Open AccessThe emission of electricity from carbon at high temperatures
Author(s) -
J. A. Harker,
G. W. C. Kaye
Publication year - 1912
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1912.0030
Subject(s) - tube (container) , carbon fibers , refractory (planetary science) , materials science , shot (pellet) , metallurgy , mechanics , composite material , physics , composite number
This paper is a first communication of the results of some experiments conducted in electric furnaces at atmospheric pressure, and mostly at very high temperatures. The investigation came about originally in an attempt to explain some contamination phenomena which were encountered when short tubes of extremely refractory rare earths were baked in various types of carbon-tube resistance furnaces at temperatures from 1500°C. upwards. An examination of the refractory tubes after baking showed that, in certain circumstances, the outer surface of each tube, instead of having the white and hard appearance of the rest, was carburised and crumbly. The action was not merely a surface one, but extended to an appreciable depth. On the other hand, the inner surface of the tube was comparatively unaffected, although it was freely open to the furnace gases, nor did the blackening occur if the tube was shielded. An explanation which at once suggests itself is that the blackening was produced by particels—possibly electrified—shot off from the carbon walls of the furnace with sufficient velocity to penetrate the material of the refractory tubes some millimetres (4 to 7) away. The circumstances pointed to the desirability of a general study of the electrical properties of the atmospheres of such furnaces.