Characterisation and sintering studies of mechanically milled nano tungsten powder

Sarkar, Rajdeep; Ghosal, Partha; Manda, Premkumar; Singh, Avtar; Muraleedharan, K.; Chakraborti, A. K.; Bagchi, Tapan P.; Sarma, Bijoy

doi:10.1179/174329008x284787

Cited by 13 publications

(8 citation statements)

References 17 publications

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“…The applications of W metal are also rapidly expanding in the account of increasing development of science and technology. Normally, W powders as raw material are selected to prepare products by powder metallurgical techniques, such as hot pressing (HP), hot isostatic pressing (HIP), and spark plasma sintering (SPS), so the performance of W particles is one of the critical factors to affect the properties of W products [5–7]. In general, there are many high requirements in W powders for preparing different products, such as the average particle size, distribution of particle size, surface area, and microstructure [8].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Nanoscale Tungsten Particles with Hollow Superstructure Using Spray Drying Combined with Calcination Process

Zhao

Cao

et al. 2019

Nanoscale Res Lett

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Nanoscale tungsten (W) powder is used in some special materials. In this study, a hollow superstructure W powder consisting of nanoparticles was synthesized by spray drying combined with two-step calcination from commercial (NH 4 ) 6 W 7 O 24 ·6H 2 O. The high-pressure gas (HPG) was the significant factor in spray drying process, which affect the BET surface area and average particles size of the spray-dried powders. The detailed influences of calcined steps and calcination temperature in the microstructure and average particles size of final W particles were investigated. The size distribution of as-synthesized nanoscale W particles with hollow superstructure was from 40 to 200 nm, and the average size was about 100 nm. The as-synthesized W powder shows good sintering properties. It should be noted that the powder technology in this study can be used to synthesize other powders with high-performance requirements. Graphical abstract .

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Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Nanoscale Tungsten Particles with Hollow Superstructure Using Spray Drying Combined with Calcination Process

Zhao

Cao

et al. 2019

Nanoscale Res Lett

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“…These include self-propagating high-temperature synthesis, [8] reverse micelle synthesis, [9] thermal methods, [10][11][12][13] mechanical milling, [14] and electrochemical techniques. [15] Most of the resulting powders from these processes are very likely heavily agglomerated, although a determination of the levels of agglomeration have not been reported in most cases.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Particle and Crystallite Size in Tungsten Nanopowder Synthesis

Graeve

Madadi

Kanakala

et al. 2010

Metall Mater Trans A

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Tungsten nanopowders were synthesized by a low-temperature technique and then heat treated in a gaseous reductive atmosphere in order to study the phase evolution, crystallite size, and particle size of the powders as the heat treatment temperature was modified. Synthesis of the powders was carried out in aqueous media using NaBH 4 as a reducing agent using careful control of the pH of the solutions. The XRD patterns of the as-synthesized powders showed an amorphous phase. After washing, energy dispersive spectroscopy showed that the powders had peaks for oxygen and tungsten. In order to promote crystallization and eliminate the oxygen, the powders were heat treated at 773 K, 923 K, and 1073 K (500°C, 650°C, and 800°C) in a H 2 /CH 4 reducing atmosphere for 2 hours. XRD after heat treatment showed a-W peaks for the powders treated at 1073 K and 923 K (800°C and 650°C) and a mixture of b-W and a-W for the powders treated at 773 K (500°C). The crystallite sizes determined from X-ray peak broadening were 12, 16, and 20 nm, whereas the average particle sizes from dynamic light scattering were 260, 450, and 750 nm, for heat treatment temperatures of 773 K, 923 K, and 1073 K (500°C, 650°C, and 800°C), respectively. The average crystallite size and particle sizes increased proportionally with the treatment temperature, in contrast to what has been found for some ceramics, in which as the heat treatment temperature is increased, the crystallite size increases, but the particle size stays constant.

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“…A commonly used method is mechanical milling (MM) or mechanical alloying (MA), a top-down approach in which micron sized particulates are milled and fractured to the nanoscale. Both pure W powder (MM) 12,13 and composite powders (MA) such as W-Y, 11,14 W-Y 2 O 3 11,15 or W-TiC 16,17 have been employed in this approach. The extended milling treatment results in powders with crystallite sizes below 20 nm.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of nanostructured W–Y2O3 materials by chemical methods

et al. 2012

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A novel method for the fabrication of highly uniform oxide dispersion-strengthened (ODS) materials made by chemical processing is presented. The powders are fabricated by a two-step route starting with a chemical synthesis at room temperature, producing nanocrystalline yttrium doped tungsten trioxide hydrate precursor powders. Thermogravimetric analysis with evolved gas analysis revealed the presence of ammonium nitrate in the precursors. The second step is the reduction of the precursor in a hydrogen atmosphere at 600 and 800 C. The reduced powders, containing W-1.2%Y 2 O 3 , showed two types of tungsten particles, cube-shaped with a size less than 250 nm and finer particles (<50 nm) of both spherical and cubic shape. The powder was consolidated by spark plasma sintering at 1100 C, producing a bulk material with a relative density of 88%. Characterization of the sintered materials by high resolution scanning electron microscopy revealed a uniform microstructure with tungsten grains of less than 300 nm and nanosized oxide particles uniformly dispersed at the tungsten grain boundaries, as well as inside the tungsten grains. Experimental determination of the elastic properties was conducted by nanoindentation tests and fracture toughness was studied by radial indentation cracking.

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Characterisation and sintering studies of mechanically milled nano tungsten powder

Cited by 13 publications

References 17 publications

Synthesis and Characterization of Nanoscale Tungsten Particles with Hollow Superstructure Using Spray Drying Combined with Calcination Process

Synthesis and Characterization of Nanoscale Tungsten Particles with Hollow Superstructure Using Spray Drying Combined with Calcination Process

Analysis of Particle and Crystallite Size in Tungsten Nanopowder Synthesis

Fabrication of nanostructured W–Y2O3 materials by chemical methods

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