Preparation and Thermoelectric Properties of SiC Matrix Composites Prepared under a Low Sintering Temperature

2010 ◽  
Vol 105-106 ◽  
pp. 333-335 ◽  
Author(s):  
Ming Liang Li ◽  
Hai Long Wang ◽  
Rui Zhang ◽  
Jing Li ◽  
Jun Hao Li
Keyword(s):  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Sintering Temperature ◽  
Pressureless Sintering ◽  
Matrix Composites ◽  
Sintering Aids ◽  
Nickel Powders ◽  
N2 Atmosphere ◽  
Low Sintering Temperature ◽  
P Type

SiC powders with nickel powders and sintering aids were prepared by pressureless sintering at 1500oC under a N2 atmosphere. XRD, TEM, SEM techniques were used to characterize the phases and microstructure of the specimens. The thermoelectric properties of SiC matrix composites were investigated by measuring the Seebeck coefficient and the electrical conductivity. The main phase of all samples was -SiC, the Ni2Si can be observed with adding nickel powders. The largest electric conductivity was close to 3.5 m-1-1 at about 973K. The highest Seeback coefficient was up to 1800 V/K at 1073K. The transition from n-type to p-type was occurred.

Pressureless Sintering of Boron Carbide-Based Superhard Materials

2010 ◽  
Vol 159 ◽  
pp. 145-148 ◽  
Author(s):  
Dimitar D. Radev
Keyword(s):  
Transition Metal ◽  
Boron Carbide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Vacuum Furnace ◽  
Pressureless Sintering ◽  
Metal Carbides ◽  
Sintering Aids ◽  
Transition Metal Carbides

Boron carbide-based materials B4C-MexBy were densified by pressureless sintering in a vacuum furnace. Some transition metal carbides (TiC, ZrC, HfC, Cr3C2 and WC) from groups IV-VI were used as sintering aids. The optimal sintering temperature in the range 2220-2250oC was used for any composition. Here we show the possibilities to activate the mass transport of the B4C by the mechanism of liquid phase sintering. The method of reactive sintering of B4C in the presence of additives of some transition metal carbides allows in situ synthesis of dense B4C-MexBy materials. Structural properties and fracture toughness of the B4C-based composite materials were discussed. The properties of some of these materials and the possibilities for their application are also discussed.

LOW TEMPERATURE THERMOELECTRIC PROPERTIES AND AGING PHENOMENA OF NANOSTRUCTURED p-TYPE Bi2-XSbXTe3 (x = 1.46, 1.48, 1.52 AND 1.55)

2013 ◽  
Vol 06 (05) ◽  
pp. 1340008 ◽  
Author(s):  
DALE HITCHCOCK ◽  
YEN-LIANG LIU ◽  
YUFEI LIU ◽  
TERRY M. TRITT ◽  
JIAN HE ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Low Temperature ◽  
Thermoelectric Properties ◽  
Optimal Composition ◽  
Ambient Conditions ◽  
Bulk Materials ◽  
The Past ◽  
Aging Phenomena ◽  
P Type ◽  
Cold Pressed

Over the past decade the widely used p-type ( Bi 2-x Sb x) Te 3 bulk thermoelectric materials have been subject to various nanostructuring processes for higher thermoelectric performance. However, these nanostructuring processing were conducted on compositions optimized for bulk materials (x ~ 1.52–1.55). This leads to the question of whether the optimal composition for bulk materials is the same for their nanoscale counterparts. In this work we hydrothermally grew Bi 2-x Sb x Te 3 nanopowders (nominally, x = 1.46, 1.48, 1.52 and 1.55) and measured their thermoelectric properties on cold-pressed vacuum-sintered pellets (74–78% of the theoretical density) below 300 K. The measurements were conducted 18 months apart to probe the aging phenomena, with the samples stored in ambient conditions. We have found that (i) the peak of thermopower shifts to lower temperatures upon nanostructuring but it shifts back to higher temperatures upon aging; (ii) the electrical conductivity degrades by a factor of 1.5–2.3 upon aging while the temperature dependence is largely retained; and (iii) the ZT of freshly made samples is sensitive to the x value, a maximum ZT ~ 1.25(~ 0.62) at ~ 270 K (~ 255 K) was attained in the freshly made sample x = 1.55(x = 1.46), respectively; while the ZT of aged samples is significantly lowered by a factor of 2–4 but lesser x-dependent. These observations have been discussed in the context of charge buildup and compensation at grain boundaries.

