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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.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21810 |
| Date | 22 July 2016 |
| Creators | Souza, Eraldo C?mara de |
| Contributors | 09621199468, Barbosa, Cleiton Rubens Formiga, 22174443449, Costa, Francine Alves da, 45327220478, Silva, Gilson Garcia da, 56634161453, Sousa, Regina Celia de, 24960187387, Alves J?nior, Clodomiro |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA MEC?NICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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