Fabrication and Electrical Conductivity of a YSZ-NiCr Cermet

2007 ◽  
Vol 336-338 ◽  
pp. 384-386
Author(s):  
Gang Qin Shao ◽  
Jia Li ◽  
Yong Li ◽  
Xing Long Duan ◽  
Xiao Liang Shi ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Particle Size ◽  
Reduction Process ◽  
Metal Phase ◽  
Crystalline Size ◽  
Hot Press ◽  
Homogeneous Microstructure ◽  
Mean Particle Size ◽  
Increasing Temperature ◽  
Hot Press Sintering

YSZ-NiCr powder was synthesized by gel-reduction process at 850°C for 2 h. YSZ-NiCr cermet was fabricated by hot-press sintering at 1350°C for 1 h. The powder has a mean particle size of 42 nm and the sintered specimen has a fine and homogeneous microstructure with a mean crystalline size of 0.2 &m. The conductivity has a tendency to decrease with increasing temperature. This behavior can be accounted for that there are two conduction paths through the cermet, an electronic path through the Ni/Cr metal phase and an ionic path through the ZrO2-Y2O3 phase. The objective of this work is to give a possible improvement in the cermet anode of SOFC.

The Properties of YSZ-Ni-Cr Cermet Fabricated by Sol-Gel Method

2012 ◽  
Vol 535-537 ◽  
pp. 787-790
Author(s):  
Shu Lan Guo ◽  
Min Wang ◽  
Su Hua Lv ◽  
Jia Li ◽  
Xian Chang Du
Keyword(s):  
Particle Size ◽  
Sol Gel ◽  
Hot Press ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Increasing Temperature ◽  
Hot Press Sintering

The properties of YSZ-Ni-Cr cermet fabricated by Sol-Gel Method（YSZ-Ni-Cr powder was synthesized by coprecipitation method at 850°C for 2 h and was processed into YSZ-Ni-Cr cermet by hot-press sintering at 1350°C for 1 h）was explored. The identification of phases was carried out using a X-ray diffractometer (XRD). The particle size and morphology was determined by electron microscopys(SEM/TEM) The conductivity had a tendency to decrease with increasing temperature. This behavior can be accounted for that there are two conduction paths through the cermet, an electronic path through the (Ni,Cr) metal phase and an ionic path through the ZrO2-Y2O3 phase.

Thermoelectric Properties of Mn Doped Cu12-xMnxSb4S13 Tetrahedrites

2016 ◽  
Vol 847 ◽  
pp. 161-165 ◽  
Author(s):  
Ju Yi Wang ◽  
Xiao Ya Li ◽  
Ye Feng Bao
Keyword(s):  
Electrical Conductivity ◽  
Substitution Effect ◽  
Hot Press ◽  
X Ray Diffraction ◽  
Doping Amount ◽  
Spectroscopy Analysis ◽  
Mn Doping ◽  
Thermoelectric Transport Properties ◽  
Hot Press Sintering ◽  
Mn Doped

In this study, Mn doped Cu12-xMnxSb4S13(x=0, 0.5, 1.0, and 2.0) tetrahedrite samples were prepared by melting and annealing followed by hot press sintering. Powder X-ray diffraction and scanning electron microscopy and electron energy dispersive spectroscopy analysis were performed for the samples, and the thermoelectric transport properties of samples were characterized. The experimental results showed that the synthetic tetrahedrites were consisted of principal Cu12Sb4S13 phase and a small amount of secondary Cu3SbS4 and CuSbS2. The electrical conductivity of the tetrahedrites decreased with increasing the Mn doping amount. Contrary to the electrical conductivity, the Seebeck coefficient of the tetrahedrites increased with increasing Mn doping amount. The thermal conductivity decreased with increasing Mn doping amount due to the suppression of the carrier contribution, as well as due to the substitution effect of Mn on the Cu site. For the Mn doped Cu12-xMnxSb4S13 compounds with x=0.5, 1.0, and 2.0, the ZT values decreased with the increase of Mn doping amount, a maximum ZT=0.89 was obtained for the Mn doped compound with x=0.5.

scholarly journals Structural and Electrical Properties of ZnO Varistor with Different Particle Size for Initial Oxides Materials

