Combustion for the Synthesis of β-SiC and Diamond/SiC Composite

1993 ◽  
Vol 327 ◽  
Author(s):  
Rohini Raghunathan ◽  
Rina Chowdhury ◽  
Jagdish Narayan
Keyword(s):  
Electron Microscopy ◽  
Exothermic Reaction ◽  
Diamond Films ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
Set Up ◽  
Spectroscopy Studies

AbstractCubic β-SiC was processed under conditions of self-propagating high-temperature synthesis, based on the exothermic reaction between elemental Si and C powders. The set up for the synthesis of SiC using a mixture of Si and C is described. X-Ray and Raman spectroscopy studies were performed to characterize the quality of the β-SiC produced using the new set up. Scanning Electron Microscopy and Transmission Electron Microscopy studies were also carried out to study the mechanism of the formation of β-SiC from the elemental powders. The density of the compact and grain size of the graphite was found to be critical in the formation of the SiC. Diamond seeds were also implanted on the SiC pellet while compaction and this implanted diamond provided the necessary seed for the growth of a thick diamond film. The adhesion of the film is good because of its growth from the implanted diamond. Diamond films were grown on SiC using HFCVD. The quality and the adhesion of the diamond films on SiC were studied using SEM.

Investigation on B, Cr Doped Ni3Al Alloy Prepared by Self-Propagation High-Temperature Synthesis and Hot Extrusion

2013 ◽  
Vol 747-748 ◽  
pp. 124-131 ◽  
Author(s):  
Li Yuan Sheng ◽  
Jian Ting Guo ◽  
Chao Yuan ◽  
F. Yang ◽  
G.S. Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Temperature ◽  
Hot Extrusion ◽  
The Self ◽  
Al Alloy ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron

The Ni3Al and Ni3Al-B-Cr alloys were fabricated by the self-propagation high-temperature synthesis with hot extrusion method. Their microstructure and mechanical properties were studied by using combination of X-ray diffraction, optical microscopy, transmission electron microscopy and compression test. Analysis of X-ray spectra exhibited that the elemental powders had been transformed to the Ni3Al phase after the self-propagation high-temperature synthesis processing. Microstructure examination showed that the alloy without extrusion consisted of coarse and fine grains, but the subsequent hot extrusion procedure homogenized the grain size and densified the alloy obviously. Transmission electron microscopy observations on the Ni3Al alloy revealed that Ni3Al, γ-Ni and Al2O3 particles were the main phases. When the boron and chromium were added, besides the β-NiAl phase, α-Cr phase and some Cr7Ni3 particles with stacking faults inside were observed. In addition, a lot of substructure and high-density dislocation arrays were observed in the extruded part, which indicated that the subsequent extrusion had led to great deformation and partly recrystallizing in the alloy. Moreover, the subsequent extrusion procedure redistributed the Al2O3 particles and eliminated the γ-Ni. These changes were helpful to refine the microstructure and weaken the misorientation. The mechanical test showed that the self-propagation high-temperature synthesis with hot extrusion improved the mechanical properties of the Ni3Al alloy significantly. The addition of B and Cr in Ni3Al alloy increased the mechanical properties further, but the compressive strength of the alloy was still lower than that synthesized by combustion. Finally, the self-propagation high-temperature synthesis with hot extrusion was a good method to prepare Ni3Al alloy from powder.

Effect of NaCl on Synthesis of Si-SiC Nanocomposites by Self Propagating High Temperature Synthesis

2013 ◽  
Vol 664 ◽  
pp. 449-453 ◽  
Author(s):  
Sutham Niyomwas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
Nano Composite ◽  
Argon Gas ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
Scanning Electron

The Si-SiC nanocomposites have been synthesized by self-propagating high temperature synthesis (SHS) from natural precursors. The effects of difference amount of added NaCl from 0 to 0.75 moles to the reactants on the Si-SiC conversion and particle size were investigated. The reaction were carried out in a SHS reactor under static argon gas at the pressure of 0.5 MPa. The nanocomposite results have been characterized by scanning electron microscope, Transmission Electron Microscopy and X-ray diffraction. The results showed that the production of nano-composite materials using SHS process is feasible and agree well with the thermodynamics calculations.

Burnishing of Aluminium Alloy Surface Using Diamond Matrix Composite Tools

2015 ◽  
Vol 641 ◽  
pp. 39-46 ◽  
Author(s):  
Magdalena Szutkowska ◽  
Daniel Toboła ◽  
Kazimierz Czechowski
Keyword(s):  
Diamond Tool ◽  
Diamond Powder ◽  
Surface Geometry ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
De Beers ◽  
High Pressure Apparatus

To make the most of unique properties of diamond and to diminish an influence its disadvantageous properties new diamond tool composites with ceramic bonding phase (MAX) has been proposed. Ti3(Si,Ge)C2 and Ti3SiC2 were produced by self-propagating high temperature synthesis (SHS). 3-6 µm (MDA, De Beers) diamond powder was mechanically mixed with 10 wt% Ti3(Si,Ge)C2 or 30 wt% Ti3SiC2, pressed and the compacts were sintered at 1962 °C at 8.0 GPa in a Bridgman-type high pressure apparatus. These mechanical properties were determined: Vickers hardness HV1, Young’s modulus, tensile strength, fracture toughness and wear resistance.Microstructure and phase composition were studied by scanning and transmission electron microscopy and X-ray and electron diffraction techniques. To improve the final quality of the AlCu4MgSi(A) alloy, balls of diamond-new composites were incorporated into the burnishing tools. The influence of burnishing parameters, such as burnishing force and feed, on surface geometry parameters were measured and profilograms of the surface roughness recorded.

