scholarly journals Preparation and Characterization of Silicon-Metal Fluoride Reactive Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2367
Author(s):  
Siva Kumar Valluri ◽  
Mirko Schoenitz ◽  
Edward Dreizin
Keyword(s):  
Metal Fluoride ◽  
Composite Powders ◽  
Particle Combustion ◽  
Reactive Milling ◽  
Lower Temperature ◽  
Thermoanalytical Measurements ◽  
Arrested Reactive Milling ◽  
Heated Filament ◽  
Measured Particle

Fuel-rich composite powders combining elemental Si with the metal fluoride oxidizers BiF3 and CoF2 were prepared by arrested reactive milling. Reactivity of the composite powders was assessed using thermoanalytical measurements in both inert (Ar) and oxidizing (Ar/O2) environments. Powders were ignited using an electrically heated filament; particle combustion experiments were performed in room air using a CO2 laser as an ignition source. Both composites showed accelerated oxidation of Si when heated in oxidizing environments and ignited readily using the heated filament. Elemental Si, used as a reference, did not exhibit appreciable oxidation when heated under the same conditions and could not be ignited using either a heated filament or laser. Lower-temperature Si fluoride formation and oxidation were observed for the composites with BiF3; respectively, the ignition temperature for these composite powders was also lower. Particle combustion experiments were successful with the Si/BiF3 composite. The statistical distribution of the measured particle burn times was correlated with the measured particle size distribution to establish the effect of particle sizes on their burn times. The measured burn times were close to those measured for similar composites with Al and B serving as fuels.

Zirconium-boron reactive composite powders prepared by arrested reactive milling

2019 ◽  
Vol 38 (2) ◽  
pp. 142-161 ◽  
Author(s):  
Daniel Hastings ◽  
Mirko Schoenitz ◽  
Edward L. Dreizin
Keyword(s):  
Composite Powders ◽  
Reactive Milling ◽  
Arrested Reactive Milling

Titanium-boron reactive composite powders with variable morphology prepared by arrested reactive milling

Fuel ◽  
2022 ◽  
Vol 310 ◽  
pp. 122313
Author(s):  
Daniel Hastings ◽  
Nikki Rodriguez ◽  
Holly McCann ◽  
Mirko Schoenitz ◽  
Edward L. Dreizin
Keyword(s):  
Composite Powders ◽  
Reactive Milling ◽  
Variable Morphology ◽  
Arrested Reactive Milling

Arrested Reactive Milling Synthesis and Characterization of Sodium-Nitrate Based Reactive Composites

2007 ◽  
Vol 32 (1) ◽  
pp. 32-41 ◽  
Author(s):  
Swati Umbrajkar ◽  
Mikhaylo A. Trunov ◽  
Mirko Schoenitz ◽  
Edward L. Dreizin ◽  
Russell Broad
Keyword(s):  
Sodium Nitrate ◽  
Synthesis And Characterization ◽  
Reactive Milling ◽  
Arrested Reactive Milling

scholarly journals Performance Characterization of Composite Powders for 3D Printing

2021 ◽  
Vol 714 (3) ◽  
pp. 032070
Author(s):  
Xiangjun Bi ◽  
Hongjie Zhao ◽  
Yuanxun Gong ◽  
Xinghong Zhou
Keyword(s):  
3D Printing ◽  
Composite Powders ◽  
Performance Characterization

The Synthesis and Characterization of Novel Cadmium Sulphide Nanocrystallites and their Thin Films

2014 ◽  
Vol 875-877 ◽  
pp. 228-231
Author(s):  
Shafique Ahmed Arain ◽  
Christopher Wilkins ◽  
Hafiz Badaruddin
Keyword(s):  
Thin Films ◽  
Vapour Deposition ◽  
Hexagonal Phase ◽  
Chemical Vapour ◽  
Cadmium Sulphide ◽  
Spherical Shape ◽  
Sem Analysis ◽  
Diethyl Dithiocarbamate ◽  
Lower Temperature

Diethyl dithiocarbamate [Cd (S2CN Et2)2] complex is used to deposit the cadmium sulphide thin film at much lower temperature by Aerosol Assisted Chemical Vapour deposition (AACVD) and same precursor is used to synthesize the nanocrystals in Oleylamine at elevated temperature. Thermogravimetric analysis shows that precursor [Cd (S2CN Et2)2] decomposes in the single stage, losing 62% of total weight. Deposition of thin films at 300°C and 400°C showed the growth of CdS clusters which were made of granular crystallites. These results are confirmed by SEM analysis. Thermolysis of the precursor in oleylamine at 240°C gave the nanoparticles most of them are monodispersed spherical shape, few having mono and dipod structures. TEM images confirm the structures. XRD results show the thin films and nanoparticles have hexagonal phase of CdS.

