scholarly journals Electric Current-Assisted Joining of Copper Plates Using Silver Formed by In-Situ Decomposition of Ag2C2O4

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 538 ◽  
Author(s):  
Dina Dudina ◽  
Alexander Matvienko ◽  
Anatoly Sidelnikov ◽  
Mikhail Legan ◽  
Vyacheslav Mali ◽  
...  
Keyword(s):  
Shear Strength ◽  
Electric Current ◽  
Reference Sample ◽  
Silver Layer ◽  
Metallic Silver ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
In Situ Decomposition

Pulsed electric current can be used for the fast sintering of powders as well as joining of macroobjects. In this work, we brazed copper plates using a silver layer that was formed in situ by the decomposition of a silver oxalate Ag2C2O4 powder placed between the plates. Joining was conducted in the chamber of a Spark Plasma Sintering (SPS) facility with and without a graphite die. In the die-assisted tooling configuration, indirect heating of the assembly from the graphite die carrying electric current occurred until the brazing layer transformed into metallic silver. The passage of electric current through a Cu/Ag2C2O4/Cu stack placed between the electrodes without a die was possible because of the formation of Cu/Cu contacts in the areas free from the Ag2C2O4 particles. Joints that were formed in the die-assisted experiments showed a slightly higher shear strength (45 MPa) in comparison with joints formed without a die (41 MPa). The shear strength of the reference sample (obtained without a die), a stack of copper plates joined without any brazing layer, was only 31 MPa, which indicates a key role of the silver in producing strong bonding between the plates. This study shows that both die-assisted tooling configurations and those without a die can be used for the SPS brazing of materials by the oxalate-derived silver interlayer.

scholarly journals Role of Ti3AlC2 MAX phase on characteristics of in-situ synthesized TiAl intermetallics. Part I: sintering and densification

2021 ◽  
Vol 1 (3) ◽  
pp. 169-175
Author(s):  
Maryam Akhlaghi ◽  
Esmaeil Salahi ◽  
Seyed Ali Tayebifard ◽  
Gert Schmidt
Keyword(s):  
Max Phase ◽  
Displacement Rate ◽  
Heating Process ◽  
Aluminum Powders ◽  
Plasma Sintering ◽  
Rate Versus ◽  
Spark Plasma ◽  
Composite Samples

Five TiAl–Ti3AlC2 composite samples containing (10, 15, 20, 25 and 30 wt% Ti3AlC2 MAX phase) were prepared by spark plasma sintering technique at 900 °C for 7 min under 40 MPa. For this purpose, metallic titanium and aluminum powders (aiming at the in-situ formation of the TiAl matrix phase) were ball-milled with predetermined contents of Ti3AlC2 MAX phase, which already was synthesized using the same metallic powders as well as graphite flakes. Displacement-time-temperature variations during the heating and sintering steps, displacement rate versus temperature, displacement rate versus time, and densification behavior were studied. Two sharp changes were detected in the diagrams: the first one, ~16 min after the start of the heating process due to the melting of Al, and the second one, after ~35 min because of the sintering progression and the applied final pressure. The highest relative densities were measured for the samples doped with 20 and 25 wt% Ti3AlC2 additives. More Ti3AlC2 addition resulted in decreased relative density because of the agglomeration of MAX phase particles.

scholarly journals Silicon carbide nanocomposites reinforced with disordered graphitic carbon formed in situ through oxidation of Ti3C2 MXene during sintering

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
M. Petrus ◽  
J. Woźniak ◽  
T. Cygan ◽  
A. Lachowski ◽  
A. Rozmysłowska-Wojciechowska ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
Reference Sample ◽  
Powder Metallurgy Technique ◽  
Sintering Process ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma ◽  
Sintering Method

AbstractThis article describes the manufacturing of silicon carbide composites with the addition of quasi-two-dimensional titanium carbide Ti3C2, known as MXene. The composites were obtained by the powder metallurgy technique, consolidated with the use of the Spark Plasma Sintering method at 1900 °C and dwelled for 30 min. The influence of the Ti3C2 MXene addition on the microstructure and mechanical properties of the composites was investigated. The structure of the MXene phase after the sintering process was also analyzed. The results showed a significant increase (almost 50%) of fracture toughness for composites with the addition of 0.2 wt% Ti3C2 MXene. In turn, the highest hardness, 23.2 GPa, was noted for the composite with the addition of the 1.5 wt% Ti3C2 MXene phase. This was an increase of over 10% in comparison to the reference sample. The analysis of chemical composition and observations using a transmission electron microscope showed that the Ti3C2 MXene phase oxidizes during sintering, resulting in the formation of crystalline, highly defected, disordered graphite structures. The presence of these structures in the microstructure, similarly to graphene, significantly affects the hardness and fracture toughness of silicon carbide.

scholarly journals Effect of Electric Current on SPS Densification of Spherical Copper Powder

2021 ◽  
Vol 5 (4) ◽  
pp. 119
Author(s):  
Romaric Collet ◽  
Sophie Le Gallet ◽  
Frédéric Charlot ◽  
Sabine Lay ◽  
Jean-Marc Chaix ◽  
...  
Keyword(s):  
Electric Current ◽  
Copper Powder ◽  
Pure Copper ◽  
Joule Effect ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Significant Temperature ◽  
Two Parameters ◽  
A Current

