Modification of Densification Mechanisms By The Timing of Mechanical Pressure During Spark Plasma Sintering

Abstract The application of mechanical pressure during a sintering process is connected with grains sliding and diffusion enhancement. However, the timing of mechanical pressure during the rapid sintering process was not addressed. In the present study, four different timings of mechanical pressure with final pressure 50 MPa starting from the beginning, 600 ℃, 900 ℃ and at sintering temperature, furthermore one pressure-less SPS have been studied during SPS of Nano-Alumina powder (Taimei, Japan) at 1100 ℃, 1150 ℃, 1200 ℃, and 1300 ℃, respectively. The density, hardness, microstructure, and grain size of each sample were measured and calculated carefully. The results show that applying the pressure at 900 ℃ brings high density and small grain size, leading to the best Vickers hardness. The interaction between pressure and vapor, leading to the different vapor transfer rate of the first sintering stage, is considered as a reason for the differences in the microstructure.

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Fabrication of Mg2Si Thermoelectric Materials by Mechanical Alloying and Spark-Plasma Sintering Process

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2006.17955 ◽

2006 ◽

Vol 6 (11) ◽

pp. 3429-3432

Author(s):

Chung-Hyo Lee ◽

Seong-Hee Lee ◽

Sung-Yong Chun ◽

Sang-Jin Lee

Keyword(s):

Grain Size ◽

Mechanical Alloying ◽

Spark Plasma Sintering ◽

Room Temperature ◽

Atomic Ratio ◽

Sintering Process ◽

X Ray Diffraction ◽

X Ray ◽

Plasma Sintering ◽

Spark Plasma

A mixture of pure Mg and Si powders with an atomic ratio 2:1 has been subjected to mechanical alloying (MA) at room temperature to prepare the Mg2Si thermoelectric material. Mg2Si intermetallic compound with a grain size of 50 nm can be obtained by MA of Mg66.7Si33.3 powders for 60 hours and subsequently annealed at 620 °C. Consolidation of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies up to 800–900 °C under 50 MPa. The shrinkage of consolidated samples during SPS was significant at about 250 °C and 620 °C. X-ray diffraction data shows that the SPS compact from 60 h MA powders consolidated up to 800 °C consists of only nanocrystalline Mg2Si compound with a grain size of 100 nm.

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Characteristics of Nanophase WC and WC-3 wt% (Ni, Co, and Fe) Alloys Using a Rapid Sintering Process for the Application of Friction Stir Processing Tools

Advances in Materials Science and Engineering ◽

10.1155/2015/343619 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9

Author(s):

Daeup Kim ◽

Young Choi ◽

Yongil Kim ◽

Seungboo Jung

Keyword(s):

Friction Stir Processing ◽

Average Particle Size ◽

Milling Process ◽

Phase Changes ◽

Average Particle ◽

Sintering Process ◽

Friction Stir ◽

Plasma Sintering ◽

Spark Plasma ◽

Rapid Sintering

Microstructures and mechanical characteristics of tungsten carbide- (WC-) based alloys, that is, WC, WC-3 wt% Ni, WC-3 wt% Co, and WC-3 wt% Fe, fabricated using a spark plasma sintering (SPS) method for the application of friction stir processing tools were evaluated. The sintered bodies with a diameter of 66 mm showed relative densities of up to 99% with an average particle size of 0.26~0.41 μm under a pressure condition of 60 MPa with an electric current for 35 min without noticeable grain growth during sintering. Even though no phase changes were observed after the ball milling process the phases of W2C andWC1-xappeared in all sintered samples after sintering. The Vickers hardness and fracture toughness of the WC, WC-3 wt% Ni, WC-3 wt% Co, and WC-3 wt% Fe samples ranged from 2,240 kg mm2to 2,730 kg mm2and from 6.3 MPa·m1/2to 9.1 MPa·m1/2, respectively.

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Fabrication and Electrical Property of SiC-AlN Composites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.561-565.607 ◽

2007 ◽

Vol 561-565 ◽

pp. 607-611 ◽

Cited By ~ 4

Author(s):

Junichi Hojo ◽

Yuki Nonaka ◽

Kai Kamada ◽

Naoya Enomoto ◽

Mikinori Hotta ◽

...

Keyword(s):

Solid Solution ◽

Electrical Conductivity ◽

Grain Size ◽

Electrical Property ◽

Sintering Temperature ◽

Molar Ratio ◽

Sintering Process ◽

Plasma Sintering ◽

Spark Plasma ◽

Wide Compositional Range

SiC and AlN form a solid solution in the wide compositional range, expectantly leading to control of the semiconductive property. In the present work, the SiC-AlN composites were fabricated by sintering process, and evaluated with emphasis on the distribution of SiC and AlN and electrical property. SiC and AlN powders were mixed at a molar ratio between 90:10 and 10:90, and sintered at 1900-2100 °C for 30 min under 50 MPa in Ar atmosphere by spark plasma sintering technique. The sintered bodies reached high densities over 95 % of theoretical, and the grain size increased with an increase in the sintering temperature and the AlN content. The SiC-AlN composites had 3C and 2H phases in SiC-rich composition, while 2H phase only in AlN-rich composition, and the mutual dissolution between SiC and AlN was enhanced at high temperatures. The electrical conductivity decreased with dissolution of AlN into SiC because of the increase in band gap.

