scholarly journals Intrinsic resistivity of sintered Nickel Manganite vs. powder activation time and density

2008 ◽  
Vol 40 (1) ◽  
pp. 27-32 ◽  
Author(s):  
S.M. Savic ◽  
M.V. Nikolic ◽  
O.S. Aleksic ◽  
M. Slankamenac ◽  
M. Zivanov ◽  
...  
Keyword(s):  
Ball Mill ◽  
Structural Changes ◽  
Sintering Temperature ◽  
Planetary Ball Mill ◽  
Dc Resistivity ◽  
Activation Time ◽  
Sample Density ◽  
Ntc Thermistor ◽  
Different Temperatures ◽  
Thermistor Material

In this work the DC resistivity of sintered nickel manganite NiMn2O4 (NTC thermistor material) was studied as a function of additional powder activation time in a planetary ball mill (0, 5, 15, 30, 45 and 60 min). The activated powders and non-activated powder were sintered at different temperatures (900, 1050 and 12000C) for an hour. Structural changes were analyzed using XRD. Sample density, porosity and DC resistivity were measured on the same sintered samples. Correlations between sample density, porosity, and intrinsic DC resistivity vs. additional powder activation time and the sintering temperature were made. It was noticed that the resistivity falls with the increase of sample density (or increase of the sintering temperature).

scholarly journals Intrinsic resistivity of sintered Nickel Manganite vs. powder activation time and density

2008 ◽  
Vol 40 (1) ◽  
pp. 27-32
Author(s):  
S.M. Savic ◽  
M.V. Nikolic ◽  
O.S. Aleksic ◽  
M. Slankamenac ◽  
M. Zivanov ◽  
...  
Keyword(s):  
Ball Mill ◽  
Structural Changes ◽  
Sintering Temperature ◽  
Planetary Ball Mill ◽  
Dc Resistivity ◽  
Activation Time ◽  
Sample Density ◽  
Ntc Thermistor ◽  
Different Temperatures ◽  
Thermistor Material

In this work the DC resistivity of sintered nickel manganite NiMn2O4 (NTC thermistor material) was studied as a function of additional powder activation time in a planetary ball mill (0, 5, 15, 30, 45 and 60 min). The activated powders and non-activated powder were sintered at different temperatures (900, 1050 and 12000C) for an hour. Structural changes were analyzed using XRD. Sample density, porosity and DC resistivity were measured on the same sintered samples. Correlations between sample density, porosity, and intrinsic DC resistivity vs. additional powder activation time and the sintering temperature were made. It was noticed that the resistivity falls with the increase of sample density (or increase of the sintering temperature).

Microwave Sintering and Electric Properties of ZnO Varistor Ceramics

2013 ◽  
Vol 833 ◽  
pp. 75-79 ◽  
Author(s):  
Xin Xin He ◽  
Guo You Gan ◽  
Ji Kang Yan ◽  
Jing Hong Du ◽  
Jia Ming Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Ball Mill ◽  
Milling Time ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Electric Properties ◽  
Planetary Ball Mill ◽  
Zno Varistor ◽  
C Doping ◽  
Zno Powder

The ZnO varistor ceramics were fabricated through microwave sintering at 800~1150°C using ZnO powder doped and undoped TiO2 prepared by planetary ball mill. And the effects of milling time, sintering temperature and doping on microwave sintering technique have been studied. The result shows that the powder is more homogeneously and with smaller particle size with the increasing of milling time, therefore the electric properties is improved. However the particle size and the electric properties tend towards stability after 20h milling time. The density and electric properties increase with the increasing of sintering temperature, but decrease sharply at 1100°C, so the best sintering temperature is 1100°C. Doping TiO2 improves the electric properties of ZnO, however the electric properties decrease with more than 2.5% doping.

Effect of Sintering Temperature on the Dielectric Properties of Pb(Zr0.52Ti0.48)O3 Ceramics Synthesized via High Planetary Ball Mill

2015 ◽  
Vol 1087 ◽  
pp. 167-171
Author(s):  
Mohd Fariz Ab Rahman ◽  
Asyraf bin Arshad ◽  
Zainal Arifin Ahmad ◽  
Julie Juliewatty Mohamed
Keyword(s):  
Dielectric Properties ◽  
Ball Mill ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Perovskite Phase ◽  
Secondary Phase ◽  
Planetary Mill ◽  
Dielectric Constants ◽  
Planetary Ball Mill ◽  
Increasing Temperature

The properties of Pb(Zr0.52Ti0.48)O3(PZT) ceramics have been studied. PZT ceramic powders were successfully prepared by high planetary ball mill method under different milling time and then were sintered at different sintering temperature. The raw materials of PbO, ZrO2 and TiO2, powders were ball milled at 40 and 60 hours using high planetary mill. The mixing powders then were compacted and sintered at 950°C and 1200°C. Formations of the perovskite phase along with some secondary phase were seen after 40 and 60 hours of milling while single phase formation of PZT was seen after sintered at both sintering temperatures. The grain size of the samples becomes larger with the increasing temperature. In dielectric properties analysis, the dielectric constants were reduced due to increasing sintering temperature. Meanwhile, the loss tangents increased with sintering temperature.