Effect of Thermal Treatment on Thermoelectric Properties of Extruded TiO2 Ceramics

2014 ◽  
Vol 604 ◽  
pp. 249-253 ◽  
Author(s):  
Agnese Pura ◽  
Janis Locs ◽  
Liga Berzina-Cimdina
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Thermal Treatment ◽  
Seebeck Coefficient ◽  
Heating Rate ◽  
Thermoelectric Properties ◽  
Sintering Temperature ◽  
Extrusion Process ◽  
Vacuum Heat Treatment ◽  
Treatment Conditions

TiO2samples were obtained by extrusion process, sintered in air at 1000 °C, 1100 °C, 1200°C and 1300 °C and, afterwards, thermally treated under vacuum conditions at 1250 °C for 1 hour applying two different heating/cooling rates (2 °C/min and 5 °C/min). It was found that thermal treatment conditions substantially affected thermoelectric properties of the samples. Increasing sintering temperature, during the sample thermal treatment in air, the electrical conductivity of the specimens increased, while Seebeck coefficient decreased. With an increase in the heating rate during the vacuum heat treatment of the samples, the electrical conductivity of the samples decreased, while Seebeck coefficient increased.

Mullite Fiber Reinforced Alumina Ceramic Matrix Composites

2008 ◽  
Vol 368-372 ◽  
pp. 710-712 ◽  
Author(s):  
Zhi Wang ◽  
Guo Pu Shi ◽  
Xiang Sun ◽  
Xian Qin Hou
Keyword(s):  
Sintering Temperature ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Alumina Ceramic ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Sintering Aids ◽  
Original Matrix ◽  
Pull Out ◽  
Mullite Fiber

Mullite fiber reinforced alumina ceramic matrix composites (MFACC) were prepared using CaO-MgO-SiO2 (CMS) and TiO2 as sintering aids. The effects of the contents of sintering aids and mullite fiber on the density and sintering temperature of MFACC are studied. The results showed that when the CMS content is 8.0% and the TiO2 content is 1.0%, the density of the as-sintered MFACC is 98.9%. When the mullite fiber content is 15.0% and the sintering temperature is 1450 °C, the flexural strength of the resultant composite increases to 504.5MPa, 70.7% higher than the original matrix, and the relative density of the composites reaches 98.4%. The reinforcement mechanisms are fibers pull-out and sticky point.

Thermoelectric Properties of Co1-xNbxSb3 Prepared by Induction Melting

2005 ◽  
Vol 486-487 ◽  
pp. 602-605 ◽  
Author(s):  
J.B. Park ◽  
S.-W. You ◽  
K.W. Cho ◽  
J.I. Lee ◽  
Soon Chul Ur ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Induction Melting ◽  
Thermoelectric Power Factor ◽  
Seebeck Coefficients ◽  
Maximum Value ◽  
High Temperature Maximum ◽  
Higher Temperature ◽  
Nb Doping ◽  
P Type

Induction melting was attempted to prepare the undoped and Nb-doped CoSb3 compounds, and their thermoelectric properties were investigated. Single phase d-CoSb3 was successfully obtained by induction melting and subsequent annealing at 400°C for 2 hours in vacuum. The positive signs of Seebeck coefficients for all the specimens revealed that Nb atoms acted as p-type dopants by substituting Co atoms. Electrical conductivity decreased and then increased withincreasing temperature, indicating mixed behaviors of metallic and semiconducting conductions. Electrical conductivity increased by Nb doping, and it was saturated at high temperature. Maximum value of the thermoelectric power factor was shifted to higher temperature with the increasing amount of Nb doping, mainly originated from the Seebeck coefficient variation.

scholarly journals Влияние легирования ванадием на термоэлектрические свойства сплавов Гейслера Fe-=SUB=-2-=/SUB=-Ti-=SUB=-1-x-=/SUB=-V-=SUB=-x-=/SUB=-Sn

