傍熱型電子管ヒータ用タングステン線の研究

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The break of tungsten filament and deformation of the electron tube heater in their on-off cycling are the subjects of our present study with respect to their tensile strength at room temperature after their heat treatment, and also with respect to their metallographic structure. The heat treatment the tungsten filament was made by the method presented in our previous report^5). The on-off cycling of the heater was carried on by applying heater voltage higher than normal rating. The results summarized as follows. (1) The tungsten filament with tensile strength that remains high at room temperature after the treatment does not break even at the on-off cycling test where heater voltage higher by 60% than normal rating is applied. In order to prevent the break of the filament or the deformation of the heater, it is necessary that the tungsten filament will have tensile strength higher than 50 g/MG at room temperature, and maintain it after being subjected to heat treatment at 1 600℃ for 20 seconds. (2) The tungsten filament with low tensile strength at room temperature easily breaks and the heater gets deformed after heat treatment or at on-off cycling test, and their metallographic structure shows grain growth considerably. (3) As evidenced by repeated experiments the tensile strength of the tungsten filament has a great deal to do with the condition of the filament itself and of the electron tube heater after their heat treatment and on-off cycling test, whether both the filament and the heater are safe and sound or ether there will be the break of the filament and deformation of the heater. This evaluation method tungsten filament will thus guarantee prevention of break of the filament and deformation of the heater.P434To examine the effect of reduced cement content upon the properties of concrete containing admixtures, as in the air-entraining agent, five water-reducing admixtures. four water reducing-set controlling admixtures, and five brands of normal portland cement have been selected and used with some combinations. Comparative tests have been performed of fresh concrete with respect to its water-reduction, bleeding, me of initial and final setting. and of hardened concrete with respect to its strength gain concretes with the above-mentioned admixtures with cement contents of 260, 280 and 300 kg/m^3, were prepared and compared with the control concrete having the cement content of 300 kg/m^3 and same consistency 7. 5 cm without admixture. The results of the test show that the good quality of water-reducing admixtures can reduce water requirement by 10 to 15 percent. irrespective of the cement contents, and that the strength gain, the time required for setting and bleeding are affected by reduction in cement contents. and by the quality water-reducing admixtures.
社団法人日本材料学会の論文
1969-05-15

傍熱型電子管ヒータ用タングステン線の研究

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