Incorporação de Nitreto de Boro e Carbeto de Nióbio na matriz cerâmica de Alumina

Abstract

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.