Electro-static discharge ignition of monolayers of nanocomposite thermite powders prepared by Arrested Reactive Milling

2015 ◽  
Vol 1758 ◽  
Author(s):  
Ian Monk ◽  
Rayon Williams ◽  
Xinhang Liu ◽  
Edward L. Dreizin
Keyword(s):  
Particle Surface ◽  
Combustion Products ◽  
Reaction Rates ◽  
Interference Filter ◽  
Gas Combustion ◽  
Reactive Milling ◽  
Discharge Ignition ◽  
Reactive Interface ◽  
Arrested Reactive Milling ◽  
Static Discharge

AbstractReactive nanocomposite powders with compositions 2Al∙3CuO, 2.35Al∙Bi2O3, 2Al∙Fe2O3, and 2Al∙MoO3 were prepared by arrested reactive milling, placed in monolayers on a conductive substrate and ignited by an electro-static discharge (ESD) or spark in air, argon, and vacuum. The ESD was produced by discharging a 2000 pF capacitor charged to a voltage varied from 5 to 20 kV. Emission from ignited particles was monitored using a photomultiplier equipped with an interference filter. Experimental variables included particle sizes, milling time used to prepare composite particles, surrounding environment, and starting ESD voltage. All materials ignited in all environments, producing individual burning particles that were ejected from the substrate. The spark duration varied from 1 to 5 µs; the duration of the produced emission pulse was in the range of 80 – 250 µs for all materials studied. The longest emission duration was observed for the nanocomposite thermite using MoO3 as an oxidizer. The reaction rates of the ESD-initiated powders were defined primarily by the scale of mixing of and reactive interface area between the fuel and oxidizer in composite materials rather than by the external particle surface or particle dimensions. In vacuum, particles were heated by ESD while remaining on the substrate until they began generating gas combustion products. In air and argon, particles initially pre-heated by ESD were lifted and accelerated to ca. 100 m/s by the generated shock wave; the airborne particles continued self-heating due to heterogeneous redox reactions.

Physico-chemical characterization of Cu2+-exchanged sepiolite

Clay Minerals ◽  
1985 ◽  
Vol 20 (4) ◽  
pp. 467-475 ◽  
Author(s):  
A. Corma ◽  
J. Pérez-Pariente ◽  
J. Soria
Keyword(s):  
Chemical Characterization ◽  
Tetrahedral Symmetry ◽  
Pyramidal Geometry ◽  
Physico Chemical ◽  
One Step ◽  
Lower Temperature ◽  
Coordinated Water ◽  
Square Pyramidal Geometry ◽  
Different Levels

AbstractCopper-sepiolites exchanged at different levels have been studied by ESR, IR, and TG. The results indicate that in the unheated samples the Cu2+ ions are located in octahedral edge positions. After dehydration, the Cu2+ ions occur in two positions with different environments. Some of the Cu2+ ions lose the two molecules of coordinated water in one step, at low dehydration temperatures, and adopt a square pyramidal geometry. Other Cu2+ ions lose the coordination water in two steps, at lower temperature than the natural sepiolite, and adopt a tetrahedral symmetry.

scholarly journals Analysis of the properties of a Cu-Al2-O3 sintered system based on ultra fine and nanocomposite powders

2007 ◽  
Vol 39 (2) ◽  
pp. 145-152 ◽  
Author(s):  
Z. Andjic ◽  
M. Korac ◽  
Z. Kamberovic ◽  
A. Vujovic ◽  
M. Tasic
Keyword(s):  
Mechanical Properties ◽  
Chemical Method ◽  
Elevated Temperatures ◽  
Hydrogen Atmosphere ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Composite Powders ◽  
Nanocomposite Powders ◽  
Final Composition

In this paper synthesis of a composite based on Cu-Al2O3 by a thermo-chemical method is shown along with a comparative analysis of the properties of the obtained nanocomposite sintered samples, which are characterized by a good combination of electric-mechanical properties, suitable for work at elevated temperatures. Ultra fine and nanocrystal powder Cu-Al2O3 is obtained by a chemical method, starting from water solutions of nitrates up to achieving the requested composition with 3 and 5% of Al2O3. Synthesis of composite powders has been developed through several stages: drying by spraying, oxidation of the obtained powder of precursor and then reduction by hydrogen until the final composition of nanocomposite powder is achieved. After characterization of the obtained powders, which comprised examination by the Scanning Electronic Microscopy (SEM) method and X-ray-structure analysis (RDA), the powders were compacted with compacting pressure of 500 MPa. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperatures of 800 and 900oC for 30, 60, 90 and 120 minutes. Characterization of the obtained Cu-Al2O3 of the nanocomposite sintered system comprised examination of microstructure by the Scanning Electronic Microscopy (SEM), as well as examining of electric mechanical properties. The obtained results show a homogenous distribution of dispersoides in the structure, as well as good mechanical and electric properties. .

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