Obtenção de fitas de scheelita (CaWO4) via tape casting em base aquosa
Scheelite, also known as calcium tungstate (CaWO4), is a mineral from the Wolframites group that holds significant economic importance due to its contribution to one of the largest quantities of tungsten production. In Brazil, the main extractiform scheelite deposits are located in the state of R...
Na minha lista:
| Autor principal: | |
|---|---|
| Outros Autores: | |
| Formato: | Dissertação |
| Idioma: | pt_BR |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
|
| Assuntos: | |
| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/55556 |
| Tags: |
Adicionar Tag
Sem tags, seja o primeiro a adicionar uma tag!
|
| Resumo: | Scheelite, also known as calcium tungstate (CaWO4), is a mineral from the
Wolframites group that holds significant economic importance due to its contribution to
one of the largest quantities of tungsten production. In Brazil, the main extractiform
scheelite deposits are located in the state of Rio Grande do Norte (RN), in the Seridó
region, constituting the country's largest concentration of tungsten. However, the
exploitation of this mineral has caused various negative environmental impacts in the
mined areas, making it essential to develop technologies to mitigate the damages caused
by the extraction and processing of this abundant resource in the state. Thin and solid
films made with tungsten compounds exhibit great potential for dielectric, electronic, and
optoelectronic applications, and can be produced through different methods. Tape casting
is one of the simplest and well-established methods for film and tape manufacturing,
being safe and non-toxic when carried out using an aqueous base. With this in mind, the
objective of this study was to produce Scheelite tapes and analyze their properties. Five
tapes were produced, gradually reducing the content of Scheelite residue (SR) from
100%, 75%, 50%, and 25% until complete substitution with concentrated Scheelite (SC).
Physical-chemical characterization of the powders was conducted through fluorescence
and X-ray diffraction tests, in addition to evaluating the rheology of the produced
suspensions. The green tapes were characterized through Scanning Electron Microscopy
(SEM), Energy Dispersive Spectroscopy (EDS), Thermogravimetric Analysis (TGA),
and dielectric measurements, aiming to assess the morphology, surface composition,
thermal behavior, and dielectric properties of the tapes. X-ray diffraction identified the
presence of scheelite, calcite, and quartz phases. The produced suspension exhibited
pseudoplastic rheological behavior, ideal for tape casting. The produced tapes showed
dielectric constants ranging from 7 to 3.4, average, in high-frequency ranges (0.1 to 1.5
GHz). Thus, a great potential is evidenced for tapes produced from the mixture of
scheelite waste powder and concentrated scheelite in dielectric applications. |
|---|