2019 ◽  
Vol 2 (2) ◽  
pp. 20-31 ◽  
Author(s):  
Susan A Amin
Keyword(s):  
Electrical Conductivity ◽  
Particle Size ◽  
Nonlinear Coefficient ◽  
Hexagonal Wurtzite Structure ◽  
The Other ◽  
Breakdown Field ◽  
Residual Voltage ◽  
Structural And Electrical Properties ◽  
Increasing Temperature ◽  
Initial Starting

We report here structural, electrical and dielectric properties of ZnO varistors prepared with two different particle sizes for initial starting oxides materials (5 µm and 200 nm). It is found that the particle size of ZnO does not influence the hexagonal wurtzite structure of ZnO, while the lattice parameters, crystalline diameter, grain size and Zn-O bond length are affected. The nonlinear coefficient, breakdown field and barrier height are decreased from 18.6, 1580 V/cm and 1.153 eV for ZnO micro to 410 V/cm, 7.26 and 0.692 eV for ZnO nano.  While, residual voltage and electrical conductivity of upturn region are increased from 2.08 and 2.38x10-5 (Ω.cm)-1 to 4.55 and 3.03x10-5 (Ω.cm)-1. The electrical conductivity increases by increasing temperature for both varistors, and it is higher for ZnO nano than that of ZnO micro.  The character of electrical conductivity against temperature is divided into three different regions over the temperature intervals as follows; (300 K ≤ T ≤ 420 K), (420 K ≤ T ≤ 580 K) and (580 K ≤ T ≤ 620 K), respectively. The activation energy is increased in the first region from 0.141 eV for ZnO micro to 0.183 eV for ZnO nano and it is kept nearly constant in the other two regions. On the other hand, the average conductivity deduced through dielectric measurements is increased from 2.54x10-7 (Ω.cm)-1 for ZnO micro to 49x10-7 (Ω.cm)-1. Similar behavior is obtained for the conductivities of grains and grain boundaries. The dielectric constant decreases as the frequency increases for both varistors, and it is higher for ZnO nano than that of ZnO micro. These results are discussed in terms of free excited energy and strength of link between grains of these varistors.

Study on Effect of Particle Size of Matrix and Reinforcement on Properties of Iron Matrix Composites

2012 ◽  
Vol 182-183 ◽  
pp. 328-331
Author(s):  
Yu Fang Yang ◽  
Kang Ju Li
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Matrix Composites ◽  
Hot Press ◽  
Iron Matrix ◽  
Direct Heating ◽  
Effect Of Particle Size ◽  
Properties Of Materials ◽  
Hot Press Sintering ◽  
Properties Of Composites

The effect of particle size of iron and size of reinforce particle on properties of materials was studied systematically by the specimen current direct heating dynamic hot press sintering. It is found that mechanical properties of composites increase with the increasing particle size of iron. The properties of SiCp/Fe composites firstly increase and decrease with particle size of SiC and properties are better when size is 15μm.

Synthesis and thermoelectric properties of tantalum-doped ZrNiSn half-Heusler alloys

2014 ◽  
Vol 07 (03) ◽  
pp. 1450032 ◽  
Author(s):  
Degang Zhao ◽  
Min Zuo ◽  
Zhenqing Wang ◽  
Xinying Teng ◽  
Haoran Geng
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Acoustic Phonon ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Heusler Alloys ◽  
Hot Press ◽  
Arc Melting ◽  
Hot Press Sintering

The Ta -doped ZrNiSn half-Heusler alloys, Zr 1-x Ta x NiSn , were synthesized by arc melting and hot-press sintering. Microstructure of Zr 1-x Ta x NiSn compounds were analyzed and the thermoelectric (TE) properties of Zr 1-x Ta x NiSn compounds were measured from room temperature to 823 K. The electrical conductivity increased with increasing Ta content. The Seebeck coefficient of Zr 1-x Ta x NiSn compounds was sharply decreased with increasing Ta content. The Hall mobility was proportional to T-1.5 above 673 K, indicating that the acoustic phonon scattering was predominant in the temperature range. The thermal conductivity was effectively depressed by introducing Ta substitution. The figure of merit of ZrNiSn compounds was improved due to the decreased thermal conductivity and increased electrical conductivity. The maximum ZT value of 0.60 was achieved for Zr 0.97 Ta 0.03 NiSn sample at 823 K.

