Synthesis of W- Cu- Ag Nanopowders Produced by a Co-Precipitation Process

2011 ◽  
Vol 312-315 ◽  
pp. 312-318 ◽  
Author(s):  
Golnaz Taghavi ◽  
Hamid Reza Rezaie ◽  
Hekmat Razavizadeh
Keyword(s):  
Silver Nitrate ◽  
Copper Nitrate ◽  
Hydrogen Atmosphere ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Oxide Powders ◽  
Co Precipitation ◽  
Nanocomposite Powders ◽  
Silver Nitrate Solutions

A homogeneous precipitation process was employed to prepare nanosized W-10%wtCu-10%wtAg powders using ammonium meta tungstate, copper nitrate and silver nitrate as precursors. The initial precipitates were obtained by reacting ammonium meta tungstate, copper nitrate and silver nitrate solutions under certain PH and temperature. In order to synthesis W-Cu-Ag composite powders, the initial precipitates washed, dried, and then calcined in air in order to prepare CuWO4-x, Ag2W4O13 and WO3 oxide powders for the next step reduction. The reduction was carried out in a hydrogen atmosphere to form the final W-Cu-Ag nanocomposite powders. The powders were characterized by X-ray diffraction (XRD) technique. The morphologies of the powders were observed by scanning electron microscopy (SEM).

Effect of h-BN on Sintering Behavior, Microstructures and Mechanical Properties of YAG Bulk Composites

2016 ◽  
Vol 697 ◽  
pp. 395-398 ◽  
Author(s):  
Shi Bin Li ◽  
Jie Guang Song ◽  
Hong Ying Ru ◽  
Xiao Bo Bai
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Precipitation Process ◽  
Sintering Behavior ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
X Ray ◽  
Co Precipitation ◽  
Scanning Electron

The shell structure YAG composite powders with different volume fraction (15, 20 and 25vol%) micro h-BN have been prepared by co-precipitation process. The bulk composites were performed by pressure sintering at 1600°C under a pressure of 30MPa in vacuum. The mechanical properties (elastic modulus, hardness, and fracture toughness) and relative density of the composites were investigated detailedly. Furthermore, phase composition and microstructure of the composites were analyzed thoroughly by X-ray diffraction, scanning electron microscopy. Meanwhile, good machinability is maintained due to the low hardness of the second phase.

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. .

Reduction Behavior of W and Cu Oxides Powder Mixture

2008 ◽  
Vol 135 ◽  
pp. 143-149
Author(s):  
Seong Lee ◽  
Joon Woong Noh ◽  
Eun Pyo Kim ◽  
Moon Hee Hong
Keyword(s):  
Gas Phase ◽  
Powder Mixture ◽  
Hydrogen Atmosphere ◽  
Hydrogen Gas ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Composite Powders ◽  
Reduction Behavior ◽  
Scanning Electron Microscopic ◽  
Increasing Temperature

The reduction behavior of WO3 and CuO powder mixture has been studied by using thermo-gravimetric(TG), X-ray diffraction, and scanning electron microscopic analyses. The powder mixture was manufactured by ball-milling. It was found that W coated W-Cu composite powders were formed when reducing the powder mixture under hydrogen atmosphere. The following reduction steps are suggested as a mechanism for the formation of W coated W-Cu composite powders: with increasing temperature, Cu is initially reduced from CuO and the reduction reactions of WO3 to WO2 via WO2.9 and WO2.72 are followed. The gas phase WO2(OH)2 is formed by the reaction of the WO2 and water vapor, and then WO2(OH)2 diffuses toward Cu surface and deposits on it as W by reducing reaction with environmental hydrogen gas. The formation mechanism of W coated W-Cu composite powders involving the gas phase transportation reaction has been confirmed by the model experiment conducted by using Cu plate and WO3 powder.

