Characterization and mechanical properties of hot-pressed tantalum carbide without sintering additives

2^nd International Conference and Expo on Ceramics & Composite Materials

July 25-26, 2016 Berlin, Germany

Vahideh Shahedifar, Firouz Rezaei, Mahdi Ghassemi Kakroudi and Mehdi Golrokhsari

University of Tabriz, Iran

Posters & Accepted Abstracts: J Material Sci Eng

Abstract :

The increasing interest and need for materials used in extremely high temperature applications such as rocket nozzles has inspired research into the behavior of ultra-high temperature ceramics (UHTCs). Tantalum carbide (TaC) is one of these materials which has the operating temperatures excess of 3000�°C. Unfortunately, monolithic TaC is difficulty densified due to its highly covalent bonding character, low self-diffusion coefficient, and high activation energy for viscous flow. In this study, ultrafine starting powder (0.1-0.5 �¼m) and high pressure (40 MPa) were used to improve TaC sintering. Densification was performed by hot pressing at temperatures of 1700�°C to 1900�°C under vacuum with a hold time of 45 min. A lattice parameter of 4.4460 �� was determined for the starting powder by XRD analysis, which corresponds to TaC0.93 calculated based on the relationship between lattice parameter and composition. The relative density increased from 96% at 1700�°C to 97.7% at 1900�°C. The average grain size of the TaC grains increased significantly with sintering temperature. As the temperature enhanced, SEM micrographs of TaC ceramics microstructures revealed extensive transgranular fracture. Moreover, mechanical properties including Youngâ��s modulus, Vickersâ�� hardness, and fracture toughness were studied.

Biography :

Email: va_shahedifar@tabrizu.ac.ir