12045-64-6Relevant articles and documents
Synthesis of plate-like ZrB2 grains
Hu, Chunfeng,Zou, Ji,Huang, Qing,Zhang, Guojun,Guo, Shuqi,Sakka, Yoshio
, p. 85 - 88 (2012)
Plate-like ZrB2 grains were synthesized at 1550°C by in situ solid/liquid reaction using Zr and B powders mixed with transition metal (Mo, Nb, Ti, or W) and Si powder. The preferred growth direction of plate grains was along a- or b-axis depending on the initial content of transition metal and silicon in the mixtures. The synthesis mechanism of plate-like grain was possibly related to the catalysis of in situ formed silicides.
Surface electronic structure of ZrB2 buffer layers for GaN growth on Si wafers
Yamada-Takamura, Yukiko,Bussolotti, Fabio,Fleurence, Antoine,Bera, Sambhunath,Friedlein, Rainer
, (2010)
The electronic structure of epitaxial, predominantly single-crystalline thin films of zirconium diboride (ZrB2), a lattice-matching, conductive ceramic to GaN, grown on Si(111) was studied using angle-resolved ultraviolet photoelectron spectroscopy. The existence of Zr-derived surface states dispersing along the Γ-M direction indicates a metallic character provided by a two-dimensional Zr-layer at the surface. Together with the measured work function, the results demonstrate that the surface electronic properties of such thin ZrB2 (0001) buffer layers are comparable to those of the single crystals promising excellent conduction between nitride layers and the substrate in vertical light-emitting diodes on economic substrates.
New borothermal reduction route to synthesize submicrometric ZrB 2 powders with low oxygen content
Guo, Wei-Ming,Zhang, Guo-Jun
, p. 3702 - 3705 (2011)
The ZrB2 powders with submicrometric particle size and low oxygen content were synthesized by a new borothermal reduction route using ZrO2 and excess boron as raw materials. The conventional process only contained the borothermal red
ZrB2 powders synthesis by borothermal reduction
Ran, Songlin,Van Der Biest, Omer,Vleugels, Jef
, p. 1586 - 1590 (2010)
High-purity zirconium diboride (ZrB2) powders with submicrometer particle size were synthesized by borothermal reduction of nanometric ZrO 2 powders in vacuum. The reaction process was experimentally and thermodynamically assessed. B2O3 was identified as a possible intermediate reaction product. ZrO2 completely converted to ZrB2 when thermally treated at 1000°C for 2 h in a vacuum, but the removal of residual boron-related species required a temperature above 1500°C. ZrB2 powders obtained at 1000°-1200°C showed a faceted morphology, whereas those prepared above 1500°C had a nearly spherical morphology. The particle size that was calculated from the measured surface area increased with the increasing synthesis temperature from 0.15 μm at 1000°C to 0.66 μm at 1650°C. The oxygen content of the ZrB 2 powders synthesized at 1650°C was as low as 0.43 wt%.
Synthesis of ZrB2 powders by carbothermal and borothermal reduction
Jung, Eun-Young,Kim, Jung-Hun,Jung, Se-Hyuk,Choi, Sung-Churl
, p. 164 - 168 (2012)
Zirconium diboride (ZrB2) powders were synthesized using ZrO2 + B2O3 + C (carbothermal reduction), ZrO2 + B4C (boron carbide reduction), and ZrO2 + B4C + C (combined reduction) with various compositions at 1250 °C for 1-3 h under flowing argon. ZrB2 powders synthesized using ZrO2 + B2O3 + C displayed rod shape growth. There was much residual impurity carbon in ZrB2 powders synthesized using ZrO2 + B4C + C. When synthesized using ZrO 2 + B4C, there were the residual impurity B 2O3 and little rod shape growth. Residual B 2O3 impurities were easily removed by washing with methanol. We concluded that the ZrB2 powder synthesis method using boron carbide reduction is the most desirable way to produce ZrB2 powders among the three synthesis routes. ZrB2 powders synthesized using ZrO2 + B4C have a particle size of 1.1 μm and a hexagonal shape, and low oxygen content (0.725 wt.%).
Reaction processes and characterization of ZrB2 powder prepared by boro/carbothermal reduction of ZrO2 in vacuum
Guo, Wei-Ming,Zhang, Guo-Jun
, p. 264 - 267 (2009)
The present work was concentrated mainly on the reaction processes of boro/carbothermal reduction (BCTR) of ZrO2 with B4C and carbon in vacuum, and characterization of morphology and sinterability of the obtained ZrB2 powd
Epitaxial growth of group III nitrides on silicon substrates via a reflective lattice-matched zirconium diboride buffer layer
Tolle,Roucka,Tsong,Ritter,Crozier,Chizmeshya,Kouvetakis
, p. 2398 - 2400 (2003)
The growth of metallic and reflecting ZrB2 films was conducted on Si(111) substrates at 900 °C using a single-source unimolecular precursor Zr(BH4)4. The ZrB2 buffer layer on Si(111) provided a near lattice-matched template for the growth of epitaxial GaN. The reflective nature of the ZrB2 surface presented an added bonus to optoelectronic applications of the 111- nitrides.
Reactive hot pressing of ZrB2-SiC-ZrC ultra high-temperature ceramics at 1800°C
Wu, Wen-Wen,Zhang, Guo-Jun,Kan, Yan-Mei,Wang, Pei-Ling
, p. 2967 - 2969 (2006)
A ZrB2-SiC-ZrC composite was prepared from a mixture of zirconium, silicon, and B4C via reactive hot pressing at a relatively low temperature (1800°C) for 60 min under 20 MPa in an argon atmosphere. The relative density was 96.8%, the micro-hardness (Hv10) was 16.7 GPa, and the fracture toughness was 5.1 MPa-m1/2. The presence of ZrC was helpful for the densification process and improved the mechanical properties of the composite. A model of the microstructure development of the composite was proposed to explain the phase distribution.
Thermal Properties of Hf-Doped ZrB2 Ceramics
Lonergan, Jason M.,McClane, Devon L.,Fahrenholtz, William G.,Hilmas, Gregory E.
, p. 2689 - 2691 (2015)
The effect of Hf additions on the thermal properties of ZrB2 ceramics was studied. Reactive hot pressing of ZrH2, B, and HfB2 powders was used to synthesize (Zr1-x,Hfx)B2 ceramics with Hf contents ranging from x = 0.0001 (0.01 at.%) to 0.0033 (0.33 at.%). Room-temperature heat capacity values decreased from 495 J·(kg·K)-1 for a Hf content of 0.01 at.% to 423 J·(kg·K)-1 for a Hf content of 0.28 at.%. Thermal conductivity values decreased from 141 to 100 W·(m·K)-1 as Hf content increased from 0.01 to 0.33 at.%. This study revealed, for the first time, that small Hf contents decreased the thermal conductivity of ZrB2 ceramics. Furthermore, the results indicated that reported thermal properties of ZrB2 ceramics are affected by the presence of impurities and do not represent intrinsic behavior.
Aerospace application on Al 2618 with reinforced – Si3N4, AlN and ZrB2in-situ composites
Mathan Kumar,Senthil Kumaran,Kumaraswamidhas
, p. 238 - 250 (2016)
In this study, the Al 2618 aluminium alloy is reinforced with Si3N4(Silicon Nitride), AlN (Aluminium Nitride) & ZrB2(Zirconium Boride) in wt. % of (0,2,4,6,8) by stir casting process. The tribological and mechanical proper
