1995 年 13 巻 4 号 p. 532-539
A comparative study has been made of characteristics of gas-tungsten-arc (GTA) cathode consisting of tungsten mixed with a small quantity of lanthanum-, yttrium-, thorium-oxide and lanthanum hexa-boride.
In this study, temperature distributions of each electrode are compared at various conditions. The temperature distribution was measured by the use of infrared thermal monitor. The influence of arc light emission on the measurement was discussed, and there was a little influence in measured temperature. It was less than 5% of its value.
The consumption test of the electrode was carried out at constant current for 1 to 5 hours. After test, the weight change was measured, and the microstructure was observed by SEM and analyzed by EDX.
In this study, the LaB6-W electrode showed good performance in high current condition. The temperature distribution of LaB6-W electrode was different from conventional La2O3(2%)-W elec-trode. LaB6(0.2%) -W electrode showed relative flat temperature distribution and La2O3(2%) -W showed steep one. The relation between temperature distribution and consumption of electrode was discussed.