Effects of Preparation Methods on the Thermoelectric Performance of SWCNT/Bi2Te3 Bulk Composites

Single-walled carbon nanotube (SWCNT)/Bi2Te3 composite powders were fabricated via a one-step in situ reductive method, and their corresponding bulk composites were prepared by a cold-pressing combing pressureless sintering process or a hot-pressing process. The influences of the preparation methods on the thermoelectric properties of the SWCNT/Bi2Te3 bulk composites were investigated. All the bulk composites showed negative Seebeck coefficients, indicating n-type conduction. A maximum power factor of 891.6 μWm−1K−2 at 340 K was achieved for the SWCNT/Bi2Te3 bulk composites with 0.5 wt % SWCNTs prepared by a hot-pressing process, which was ~5 times higher than that of the bulk composites (167.7 μWm−1K−2 at 300 K) prepared by a cold-pressing combing pressureless sintering process, and ~23 times higher than that of the bulk composites (38.6 μWm−1K−2 at 300 K) prepared by a cold-pressing process, mainly due to the enhanced density of the hot-pressed bulk composites.

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Investigation of Phase Composition and Microstructure of the B4C/BN Nanocomposite Powders and the B4C/BN Nanocomposites Sintered Bulks

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.328-330.1572 ◽

2011 ◽

Vol 328-330 ◽

pp. 1572-1575

Author(s):

Tao Jiang

Keyword(s):

Heat Treatment ◽

Phase Composition ◽

Chemical Reaction ◽

Hot Pressing ◽

Treatment Process ◽

Heat Treatment Process ◽

Composite Powders ◽

Pressing Process ◽

Xrd Patterns ◽

Nanocomposite Powders

In this research, the B4C/BN nanocomposite powders were fabricated by chemical reaction and heat treatment process, then the B4C/BN nanocomposites bulks were fabricated by hot-pressing process. The B4C/BN nanocomposite powders were fabricated by chemical reaction at 550°C for 15h and heat treatment at 850°C for 6h. The B4C/BN nanocomposites bulks were fabricated by hot-pressing process at 1850°C for 1h under the pressure of 30MPa. In this research, the phase composition and microstructure of the B4C/BN nanocomposite powders produced by chemical reaction and heat treatment process were investigated. The phase composition and microstructure of the B4C/BN nanocomposites produced by hot-pressing process were investigated. The XRD patterns results showed that there existed the B4C phase and amorphous BN phase in the composite powders produced by chemical reaction and heat treatment, and the amorphous BN phase completely transformed into the h-BN phase by hot-pressing process. The XRD patterns results showed that there existed the B4C phase and h-BN phase in the composites sintered bulks. The microstructure of the synthesized B4C/BN composite powders showed that the B4C particles were surrounded with the amorphous BN nano-sized particles, the thickness of amorphous BN coated layer was about 300-500nm. The B4C/BN nanocomposites exhibited the homogenous and compact microstructure, and the nano-sized h-BN particles were homogenously distributed in the B4C matrix. The mean particles size of B4C matrix was about 2-3μm, the length of nano-sized h-BN particles was about 1-2μm and width of nano-sized h-BN particles was about 100-200nm. The B4C/BN nanocomposites bulks exhibited more homogenous and compact microstructure with the increase of h-BN content.

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Investigation of Microstructure and Mechanical Property of the Fe3Al/Al2O3 Composites Fabricated by Mechanical Alloying Process and Hot-Pressing Process

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.492.102 ◽

2011 ◽

Vol 492 ◽

pp. 102-106

Author(s):

Tao Jiang ◽

Xiao Ping Shi

Keyword(s):

