粉末粒形对钡钨阴极多孔钨基体孔隙的影响

Effect of powder shape on porosity of porous tungsten matrix for barium-tungsten cathode

采用粉末注射成形工艺制备钡钨阴极多孔钨基体,定量表征钨粉的粉末粒度和粒形,重点研究粉末粒形对多孔钨基体孔隙特性的影响。通过对比粉末的球形度、形状因子、圆润度、粗糙度、赘生物指数和凹度等特征参数,发现球形钨粉比商品还原钨粉和窄粒度钨粉具有更好的球形度、表面光滑度以及分散度。当粉末粒度相差不多时,通过改善钨粉的颗粒形状,粉末分散度得到提高,SW粉末经注射成形得到的多孔钨基体(P_(SW))的孔隙结构均匀性最佳,其平均孔隙度、平均开孔孔隙度、平均孔径和孔隙总容积分别为24.0%、23.9%、1.17μm、0.0206 mL/g。

Porous tungsten matrix for barium-tungsten cathode was prepared by powder injection molding method.Particle size and particle shape of the selected tungsten powder were quantitatively characterized by image analysis technology.The influence of the particle shape on the pore characteristics of porous tungsten matrix was investigated in detail.By comparing the characteristic parameters such as sphericity,form factor,roundness,roughness,outgrow and concavity of the tungsten powders,it is found that the spherical tungsten(SW) powders exhibit better sphericity,surface smoothness and dispersion than the commercial reduced tungsten(GW) powders and narrow particle tungsten(NPW) powders.When the particle size is almost the same,the porous tungsten matrix obtained by SW powders(P_(SW)) shows the most homogeneous pore structure,due to the improved particle shape and dispersion of SW powders.The average porosity,average open porosity,average pore diameter and total pore volume of the PSW are 24.0%,23.9%,1.17 m and 0.0206 mL/g,respectively.