The effect of B4C on the microstructure and thermo-mechanical properties of HfB2-based ceramics

Hot Pressed HfB2 and HfB2–20 vol%SiC Ceramics Based on HfB2 Powder Synthesized by Borothermal Reduction of HfO2*

“…The hardness of HS was 20.2±1.0 GPa, which was higher than the reported value (17.25 GPa) 2 for HfB 2 –20 vol%SiC, but slightly lower than the value for HfB 2 –20 vol%SiC–3 vol%HfN reported by Bellosi et al (22.3 GPa) 28 . The bending strength of HS was 993±90 MPa, which was significantly higher than the value reported by Weng et al (476±30MPa) 29 …”

Densification, microstructure evolution and mechanical properties of WC doped HfB2–SiC ceramics

“…HfB 2 -SiC ceramic with relative density of 99.2% has been hot pressed at 2000 • C using fine HfB 2 powder [7]. Several silicides and carbides, such as HfSi 2 , MoSi 2 , TaSi 2 , B 4 C and WC, were selected as sintering additives to enhance densification of HfB 2 via either liquid phase sintering or oxygen removal mechanisms [6,[8][9][10][11][12][13]. For example, sample closing to full density with average HfB 2 grain size of 4 m was obtained from the addition of 5 vol.%HfSi 2 doped HfB 2 ceramic.…”

“…The enhancement of mass transportation and acceleration of densification was ascribed to the formation of Hf-Si liquid phase around 1600 • C during hot pressing [8]. Wang et al [11], prepared HfB 2 -SiC ceramic with relative density of 98.9% and average HfB 2 grain size of 3 m by hot pressing at 1850 • C using 10 vol.%B 4 to accelerate densification and improve oxidation resistance of HfB 2 -SiC ceramics [12][13][14][15].…”

Mechanical activation-assisted autoclave processing and sintering of HfB2-HfO2 ceramic powders

“…The combined effect of properties in the borideoxide, boride-carbide and etc. systems enables the resultant materials to be resistant in the extreme conditions [11][12][13]. 3 The preparation of HfB 2 powders have been reported via diverse production methods starting from various different raw materials.…”