Heat Treatment ◽

Phase Composition ◽

Mechanical Alloying ◽

Hot Pressing ◽

Composite Powders ◽

Al Content ◽

Pressing Process ◽

The Mean ◽

Xrd Patterns ◽

Microstructure And Mechanical Property

The Fe3Al/Al2O3composites were fabricated by hot-pressing process in this research. The Fe3Al intermetallics compounds powders were fabricated by mechanical alloying and heat treatment, then the Fe3Al powders and Al2O3powders were mixed and the Fe3Al/Al2O3composite powders were prepared, so the Fe3Al/Al2O3composites were fabricated by hot-pressing process at 1300°C for 2h under the pressure of 35MPa. The phase composition and microstructure of the Fe3Al intermetallics compounds powders produced by mechanical alloying and heat treatment were investigated. The phase composition, microstructure and mechanical properties of the Fe3Al/Al2O3composites sintered bulks were investigated. The XRD patterns results showed that there existed Fe3Al phase and Al2O3phase in the sintered composites. The Fe3Al/Al2O3composites sintered bulks exhibited the homogenous and compact microstructure, the Fe3Al particles were homogenously distributed in the Al2O3 matrix, the mean particles size of Fe3Al intermetallics compounds was about 3-4μm. The Fe3Al/Al2O3composites exhibited more homogenous and compact microstructure with the increase of Fe3Al content in the Al2O3matrix. The density and relative density of the Fe3Al/Al2O3composites increased gradually with the increase of Fe3Al content. The fracture strength and fracture toughness of the Fe3Al/Al2O3composites increased gradually with the increase of Fe3Al content. The elastic modulus and hardness (HRA) of the Fe3Al/Al2O3composites decreased gradually with the increase of Fe3Al content.

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Synthesis of CuIn0.7Ga0.3Se2 Nanoparticles and its Quarternary Sputtering Target

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.483.65 ◽

2013 ◽

Vol 483 ◽

pp. 65-70 ◽

Cited By ~ 1

Author(s):

Jun Zhou ◽

Fu Qing Zhang ◽

Li Hong Xia

Keyword(s):

Hot Pressing ◽

Rotation Speed ◽

Mixing Time ◽

Pressureless Sintering ◽

Sintering Process ◽

X Ray Diffraction ◽

Sputtering Deposition ◽

X Ray ◽

Cigs Nanoparticles ◽

Scanning Electron

The chalcopyrite-type of CuIn0.7Ga0.3Se2 nanoparticle was successfully prepared by mechanical alloying method (MA). The phase of the obtained powder was analyzed by x-ray diffraction (XRD), and its microstructure was analyzed by scanning electron microscope (SEM) and transmission election microscope (TEM). Subsequently, the sintering process of CIGS quarternary target was investigated. The result suggests that only CuIn0.7Ga0.3Se2 phase exist in the powder with the rotation speed of 350 r/min and 2 hours mixing time by planetary ball milling. The particles were seriously agglomerated and the size of agglomerates was about 100 nm. Finally the as-made CIGS nanoparticles were used to fabricate CIGS target through both pressureless sintering and hot pressing methods. The hot pressing was fairly effective to increase the density of CIGS target. This fabricated target can be used for magnetron-sputtering deposition of CIGS absorbers.

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Investigation of Phase Composition and Microstructure of the FeAl/Al2O3 Composites Fabricated by Mechanical Alloying Process and Pressureless Sintering Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.239-242.968 ◽

2011 ◽

Vol 239-242 ◽

pp. 968-971

Author(s):

Tao Jiang

Keyword(s):

Heat Treatment ◽

Phase Composition ◽

Mechanical Alloying ◽

Treatment Process ◽

Pressureless Sintering ◽

Heat Treatment Process ◽

Sintering Process ◽

Composite Powders ◽

The Mean ◽

Xrd Patterns

The FeAl/Al2O3composites were fabricated by pressureless sintering process. The FeAl intermetallics compounds powders were fabricated by mechanical alloying and heat treatment process. The FeAl intermetallics compounds powders and Al2O3powders were mixed and the FeAl/Al2O3composite powders were prepared. The FeAl/Al2O3composites bulks were fabricated by pressureless sintering process at 1600°C for 2h. The phase composition and microstructure of FeAl intermetallics compounds powders produced by mechanical alloying and heat treatment were investigated. The phase composition and microstructure of the FeAl/Al2O3composites sintered bulks were investigated. The XRD patterns results showed that the Fe-Al intermetallics compounds powders were fabricated by mechanical alloying for 60h. The FeAl intermetallics compounds powders were fabricated by heat treatment at 800°C, 900°C and 1000°C. The microstructure showed that the mean particles size of the FeAl intermetallics compounds powders produced by mechanical alloying and heat treatment process was rather fine and about 4-5μm. The XRD patterns results showed that there existed the FeAl phase and Al2O3phase in sintered composites. The FeAl/Al2O3composites bulks exhibited the homogenous and compact microstructure. The mean particles size of FeAl was about 4-5μm and the mean particles size of Al2O3was about 5-10μm. The density and relative density of the FeAl/Al2O3composites increased gradually with the increase of FeAl content.

