Effect of tungsten powder particle shape on the emission properties of the barium-tungsten cathode
WANG Minghui1，2，HU Ke2，YANG Shisong2，WU Renjun3，ZHANG Fangyang3，LIN Bo1
（1.School of Mechanical Engineering, Guizhou University, Guiyang 550025, China； 2. Institute of New Materi‐ als, Guangdong Academy of Sciences, National Engineering Research Center of Powder Metallurgy of Titanium & Rare Metals, Guangzhou 510650, China； 2. School of Intelligent Manufacturing, City College of Huizhou, Hui‐ zhou 516025, China）
Abstract：Porous W matrixes for dispenser Ba-W cathodes were prepared by metal injection molding (MIM) us‐ ing W powders with different particle shapes as raw materials. The influence of the powder particle shape on the pore characteristics of porous W matrix and the emission properties of the Ba-W cathode was studied. The results show that although the particle size distribution of spherical W powders （SW）and narrow particle size distribution W powders （NPW）powders are basically the same, the NPW powders have a higher specific surface area than SW powders for the higher“Outgrow”and Concavity value. The pore-specific volume of porous W matrix prepared by two different powders is almost the same, compared with the PNPW matrix, the PSW matrix has higher open porosity and larger average pore size. However, the sinuous pore channels formed by the irregularly shaped W powder parti‐ cles and sintered necks inside the P NPW matrix have a higher pore-specific surface area, which results a higher con‐ tact area between the impregnants and the W powder particles. Therefore, more barium atoms are reduced in the same time, which make the coverage of the active barium atoms on the cathode emission surface higher, reduces the cathode work function, and the emission current density of the cathode is improved.
2024, Vol. 34 
