Incorporação de Nitreto de Boro e Carbeto de Nióbio na matriz cerâmica de Alumina
Obtaining new advanced and structural ceramics using high purity and ultra-fine powders combined with shorter sintering time and temperature is being privileged. This faster process with lower temperatures can be used as a new way to produce ceramic cutting tools, usually produced with aluminum o...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/48341 |
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| Resumo: | Obtaining new advanced and structural ceramics using high purity and ultra-fine
powders combined with shorter sintering time and temperature is being privileged. This
faster process with lower temperatures can be used as a new way to produce ceramic
cutting tools, usually produced with aluminum oxide (Al2O3) as the only material, or
with the addition of metal carbides in its matrix to improve its properties, such as:
Niobium carbide (NbC), Silicon carbide (SiC) and tungsten carbide (WC). Another
material that has been used in the machining industry is Boron nitride (hBN), as it has a
high melting point (2527°C) which is a very important parameter for the material used
at the tip of the cutting tool. Aiming at new forms of cutting tool production, the Tape
Casting technique was used for manufacturing, thus being able to obtain complex
geometries and desired thicknesses. The present work has as general objective to study
how properties and mechanics of ceramic composites of alumina incorporated with
Boron Nitride and Niobium Carbide. The work was carried out with two different types
of, a group was built from SPS (Spark Plasma Sintering), this being the composite of
Al2O3 + 30% wt of NbC, sintered at 1350°C, 1400°C and 1450 °C; the other group was
included via Tape Casting, where h-BN (3%, 5% and 10 %) was incorporated into the
ceramic alumina matrix. As green ribbon, laminates were awarded, these were mainly
calcined at 500 °C with a heating rate of 1 °C / min and subsequently sintered at 1500,
1550 and 1600 °C. The results obtained, for the samples produced by SPS, showed to
be promising, presenting good mechanical properties such as, for example, hardness of
18.56 GPa, using lower temperature and sintering time. The results of samples obtained
via Tape Casting demonstrated that hBN does not significantly contribute to
improvements in the mechanical properties of nanocomposites. |
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