Microstructural evolution of La-doped SiB6 high-temperature thermoelectric material during a Spark Plasma Sintering

2001 ◽  
Vol 691 ◽  
Author(s):  
D.W. Lee ◽  
J.H. Won ◽  
K.H. Kim ◽  
J. Matsushita ◽  
K.B. Shim
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Spark Plasma Sintering ◽  
Earth Element ◽  
Sintering Temperature ◽  
Plasma Sintering ◽  
Conventional Sintering ◽  
Spark Plasma ◽  
High Degree ◽  
La Doped

ABSTRACTSiB6 has proved to a potentially useful material because of its excellent thermoelectrical properties above 700°C, low specific gravity, high degree of hardness, and moderate melting point. SiB6, which has poor sinterability with a conventional sintering technique due to the covalent characteristic, has been successfully densified fully using a spark plasma sintering(SPS) method. The SPS-processed specimens consisted of SiB6, SiB4 and SixBy phases. Pure SiB6 powder were densified fully at the sintering temperature of 1600°C. In particular, it was found that the rare earth element was very effective in evolving the microstructure of SiB6 phase, resulting in reducing the sintering temperature and controlling grain growth. These effects were discussed in details in terms of microstructure evolution during the SPS process.

Study on Mechanisms of Rare Earth Elements on Improving Thermoelectric Properties of RExCo4Sb12

2011 ◽  
Vol 71-78 ◽  
pp. 3737-3740
Author(s):  
Ke Gao Liu ◽  
Jing Li
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Mechanical Alloy ◽  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
Rare Earth Element ◽  
Figure Of Merit ◽  
Earth Element ◽  
Plasma Sintering ◽  
Spark Plasma

It is the important way to improve thermoelectric properties of skutterudite materials by doping with rare earth elements. The mechanisms of improving properties of bulk RExCo4Sb12materials prepared by mechanical alloy and spark plasma sintering (MA-SPS) at 650°C were investigated by analyzing the composition, microstructure and atomic occupying locations. According the results it can be considered that the mechanism to improve the thermoelectric properties of rare earth elements is that rare earth element Ce in the samples mainly plays the doping role in reducing the resistivity of the sample and improving the conductivity, so that it makes the figure of merit ZT of samples increase significantly.

Structure and Properties of Ti55Al45 Alloys Prepared by Mechanical Alloying and Spark Plasma Sintering

2011 ◽  
Vol 308-310 ◽  
pp. 2547-2550
Author(s):  
Yao Dong Liu ◽  
Jing Xing ◽  
Di Ai ◽  
Song Zhe Jin
Keyword(s):  
Grain Size ◽  
Spark Plasma Sintering ◽  
Sintering Temperature ◽  
Compaction Pressure ◽  
Al Alloy ◽  
Structure And Properties ◽  
Plasma Sintering ◽  
Conventional Sintering ◽  
Spark Plasma ◽  
Short Time

Amorphization and crystallization behaviors of Ti55Al45 powders during mechanical alloys (MA) and subsequent Spark Plasma Sintering are studied. It is found that the nanocrystallization process of the Ti-Al alloy proceeds and the sintering temperature can control the microstructure of alloy. The sintering of the compacts is carried out at the temperatures of 1100—1200°C with a compaction pressure of 30MPa and a heating rate of 30°C min-1. Specimens with high densities and approaching the equilibrium state can be obtained in short time of 180s by spark sintering than conventional sintering. Such shorter high temperature is important to prevent grain growth. The microstructures of the alloy contains equiaxed gamma TiAl with sub-micron grain size and small amount alpha Ti3Al phase.

scholarly journals Effects of theTiB2-SiC Volume Ratio and Spark Plasma Sintering Temperature on the Properties and Microstructure of TiB2-BN-SiC Composite Ceramics

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 29
Author(s):  
Shi Tian ◽  
Zelin Liao ◽  
Wenchao Guo ◽  
Qianglong He ◽  
Heng Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Spark Plasma Sintering ◽  
Sintering Temperature ◽  
Volume Ratio ◽  
Expansion Rate ◽  
Composite Ceramics ◽  
Plasma Sintering ◽  
Spark Plasma

TiB2-BN composite ceramics combine excellent electrical conductivity, thermal shock resistance, high-temperature resistance, corrosion resistance, and easy processing of TiB2 and BN. However, in practical applications, their high-temperature oxidation resistance is poor and the resistivity distribution is uneven and changes substantially with temperature. A TiB2-BN-SiC composite ceramic with stable and controllable resistivity was prepared by introducing SiC into the TiB2-BN composite ceramics. In this work, spark plasma sintering (SPS) technology was used to prepare TiB2-BN-SiC composite ceramics with various TiB2-SiC ratios and sintering temperatures. The samples were tested by XRD, SEM, and thermal and mechanical analysis. The results show that as the volume ratio of TiB2-SiC was increased from 3:1 to 12:1, the resistivity of the sample decreased from 8053.3 to 4923.3 μΩ·cm, the thermal conductivity increased from 24.89 to 34.15 W/(m k), and the thermal expansion rate increased from 7.49 (10−6/K) to 10.81 (10−6/K). As the sintering temperature was increased from 1650 to 1950 °C, the density of the sample increased, the mechanical properties were slightly improved, and the resistivity, thermal expansion rate, and thermal conductivity changed substantially. The volume ratio and sintering temperature are the key factors that control the resistivity and thermal characteristics of TiB2-SiC-BN composite ceramics, and the in situ from liquid phases of FeB and FeO also promotes the sintering of the TiB2-BN-SiC ceramics.

