Preparation and emission property of scandia pressed cathode

Scandia pressed cathodes were prepared by powder metallurgy method using mixed powder of scandia doped tungsten and barium-calcium aluminates obtained by different mixing methods. The element distribution uniformity greatly affected the emission property. The powder prepared by ball-milling had small particle size and uniform distribution of different elements. This kind of powder was favorable for the chemical reaction among Ba, Ca aluminates, scandia and tungsten to take place sufficiently to form active substance which can improve the emission property. The emission current density of the cathode prepared with ball-milling powder was about 8 times higher than that prepared by manually mixing method, 4 times higher than Os coated M-type cathode. The higher content of the active substance on the cathode surface prepared by ball-milling led to the better emission performance of the cathode.