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Sumulation of Plasma Torche Simulación de antorcha de plasma
Javier García de la Figal,Abel Fumero Pérez,René Collazo Carceller,Clodomiro Alves Junior
Revista Cubana de Ingeniería , 2010, DOI: 10.1234/rci.v1i3.26
Abstract: The work is a study about main work features and properties of plasma of argon for designing and building plasma torches, to be employed in the projection of fine particles. The plasma properties in feature of their temperature and pressure are determinate and their behaviors inside the main element of the torche: the nozzle, is simulated. The influence of nozzles characteristics in the obtained plasma is determined, from finite elements models developed, being ended up defining the best nozzle parameters to be designed and built. Se realiza un estudio de las principales características de trabajo y propiedades del plasma de argón para el posterior dise o y construcción de una antorcha de plasma y su empleo en la proyección de partículas finas. Se determinan las propiedades del plasma en función de su temperatura y presión, simulando su comportamiento dentro del principal elemento de la antorcha: la boquilla. A partir de los modelos de elementos finitos desarrollados se determinan las influencias de las características de la boquilla en el plasma obtenido, llegándose a definir los mejores parámetros de la boquilla y de la antorcha a ser dise ada y construida.
Estudio preliminar acerca de recubrimientos de hidroxiapatita HAP-200 obtenidos por plasma atmosférico A preliminary study about HAP-200 hydroxyapatite coatings obtained by atmospheric plasma
Abel Fumero Pérez,Héctor López Salinas,Leonardo Goyos Pérez,Clodomiro Alves Junior
Revista Cubana de Investigaciones Biom??dicas , 2011,
Abstract: La hidroxiapatita es catalogada como un material bioactivo cuya capacidad de interacción con el hueso ha permitido su uso de forma satisfactoria para aplicaciones ortopédicas y dentales. En el presente trabajo la hidroxiapatita producida por el Centro Nacional de Investigaciones Científicas fue proyectada mediante una antorcha de plasma atmosférico sobre un sustrato de acero inoxidable austenítico. El tama o de partículas fue determinado por dispersión láser y la distancia de proyección fue variada entre 20 y 60 mm. La microestructura y composición de fase del polvo, así como la del recubrimiento obtenido fueron examinados por microscopia óptica, microscopia electrónica de barrido y difracción de rayos X (DRX). La composición química puntual del recubrimiento fue analizada por espectrometría de dispersión de energía (EDS), también fueron medidos la dureza, el espesor de capa y la cristalinidad. Los resultados indican que la cristalinidad disminuye con el incremento de la distancia de proyección, no así su dureza y espesor de capa. Hydroxyapatite is classified as a bioactive material whose ability of interaction with bone allowed its use in a satisfactory way for orthopedic and dental application. In present paper the hydroxyapatite produced by the National Center of Scientific Researches, was projected by means of an atmospheric plasma torch on an austenitic stainless steel substrate. The particles' size was determined by laser dispersion and the projection distance fluctuates between 20 and 60 mm. The microstructure and the powder phase composition, as well as the coating achieved were examined by optical microscopy, scanning electron microscopy and X-rays diffraction (XRD). The coating's point chemical composition was analyzed by energy-dispersion spectrometry (EDS) and the hardness, layer thickness and crystallization were measured. Results showed that crystallization decreases according to the increase of projection distance, but not its hardness and layer thickness.
Estudio preliminar acerca de recubrimientos de hidroxiapatita HAP-200 obtenidos por plasma atmosférico
Fumero Pérez,Abel; López Salinas,Héctor; Goyos Pérez,Leonardo; Alves Junior,Clodomiro; Lariot Sánchez,Carlos;
Revista Cubana de Investigaciones Biom??dicas , 2011,
Abstract: hydroxyapatite is classified as a bioactive material whose ability of interaction with bone allowed its use in a satisfactory way for orthopedic and dental application. in present paper the hydroxyapatite produced by the national center of scientific researches, was projected by means of an atmospheric plasma torch on an austenitic stainless steel substrate. the particles' size was determined by laser dispersion and the projection distance fluctuates between 20 and 60 mm. the microstructure and the powder phase composition, as well as the coating achieved were examined by optical microscopy, scanning electron microscopy and x-rays diffraction (xrd). the coating's point chemical composition was analyzed by energy-dispersion spectrometry (eds) and the hardness, layer thickness and crystallization were measured. results showed that crystallization decreases according to the increase of projection distance, but not its hardness and layer thickness.
A comparative study of mechanical and tribological properties of AISI-304 and AISI-316 submitted to glow discharge nitriding
Nascimento, Fabiana Cristina;Foerster, Carlos Eugênio;Silva, Silvio Luiz Rutz da;Lepienski, Carlos Mauricio;Siqueira, Carlos José de Mesquita;Alves Junior, Clodomiro;
Materials Research , 2009, DOI: 10.1590/S1516-14392009000200011
Abstract: mechanical and tribological properties os aisi 304 and aisi 316 stainless steels submited to glow discharge ion nitriding are reported.the atmosphere was 20:80 - n2:h2 with substrate temperatures ranging from 300 to 500 °c. treatment at 300 °c produced expanded austenite (γn) in both steels. increasing the temperature, the phases γ′-fe4n and - fe2+xn were present and the latter is the major phase for aisi 304. at 500 °c, the crn phase was also identified in both steels. hardnesses of about 13-14 gpa at near surface regions were obtained in both steels. moreover, aisi 316 nitrided at 500 °c has the deepest hard layer. tribological tests showed that wear can be reduced by up to a factor of six after the nitriding processes, even for a working temperature of 300 °c. the profiles during and after nanoscratch tests did not reveal significant differences after nitriding processes in both steels.
Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4
Sousa, R?mulo Ribeiro Magalh?es de;Araújo, Francisco Odolberto de;Costa, José Alzamir Pereira da;Oliveira, Antonio Maia de;Melo, Mineia Sampaio;Alves Junior, Clodomiro;
Materials Research , 2012, DOI: 10.1590/S1516-14392012005000016
Abstract: aisi 409 ferritic stainless steel samples were nitrided using the cathodic cage plasma nitriding technique (ccpn), with the addition of methane to reduce chromium precipitation, increase hardness and wear resistance and reduce the presence of nitrides when compared to plasma carbonitriding. microhardness profiles and x-ray analysis confirm the formation of a very hard layer containing mainly ε-fe3n and expanded ferrite phases.
Human work in the interface of the liberal and social states and the reflections of its valorization in the 1988 Constitution O trabalho humano na interface dos estados liberal e social e o desdobramento de sua valoriza o na Constitui o de 1988
Clodomiro José Bannwart Junior,Sharon Cristine Ferreira de Souza
Scientia Iuris , 2009,
Abstract: This work focuses on the conception of work from the Critical Social Theory by Jürgen Habermas, highlighting its importance in the process of self-constitution of the human societies. In the general level of analysis, this study observes the effects of the modern State, emphasizing the configuration of the Liberal and Interventionist States. Regarding the latter, mainly after the liberalism crisis in the first half of the last century, this work seeks to highlight the role of the State intervention in the economic domain, directing the discussion to the ambit of the Brazilian Constitutions, particularly the 1988 Constitution, Art. 170, in the light of the valorization of the human work. Ressalta-se a concep o de trabalho a partir da Teoria Social Crítica de Jürgen Habermas, destacando a importancia do mesmo no processo de autoconstitui o das sociedades humanas. Ainda no plano geral da análise, acompanha-se o desdobramento do Estado moderno, enfatizando a configura o dos Estados Liberal e Intervencionista. Nesse último, sobretudo, após a crise do liberalismo na primeira metade do século passado, busca-se real ar o papel de interven o do Estado no domínio econ mico, trazendo a discuss o para o ambito das Constitui es brasileiras, com destaque especial à Constitui o de 1988, no seu Art. 170, à luz da valoriza o do trabalho humano.
Teoria de sinteriza??o por fase sólida; uma análise crítica de sua aplica??o
Silva, Angelus Giuseppe Pereira da;Alves Júnior, Clodomiro;
Ceramica , 1998, DOI: 10.1590/S0366-69131998000500004
Abstract: solid phase sintering is a very complex phenomenon. theories describing sintering are unsatisfactory. furthermore, their practical use leads to a series misunderstandings with consequent misleading conclusions. this work presents the structure of the traditional theory of single phase solid state sintering, makes an analysis of its limits and criticizes its use, proposing a way of approaching the sintering process
A sinteriza??o rápida: sua aplica??o, análise e rela??o com as técnicas inovadoras de sinteriza??o
Silva, Angelus Giuseppe Pereira da;Alves Júnior, Clodomiro;
Ceramica , 1998, DOI: 10.1590/S0366-69131998000600004
Abstract: recently some innovative sintering techniques have been reported. they are able to densify structures in rather short times. moreover it is known that samples heated up fastly present high sintering rates. this paper presents these innovative sintering techniques as well as reviews the rapid sintering process. the main topics are: results of rapid sintering, rapid sintering mechanisms in solid and liquid phases, and its applicability. it is concluded that the attractive results of the innovative sintering techniques are just consequence of the fast heating which is their characteristic. in other words, these techniques are only a way to obtain fast sintering.
Teoria de sinteriza o por fase sólida; uma análise crítica de sua aplica o
Silva Angelus Giuseppe Pereira da,Alves Júnior Clodomiro
Ceramica , 1998,
Abstract: A sinteriza o por fase sólida é um processo muito complexo. A teoria que trata o fen meno n o oferece respostas satisfatórias e, além disso, sua aplica o contém uma série de enganos que levam a conclus es equivocadas. Este trabalho apresenta a estrutura da teoria tradicional de sinteriza o por fase sólida, comenta seus limites, critica seu uso e prop e uma forma de investigar e interpretar este processo de sinteriza o.
A sinteriza o rápida: sua aplica o, análise e rela o com as técnicas inovadoras de sinteriza o
Silva Angelus Giuseppe Pereira da,Alves Júnior Clodomiro
Ceramica , 1998,
Abstract: Algumas técnicas consideradas inovadoras de sinteriza o s o capazes de sinterizar estruturas em curtíssimos intervalos de tempo. Por outro lado, é sabido que, quando se emprega altas taxas de aquecimento, obtém-se igualmente altas taxas de sinteriza o. Tem-se a sinteriza o rápida. Este artigo introduz estas técnicas inovadoras de sinteriza o, assim como faz uma revis o sobre a sinteriza o rápida, abordando alguns resultados, mecanismos de sinteriza o rápida em fases líquida e sólida e discute sobre sua aplicabilidade como forma de sinteriza o e conclui que os resultados produzidos pelas técnicas inovadoras abordadas s o apenas o resultado da sinteriza o rápida, provocada pelo rápido aquecimento associado a estas técnicas.
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