Characterization of Mechanically Alloyed Al5083 Alloy and Composite and Consolidation by Equal Channel Angular Pressing

2015 ◽  
Vol 764-765 ◽  
pp. 23-27 ◽  
Author(s):  
G. Kondaiah ◽  
K. Chandra Sekhar ◽  
B. Chaithanyakrushna ◽  
Balasubramanian Ravisankar ◽  
S. Kumaran
Keyword(s):  
Equal Channel Angular Pressing ◽  
Back Pressure ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Composite Powders ◽  
Oxide Powders ◽  
Angular Pressing ◽  
Al 5083 Alloy ◽  
Milled Powders

In the present work a comparative study was carried out on consolidation of Al-5083 alloy and 5wt. % nanoyttrium oxide powders by Equal channel angular pressing (ECAP). The powders were milled for 10, 15 and 20 hrs using planetary ball mill under optimized process parameters. The milled powders were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Milled powders exhibit nanocrystalline single phase after 10hrs. The crystallite size after 20 hr of milling, alloy and composite powders were found to be 23nm and 57nm respectively. The 20hr milled alloy and composite powder was consolidated by equal channel angular pressing (ECAP) through 90o die channel angle using route-A for two passes with and without back pressure. Density of ECAPed samples were measured using Archimedes principle. The highest density was found as 96% for the alloy after 2 passes without backpressure and sintering and 94% for the composite after 2 passes with back pressure and sintering.

Copper (I) oxide powder generation by spray pyrolysis

1996 ◽  
Vol 11 (11) ◽  
pp. 2861-2868 ◽  
Author(s):  
D. Majumdar ◽  
T. A. Shefelbine ◽  
T. T. Kodas ◽  
H. D. Glicksman
Keyword(s):  
Spray Pyrolysis ◽  
Solid Phase ◽  
Average Crystallite Size ◽  
Copper Nitrate ◽  
Nitrogen Atmosphere ◽  
X Ray Diffraction ◽  
Oxide Powders ◽  
Phase Pure ◽  
Pure Cu ◽  
Solid Spheres

Copper oxide powders were prepared by the spray pyrolysis of copper nitrate solutions over a range of temperatures (400–1300 °C) and residence times (3–7 s). Phase-pure [by x-ray diffraction (XRD)] copper (I) oxide was obtained at 800–1300 °C in an inert (nitrogen) atmosphere. The particles varied from smooth, solid spheres at 1300 °C to irregularly shaped and hollow particles at 800 °C with dense particles of Cu2O being made only at 1000 °C or higher. The particles were polycrystalline with an average crystallite size of 42 nm at 800 °C, while at 1000–1200 °C, the particles were single crystals. Spray pyrolysis in forming gas (7% H2–N2) atmosphere at 500–700 °C gave Cu while spray pyrolysis in air yielded CuO over 800–1000 °C and a mixture of Cu2O/CuO at 1200 °C. These results show that solid, phase-pure Cu2O particles can be produced by aerosol-phase densification at temperatures below its melting point (1235 °C).

The Effect of Pore-Formers on the Performance of YSZ/NiO Composite Material

2012 ◽  
Vol 624 ◽  
pp. 186-189
Author(s):  
Zhong Zhou Yi ◽  
Hong Yan Sun ◽  
Yi Ming Liu ◽  
Feng Rui Zhai
Keyword(s):  
Composite Material ◽  
Liquid Phase ◽  
Composite Ceramic ◽  
Precipitation Process ◽  
Corn Meal ◽  
Composite Powders ◽  
Pore Former ◽  
Gel Casting ◽  
Different Types ◽  
Co Precipitation

YSZ/NiO composite powders were successfully synthesized by chemical liquid phase co-precipitation process. YSZ/NiO composite ceramic bodies were prepared by gel casting. Three different types and amounts of pore-formers were added into the YSZ/NiO suspension. The results show that the YSZ/NiO composite with the best properties and optimal porosity of 42.18% was obtained when the 7wt.% corn meal was used as pore-former.

scholarly journals Avrami behavior of magnetite nanoparticles formation in co-precipitation process

2011 ◽  
Vol 47 (2) ◽  
pp. 211-218 ◽  
Author(s):  
R. Ahmadi ◽  
Madaah Hosseini ◽  
A. Masoudi
Keyword(s):  
Magnetite Nanoparticles ◽  
Morphological Characterization ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Nanoparticle Formation ◽  
Transmission Electron ◽  
Formation Behavior ◽  
Simplifying Assumptions ◽  
Co Precipitation ◽  
20 Nm

In this work, magnetite nanoparticles (mean particle size about 20 nm) were synthesized via coprecipitation method. In order to investigate the kinetics of nanoparticle formation, variation in the amount of reactants within the process was measured using pH-meter and atomic absorption spectroscopy (AAS) instruments. Results show that nanoparticle formation behavior can be described by Avrami equations. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were performed to study the chemical and morphological characterization of nanoparticles. Some simplifying assumptions were employed for estimating the nucleation and growth rate of magnetite nanoparticles.