2019 ◽  
Vol 53 (6) ◽  
pp. 777
Author(s):  
А.И. Таранова ◽  
А.П. Новицкий ◽  
А.И. Воронин ◽  
С.В. Таскаев ◽  
В.В. Ховайло
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Experimental Study ◽  
Seebeck Coefficient ◽  
Transport Properties ◽  
Thermoelectric Properties ◽  
Pristine Sample ◽  
Electrical Conductivity Behavior ◽  
P Type ◽  
Conductivity Behavior

In this work the results of an experimental study of Fe2Ti1-xVxSn alloys (x = 0; 0.06; 0.15; 0.2) are presented. According to the temperature dependencies of the electrical conductivity, Seebeck coefficient and thermal conductivity, it is established, that the studied compositions exhibit transport properties typical for semiconductors. The substitution of V at the Ti site leads to a change of the p-type electrical conductivity behavior to n-type; the pristine sample of Fe2TiSn has the best thermoelectric properties.

Synthesis and High Temperature Thermoelectric Properties of Alkaline-Earth Metal Hexaborides MB6 (M=Ca, Sr, Ba)

2003 ◽  
Vol 793 ◽  
Author(s):  
Masatoshi Takeda ◽  
Yosuke Kurita ◽  
Keisuke Yokoyama ◽  
Takahiro Miura ◽  
Tsuneo Suzuki ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Thermoelectric Device ◽  
Alloying Effect ◽  
P Type

ABSTRACTPolycrystalline alkaline-earth hexaborides (MB6: M =Ca, Sr, Ba) were synthesized and their thermoelectric and transport properties were examined to discuss their possibility as high temperature thermoelectric materials. Hall measurements showed that carrier concentration of the BaB6 was the highest among the three hexaborides and that of CaB6 was the lowest. Substitution of part of the alkaline earth metals with one of the others changed the carrier concentration of the hexaboride. As the carrier concentration increased, Seebeck coefficient increased and electrical conductivity decreased. These results suggest that the thermoelectric properties of the divalent hexaborides depend largely on the carrier concentration, and optimum carrier concentration which gives maximum power factor was estimated to be approximately 2x1026 m−3. Consequently, such a substitution enables us to control Seebeck coefficient and electrical conductivity of the hexaborides, and will also be effective to reduce the lattice heat conduction due to the alloying effect. A thermoelectric device was fabricated using SrB6 and boron carbide thin films as n-type and p-type elements, respectively. To the best of our knowledge, this is the first demonstration of a thermoelectric device composed of only boron-rich solids.

The mechanism of alkylamine-stabilized copper fine particles towards improving the electrical conductivity of copper films at low sintering temperature

2015 ◽  
Vol 3 (23) ◽  
pp. 5890-5895 ◽  
Author(s):  
Yingqiong Yong ◽  
Tetsu Yonezawa ◽  
Masaki Matsubara ◽  
Hiroki Tsukamoto
Keyword(s):  
Electrical Conductivity ◽  
Fine Particles ◽  
Oxidation Process ◽  
Sintering Temperature ◽  
Copper Films ◽  
Low Sintering Temperature ◽  
First Time

A facile oxidation process was demonstrated, for the first time, and it can facilitate particle sintering by generating nanostructures.

THERMOELECTRIC PROPERTIES OF p-TYPE SKUTTERUDITES (Pr0.25Nd0.75)xFe3CoSb12 BY LEVITATION MELTING AND SPARK PLASMA SINTERING

2013 ◽  
Vol 06 (05) ◽  
pp. 1340006 ◽  
Author(s):  
JINGSHU XU ◽  
CHENGUANG FU ◽  
JIAN XIE ◽  
XINBING ZHAO ◽  
TIEJUN ZHU
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
Lattice Thermal Conductivity ◽  
Levitation Melting ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

The p-type skutterudite compounds of ( Pr 0.25 Nd 0.75)x Fe 3 CoSb 12 (x = 0.67–0.78) have been successfully synthesized by levitation melting followed by annealing and spark plasma sintering. The thermoelectric properties have been characterized by the measurements of Seebeck coefficient, electrical conductivity and thermal conductivity in the temperature range from 300 K to 850 K. The improvement in the thermoelectric properties was realized due to the reduction in the lattice thermal conductivity when the voids were partially filled by Pr 0.25 Nd 0.75. The maximum ZT value of ~ 0.83 for ( Pr 0.25 Nd 0.75)0.76 Fe 3 CoSb 12 was obtained at 700 K.

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