scholarly journals High-pressure synthesis of SmGe3

2020 ◽  
Vol 235 (8-9) ◽  
pp. 333-339
Author(s):  
Julia-Maria Hübner ◽  
Wilder Carrillo-Cabrera ◽  
Raul Cardoso-Gil ◽  
Primož Koželj ◽  
Ulrich Burkhardt ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Temperature Synthesis ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Unknown Phase ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
High Pressure High Temperature ◽  
Pressure Synthesis

AbstractThe new samarium germanide SmGe3 is obtained by high-pressure high-temperature synthesis of pre-reacted mixtures of samarium and germanium at a pressure of 9.5 GPa and temperatures between 1073 and 1273 K. SmGe3 decomposes at 470(5) K into SmGe2, α-Sm3Ge5 and a hitherto unknown phase. SmGe3 exhibits a superstructure of the cubic Cu3Au-type. Transmission electron microscopy measurements of crystalline particles and prepared lamellae indicate a high density of defects on the nanoscale. Selected area electron diffraction and elaborate X-ray powder diffraction measurements consistently indicate a 2a0 × 2a0 × 2a0 superstructure adopting space group $Fm\overline{3}m$ with a = 8.6719(2) Å.

Study of Tungsten and Molybdenum Nanopowders Interaction with Sulphur in SHS Conditions and Synthesized Product Properties

2014 ◽  
Vol 1040 ◽  
pp. 171-175 ◽  
Author(s):  
Yuriy Irtegov ◽  
Vladimir An
Keyword(s):  
Electron Microscopy ◽  
Electrical Explosion ◽  
Initial Mixture ◽  
Metal Sulfides ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
Elementary Sulphur ◽  
Composition Of Products

X-ray and transmission electron microscopy results of initial tungsten and molybdenum nanopowders produced by electrical explosion of wire and used in metal sulfides synthesis is presented. Sulphur excess effect on metal nanopowders combustion with elementary sulphur and phase composition of products is studied. Tungsten and molybdenum disulfides obtained by self-propagating high-temperature synthesis under argon pressure 3 MPa and sulphur excess 15 wt. % in initial mixture are crystallized in layered aggregates with layer thickness 20-30 nm.

Selective Synthesis of Boron Nitride Nanotubes

2011 ◽  
Vol 694 ◽  
pp. 408-412
Author(s):  
Lai Ping Zhang ◽  
Ji Lin Wang ◽  
Guo Wei Zhao ◽  
Zhan Hui Zhang ◽  
Fang Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Boron Nitride ◽  
Boron Nitride Nanotubes ◽  
Selective Synthesis ◽  
Controllable Synthesis ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
Bn Nanotubes ◽  
Shs Method

Four types of boron nitride (BN) nanotubes are selectively synthesized by annealing porous precursor in flowing NH3 and NH3/H2 atmosphere at temperature ranging from 1000 to 1200°C in a vertical furnace. The as-synthesized BN nanotubes, including cylinder, wave, bamboo and bubble-chain, are characterized by scanning and transmission electron microscopy. Selectivity of BN nanotubes is estimated as approximately 80 to 95%. The porous precursor B31Fe17(MgO)27 prepared by self-propagation high-temperature synthesis (SHS) method plays a key role in controllable synthesis of the as-grown BN nanotubes. The chemical reaction and annealing mechanism are also discussed.

High-Pressure, High-Temperature Synthesis of Superhard Boron Suboxide

1995 ◽  
Vol 410 ◽  
Author(s):  
H. Hubert ◽  
L. A. J. Garvie ◽  
K. Leinenweber ◽  
P. R. Buseck ◽  
W. T. Petuskeyt ◽  
...  
Keyword(s):  
Pressure Range ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
High Pressure High Temperature ◽  
Boron Suboxide ◽  
Electron Energy Loss ◽  
Rhombohedral Boron

ABSTRACTA multianvil device was used to investigate the formation of BxO phases produced in the 2 to 10 GPa pressure range with temperatures between 1000 and 1800 °C.Amorphous and crystalline B and BP were oxidized using B2O3 and CrO3. Using powder X-ray diffraction and parallel electron energy-loss spectroscopy (PEELS), we were unable to detect graphitic or diamondstructured B2O, reported in previous studies. The refractory boride B6O, which has the α-rhombohedral boron structure, is the dominant suboxide in the P and T range of our investigation. PEELS with a transmission electron microscope was used to characterize the boron oxides.

Characterization and Growth Mechanism of B12As2 Epitaxial Layers Grown on (1-100) 15R-SiC

2008 ◽  
Vol 1069 ◽  
Author(s):  
Hui Chen ◽  
Guan Wang ◽  
Michael Dudley ◽  
Zhou Xu ◽  
James. H. Edgar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Growth Mechanism ◽  
Heteroepitaxial Growth ◽  
High Quality ◽  
X Ray ◽  
Transmission Electron ◽  
Substrate Choice

ABSTRACTA systematic study is presented of the heteroepitaxial growth of B12As2 on m-plane 15R-SiC. In contrast to previous studies of B12As2 on other substrates, including (100) Si, (110) Si, (111) Si and (0001) 6H-SiC, single crystalline and untwinned B12As2 was achieved on m-plane 15R-SiC. Observations of IBA on m-plane (1100)15R-SiC by synchrotron white beam x-ray topography (SWBXT) and high resolution transmission electron microscopy (HRTEM) confirm the good quality of the films on the 15R-SiC substrates. The growth mechanism of IBA on m-plane 15R-SiC is discussed. This work demonstrates that m-plane 15R-SiC is potentially a good substrate choice to grow high quality B12As2 epilayers.

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