Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-01-27T12:30:35Z No. of bitstreams: 1 EraldoCamaraDeSouza_TESE.pdf: 1960987 bytes, checksum: aaf762025bc316dd0b3bce3590afc7a7 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-01-30T14:17:00Z (GMT) No. of bitstreams: 1 EraldoCamaraDeSouza_TESE.pdf: 1960987 bytes, checksum: aaf762025bc316dd0b3bce3590afc7a7 (MD5) / Made available in DSpace on 2017-01-30T14:17:00Z (GMT). No. of bitstreams: 1 EraldoCamaraDeSouza_TESE.pdf: 1960987 bytes, checksum: aaf762025bc316dd0b3bce3590afc7a7 (MD5) Previous issue date: 2016-07-22 / Neste trabalho foram obtidos comp?sitos alumina - tungst?nio (Al2O3 ? W), a partir da rea??o aluminot?rmica dos p?s de paratungstato de am?nia (APT) e alum?nio, misturados e mo?dos em moinho de alta energia. O p? obtido na moagem foi inserido numa tocha de plasma, impulsionado por um jato de arg?nio, e ao interagir com o plasma, foi aquecido abruptamente at? a temperatura de igni??o do alum?nio, reagindo exot?rmicamente. O produto da rea??o foi depositado sobre um substrato met?lico confeccionado em lat?o. Foram analisadas a influ?ncia da varia??o do fluxo de igni??o/alimenta??o e das dist?ncias tocha - substrato. Alternativamente, foi acoplado ? tocha, um dispositivo de confinamento do jato de plasma para as dimens?es do substrato. Os comp?sitos foram caracterizados quanto ? composi??o, fases e distribui??o de fases. A caracteriza??o das fases foi obtida por difra??o de raios X, a an?lise morfol?gica, atrav?s de microscopia eletr?nica de varredura - MEV e a an?lise qu?mica, atrav?s de espectroscopia de energia dispersiva - EDS. Os comp?sitos obtidos com o fluxo de plasma confinado apresentaram maior percentual de redu??o em rela??o a quantidade de W obtido, principalmente, com o fluxo de alimenta??o/igni??o de 5,0 l/min e 40mm de dist?ncia tocha-substrato. / In this work composite alumina ? tungsten (Al2O3 ? W) was obtained from the aluminothermic reaction of ammonium paratungstate (APT) and aluminum powders, mixed and grounded in high-energy mill. So the powder obtained was inserted in a plasma torch feeder, driven by a flux of argon, and when interacted with the plasma, was abruptly heated to the aluminum ignition temperature, reacts exothermically. The product of this reaction was deposited on a brass substrate. The influence of variation ignition/powder feeding as well as the distance from torch until substrate were analysed. Alternatively a confinement device for the plasma jet was attached in order to adjust the substrate dimensions. Chemical composition, phases and phase distribution of these composite materials were characterized. The X ? ray diffraction was used to analyze the existent phases; the Scanning Electron Microscopy (SEM) was used to perform the morphological aspect of the powder; and finally the Energy Dispersive Spectroscopy (EDS) was used for analyzing the chemical composition. The composites obtained by using confined plasma flux showed greater percentage reduction from the amount of W mainly when the feed/injection flow of 5 l/min and 40 mm of distance away torch-substrate were set up.