Sintering in Gas Discharges

Bennett, C. E. G.; McKinnon, N. A.; Williams, L. S.

doi:10.1038/2171287a0

Cited by 78 publications

(32 citation statements)

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“…Advantages of non-plasma microwave processing over furnace treatment are reported to include finer grain sizes, rounded porosity and higher ductility and toughness [29]. Increased shrinkage rates and decreased grain sizes can be achieved with microwave plasma treatments compared with furnace sintering [30][31][32]. With these advantages and significantly reduced cycle times, microwave-assisted plasma sintering offers an economic route for the production and reduced energy consumption per process.…”

Section: Introductionmentioning

confidence: 99%

Application of a novel microwave plasma treatment for the sintering of nickel oxide coatings for use in dye-sensitized solar cells

Awais

Rahman

MacElroy

et al. 2011

Surface and Coatings Technology

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In this study the use of microwave plasma sintering of nickel oxide (NiO x ) particles for use as ptype photoelectrode coatings in dye-sensitized solar cells (DSSCs) is investigated. NiO x was chosen as the photocathode for this application due to its stability, wide band gap and p-type 2 nature. For high light conversion efficiency DSSCs require a mesoporous structure exhibiting a high surface area. This can be achieved by sintering particles of NiO x onto a conductive substrate. In this study the use of both 2.45 GHz microwave plasma and conventional furnace sintering were compared for the sintering of the NiO x particles. Coatings 1 to 2.5 µm thick were obtained from the sintered particles (mean particle size of 50 nm) on 3 mm thick fluorine-doped tin oxide (FTO) coated glass substrates. Both the furnace and microwave plasma sintering treatments were carried out at ~450 ºC over a 5 minute period. Dye sensitization was carried out using Erythrosin B and the UV-vis absorption spectra of the NiO x coatings were compared. A 44% increase in the level of dye adsorption was obtained for the microwave plasma sintered samples as compared to that obtained through furnace treatments. While the photovoltaic performance of the DSSC fabricated using the microwave plasma treated NiO x coatings exhibited a tenfold increase in the conversion efficiency in comparison to the furnace treated samples. This enhanced performance was associated with the difference in the mesoporous structure of the sintered NiO x coatings.

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Section: Introductionmentioning

confidence: 99%

Application of a novel microwave plasma treatment for the sintering of nickel oxide coatings for use in dye-sensitized solar cells

Awais

Rahman

MacElroy

et al. 2011

Surface and Coatings Technology

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“…Advantages of non-plasma microwave processing over furnace treatment include finer grain sizes, due to the faster processing times, rounded porosity and higher ductility and toughness [7]. Increased shrinkage rates and decreased grain sizes can be achieved with microwave and plasma processing compared with furnace sintering [1,8,9]. This study compares, for the first time, furnace and plasma microwave assisted treatments for the sintering of diamond metal matrix composites (MMCs).…”

Section: Introductionmentioning

confidence: 99%

“…Plasma sintering has been demonstrated as a rapid and uniform sintering technique since its first reported studies by Bennett et al [1]. Sintering has been carried out in plasmas generated using microwave, rf or DC power supplies [1][2][3] and the dominant heating mechanism is associated with ion and fast neutral bombardment.…”

Section: Introductionmentioning

confidence: 99%

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Rapid discharge sintering of nickel–diamond metal matrix composites

Twomey

Breen

Byrne

et al. 2011

Journal of Materials Processing Technology

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Publication information Journal of Materials Processing Technology, 211 (7): 1210-1216Publisher Elsevier Item record/more information http://hdl.handle.net/10197/5260 Publisher's statementThis is the author's version of a work that was accepted for publication in Journal of Materials Processing Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Materials Processing Technology, 211 (7) AbstractThere is considerable interest in processing technologies which can lead to more energy efficient sintering of abrasive metal matrix composites. In this study the use of a novel microwave plasma processing technique called Rapid Discharge Sintering (RDS) for sintering nickel-diamond metal matrix composites (MMCs) is evaluated. Nickel-diamond powder composites (80 -20 % by weight respectively) were uniaxially pressed into 20 mm discs at compaction pressures of 100, 200 and 300 MPa. The discs were sintered using a microwave plasma formed with hydrogen and hydrogen/nitrogen as the discharge gases. For comparison, discs were also sintered using a tube furnace in a gas flow of hydrogen and nitrogen (3:1). Discs pressed to 300 MPa were treated at both 850 and 1000 o C. The properties of the sintered nickel-diamond composites were characterised using density, flexural stress, hardness, wear resistance, SEM and XRD. The RDS samples sintered at 1000 o C achieved the maximum disc strength of approximately 470 MPa within a 20 minute chamber processing time, compared with 6 hours for furnace sintered samples. RDS samples exhibited increased hardness values and a finer nickel matrix over furnace sintered samples. RDS has shown the ability to process nickel-diamond MMCs without oxidation or graphitisation at higher temperatures. As a result, minimal diamond destruction was observed during abrasive wear testing for RDS samples.

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“…During the RDS process gas molecules become excited by the microwaves and a plasma is formed, this in turn heats the material placed inside a plasma ball. In an early paper in this area, it was proposed that the discharge may cause activation of the particle surfaces that results in concentrated heat effects and hence, in an in situ cleaning action of powder particles [10].…”

Section: Introductionmentioning

confidence: 99%