• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An?lise dos par?metros de s?ntese de NbN via rea??o g?s-s?lido / Analysis of the synthesis parameters of NbN via gas-solid reaction

Silva, Rayane Ricardo da 02 March 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-09-04T20:41:25Z No. of bitstreams: 1 RayaneRicardoDaSilva_DISSERT.pdf: 3651048 bytes, checksum: 6930b6cb5290f28628f512cd882c69ad (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-09-06T20:43:02Z (GMT) No. of bitstreams: 1 RayaneRicardoDaSilva_DISSERT.pdf: 3651048 bytes, checksum: 6930b6cb5290f28628f512cd882c69ad (MD5) / Made available in DSpace on 2017-09-06T20:43:03Z (GMT). No. of bitstreams: 1 RayaneRicardoDaSilva_DISSERT.pdf: 3651048 bytes, checksum: 6930b6cb5290f28628f512cd882c69ad (MD5) Previous issue date: 2017-03-02 / Este trabalho tem como objetivo a s?ntese do Nitreto de Ni?bio, a partir do precursor tris (oxalato) oxiniobato de am?nio hidratado, atrav?s de rea??o g?s-s?lido em reator de leito fixo. Os par?metros reacionais para o tratamento t?rmico para obter o NbN foram com as temperaturas de 700, 800, 900, 1000 e 1100 ?C variando o tempo na isoterma entre 3, 4 e 5 horas. A mistura gasosa ? composta de nitrog?nio e hidrog?nio. A composi??o e a vaz?o total do fluxo de gases foram variadas, como tamb?m a massa do precursor utilizado na rea??o. Os materiais obtidos foram caracterizados atrav?s de difra??o de raios-X (DRX), Refinamento Rietveld e Microscopia Eletr?nica de Varredura (MEV). Com o aumento da temperatura de rea??o e tempo na isoterma observamos a mudan?a de fase de ?xido de ni?bio para nitreto de ni?bio. Houve a forma??o de duas fases de nitreto, estando a fase hexagonal presente em maior quantidade, e a tetragonal em menor quantidade. Com a maior vaz?o, foi obtido o nitreto de ni?bio com alto teor de pureza. / The aim of this work is to study the synthesis of Niobium Nitride, starting from the precursor tris (oxalate) oxiniobate ammonium hydrate, through the gas-solid reaction in a fixed-bed reactor. The heat treatment reaction parameters to obtain the NbN were at temperatures 700, 800, 900 and 1000?C varying the time in the isotherm between 3, 4 and 5 hours. The gas mixture is composed of nitrogen and hydrogen. The composition and the total flow of the gas flow were varied, as well as the mass of the precursor used in the reaction. The obtained materials were characterized by X-ray diffraction (XRD), Rietveld Refinement and Scanning Electron Microscopy (SEM). Increasing the reaction temperature and time in the isotherm it was observed the phase change of niobium oxide to niobium nitride. There was formation of two phases of nitride, and the hexagonal phase is present in greater quantity, and the tetragonal phase in less quantity. With the higher flow rate, the high purity niobium nitride was obtained.

Page generated in 0.0925 seconds