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Densification of Al2O3 Powder Using Spark Plasma Sintering

Journal of Materials Research ◽

10.1557/jmr.2000.0140 ◽

2000 ◽

Vol 15 (4) ◽

pp. 982-987 ◽

Cited By ~ 121

Author(s):

S. W. Wang ◽

L. D. Chen ◽

T. Hirai

Keyword(s):

Heating Rate ◽

Spark Plasma Sintering ◽

Holding Time ◽

Mechanical Pressure ◽

Fine Grained ◽

Plasma Sintering ◽

Edge Part ◽

Spark Plasma ◽

Rapid Sintering ◽

Lower Heating

Al2O3 powders with four different particle sizes were densified using a spark plasma sintering (SPS) apparatus under three different sintering conditions: holding time, heating rate, and mechanical pressure. The Al2O3 powder compact sintered at a higher heating rate produced a sample with a higher density and a fine-grained microstructure, while abnormal grain growth and a lower density resulted when a lower heating rate was applied, though the sintering temperature and holding time were the same in both cases. This revealed that rapid sintering by SPS was effective for promoting the densification of the powder. However, the powder with a coarse particle size was hard to sinter at a higher heating rate. Microstructural observation revealed that the edge part was denser than the inside of the sample when the holding time was short. Increasing the holding time made it possible for the inside to be sintered almost as dense as the edge part. Mechanical pressure was found to enhance densification of the Al2O3 powder. On the basis of these results, the SPS process is discussed.

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Fabrication and Mechanical Properties of ultra fine WC-6wt.%Co by Spark Plasma Sintering Process

Korean Journal of Metals and Materials ◽

10.3365/kjmm.2011.49.1.040 ◽

2011 ◽

Vol 49 (01) ◽

pp. 40-45 ◽

Cited By ~ 4

Author(s):

Hyun-Kuk Park ◽

Seung-Min Lee ◽

Hee-Jun Youn ◽

Ki-Sang Bang ◽

Ik-Hyun Oh

Keyword(s):

Mechanical Properties ◽

Spark Plasma Sintering ◽

Sintering Process ◽

Plasma Sintering ◽

Spark Plasma

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Effect of drying methods of alumina powder and grapheme oxide mixture on the mechanical and electrical properties of sintered composites obtained by spark plasma sintering

Perspektivnye Materialy ◽

10.30791/1028-978x-2018-1-74-82 ◽

2018 ◽

Author(s):

P. V. Fokin ◽

◽

N. W. Solis Pinargote ◽

E. V. Kuznetsova ◽

P.Y. Peretyagin ◽

...

Keyword(s):

Electrical Properties ◽

Spark Plasma Sintering ◽

Drying Methods ◽

Alumina Powder ◽

Oxide Mixture ◽

Mechanical And Electrical Properties ◽

Plasma Sintering ◽

Spark Plasma

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Synthesis, microstructure, and properties of high purity Mo2TiAlC2 ceramics fabricated by spark plasma sintering

Journal of Advanced Ceramics ◽

10.1007/s40145-020-0412-7 ◽

2020 ◽

Vol 9 (6) ◽

pp. 759-768

Author(s):

Yunhui Niu ◽

Shuai Fu ◽

Kuibao Zhang ◽

Bo Dai ◽

Haibin Zhang ◽

...

Keyword(s):

Grain Size ◽

Flexural Strength ◽

Spark Plasma Sintering ◽

Layered Structure ◽

High Purity ◽

High Fracture Toughness ◽

Temperature Range ◽

Microstructure And Properties ◽

Plasma Sintering ◽

Spark Plasma

AbstractThe synthesis, microstructure, and properties of high purity dense bulk Mo2TiAlC2 ceramics were studied. High purity Mo2TiAlC2 powder was synthesized at 1873 K starting from Mo, Ti, Al, and graphite powders with a molar ratio of 2:1:1.25:2. The synthesis mechanism of Mo2TiAlC2 was explored by analyzing the compositions of samples sintered at different temperatures. It was found that the Mo2TiAlC2 phase was formed from the reaction among Mo3Al2C, Mo2C, TiC, and C. Dense Mo2TiAlC2 bulk sample was prepared by spark plasma sintering (SPS) at 1673 K under a pressure of 40 MPa. The relative density of the dense sample was 98.3%. The mean grain size was 3.5 μm in length and 1.5 μm in width. The typical layered structure could be clearly observed. The electrical conductivity of Mo2TiAlC2 ceramic measured at the temperature range of 2–300 K decreased from 0.95 × 106 to 0.77 × 106 Ω–1·m–1. Thermal conductivity measured at the temperature range of 300–1273 K decreased from 8.0 to 6.4 W·(m·K)–1. The thermal expansion coefficient (TEC) of Mo2TiAlC2 measured at the temperature of 350–1100 K was calculated as 9.0 × 10–6 K–1. Additionally, the layered structure and fine grain size benefited for excellent mechanical properties of low intrinsic Vickers hardness of 5.2 GPa, high flexural strength of 407.9 MPa, high fracture toughness of 6.5 MPa·m1/2, and high compressive strength of 1079 MPa. Even at the indentation load of 300 N, the residual flexural strength could hold 84% of the value of undamaged one, indicating remarkable damage tolerance. Furthermore, it was confirmed that Mo2TiAlC2 ceramic had a good oxidation resistance below 1200 K in the air.

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