When a current is involved, as in spark plasma sintering, metallic powders are heated by the Joule effect through both tool and specimen. Other mechanisms might occur, but it is difficult to separate the role of the temperature from the role of the current inside the sample as, in most cases, the two parameters are not controlled independently. In this paper, the consolidation and the densification of a pure copper powder were studied in three configurations for obtaining different electric current paths: (i) current flowing through both the powder and the die, (ii) current forced into the powder and (iii) no current allowed in the powder. Electrical conductivity measurements showed that even low-density samples displayed higher conductivities than graphite by several orders of magnitude. FEM simulations confirmed that these copper specimens were mainly heated by the graphite punches. No modification of the microstructure by the flow of current could be observed. However, the absence of current in the specimen led to a decrease in densification. No significant temperature difference was modeled between the configurations, suggesting that differences are not linked to a thermal cause but rather to a current effect.

scholarly journals Large strain hardening of magnesium containing in situ nanoparticles

2021 ◽  
Vol 10 (1) ◽  
pp. 1018-1030
Author(s):  
Zhongxue Feng ◽  
Yuhua Zhang ◽  
Jun Tan ◽  
Yuming Chen ◽  
Yiming Chen ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Work Hardening ◽  
High Strain ◽  
Large Strain ◽  
Plasma Sintering ◽  
Pile Up ◽  
Spark Plasma ◽  
Dislocation Cells

Abstract In this work, in situ magnesium-based composite composed of nanoscale magnesium oxide (MgO), prepared by spark plasma sintering, shows significant plasticity and high strain hardening. During the strain-hardening stage, the incremental work-hardening exponent shows drastic fluctuations due to the pile-up and release of dislocations. The dislocation pile-up at the interface makes it possible to form dislocation cells. Mixed dislocations can be generated within the cells surrounding the MgO particles, which can interact with the stress field and effectively hinder the movement of dislocations, leading to an increase in dislocation density. What is more, grain boundaries have higher elastic modulus and hardness, which may lead to the appearance of microcracks and eventually intergranular fractures. Our results may shed some light on understanding the role of MgO particles in influencing the mechanical properties of Mg alloys and Mg-based composites, especially in work hardening.

Gas Analysis in Spark Plasma Sintering of Hydroxyapatite

2004 ◽  
Vol 449-452 ◽  
pp. 793-796
Author(s):  
N. Yamaguchi ◽  
H. Tanaka ◽  
Osamu Ohashi
Keyword(s):  
Thermal Analysis ◽  
Electric Current ◽  
Spark Plasma Sintering ◽  
Mass Spectroscopy ◽  
Gas Analysis ◽  
The Other ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Lower Temperature

In this paper, the effect of electric current on sintering of hydroxyapatite (HAp) in spark plasma sintering (SPS) process was investigated. The carbonate partially substituting hydroxyapatite was sintered up to 900 °C, and CO2 evolved from HAp powder were measured in situ by using mass spectroscopy apparatus in the same time. The same gas analysis was performed in thermal analysis as comparison. In the thermal analysis, CO2 gas was evolved at about 600 °C. On the other hand, in the SPS process, CO2 gas was detected at lower temperature than that of thermal analysis. This result indicates that the surface of hydroxyapatite particles would be heated up locally in SPS process due to electric current.

Preparing Magnetocaloric LaFeSi Uniform Microstructures by Spark Plasma Sintering

2014 ◽  
Vol 802 ◽  
pp. 491-495
Author(s):  
N. Vicente ◽  
J. Ocanã ◽  
H.N. Bez ◽  
C.S. Teixeira ◽  
Izabel Fernanda Machado ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electric Current ◽  
Spark Plasma Sintering ◽  
Joule Effect ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Vicker’S Microhardness ◽  
Scanning Electron

Spark Plasma Sintering (SPS) of LaFeSi alloy powders was conducted to prepare magnetocaloric La-Fe-Si-based uniform microstructures. Two electrically insulating discs made of alumina were interposed between the punches and powder sample inhibiting the flow of electric current across the powder. This approaching aiming at improving the sample temperature distribution by deviating the electric current throughout the graphite die, since the electric current induces overheating byin situJoule effect on powder. The LaFeSi powder with particles under 150 µm was obtained by mechanical milling of particles from hydrogenated and decrypted casting ingot. The characterizations of sintered samples were performed by Scanning Electron Microscopy (SEM), Archimedes principle, Vicker’s hardness and microhardness. The uniformity of the microstructure was evaluated by checking the evidence of position on the Vicker’s microhardness by means of ANOVA statistics.

scholarly journals Microstructure and properties of nano-laminated Y3Si2C2 ceramics fabricated via in situ reaction by spark plasma sintering

2021 ◽  
Vol 10 (3) ◽  
pp. 578-586
Author(s):  
Lin-Kun Shi ◽  
Xiaobing Zhou ◽  
Jian-Qing Dai ◽  
Ke Chen ◽  
Zhengren Huang ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Atomic Scale ◽  
Max Phase ◽  
X Ray Diffraction ◽  
Selected Area Electron Diffraction ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma ◽  
Diffraction Patterns

AbstractA nano-laminated Y3Si2C2 ceramic material was successfully synthesized via an in situ reaction between YH2 and SiC using spark plasma sintering technology. A MAX phase-like ternary layered structure of Y3Si2C2 was observed at the atomic-scale by high resolution transmission electron microscopy. The lattice parameters calculated from both X-ray diffraction and selected area electron diffraction patterns are in good agreement with the reported theoretical results. The nano-laminated fracture of kink boundaries, delamination, and slipping were observed at the tip of the Vickers indents. The elastic modulus and Vickers hardness of Y3Si2C2 ceramics (with 5.5 wt% Y2O3) sintered at 1500 °C were 156 and 6.4 GPa, respectively. The corresponding values of thermal and electrical conductivity were 13.7 W·m-1·K-1 and 6.3×105 S·m-1, respectively.

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