidade do material considerando a for a e potência de maquinagem, o acabamento de superfície obtido na pe a e o desgaste da ferramenta. The sintering Tungsten/Copper composite (WCu25) is a material used in electrodes for electric discharge machining (EDM). The current work has as objective study the influence of the lubrication in machinability of sintering Tungsten/Copper composite (WCu25) using polycrystalline diamond tools (PCD). The present article shows that the lubrication use is fundamental to improve the machinability of the material considering the machining power and force, the workpiece surface finish and tool wear.
Influence of Coolant in Machinability of Titanium Alloy (Ti-6Al-4V)  [PDF]
Muthukrishnan Namb, Davim Paulo
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2011, DOI: 10.4236/jsemat.2011.11002
Abstract: Application of titanium alloy has increased many fields since the past 50 years. The major drawback encountered during machining was difficult to cut and the formation of BUE (Built up Edge). This paper presents the tool wear study of TTI 15 ceramic insert (80% Aluminum oxide and 20 % Titanium carbide) on machining Ti-6Al-4V at moderate speed with and without the application of water soluble servo cut S coolant. Titanium alloy is highly refractory metal and machining titanium is challenging to the manufacturers. Experiments were carried out on medium duty lathe. Application of coolant tends to reduce toolwear and minimize adhesion of the work material on the cutting tool during machining and also improves the surface finish. Result provides some useful information.
Generalized Löb’s Theorem. Strong Reflection Principles and Large Cardinal Axioms  [PDF]
J. Foukzon, E. R. Men’kova
Advances in Pure Mathematics (APM) , 2013, DOI: 10.4236/apm.2013.33053
Abstract: In this article, a possible generalization of the Lob’s theorem is considered. Main result is: let κ be an inaccessible cardinal, then \"\"
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