Synthesis of Wc-Co Nanocomposites Using Polymer as Carbon Source

1994 ◽  
Vol 346 ◽  
Author(s):  
A. Manthiram ◽  
Y. T. Zhu
Keyword(s):  
Critical Role ◽  
High Hardness ◽  
X Ray Diffraction ◽  
Novel Approach ◽  
Chemical Inertness ◽  
Synthesis And Processing ◽  
And Performance ◽  
Temperature Time ◽  
Resistance To Heat

ABSTRACTCeramic-metal composites such as WC-Co are attractive for cutting-tool applications as they have high hardness, chemical inertness and resistance to heat. The properties and performance of these composites can be enhanced by keeping the size of the components on a nanometer scale. Synthesis of WC-Co nanocomposites generally involves gas-phase carburization. We have developed a novel approach in which a polymer precursor such as polyacrylonitrile serves as an in situ source for carbon. The WC-Co nanocomposites formed are characterized by x-ray diffraction and electron microscopy. The synthesis and processing conditions such as firing temperature, time and atmosphere play a critical role in obtaining phase-pure products.

scholarly journals In situ observation of phase changes of a silica-supported cobalt catalyst for the Fischer–Tropsch process by the development of a synchrotron-compatible in situ/operando powder X-ray diffraction cell

2018 ◽  
Vol 25 (6) ◽  
pp. 1673-1682 ◽  
Author(s):  
Adam S. Hoffman ◽  
Joseph A. Singh ◽  
Stacey F. Bent ◽  
Simon R. Bare
Keyword(s):  
High Pressure ◽  
Elevated Pressure ◽  
Phase Changes ◽  
In Situ Observation ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
X Ray ◽  
And Performance ◽  
Co Nanoparticles

In situ characterization of catalysts gives direct insight into the working state of the material. Here, the design and performance characteristics of a universal in situ synchrotron-compatible X-ray diffraction cell capable of operation at high temperature and high pressure, 1373 K, and 35 bar, respectively, are reported. Its performance is demonstrated by characterizing a cobalt-based catalyst used in a prototypical high-pressure catalytic reaction, the Fischer–Tropsch synthesis, using X-ray diffraction. Cobalt nanoparticles supported on silica were studied in situ during Fischer–Tropsch catalysis using syngas, H2 and CO, at 723 K and 20 bar. Post reaction, the Co nanoparticles were carburized at elevated pressure, demonstrating an increased rate of carburization compared with atmospheric studies.

Dynamics of the nanocrystal structure and composition in growth solutions monitored by in situ lab-scale X-ray diffraction

Nanoscale ◽  
2021 ◽  
Author(s):  
Helena Fridman ◽  
Michael Volokh ◽  
Taleb Mokari
Keyword(s):  
Real Time ◽  
Growth Dynamics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nanocrystal Growth ◽  
Novel Approach ◽  
Phase Size ◽  
Time Observation ◽  
Real Time Observation

Nanocrystal growth dynamics are investigated by a novel approach: real-time observation of nanocrystals in growth solutions using lab-scale in situ X-ray diffraction. The method reveals the evolution of crystal phase, size, shape, and composition.

scholarly journals RISING beamline (BL28XU) for rechargeable battery analysis

2013 ◽  
Vol 21 (1) ◽  
pp. 268-272 ◽  
Author(s):  
H. Tanida ◽  
K. Fukuda ◽  
H. Murayama ◽  
Y. Orikasa ◽  
H. Arai ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Rechargeable Batteries ◽  
Time Range ◽  
Rechargeable Battery ◽  
X Ray Diffraction ◽  
Battery Charging ◽  
X Ray ◽  
And Performance ◽  
X Ray Absorption

The newly installed BL28XU beamline at SPring-8 is dedicated toin situstructural and electronic analysis of rechargeable batteries. It supports the time range (1 ms to 100 s) and spatial range (1 µm to 1 mm) needed for battery analysis. Electrochemical apparatus for battery charging and discharging are available in experimental hutches and in a preparation room. Battery analysis can be carried out efficiently and effectively using X-ray diffraction, X-ray absorption fine-structure analysis and hard X-ray photoelectron spectroscopy. Here, the design and performance of the beamline are described, and preliminary results are presented.

