Correlation between Thermal and Electrical Properties of Spark Plasma Sintered (SPS) Porous Copper

Gelbstein, Yaniv; Haim, Y.; Kalabukhov, Sergey; VladimirKasiyan,; Hartmann, Steffen; Rothe, Steffen; Frage, N.

doi:10.5772/59010

Cited by 4 publications

(5 citation statements)

References 16 publications

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“…[49]) due to porosity and oxidation issues [50]. On the contrary, a steep growth towards one order of magnitude higher-values is observed for Cu-25WS2 and Cu-30WS2.…”

Section: Electrical Resistivitymentioning

confidence: 99%

Investigation of second phase concentration effects on tribological and electrical properties of Cu–WS2 composites

Freschi

Virgilio

Haiko

et al. 2022

Tribology International

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“…[49]) due to porosity and oxidation issues [50]. On the contrary, a steep growth towards one order of magnitude higher-values is observed for Cu-25WS2 and Cu-30WS2.…”

Section: Electrical Resistivitymentioning

confidence: 99%

Investigation of second phase concentration effects on tribological and electrical properties of Cu–WS2 composites

Freschi

Virgilio

Haiko

et al. 2022

Tribology International

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“…Although the porosity was not directly measured on these samples, such a linkage was demonstrated in Refs. [39,40]. A similar positive effect is achieved by powder treatment in the reducing atmosphere (CLC2 vs. ULC2).…”

Section: Thermal Propertiesmentioning

confidence: 75%

On the Structural and Chemical Homogeneity of Spark Plasma Sintered Tungsten

Matějíček

Vilémová

Veverka

et al. 2019

Metals

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Tungsten-based materials are the prime candidate plasma-facing materials for future fusion reactors, such as DEMO. Spark plasma sintering is a prospective fabrication technology with several advantageous features. The concurrent application of electric current, temperature and pressure enhances the sintering process, allowing for lower temperatures and shorter sintering times than traditional powder metallurgy processes. This in turn helps to avoid excessive grain growth and phase segregation in W-alloys. This study is focused on several factors that may influence the homogeneity of the sintered compacts-namely the diffusion of carbon from the graphite die, purity of the powder and sintering conditions. The following characteristics of spark plasma-sintered tungsten compacts were studied: composition (especially carbon and oxygen content), porosity, mechanical properties (hardness and fracture strength), and thermal diffusivity. The effects of the abovementioned processing factors were quantified, and local variations of selected properties were assessed. plasma sintering (SPS, also called Field Assisted Sintering Technology, FAST) is a progressive technique to consolidate various materials, metals as well as ceramics, glass etc. Relatively low temperatures, high heating rates and short processing times-compared to traditional sintering techniques-are generally favorable for the retention of fine grains. In SPS, the sintered material in the form of powder is introduced into a die and, subsequently, high-intensity (pulsed or steady) electric currents up to several thousand A and uniaxial pressure up to hundreds MPa are applied. The die and the powder are heated by Joule heating. Graphite foil is usually inserted between the powder and the die in order to eliminate undesirable bonding of sintered material to the die. Depending on the parameters and the sintered material, temperature can reach up to~2400 • C and with suitable parameters, fully dense samples can be obtained [5][6][7]. Sintering parameters have a considerable effect on the resulting microstructure, homogeneity and other properties of the samples. Basic variables characterizing the sintering process are: (i) sintering temperature, (ii) applied pressure, and (iii) duration of the holding time at the sintering temperature. The results are also sensitive to the heating rate, manner of pressure application, die dimensions, sintering atmosphere etc.

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“…The width of the semi-melted layer that connects the HAZ and NZ for joints without USV was approximately 100–200 µm. The formation of H 2 O steam bubbles at the fusion line formed a microporosity that may have reduced the electrical conductivity of the copper joint [ 7 ]. In this study, the attached transducer at 28 KHz and 60 W provided USV at the contact line between the solid and liquid metal ( Figure 13 a).…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, it is difficult to obtain a joint for thin copper sheets with high electrical conductivity. On the other hand, the presence of porosity in the nugget zone (NZ) of a pure copper-welded joint reduces the electrical conductivity [ 7 ] , in which porosity at NZ is caused by a high diffusivity of hydrogen in the weld pool during Gas Tungsten Arc Welding process (GTAW) [ 8 ]. Although the effect of ultrasonic vibration (USV) on grain refinement and hydrogen removal from non-ferrous light metal alloys was examined [ 9 , 10 , 11 ], research on nugget degassing for heavy non-ferrous metal melts such as copper is still lacking.…”

Section: Introductionmentioning

confidence: 99%

The Mechanism of Ultrasonic Vibration on Grain Refining and Degassing in GTA Spot Welding of Copper Joints

2018

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This paper examines the effect of ultrasonic vibration (USV) on grain size and interrupted porosity in Gas Tungsten Arc (GTA) spot-welded copper. Grain size was refined by perpendicularly attaching a transducer to the welded sheet and applying USV to the weld pool for a short time (0, 2, 4, and 6 s) in addition improvements to the degassing process. Results illustrate a significant reduction of grain size (57%). Notably, USV provided interaction between reformations (fragmentation) and provided nucleation points (detaching particles from the fusion line) for grains in the nugget zone and the elimination of porosity in the nugget zone. The GTA spot welding process, in conjunction with USV, demonstrated an improvement in the corrosion potential for a copper spot-welded joint in comparison to the joint welded without assistance of USV. Finally, welding of copper by GTA spot welding in conjunction with ultrasound for 2 s presented significant mechanical properties.

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Correlation between Thermal and Electrical Properties of Spark Plasma Sintered (SPS) Porous Copper

Cited by 4 publications

References 16 publications

Investigation of second phase concentration effects on tribological and electrical properties of Cu–WS2 composites

Investigation of second phase concentration effects on tribological and electrical properties of Cu–WS2 composites

On the Structural and Chemical Homogeneity of Spark Plasma Sintered Tungsten

The Mechanism of Ultrasonic Vibration on Grain Refining and Degassing in GTA Spot Welding of Copper Joints

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