X-ray observation of the formation of diamond and cubic boron nitride at high pressure and temperature

Physica B+C ◽  
1986 ◽  
Vol 139-140 ◽  
pp. 668-670 ◽  
Author(s):  
S. Yamaoka ◽  
O. Shimomura ◽  
M. Akaishi ◽  
H. Kanda ◽  
T. Nagashima ◽  
...  
Keyword(s):  
High Pressure ◽  
Boron Nitride ◽  
Cubic Boron Nitride ◽  
High Pressure And Temperature ◽  
X Ray

scholarly journals Production of alumo-matrix composite material modified by nanostructured cubic boron nitride

2018 ◽  
Vol 63 (3) ◽  
pp. 271-279
Author(s):  
P. A. Vityaz ◽  
V. T. Senyut ◽  
M. L. Kheifetz ◽  
A. G. Kolmakov
Keyword(s):  
High Pressure ◽  
Aluminum Alloy ◽  
Boron Nitride ◽  
Cubic Boron Nitride ◽  
Aluminum Matrix ◽  
Treatment Temperature ◽  
Chemical Affinity ◽  
High Temperature Annealing ◽  
High Pressure And Temperature ◽  
Primary Particles

The structure and microhardness of an aluminum alloy with additives of nanostructured cubic boron nitride (cBN) after treatment under high pressure and temperature are investigated. А nanostructured powder of cBN with primary particles within 50–200 nm is used as a filler. A preliminary chemical-thermal modifying of the nanostructured cBN, which consists in its high-temperature annealing in the temperature range of 750–950 °C in a medium of aluminum-contai ning compounds, is carried out to increase the chemical affinity of the nanostructured cBN to the aluminum matrix. It is shown that the modifying of nanostructured cBN with aluminum increases the strength of the additives retention in the aluminum matrix. At the same time the increase in the concentration of BN additives from 1.5 to 5 wt.% as well as the increase in the treatment temperature at a fixed pressure promotes the increase in the microhardness of the material by a factor of 1.5 to 2 as compared with the base aluminum alloy without the addition of a modifier. An increase in the cBN concentration to 5 % by weight results in an increase in the fraction of smaller particle conglomerates (1–5 μm) in the material and in a decrease in the size of large inclusions to 10–20 μm. In this case, the distribution of BN particles in the aluminum matrix is more uniform in comparison with a material with a cBN content of 1.5 wt.%. In the material with the growth of temperature up to 1000 °С, cBN in aggregates is recrystallized with the formation of single-crystal (polycrystalline) particles with the size of 1–10 μm  with faceting specific for cBN micron particles.

Synthesis and Decomposition of Ti3SiC2 under 1-5GPa at 1400°C

2014 ◽  
Vol 602-603 ◽  
pp. 499-502 ◽  
Author(s):  
Yuan Yuan Zhu ◽  
Shang Sheng Li ◽  
Liang Li ◽  
Ai Guo Zhou
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Phase Transformation ◽  
Boron Nitride ◽  
Cubic Boron Nitride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ternary Carbide ◽  
Scanning Electron

Ternary carbide Ti3SiC2 is a good binder to make superhard composites with diamonds or cubic boron nitride. Superhard composites are normally made at high temperature and under high pressure around 5 GPa to avoid the phase transformation of diamonds or cubic boron nitride. This paper researched the synthesis of Ti3SiC2 from the powders of Ti, Si, and graphite by a cubic presser under 1 GPa to 4 GPa at 1400°C. The decomposition of Ti3SiC2 under 5GPa at 1400°C was also researched. From X-ray diffraction (XRD) and scanning electron microscopy (SEM) results, Ti3SiC2 was synthesized in 30 min under 1 GPa at 1400°C. The impurities were TiSi2, Ti5Si3Cx, and TiC. As the pressure increased from 1GPa to 4GPa, less Ti3SiC2 more TiSi2 was synthesized. Therefore, high presser > 1GPa is unfavorable for the synthesis of Ti3SiC2. After treated under 5GPa at 1400°C, pure Ti3SiC2 was decomposed.

Application of a new composite cubic-boron nitride gasket assembly for high pressure inelastic x-ray scattering studies of carbon related materials

2011 ◽  
Vol 82 (7) ◽  
pp. 073902 ◽  
Author(s):  
Lin Wang ◽  
Wenge Yang ◽  
Yuming Xiao ◽  
Bingbing Liu ◽  
Paul Chow ◽  
...  
Keyword(s):  
High Pressure ◽  
Boron Nitride ◽  
Cubic Boron Nitride ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

High Pressure and High Temperature Sintered PcBN Using Al, B4C and C as Sintering Additive

2016 ◽  
Vol 697 ◽  
pp. 521-525 ◽  
Author(s):  
Yao Ma ◽  
Jian Li ◽  
Hai Long Wang ◽  
Rui Zhang
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Boron Nitride ◽  
Cubic Boron Nitride ◽  
High Strength ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polycrystalline Cubic Boron Nitride ◽  
Starting Mixture ◽  
Sintering Additive

Polycrystalline cubic boron nitride (PcBN) composites were sintered by high pressure and high temperature sintering (HPHT) at 1450 °C for 3 min under a pressure of 5.0 GPa. Aluminium,boron carbide and carbon in the starting mixture reacts with cubic boron nitride (cBN) to form Al3BC3 and AlN bonding among cBN grains during sintering. X-ray diffraction (XRD) and Scanning electron microscope (SEM) were used to analyze phases and micro-structure of the sintered samples. The dense structure of super hard cBN grains bonded together with Al3BC3 and AlN offers superior hardness and high strength. The Vickers hardness of PcBN composites was 45±5 GPa, and the strength of PcBN composites was 345±15 MPa.

Theoretical and experimental investigation of point defects in cubic boron nitride

MRS Advances ◽  
2017 ◽  
Vol 2 (29) ◽  
pp. 1545-1550 ◽  
Author(s):  
Nicholas L. McDougall ◽  
Jim G. Partridge ◽  
Desmond W. M. Lau ◽  
Philipp Reineck ◽  
Brant C. Gibson ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Cubic Boron Nitride ◽  
Optical Emission ◽  
Wide Band ◽  
Wide Band Gap ◽  
Edge Structure ◽  
X Ray ◽  
Substitutional Defects ◽  
X Ray Absorption ◽  
Annealing Experiments

ABSTRACTCubic boron nitride (cBN) is a synthetic wide band gap material that has attracted attention due to its high thermal conductivity, optical transparency and optical emission. In this work, defects in cBN have been investigated using experimental and theoretical X-ray absorption near edge structure (XANES). Vacancy and O substitutional defects were considered, with O substituted at the N site (ON) to be the most energetically favorable. All defects produce unique signatures in either the B or N K-edges and can thus be identified using XANES. The calculations coupled with electron-irradiation / annealing experiments strongly suggest that ON is the dominant defect in irradiated cBN and remains after annealing. This defect is a likely source of optical emission in cBN.

Sign in / Sign up

Export Citation Format

Share Document