Observation of particle behavior in copper powder compact during pulsed electric discharge

Yanagisawa, Osamu; Kuramoto, Hideaki; Matsugi, Kazuhiro; Komatsu, Masaaki

doi:10.1016/s0921-5093(02)00726-8

Cited by 63 publications

(34 citation statements)

References 14 publications

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“…With powder compaction methods such as hot pressing, hot isostatic pressing, extrusion, and field-assisted sintering processes, the density of the powder increases with the applied loads and dwell time. In order to model such densification phenomena, reliable material data on the porosity dependence of thermal properties of the material under study is an essential requirement to achieve successful results [2][3][4][5][6]. Although many models for the porosity dependence of physical properties for ceramics and other materials have been derived in the past, the available database and models are often inadequate to quantitatively predict the thermal properties for many powder systems of practical interest [7].…”

Section: Introductionmentioning

confidence: 99%

Effect of Porosity on Thermal Conductivity of Al?Si?Fe?X Alloy Powder Compacts

Sastry

Froyen

Zhang

et al. 2004

International Journal of Thermophysics

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The thermal conductivity and thermal diffusivity of hot-and cold-pressed Al-17Si-5Fe-3.5Cu-1.1Mg-0.6Zr (mass%) alloy powder compacts were investigated as a function of the porosity volume fraction. Samples with a very low degree of porosity were produced by hot-pressing air atomized alloy powder with a particle size of 45-100 µm. The same powder was used to produce highly porous compacts by cold compaction using a manual press. The thermal diffusivity of the powder compacts was measured using a sinusoidal modulation photopyroelectric technique in a configuration that is similar to the laser flash method. The thermal diffusivity of the material decreases by a factor of about 13 with an increasing porosity of 25 vol% and a factor of about 300 at 60 vol % porosity. Since the calculated specific heat (weighted average of mass specific heat values of major alloy compounds) is much less porosity dependent, the porosity dependence of the thermal conductivity is similar to the thermal diffusivity and decreases exponentially with increasing porosity. Microstructural characterization of high porosity samples prepared by cold compaction indicated that the distribution of pores is not uniform over the cross-section. An interconnecting network of open and closed pores in the form of channels created pockets of porosity,

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Section: Introductionmentioning

confidence: 99%

Effect of Porosity on Thermal Conductivity of Al?Si?Fe?X Alloy Powder Compacts

Sastry

Froyen

Zhang

et al. 2004

International Journal of Thermophysics

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“…A recent extensive review of the consolidation-synthesis of materials by electric current-activated/assisted sintering (ECAS) [12] did not mention any relation between the applied pressure and current. However, such phenomena can have significant consequences for the understanding of the SPS process.…”

Section: Discussionmentioning

confidence: 99%

Can the use of pulsed direct current induce oscillation in the applied pressure during spark plasma sintering?

Salamon

Eriksson

Nygren

et al. 2012

Science and Technology of Advanced Materials

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The spark plasma sintering (SPS) process is known for its rapid densification of metals and ceramics. The mechanism behind this rapid densification has been discussed during the last few decades and is yet uncertain. During our SPS experiments we noticed oscillations in the applied pressure, related to a change in electric current. In this study, we investigated the effect of pulsed electrical current on the applied mechanical pressure and related changes in temperature. We eliminated the effect of sample shrinkage in the SPS setup and used a transparent quartz die allowing direct observation of the sample. We found that the use of pulsed direct electric current in our apparatus induces pressure oscillations with the amplitude depending on the current density. While sintering Ti samples we observed temperature oscillations resulting from pressure oscillations, which we attribute to magnetic forces generated within the SPS apparatus. The described current-pressure-temperature relations might increase understanding of the SPS process.

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“…Перспективным способом получения матери-алов с высокоплотной нано-и ультрамелкозерни-стой структурой является технология электроим-пульсного плазменного спекания (ЭИПС) (в ино-странной литературе -«Spark Plasma Sintering») [12,13]. Основная его идея состоит в высокоско-ростном нагреве порошковых материалов в ва-кууме или инертной среде путем пропускания через оснастку и образец постоянного импульс-ного тока большой мощности с одновременным приложением давления.…”

Section: Introductionunclassified

“…Большие скорости на-грева приобретают особую важность при спека-нии наноматериалов, способствуя ограничению роста нанозерен и формированию однородной и высокоплотной наноструктуры при понижен-ных температурах консолидации. Металлические и керамические материалы, полученные методом ЭИПС, характеризуются повышенными плотно-стью и механическими свойствами, что открывает новые возможности создания конструкционных материалов различного функционального назна-чения [12][13][14][15][16].…”

Section: Introductionunclassified