Study on Preparation of Mullite Powder Using Fly Ash by Mechanochemical Method

2013 ◽  
Vol 318 ◽  
pp. 326-330
Author(s):  
Lei Zhang ◽  
Qun Yu Chen ◽  
Ding Gao
Keyword(s):  
Fly Ash ◽  
Ball Mill ◽  
Structural Changes ◽  
Planetary Ball Mill ◽  
Mechanochemical Method ◽  
Signal Phase ◽  
Direct Formation ◽  
Ft Ir ◽  
Mullite Powder ◽  
Grinding Time

This paper studies the structural changes of the mixture of fly ash and A12O3 grinded by planetary ball mill . By investigating the structure of the ground product by SEM, XRD and FT-IR, the mechanism of mullite formation is discussed. The crystal structure of the mixture was destroyed by the grinding of planetary ball mill, and with the grinding time increases, the specific surface area of the mixture increases as well. And this leads to the decrease of bond energy, the increase of the internal energy and the decrease of the activation energy. After this process,uniform mixture and direct formation of signal phase mullite can be obtained from the mixture grinded for 30 hours and calcined at 1150°C for 2 hours and the temperature for mixture ungrinded needs to reach 1450°C.

scholarly journals Influence of Bi2O3 on microstructure and electrical properties of ZnO-SnO2 ceramics

2007 ◽  
Vol 39 (3) ◽  
pp. 229-240 ◽  
Author(s):  
T. Ivetic ◽  
M.V. Nikolic ◽  
M. Slankamenac ◽  
M. Zivanov ◽  
D. Minic ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ball Mill ◽  
Energy Dispersive Spectrometer ◽  
Molar Ratio ◽  
Dc Resistivity ◽  
Impedance Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Scanning Electron

The effects of small amounts (0.5; 1.0 and 1.5 mol. %) of bismuth oxide on the microstructure and electrical properties of ZnO-SnO2 ceramics have been studied. Starting powders of ZnO and SnO2 were mixed in the molar ratio 2:1. After adding Bi2O3 this mixture was mechanically activated for 10 minutes in a planetary ball mill, uniaxially pressed and sintered at 1300?C for 2h. The phase composition of the sintered samples was analyzed by X-Ray Diffraction (XRD) and by Energy Dispersive Spectrometer (EDS). Morphologies were examined by Scanning Electron Microscopy (SEM). An Impedance/Gain Phase Analyzer (HP 4194A) was used to measure the impedance spectra (100Hz - 10MHz) at different temperatures. The electrical DC resistivity/conductivity at different temperatures was measured using a High Resistance Meter (HP 4329A).

Heat Treatment Influence on the Corrosion Resistance of a Cu-Al-Fe-Mn Bronze

2018 ◽  
Vol 69 (5) ◽  
pp. 1055-1059 ◽  
Author(s):  
Mariana Ciurdas ◽  
Ioana Arina Gherghescu ◽  
Sorin Ciuca ◽  
Alina Daniela Necsulescu ◽  
Cosmin Cotrut ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Structural Changes ◽  
Heating Temperature ◽  
Galvanic Corrosion ◽  
Cooling Water ◽  
Open Circuit ◽  
Water Quenching ◽  
Heat Treated ◽  
Different Temperatures

Aluminium bronzes are exhibiting good corrosion resistance in saline environments combined with high mechanical properties. Their corrosion resistance is obviously confered by the alloy chemical composition, but it can also be improved by heat treatment structural changes. In the present paper, five Cu-Al-Fe-Mn bronze samples were subjected to annealing heat treatments with furnace cooling, water quenching and water quenching followed by tempering at three different temperatures: 200, 400 and 550�C. The heating temperature on annealing and quenching was 900�C. The structure of the heat treated samples was studied by optical and scanning electron microscopy. Subsequently, the five samples were submitted to corrosion tests. The best resistance to galvanic corrosion was showed by the quenched sample, but it can be said that all samples are characterized by close values of open-circuit potentials and corrosion potentials. Concerning the susceptibility to other types of corrosion (selective leaching, pitting, crevice corrosion), the best corrosion resistant structure consists of a solid solution, g2 and k compounds, corresponding to the quenched and 550�C tempered sample.

Fast, solvent-free and highly enantioselective fluorination of β-keto esters catalyzed by chiral copper complexes in a ball mill

2017 ◽  
Vol 19 (7) ◽  
pp. 1674-1677 ◽  
Author(s):  
Yifeng Wang ◽  
Haojiang Wang ◽  
Yidong Jiang ◽  
Cheng Zhang ◽  
Juanjuan Shao ◽  
...  
Keyword(s):  
Ball Mill ◽  
Copper Complexes ◽  
Solvent Free ◽  
Planetary Ball Mill ◽  
Keto Esters ◽  
Solvent Free Conditions

A fast and highly enantioselective fluorination of β-keto esters catalyzed by diphenylamine linked bis(oxazoline)-Cu(OTf)2 complexes under solvent-free conditions has been developed using a planetary ball mill.

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