Formation and size control of tungsten nano particles produced by Nd:YAG laser irradiation

Ozawa, Eiichi; Kawakami, Yuji; Seto, Takafumi

doi:10.1016/s1359-6462(01)00758-8

Cited by 41 publications

(30 citation statements)

References 6 publications

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“…The production rate varies with helium gas pressure and laser pulse energy [93]. Several workers then employed the laser ablation and gas condensation to produce nanoparticles of metals, metal oxides and metal carbides [94][95][96][97][98][99].…”

Section: Physical Vapor Depositionmentioning

confidence: 99%

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Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

835

345

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In recent years, near-nano (submicron) and nanostructured materials have attracted increasingly more attention from the materials community. Nanocrystalline materials are characterized by a microstructural length or grain size of up to about 100 nm. Materials having grain size of $0.1 to 0.3 mm are classified as submicron materials. Nanocrystalline materials exhibit various shapes or forms, and possess unique chemical, physical or mechanical properties. When the grain size is below a critical value ($10-20 nm), more than 50 vol.% of atoms is associated with grain boundaries or interfacial boundaries. In this respect, dislocation pile-ups cannot form, and the Hall-Petch relationship for conventional coarse-grained materials is no longer valid. Therefore, grain boundaries play a major role in the deformation of nanocrystalline materials. Nanocrystalline materials exhibit creep and super plasticity at lower temperatures than conventional micro-grained counterparts. Similarly, plastic deformation of nanocrystalline coatings is considered to be associated with grain boundary sliding assisted by grain boundary diffusion or rotation. In this review paper, current developments in fabrication, microstructure, physical and mechanical properties of nanocrystalline materials and coatings will be addressed. Particular attention is paid to the properties of transition metal nitride nanocrystalline films formed by ion beam assisted deposition process. #

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Section: Physical Vapor Depositionmentioning

confidence: 99%

“…19a and b). Unlike SiC nanorods which are straight [96], the carbon nanotubes with a circular cross section are smooth and curvy (Fig. 19d).…”

Section: Chemical Vapor Depositionmentioning

confidence: 99%

Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

835

345

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“…Much interest has been focused on α-W (bcc) and β-W (A15) nanostructures including nanorods 1-3 , nanoparticles [4][5][6][7] , and thin films [8][9][10] . Due to the technological importance of tungsten, classical interatomic potentials of various forms have been developed to study this metal [11][12][13][14][15][16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

Ab initio based empirical potential applied to tungsten at high pressure

et al. 2017

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Density-functional theory forces, stresses and energies comprise a database from which the optimal parameters of a spline-based empirical potential combining Stillinger-Weber and modified embeddedatom forms are determined. Accuracy of the potential is demonstrated by calculations of ideal shear, stacking fault, vacancy migration, elastic constants and phonons all between 0 and 100 GPa. Consistency with existing models and experiments is demonstrated by predictions of screw dislocation core structure and deformation twinning in a tungsten nanorod. Lastly, the potential is used to study the stabilization of fcc tungsten at high pressure.

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“…The WEE method also offers the advantages of high energy efficiency and low production of by-products. The most attractive feature of this technique is its ability to produce a metal nanopowder at a high speed (∼200 g/h per each machine) on an industrial scale (Jiang and Yatsui 1998;Ozawa et al 2001). However, nanoparticles created by the WEE method have a broad size distribution, or are agglomerated due to their rapid cooling rate and high evaporation rate.…”

Section: Introductionmentioning

confidence: 99%

In-Situ Characterization of Metal Nanopowders Manufactured by the Wire Electrical Explosion Process

Lee

Jung

Lee³

2010

Aerosol Science and Technology

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In order to understand the size distributions of metal nanopowders inside manufacturing equipment operated at elevated pressures, a scanning mobility particle sizer is used to carry out in-situ measurements of metal nanopowders manufactured by the wire electrical explosion process. A pressure reducer and rotating disk diluter are used for conditioning metal nanopowder samples appropriate for real-time aerosol instruments operated at atmospheric pressure. Based on measurement data collected downstream of the evaporation chamber, the production of metal nanopowders shows good stability and uniformity for a total number concentration of approximately 5 × 10 7 particles/cm 3 , and a unimodal size distribution with a mean diameter of approximately 170 nm. Using an aerosol electrometer and two sets of electrostatic classifiers, positively charged particles slightly outnumber negatively charged particles. The performance of the rotating disk diluter is confirmed by comparing the size distributions of metal nanopowders diluted with five different dilution factors, ranging from 235 to 2500. SEM and TEM image analysis indicates that most metal nanopowders manufactured by this process consist of aggregated particles, and their size distributions obtained from SEM images are similar to those measured by the SMPS. The changes in particle size distribution at each stage of the manufacturing process, including the evaporation chamber, trap buffer, cyclone, and mesh filter, are also monitored using the above in-situ monitoring system. The resulting in-situ measurement data can be used for design modifications of equipment, as well as for investigating the sources of nanopowder release to the workplace environment.

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Formation and size control of tungsten nano particles produced by Nd:YAG laser irradiation

Cited by 41 publications

References 6 publications

Nanocrystalline materials and coatings

Nanocrystalline materials and coatings

Ab initio based empirical potential applied to tungsten at high pressure

In-Situ Characterization of Metal Nanopowders Manufactured by the Wire Electrical Explosion Process

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