Crystallization Dynamics and Rapid Thermal Processing of PZT Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Jiayu Chen ◽  
Keith G. Brooks ◽  
K.R. Udayakumar ◽  
L. Eric Cross
Keyword(s):  
Thin Films ◽  
Thermal Processing ◽  
Crystallization Process ◽  
Rapid Thermal Processing ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Pzt Thin Films ◽  
Temperature Time

AbstractThe crystallization process of PZT thin films has been studied in situ by means of Environmental Scanning Electron Microscopy ( ESEM ). Based on the ESEM observations, the Rapid Thermal Processing (RTP) technique has been employed to crystallize ferroelectric thin films. Various annealing temperature-time combinations were investigated; the results indicate the crystallization process to be very fast. X-ray diffraction data shows the crystallization to be complete in 10 seconds at 600°C, and in 1 second at 700°C. In comparison with conventionally furnace processed films, the RTP films have comparable ferroelectric and dielectric properties, but are distinguished by superior breakdown strengths and morphologically smoother surface. The relation between microstructure of films and crystallizing parameters has been studied.

Effect of Thermomechanical Processing on the Microstructure and Retained Austenite Stability during In Situ Tensile Testing Using Synchrotron X-Ray Diffraction of NbMoAl TRIP Steel

2011 ◽  
Vol 172-174 ◽  
pp. 741-746 ◽  
Author(s):  
Elena V. Pereloma ◽  
Lai Chang Zhang ◽  
Klaus Dieter Liss ◽  
Ulf Garbe ◽  
Jonathan Almer ◽  
...  
Keyword(s):  
Tensile Testing ◽  
Retained Austenite ◽  
Thermomechanical Processing ◽  
Critical Role ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Stability

In this work we compare and contrast the stability of retained austenite during tensile testing of Nb-Mo-Al transformation-induced plasticity steel subjected to different thermomechanical processing schedules. The obtained microstructures were characterised using optical metallography, transmission electron microscopy and X-ray diffraction. The transformation of retained austenite to martensite under tensile loading was observed by in-situ high energy X-ray diffraction at 1ID / APS. It has been shown that the variations in the microstructure of the steel, such as volume fractions of present phases, their morphology and dimensions, play a critical role in the strain-induced transition of retained austenite to martensite.

scholarly journals Redefining Solution-Mediated Transformations: Pharmaceutical Systems

2014 ◽  
Vol 70 (a1) ◽  
pp. C1571-C1571
Author(s):  
Marcus O'Mahony ◽  
Anthony Maher ◽  
Denise Croker ◽  
Ake Rasmuson ◽  
Benjamin Hodnett
Keyword(s):  
Reaction Pathway ◽  
Metastable Phase ◽  
Active Pharmaceutical Ingredient ◽  
Solution Concentration ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
And Performance ◽  
State Composition

Engineering the isolation of a metastable or stable crystalline phase of an active pharmaceutical ingredient (API) is of critical importance when crystallizing from solution as an uncontrolled outcome can directly affect API manufacture and performance. The theoretical framework for understanding solution-mediated crystal phase or polymorphic transformation (SMPT) was first established by Cardew & Davey.[1] The process is defined to consist of a metastable phase that dissolves and a stable phase that nucleates and grows independently from the solution. That paper also identified that in terms of a reaction pathway, SMPT could be controlled in either of two ways: by growth of the stable phase or dissolution the metastable phase. Studies concerning SMPT since then have brought the definition and those conclusions into question. Firstly, the recent case of the SMPT from FI to FIII carbamazepine and FII to FIII piractem were studied separately where data on both the solid state composition and solution concentration were collected during the transformation using powder X-ray diffraction and in situ infra-red spectroscopy, respectively. These studies, in combination with a brief review of the literature, reveal that SMPT can be controlled not only in the two ways described by Cardew & Davey but rather in 4 principal ways (Figure 1).[2] Secondly, many studies now identify that nucleation of the stable phase often occurs on the surface of the metastable phase during SMPT [3] and not independently from solution. Again when the literature is examined, this surface supported nucleation event is identified as being either epitaxial in nature or having no or inconclusive evidence of epitaxy. It is concluded that the term "independently" in the definition by Cardew & Davey be redefined to recognize that the crystallization of the stable phase during SMPT is often dependent on the surface of the metastable phase in solution.

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