Full densification of zirconium carbide ceramics sintered under high pressure at low temperature

Abstract

Zirconium carbide (ZrC) ceramic is one of the most important and promising materials with a high melting point. However, its low diffusion coefficient affects its densification behavior, which dramatically limits its engineering application. For polycrystal ceramic materials, sintering by thermal diffusion is the most widely used method for consolidation. But in view of the difficult densification behavior of ZrC, it is necessary to develop new sintering methods together with another driving force. In the study, we reported an ultra-high-pressure sintering strategy to fully densify ZrC ceramic under 1.7 GPa at 1600°C. The sintered sample exhibited high density, fine grain size, excellent mechanical properties, and a large number of crystal defects, including dislocation networks and walls, which were similar to those in deformed metals. Its hardness increased to 2057.44 HV0.1 because of its unique microstructure.

High-aspect-ratio single-crystalline (HfxZr(1−x))B2 micron-rods: low-temperature, highly-efficient synthesis and oriented growth mechanism

“…However, due to the intrinsically strong covalent bonding of TMB 2 and the sluggish diffusion effect strengthened by improved formation entropy, 9,10 it was still a challenging task to synthesize (Hf x Zr (1−x) )B 2 powders with an anisotropic morphology by a conventional reduction process that is widely adopted for industrial preparation of TMB 2 powders, due to its strict requirement of energy-intensive and timeconsuming processing conditions even by using strong but high-price reducing agents (active metals or elemental boron). 11,12 With respect to this, the advanced techniques of molten-salt medium and microwave heating were utilized to modify the conventional reduction process for synthesizing TMB 2 .…”

Microstructure characterization of high‐pressure induced texture in fully densified zirconium diboride ceramics

“…Sintering under high pressure has been proved to be an effective approach to obtain denser advanced ceramics. Moreover, it is proposed that plastic deformation is one of the dominant densification mechanisms in high‐pressure‐assisted sintering 9–11 . Ji 9 fabricated fully dense micro‐sized B 4 C ceramics via spark plasma sintering (SPS) method under 80 MPa at 1700°C.…”

“…Liu 10 prepared nanocrystalline Y 2 O 3 by combustion reaction plus quick pressing method under 170 MPa at 1350°C. Ke 11 sintered nearly fully densified ZrC bulks using a piston–cylinder apparatus under 1.7 GPa at 1600°C. However, none of these works reported a direct evidence of plastic deformation such as texture formation during sintering.…”