Aluminum nitride, AlN, and titanium diborite,TiB2, are covalent-based ceramics with wide technological applications. However, sintering of these ceramics using conventional methods of high pressure requires not only elevated temperatures but also long processing time. This causes excessive grain growth, which impairs strength and hardness. In the present work, 70%AlN-30%TiB2 ceramic composites were sintered to relatively higher density and hardness by means of the Spark Plasma Sintering (SPS) at temperatures in the interval from 1500 to 1900°C in order to improve the properties of both compounds and decrease the processing time. The SPS was applied for different sintering temperatures and the effects on density, hardness and surface structure were evaluated. Maximum values obtained for density and hardness were 98.8% of the theoretical value and 13.7 GPa, respectively.
A brief review of the characteristics and properties of cubic boron nitride (cBN) is presented, including different processing methods. The influence of bonding substances, as well as other ceramic composites, is also discussed. Finally, it is highlighted the great practical importance of the cBN as a ceramic with elevated hardness in substitution for the diamond in cutting tools.
Resumo Compósitos cerâmicos de TiB2-AlN foram preparados por técnica de "spark plasma sintering". A densidade máxima relativa e resistência foram de 96,9% e 16,2 GPa, respectivamente. As amostras foram submetidas a testes de usinagem de curto tempo. Os compósitos com 70% de AlN foram utilizados como ferramenta de corte e apresentaram resultados satisfatórios para os parâmetros de corte. Análises de Microscopia Eletrônica de Varredura (MEV) permitiram a análise da microestrutura e o desgaste da superfícies após os testes de corte.
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