scholarly journals Preparation of YAG Nanoparticles and their Characteristics

2010 ◽  
Vol 636-637 ◽  
pp. 697-702
Author(s):  
J. Grabis ◽  
D. Jankoviča ◽  
Ints Šteins ◽  
Aloizijs Patmalnieks
Keyword(s):  
Rare Earth ◽  
Relative Density ◽  
Combustion Synthesis ◽  
Spark Plasma Sintering ◽  
Yttrium Aluminium Garnet ◽  
Organic Fuel ◽  
Yttrium Aluminium ◽  
Plasma Sintering ◽  
Conventional Sintering ◽  
Spark Plasma

The nanosized yttrium aluminium garnet powders doped with rare earth oxides are prepared by combustion synthesis using several organic fuel. Dense materials are manufactured by conventional sintering and spark plasma sintering (SPS). The combustion synthesis provides preparation of pure crystalline YAG nanopowders at ratio Y/Al = 3/5 after additional calcination at 1000 oC. The relative density of the SPS sintered samples at 1500 oC for 2 min is in the range of 95.4–98.5% depending on dispersity of powders.

Preparation and Electrical Properties of Dense Bi4Ti3O12 Ceramics by Spark Plasma Sintering

2007 ◽  
Vol 280-283 ◽  
pp. 141-144
Author(s):  
Jun Jie Hao ◽  
Xiao Hui Wang ◽  
Long Tu Li ◽  
Zhi Lun Gui
Keyword(s):  
Electrical Properties ◽  
Spark Plasma Sintering ◽  
Electronic Materials ◽  
Sintering Temperature ◽  
Sintering Process ◽  
Plasma Sintering ◽  
The Family ◽  
Conventional Sintering ◽  
Spark Plasma ◽  
Sintering Method

The family of bismuth layer-structured ferroelectrics is attractive from the viewpoint of their application as electronic materials such as dielectrics, piezoelectrics and pyroelectrics. However, during conventional sintering method, high sintering temperature and long sintering time were needed and it is difficult to get BIT ceramic with a density more than 95% of its theoretic value. In the present paper, we produce dense BIT pellet using a spark plasma sintering process. The results show that at a sintering temperature as low as 7000C/5min under a pressure of 25MPa, BIT ceramics with a density about 99% of its theoretic can be produced. The densities, grain size and electrical properties of the resulting ceramic were also investigated.

AlN/CNT Composites Ceramics by Spark Plasma Sintering

2014 ◽  
Vol 602-603 ◽  
pp. 570-573
Author(s):  
Hai Long Liang ◽  
Chun Peng Wang ◽  
Yan Li Huo ◽  
Chuan Qi Hu ◽  
Xiao Ting Huang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Spark Plasma Sintering ◽  
Imaginary Part ◽  
Loss Factor ◽  
Sintering Temperature ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Plasma Sintering ◽  
Spark Plasma

Highly dense AlN/CNT composite ceramics with 1-10% volume fractions of CNT were fabricated by spark plasma sintered (SPS) at 1400°C-1700°C. The results indicated that origination diameter of AlN had a great effect on microstructure and thermal conductivity. In details, for the system with AlN origination diameter of nanosized, the tubular structure of CNT has not been destructed, but when micro-sized AlN powder was adopted, the structure of CNT showed unstable at high temperature. Even though the degradation with incorporation of CNT into AlN, thermal conductivity of sintered AlN/CNT composites ceramics was evidently improved by adjusting content of additive Y2O3and the sintering process. Both the real part and imaginary part of the composites of Ka-Band (26.540.0 GHz) increase with the increase of CNT content, in which the increase of imaginary part is more than that of real part, resulting in an increase of loss factor. The AlN/ CNT thermal conductivity composites with appropriate CNT content and sintering temperature possess good dielectric dissipation and thermal conductivity.

Spark Plasma Sintering Process of Fe-6.5%Si Alloy from Fe and FeSi Powders

2009 ◽  
Vol 66 ◽  
pp. 270-272 ◽  
Author(s):  
Xiang Zhang ◽  
Jun Guo Li ◽  
Qing Qing Qi ◽  
Lian Meng Zhang
Keyword(s):  
Spark Plasma Sintering ◽  
Lower Energy ◽  
Sintering Temperature ◽  
Silicon Steel ◽  
Powder Size ◽  
Sintering Process ◽  
Plasma Sintering ◽  
Conventional Sintering ◽  
Spark Plasma ◽  
Shrinkage Behavior

Powder metallurgy (PM) method to fabricate 6.5% silicon steel attracts much attention due to the lower energy consumption and cost. In this paper, Fe-6.5%Si alloy was prepared by spark plasma sintering (SPS) from the mixture of Fe and FeSi powders with different size. The sintering process was investigated through the shrinkage behavior, phase change and microstructure. The results show that the shrinkage starts from 500°C, lower than conventional sintering methods. The sintering temperature and FeSi powder size influence the reaction between Fe and FeSi.

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