In-situ synthesis of Si3N4/TiN nanocomposite powders in cryogenic solution

2007 ◽  
Vol 1056 ◽  
Author(s):  
Mei Yang ◽  
Mingli Lü ◽  
Hongmin Zhu
Keyword(s):  
Liquid Ammonia ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
Titanium Chloride ◽  
Transmission Electron ◽  
C 50 ◽  
Co Precipitation ◽  
Nanocomposite Powders ◽  
In Situ Coating

ABSTRACTA new method of Si3N4/TiN nanocomposite powders through reaction at low temperatures was proposed and tested. The reduction of titanium chloride and silicon chloride by sodium was conducted in liquid ammonia at the temperature range of −40°C∼−50°C, and titanium nitride and silicon nitride nanopowders were obtained. Based on these reactions, in-situ coating and co-precipitation were conducted. The TiN nano-particles deposited on the surface of Si3N4 particles as the nuclei in the in-situ coating and in the co-precipitation two or more source of ions were reduced uniformly in the liquid ammonia. Si3N4/TiN nanocomposite powders were prepared by the both routes and were characterized with X-ray diffraction, transmission electron microscopy. The effects of in-situ and the particle size on the morphology of the composite were discussed.

scholarly journals One-step synthesis and microstructure of CuO-SDC composites

Cerâmica ◽  
2017 ◽  
Vol 63 (365) ◽  
pp. 52-57 ◽  
Author(s):  
H. C. T. Firmino ◽  
A. J. M. Araújo ◽  
R. P. S. Dutra ◽  
R. M. Nascimento ◽  
S. Rajesh ◽  
...  
Keyword(s):  
Particulate Material ◽  
Transport Processes ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Chemical Route ◽  
One Step ◽  
Microstructural Design ◽  
Nanocomposite Powders

Abstract An in situ one step synthesis route based on the polymeric precursor method was used to produce dual phase CuO-samaria doped ceria (SDC) nanocomposite powders. This chemical route allowed to obtain composite powders with reduced particle size and uniform distribution of Cu, Ce and Sm elements. The particulate material was characterized by powder X-ray diffraction (XRD) combined with Rietveld refinement. CuO-SDC sintered in air between 950 to 1050 °C and subsequently reduced to Cu-SDC cermets were further characterized by XRD and scanning electron microscopy. The open porosity was measured using the Archimedes’ principle. Suitable microstructures for both charge transfer and mass transport processes (30 to 45% porosity) were attained in Cu-SDC cermets previously fired at 1000 to 1050 °C. Overall results indicated that CuO-SDC composites and Cu-SDC cermets with potential application as anodes for solid oxide fuel cells (SOFCs) can be obtained by microstructural design. An anode supported half-cell was prepared by co-pressing and co-firing gadolinia doped ceria (CGO) and the herein synthesized CuO-SDC nanocomposite powder.

W-Cu Nano-Composite Powders Prepared by Hydrothermal Method

2014 ◽  
Vol 541-542 ◽  
pp. 239-242 ◽  
Author(s):  
Jing Pei Xie ◽  
Shu Liu ◽  
Dou Qin Ma ◽  
Feng Mei Wang ◽  
Ai Qin Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Hydrothermal Method ◽  
Reduction Process ◽  
Good Method ◽  
Copper Nitrate ◽  
Composite Powders ◽  
Transmission Electron ◽  
Nanocomposite Powders ◽  
Co Reduction

The grain size of W-Cu nanocomposites would greatly affect the density of W-Cu alloy. In this work, W-Cu oxide nanocomposite powders were prepared by sodium tungstate and copper nitrate via hydrothermal method, and W-Cu nanocomposite powders were obtained by subsequently co-reduction process. The characterization of W-Cu nanocomposite powders were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), energy spectrum analysis (EDS) and transmission electron microscope (TEM). The results indicated that hydrothermal method was a good method for the preparation of W-Cu oxide nanocomposite powders. W-Cu nanocomposite powders, whose grain size was about 70nm and distributed uniformity, were manufactured by co-reduction process.

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