Preparation and Characterization of WC Matrix Nanocomposite Cermet

2009 ◽  
Vol 628-629 ◽  
pp. 459-464 ◽  
Author(s):  
Fa Zhan Yang ◽  
Xing Ai ◽  
Jun Zhao
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Sintering Temperature ◽  
Fracture Morphology ◽  
Particle Sizes ◽  
Growth Inhibitors ◽  
Hot Press ◽  
Hot Press Sintering ◽  
Matrix Nanocomposite

A new WC matrix nanocomposite cermet was prepared by hot-press sintering. In the composite, certain amounts of VC is added to the composite as grain growth inhibitors. The consolidation is carried out under pressure 30～35Mpa and sintering temperature 1610°C for soaking 30min sintering. Microstructure of the nanocomposite cermet is scanned by SEM and mechanical properties are measured. It is detected that microstructure and fracture morphology is dissimilar to different particle sizes. Experimental results show that particle size of WC is important to the composite. Results show that relative density and hardness have the similar trend in growth. Meanwhile, the function of Al2O3 addition is also investigated in this paper.

Study on Effect of Particle Size of Iron on Properties of Pure Iron Sintered

2012 ◽  
Vol 182-183 ◽  
pp. 332-335
Author(s):  
Yu Fang Yang ◽  
Jing Yao Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Pure Iron ◽  
Hot Press ◽  
Direct Heating ◽  
Effect Of Particle Size ◽  
Hot Press Sintering

The effect of particle size of iron on properties of pure iron sintered was studied systematically by the specimen current direct heating dynamic hot press sintering. It is found that mechanical properties of pure iron sintered decreased with the increasing particle size of iron. This is because big particle size of iron leads to big grain in microstructure of pure iron sintered.

Synthesis and Electrical Properties of Mo-ZrO2 Cermet

2011 ◽  
Vol 311-313 ◽  
pp. 2121-2126
Author(s):  
Ji Fang Xu ◽  
Gong Yuan Liu ◽  
Lei Tang ◽  
Jie Yu Zhang ◽  
Chang Jie
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Electrical Properties ◽  
Room Temperature ◽  
Optical Microscope ◽  
Metal Phase ◽  
Phase Zone ◽  
Ceramic Phase ◽  
Mo Content ◽  
Increasing Temperature

Under the protected condition of the purified argon atmosphere, Mo-ZrO2cermets were sintered by Mo powder and ZrO2powder at 1873K for 2 hours. Mircostructure of cermets were observed by means of XRD, optical microscope and SEM anslysis. Electrical properties of sintered samples with different Mo content and temperature were measured using DC four-electrode method. The results showed that metal phase and ceramic phase were independent of each other. With the reduction of Mo content, Mo metal phase as the continuous network structure is dispersedly distributed in the ceramic phase zone. The electrical conductivity of cermets at room temperature increased with decreaseing of the Mo content. The trend that the high-temperature electrical conductivity of cermets changed with the Mo content is the same as the trend that at the room temperature. When the Mo content is greater than 40%, the high-temperature electrical conductivity increased linearly with increasing temperature. The electrical conductivity of 40mol-% Mo-ZrO2reached the peak at 1223K and 1473K.

scholarly journals Sintering Behavior and Properties of Mo-Cu Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Aokui Sun ◽  
Yuejun Liu ◽  
Dezhi Wang ◽  
Zhihua Zhou
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Bending Strength ◽  
Hydrogen Reduction ◽  
Sintering Temperature ◽  
Reduction Process ◽  
Physical And Mechanical Properties ◽  
Critical Factor ◽  
Sintering Behavior ◽  
Homogeneous Microstructure

A simple microwave-assisted aqueous solution strategy combined with a subsequent low-temperature hydrogen reduction process was used to prepare Mo-Cu nanopowders. In order to systematically investigate the densification behavior and properties of Mo-Cu composites, the densification, microstructure, hardness, electrical conductivity, thermal conductivity, and bending strength of Mo-Cu compacts were tested after sintering at different temperatures. Results show that the sintering temperature is a critical factor in the densification process of Mo-Cu composites. The shrinkage rate, density, and hardness of sintered composites increase as the temperature rises. However, too high sintering temperature resulted in the decrease in electrical conductivity (EC), thermal conductivity (TC), and bending strength. By optimizing all the performance indicators, high-performance Mo-25 wt.% Cu composites with a homogeneous microstructure accompanied with good physical and mechanical properties could be successfully obtained by sintering for 2 h at 1200°C.

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