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Effect of Co Content on the Densification, Microstructure and Mechanical Properties of cBN-WC/Co Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.655.41 ◽

2015 ◽

Vol 655 ◽

pp. 41-44

Author(s):

Qiu Shuang He ◽

Hai Yan Chen ◽

Kun Li ◽

Li Hua Dong

Keyword(s):

Mechanical Properties ◽

Vickers Hardness ◽

Hot Pressing ◽

Cemented Carbide ◽

Sintering Process ◽

Composite Powders ◽

Flexure Strength ◽

Microstructure And Mechanical Properties ◽

Hot Pressing Sintering ◽

Full Densification

Hot pressing sintering process for cemented carbide preparation was investigated with cBN-WC/Co composite powders with different Co content from 4wt% to 10wt% at temperatures between 1300°C and 1400°C. The results showed that the Co content had remarkable influence on the densification and mechanical properties of cBN-WC/Co composites. Near-full densification can be obtained when cBN-WC/8wt%Co powders were sintered at temperatures at 1350°C, and pressures at 20MPa, combining an excellent Vickers hardness of 17.57GPa with an acceptable flexure strength of 601.58MPa.

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Investigation of Phase Composition and Microstructure of the FeAl/Al2O3 Composites Fabricated by Mechanical Alloying and Hot-Pressing Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.311-313.323 ◽

2011 ◽

Vol 311-313 ◽

pp. 323-326

Author(s):

Tao Jiang

Keyword(s):

Heat Treatment ◽

Phase Composition ◽

Mechanical Alloying ◽

Hot Pressing ◽

Composite Powders ◽

Pressing Process ◽

Feal Phase ◽

The Mean ◽

Xrd Patterns

The FeAl/Al2O3composites were fabricated by hot-pressing process in this research. The Fe-Al intermetallics compounds powders were fabricated by mechanical alloying and heat treatment. The FeAl powders and Al2O3powders were mixed and the FeAl/Al2O3composite powders were prepared. The FeAl/Al2O3composites bulks were fabricated by hot-pressing process at 1300°C for 2h under the pressure of 35MPa. The phase composition and microstructure of the FeAl intermetallics compounds powders produced by mechanical alloying and heat treatment were investigated. The phase composition and microstructure of the FeAl/Al2O3composites produced by hot-pressing process were investigated. The XRD patterns results showed that the Fe-Al intermetallics compounds powders were fabricated by mechanical alloying for 60h. The FeAl intermetallics compounds powders were fabricated by heat treatment at 800°C, 900°C and 1000°C. The microstructure showed that the mean particles size of the FeAl intermetallics compounds powders produced by mechanical alloying and heat treatment was rather fine and about 4-5μm. The XRD patterns results showed that there existed FeAl phase and Al2O3phase in sintered composites. The FeAl/Al2O3composites bulks exhibited the homogenous and compact microstructure. The mean particles size of FeAl was about 4-5μm and the mean particles size of Al2O3was about 4-5μm. The microstructure of the FeAl/Al2O3composites became more homogenous and compact with the increase of FeAl content.

