Reactive spark plasma sintering of ZrB2-TiC composites: Role of nano-sized carbon black additive

Abstract

ZrB2-TiC composites with and without nano-sized carbon black as the sintering additive were densified through spark plasma sintering at 1900 °C for 7 minutes under the applied pressure of 40 MPa. The role of carbon black in densification behavior, phase arrangement, microstructural characteristics and mechanical properties of the sintered composites were then investigated. While both of the composite samples were found to be fully sintered, the thermodynamic of the reactive sintering was also studied. Results indicated that whereas the reactive sintering process leads to complete consumption of TiC through the formation of the solid solution as the matrix in both of the composite samples, the presence of carbon black at the initial composition of the samples can result in remained carbon at the final microstructure. Besides the in-situ synthesized zirconium carbide as the major reinforcement phase, such a remained carbon can lead to significantly different mechanical behavior of the composites. Accordingly, the hardness of 21.8 and 24.3 GPa and the indentation fracture toughness of 3.3 and 4.5 MPa.m0.5 were obtained for carbon-black free and doped samples, respectively. The densification, hardening, and toughening mechanisms in both of the composite samples were finally discussed.

A TEM study of nanostructures and interfaces in the hot-press sintered ZrB2–SiC–Si3N4 composites

“…Non-oxide ceramics including nitride, carbide, and boride compounds of a few transition metal elements are categorized as ultra-high temperature ceramics (UHTCs). Based on their significant combination of characteristics such as high strength, high hardness, acceptable thermal shock resistance, high melting point, and machinability, these ceramics attracted a considerable amount of attention in applications like aerospace vehicles, propulsion systems, and in general, high-temperature industries [1][2][3][4][5]. Among the UHTCs, ZrB 2 -based ceramics are in priority and are the best candidates for applications like thermal protection systems (TPS) or refractory crucibles [6].…”

Oxidation response of ZrB2–SiC–ZrC composites prepared by spark plasma sintering

“…Some parts of hypersonic vehicles and aircraft must be made of special materials that are resistant to oxidation at elevated temperatures. Ultrahigh temperature ceramics (UHTCs) have been scrutinized extensively as proper candidates for such applications [1][2][3][4][5]. It was elucidated that the UHTCs reinforced with a silicon carbide-like binary system of ZrB 2 -SiC have excellent oxidation resistance [6].…”