TANSO

Carbon Electrode in Electric Spark Discharge

II-Electric Discharging Properties of Coal Carbons in Air

H. Honda, Y. Sanada, T. Furuta

1967 Volume 1967 Issue 48 Pages 2-7
Published: March 05, 1967
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.7209/tanso.1967.2

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The electric discharging tests under various conditions have been examined on those coal carbon electrodes which were heat-treated at temperatures between 800°C and 2800°C. The electrode specimens were prepared from Akabira weakly-caking coal (d.a.f.C=83.40%) and from Itmann strongly-coking coal (d.a.f.C=90.2%) by means of the cold binderless molding at pressures of 1000 and 2000kg/cm² respectively.
The change in the threshold voltage before and after repeating the short-duration discharge (ΔVr) was found to be sensitive to temperature and retention time of the heat treatment.The voltage change caused by a continuous discharge for five minutes (ΔVc) and thedimension of craters as well as the amount of consumption (Nc) exibited minima at about2000°C when they were plotted against heat treatment temperature (HTT). The voltagechange due to impulsive discharge (ΔVi) as well as the occurence of short-circuit (Ni) showed a maximum and a minimum for HTT. It was concluded that the coal carbon heattreated at about 2000°C was the most able one in all kinds of the discharging test examined.
For Akabira-coal carbons, moreover, some correlations between ΔVr and HB/ρ (Brinnel hardness/electrical resistance), between ΔVi and σ/E (flexural strength/Young's modulus), and between ΔVc or Ni and contact potential have been found. It seems that the larger the mechanical strength, the flexibility and the electrical conductivity of carbon electrodes are, the better the electric discharging properties

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Erratum to : Plasticity and Thermal Analysis of Coal Tar Pitch at High Temperature

1967 Volume 1967 Issue 48 Pages 7
Published: 1967
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.7209/tanso.1967.48_7

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Research on Metal-Graphite Brush Prepared from Graphiterich Coated Powder

T. Matsukawa, K. Shoji

1967 Volume 1967 Issue 48 Pages 8-12
Published: March 05, 1967
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.7209/tanso.1967.8

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Copper-lead-alloy coated graphite powders containing 40-50% graphite were pressed and sintered in hydrogen. The sintering process and properties of sintered brush were examined. The results obtained are as follows:
(1) Thermal expansion in the pressed direction during sintering affects the properties of sintered brush.
(2) The brushes sintered at 400-500°C have sufficient bending strength and low electrical resistivity.
(3) Friction coefficient of sintered brushdecreases with increasing graphite content, and 1-2% lead in brush structure lowers and stabilizes friction coefficient.
(4) Thermal expansion of sintered brush shows much higher value in the pressed direction than in the direction perpendicular to it.
(5) The distributions of copper and graphite are very uniform in the structure of sintered brush, and wearing characteristics of the brush are superior.

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[title in Japanese]

[in Japanese], [in Japanese]

1967 Volume 1967 Issue 48 Pages 13-23
Published: March 05, 1967
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.7209/tanso.1967.13

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[in Japanese]

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[title in Japanese]

[in Japanese], [in Japanese], [in Japanese]

1967 Volume 1967 Issue 48 Pages 24-31
Published: March 05, 1967
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.7209/tanso.1967.24

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