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Densification and Strengthening of Tricalcium Phosphate/Titania Composite by Hot Pressing

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.317-318.101 ◽

2006 ◽

Vol 317-318 ◽

pp. 101-104

Author(s):

Jong Kook Lee ◽

Dong Seok Seo ◽

Hang Chul Jung

Keyword(s):

Mechanical Properties ◽

Tricalcium Phosphate ◽

Hot Pressing ◽

Sintered Density ◽

Pressureless Sintering ◽

Sintering Process ◽

N2 Atmosphere ◽

Moisture Protection ◽

Sintering Condition ◽

Hydrothermal Methods

Tricalcium phosphate [TCP, β-Ca3(PO4)2]/titania composite having high mechanical properties was prepared and characterized. The TiO2 and HAp powders, as starting materials, were synthesized by precipitation and hydrothermal methods, respectively. The sintered β-TCP/TiO2 composite was prepared by hot pressing at 1000°C for 30 min under the pressure of 30 MPa in N2 atmosphere or by pressureless sintering at 1200°C for 2 h in air with moisture protection. The influence of sintering condition on the microstructures and mechanical properties of the composite was investigated. During the sintering process, hydroxyapatite used as a starting material was decomposed to β-TCP and CaTiO3 at elevated temperature because TiO2 could accelerate the decomposition of hydroxyapatite. The hot-pressed composite with 98% of sintered density showed high hardnessvalue of 1080 Hv compared with the pure hydroxyapatite (600 Hv).

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Effect of TiB2 on Pressureless Sintering and Hot Pressing of ZrB2

Materials Science Forum ◽

10.4028/www.scientific.net/msf.881.97 ◽

2016 ◽

Vol 881 ◽

pp. 97-102 ◽

Cited By ~ 2

Author(s):

Carolyne Oliveira Davi ◽

Miriam K.H. Yassuda ◽

Rosa Maria Rocha

Keyword(s):

Thermal Conductivity ◽

Solid Solution ◽

Hot Pressing ◽

Planetary Mill ◽

Unique Property ◽

Pressureless Sintering ◽

High Melting ◽

Sintering Process ◽

High Melting Point ◽

Hot Pressing Sintering

Zirconium diboride (ZrB2) is a material of particular interest because of the excellent and unique property combination of high melting point and high electrical and thermal conductivity. In this work, the effect of TiB2 addition on pressureless sintering and hot pressing sintering of ZrB2 was investigated. Four compositions were prepared with 0, 5, 10 and 20 wt% of TiB2. First, ZrB2 and TiB2 powders were milled by planetary mill with SiC spheres at for 4 h and then they were wet mixed. Compacted samples were pressureless sintered at 2150 oC/1h and hot pressed at 1850 °C/30min with 20 MPa, both in Ar atmosphere. The added TiB2 completely dissolved into the structure and formed a solid solution with ZrB2. Addition of TiB2 in ZrB2 ceramic improved densification and hardness for both sintering process, but hot pressed samples exhibited better results.

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Pressureless Sintering of YIG Ceramics from Coprecipitated Nanopowders

Magnetochemistry ◽

10.3390/magnetochemistry7050056 ◽

2021 ◽

Vol 7 (5) ◽

pp. 56

Author(s):

Yimin Yang ◽

Xiaoying Li ◽

Ziyu Liu ◽

Dianjun Hu ◽

Xin Liu ◽

...

Keyword(s):

High Temperature ◽

Calcination Temperature ◽

Sintering Temperature ◽

Raw Materials ◽

Secondary Phase ◽

Coprecipitation Method ◽

Pressureless Sintering ◽

Densification Behavior ◽

Sintering Process

Nanoparticles prepared by the coprecipitation method were used as raw materials to fabricate Y3Fe5O12 (YIG) ceramics by air pressureless sintering. The synthesized YIG precursor was calcinated at 900–1100 °C for 4 h in air. The influences of the calcination temperature on the phase and morphology of the nanopowders were investigated in detail. The powders calcined at 1000–1100 °C retained the pure YIG phase. YIG ceramics were fabricated by sintering at 1200–1400 °C for 10 h, and its densification behavior was studied. YIG ceramics prepared by air sintering at 1250 °C from powders calcinated at 1000 °C have the highest in-line transmittance in the range of 1000-3000 nm. When the sintering temperature exceeds 1300 °C, the secondary phase appears in the YIG ceramics, which may be due to the loss of oxygen during the high-temperature sintering process, resulting in the conversion of Fe3+ into Fe2+.

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