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Previous issue date: 2010-09-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Metal substrates were coated by thermal spraying plasma torch, they were positioned at a
distance of 4 and 5 cm from the nozzle exit of the plasma jet. The starting materials were used
for deposition of tantalum oxide powder and aluminium. These two materials were mixed and
ground into high-energy mill, then immersed in the torch for the production of alumina
coating infused with particles of tantalum with nano and micrometric size. The spraying
equipment used is a plasma torch arc not transferred, which operating in the range of 250 A
and 80 V, was able to produce enough heat to ignite aluminothermic between Ta2O5 and
aluminum. Upon reaching the plasma jet, the mixing powders react with the heat of the blaze,
which provides sufficient energy for melting aluminum particles. This energy is transferred
through mechanisms of self-propagating to the oxide, beginning a reduction reaction, which
then hits on the surface of the substrate and forms a coating on which a composite is formed
by a junction metal - ceramic (Ta +Al2O3). The phases and quantification of each were
obtained respectively by X-ray diffraction and the Rietveld method. Morphology by scanning
electron microscopy and chemical analysis by energy dispersive spectroscopy EDS. It was
also performed measurements of the substrate roughness, Vickers microhardness
measurements in sprays and determination of the electron temperature of the plasma jet by
optical emission spectroscopy EEO. The results confirmed the expectation generated around
the end product of spraying the mixture Ta2O5 + Al, both in the formation of nano-sized
particles and in their final form. The electron excitation temperature was consistent with the
purpose of work, in addition, the thermodynamic temperature was efficient for the reduction
process of Ta2O5. The electron excitation temperature showed values of 3000, 4500 and 8000
K for flows10, 20 and 30 l / min respectively, these values were taken at the nozzle exit of the
plasma jet. The thermodynamic temperature around 1200 ? C, was effective in the reduction
process of Ta2O5 / Substratos met?licos de a?o inox 416 foram revestidos por aspers?o t?rmica em tocha de
plasma. Eles foram posicionados a uma dist?ncia de 4 e 5 cm em rela??o ao bocal de sa?da do
jato de plasma. Os materiais de partida utilizados para as deposi??es foram p?s de ?xido de
t?ntalo e alum?nio. Esses dois p?s foram misturados e mo?dos em moinho de alta energia, em
seguida, imersos na tocha para produ??o de revestimento de alumina impregnada com
part?culas de t?ntalo com tamanho nano e microm?tricos. O equipamento de aspers?o
utilizado foi uma tocha de plasma de arco n?o transferido que opera na faixa de 250 A e 30 V.
Ao atingirem o jato de plasma, os p?s da mistura aquecem at? a temperatura de igni??o da
rea??o aluminot?rmica. O calor gerado fornece energia suficiente para a fus?o do produto da
rea??o. Esse produto fundido ao chocar-se na superf?cie do substrato forma um revestimento
composto por uma jun??o metal cer?mica (Ta + Al2O3). A identifica??o das fases e sua
quantifica??o foram obtidas respectivamente por difra??o de raios X e pelo m?todo de
Rietveld. Para determina??o da morfologia e composi??o das part?culas foram utilizados
microscopia eletr?nica de varredura e an?lise qu?mica por espectroscopia de energia
dispersiva EDS, respectivamente. Tamb?m foram executadas medidas de rugosidades no
substrato, medi??es de microdureza Vickers nas aspers?es e determina??o da temperatura
eletr?nica do jato de plasma por espectroscopia de emiss?o ?tica EEO. Os resultados
obtidos confirmaram a expectativa gerada em torno do produto final da aspers?o da mistura
Ta2O5 + Al, tanto na forma??o de part?culas nanom?tricas de t?ntalo quanto no formato final
delas. A temperatura de excita??o dos el?trons apresentou valores de 3000, 4500 e 8000 K
para fluxos de 10, 20 e 30 l/min respectivamente, esses valores foram tomados na sa?da do
bocal do jato de plasma. A temperatura termodin?mica, em torno de 1200 ?C mostrou-se
eficiente para o processo de redu??o do Ta2O5
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/12764 |
| Date | 17 September 2010 |
| Creators | Mendes, Marcio Willians Duarte |
| Contributors | CPF:09621199468, http://lattes.cnpq.br/7441669258580942, Costa, Francin? Alves da, CPF:45327220478, http://lattes.cnpq.br/8698567925323942, Lima, Jos? de Anchieta, CPF:36973637434, http://lattes.cnpq.br/0742445504420593, Maciel, Theophilo Moura, CPF:13264850400, http://lattes.cnpq.br/9476858938351846, Gomes, Uilame Umbelino, Alves J?nior, Clodomiro |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Ci?ncia e Engenharia de Materiais, UFRN, BR, Processamento de Materiais a partir do P?; Pol?meros e Comp?sitos; Processamento de Materiais a part |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| 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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