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Wenbo H.,Harbin Institute of Technology | Shanbao Z.,Harbin Institute of Technology | Jihong Z.,Mudanjiang Jingangzuan Boron Carbide Co.
Ceramics International | Year: 2014

SiC nanoparticles were introduced in a ZrB2 matrix prepared via vacuum hot pressing sintering to improve the thermal shock resistance of ultra-high temperature ZrB2-SiC ceramics, namely, ZrB2-20 vol% nanoparticle SiC composites (ZrB2-20SiCnp). The thermal shock resistance of the material were determined at different temperatures via the water quenching-residual strength test method. The specific temperature of the water bath environment and the influence of different nanoparticle sizes on the thermal shock resistance of the material were also investigated. The results show that the critical thermal shock temperature difference (ΔTc) of the ZrB2-20SiCnp composite is 428 °C, which is 11.2% higher than 385 °C, ΔTc of a SiC microparticle-strengthened ZrB2 composite material. The results from the thermal shock analysis of the ZrB2-SiCnp composite indicate that ΔTc is strongly dependent on the formation of unusual intragranular nanostructures. © 2014 Elsevier Ltd and Techna Group S.r.l. Source


Han W.,Harbin Institute of Technology | Yu J.,Northwest Institute for Nonferrous Metal Research | Gao J.,Harbin Institute of Technology | Zhang J.,Mudanjiang Jingangzuan Boron Carbide Co.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2014

Based on the density functional theory (DFT) and using the plane waves ultra-soft pseudo-potential technique, some basic properties of Nb3AlN were simulated, such as ground electronic states and thermodynamic performances. The simulation results show that the properties of Nb3AlN were similar to those of metals, with good electrical conductivity and thermal conductivity. The heat capacity increases with increasing of temperature and decreasing of pressure. The Grüneisen parameter γ increases with increasing of temperature, and decreases non-linearly as the pressure climbs up. The Debye temperature is influenced by temperature and pressure, which decreases sharply with increasing of temperature and climbs up with the increasing of pressure rapidly. The simulation results of the relationship between Gibbs free energy and temperature show that Nb3AlN can be synthesized through an appropriate process. Copyright © 2014, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved. Source


Wang G.,National Key Laboratory of Precision Hot Processing of Metals | Zhang J.,Mudanjiang Jingangzuan Boron Carbide Co. | Zhang C.,National Key Laboratory of Precision Hot Processing of Metals | Zhang K.,National Key Laboratory of Precision Hot Processing of Metals
Key Engineering Materials | Year: 2010

Boron carbide (B4C) possesses unique physical and thermal properties. In this paper, B4C based composites toughened by TiB 2 were fabricated by in-situ reaction sintering with the original microcrystalline powders B4C, TiO2 and glucose. The influences of sintering temperature and content of TiO2 on the sintering behavior and mechanical properties were investigated. (TiB 2, Al2O3)/B4C and (TiB 2,SiC)/B4C composites with almost fully dense were fabricated by using additives of Al2O3 and Si powders and sintering at 1950°C and 1900°C, the fracture toughness of composites reach to 7.09 and 6.35 MPa·m1/2 respectively. The analysis of microstructure shows that the main toughen mechanism is the crack deflection due to the existence of residual stress. © (2010) Trans Tech Publications. Source


Kang P.C.,Harbin Institute of Technology | Cao Z.W.,Mudanjiang Jingangzuan Boron Carbide Co. | Wu G.H.,Harbin Institute of Technology | Zhang J.H.,Mudanjiang Jingangzuan Boron Carbide Co. | And 2 more authors.
International Journal of Refractory Metals and Hard Materials | Year: 2010

A series of boron carbide (B4C) matrix composites with different contents of Al, were synthesized by reaction hot-press sintering with milled B4C and pure metallic Al powder at 1600 °C for 1 h. X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to identify the phase constituent of the milled powders and the composites. The results have shown that parts of B4C and Al particles were oxidized to boron oxide (B2O3) and alumina (Al2O3) during the milling. Thermit reaction occurred and B2O3 was reverted during hot-press sintering. A ternary phase of Al boron carbide (Al8B4C7) was found in the composites, and the B4C transformed to a rich boron phase (B6.5C) because of the superfluous boron in the system. © 2009 Elsevier Ltd. All rights reserved. Source

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