Made available in DSpace on 2014-12-17T14:58:04Z (GMT). No. of bitstreams: 1
EraldoCS_DISSERT.pdf: 3770041 bytes, checksum: 781cd8af5bcf3a0660e0344b0a08f87a (MD5)
Previous issue date: 2010-10-14 / The nanometric powders have special features that usually result in new properties,
originating applications or expanding them in various fields of knowledge. Because having a
high area/volume ratio, phenomena such as superficial strength of adsorption becomes greater
than the weight of the powder which makes more difficult its handling. The high power of
agglomeration of these powders requires study and development of equipments to enable its
management into the plasma torch. The objective of this work is to develop a powder feeder
which can solve the mainly problems about insertion of powder into the thermal spray
developed in the laboratory of plasmas, which are carried out with plasma torch arc not
transferred (plasma spray). Therefore, it was made a aluminum s powder feeder and tests
were performed to verify their operation and determine its rate of deposition by spraying
powders of niobium pentoxide (Nb2O5) and titanium dioxide (TiO2) with particle sizes less
than 250 mesh (<0.063 mm). We used masses of 0.5 g - 1.0 g and 1.5 g of each powder in
tests lasting 15 seconds - 20 to 25 seconds for each mass. The tests were performed in two
ways: at atmospheric pressure using argon gas with a flow of 9 l / min as carrier gas and
through a Venturi pipe also using argon gas with a flow of 9 l / min as carrier gas and with a
flow of 20 l/min as the feed gas passing through the Venturi pipe. The powder feeder
developed in this paper is very easy to be handling and building, resulting in feeding rate of
0.25 cm3/min - 1.37 cm3/min. The TiO2 showed higher feeding rates than the Nb2O5 in all
tests, and the best rates were obtained with tests using mass 1.5 g and time of 15 seconds,
reaching feeding rate of 1.37 cm3/min. The flow of feed had low interference in feeding rate
during the tests / Os p?s nanom?tricos apresentam caracter?sticas especiais que geralmente resultam em
novas propriedades, ampliando ou originando melhores aplica??es nas diversas ?reas de
conhecimento. Devido ao fato de possuir uma alta raz?o ?rea/volume, fen?menos como a
for?a de adsor??o de superf?cie tornam-se superiores ao peso, dificultando o seu manuseio. O
alto poder de aglomera??o dificulta processos como o de alimenta??o de p?s em tochas de
plasma, por exemplo. O objetivo do presente trabalho ? desenvolver um alimentador de p?s,
para trabalhos com aspers?o t?rmica, que s?o realizados em tocha de plasma de arco n?o
transferido (plasma spray). Para tanto, foi confeccionado um dispositivo em alum?nio, sendo
realizados testes para verificar seu funcionamento e determinar sua taxa de alimenta??o
durante aspers?o de p?s de pent?xido de ni?bio (Nb2O5) e di?xido de tit?nio (TiO2), com
tamanhos de part?culas inferiores a mesh 250 (< 0,063 mm). Foram utilizadas massas de 0,5 g
- 1,0 g e 1,5g de cada p?, em testes com dura??o de 15 s - 20 s e 25 segundos para cada
massa. Os ensaios foram realizados de duas maneiras: ? press?o atmosf?rica utilizando-se g?s
arg?nio com fluxo de 9 l/min como g?s de arraste e atrav?s de um tubo de Venturi utilizando
tamb?m o g?s arg?nio com fluxo de 9 l/min como g?s de arraste e com fluxo de 20 l/min
como g?s de alimenta??o, passando pelo interior do tubo de Venturi. O alimentador de p?
desenvolvido neste trabalho ? de f?cil constru??o e manuseio, obtendo-se taxas de
alimenta??o de 0,25 cm3/min - 1,37 cm3/min. O TiO2 apresentou maiores taxas de alimenta??o
que o Nb2O5 em todos os testes, e as melhores taxas foram obtidas com os ensaios utilizando
massa de 1,5 g e tempo de 15 segundos, atingindo taxa de alimenta??o de 1,37 cm3/min. O
fluxo de alimenta??o apresentou pouca interfer?ncia na taxa de alimenta??o durante a
realiza??o dos testes
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15629 |
| Date | 14 October 2010 |
| Creators | Souza, Eraldo C?mara de |
| Contributors | CPF:09621199468, http://lattes.cnpq.br/7441669258580942, Fontes, Francisco de Assis Oliveira, CPF:20300190468, http://lattes.cnpq.br/9043538628554844, Louren?o, Jorge Magner, CPF:65515404491, http://lattes.cnpq.br/0636102944565252, Alves J?nior, Clodomiro |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Engenharia Mec?nica, UFRN, BR, Tecnologia de Materiais; Projetos Mec?nicos; Termoci?ncias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| 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 |
Page generated in 0.0022 seconds