In-situ synthesis of tungsten nanoparticle attached spherical tungsten micro-powder by inductively coupled thermal plasma process

Tungsten spherical micro-powder, tungsten nanoparticle, and tungsten nanoparticle attached spherical micro-powder were synthesized by manipulating feedstock and plasma gas composition in the present study. Powder preparation strategy is simple and phase evolution pathway of each component was tailored by exploiting thermos-physical properties of feedstock and thermal plasma reactivity. Irregular W aggregates underwent melting-solidification pathway and accordingly, spherical micro-powders were obtained. On the other hand, low boiling point WO3 micro-powders were vaporized and reduced in Ar-H2 thermal plasma. After that, vapor species condensed to nanoparticles which were composed of α-W and β-W. These results demonstrated that phase evolution pathway and resulting powder properties were determined by feedstock powders. In this context, W and WO3 blended powders were prepared by a simple blending and they were fed into Ar-H2 thermal plasma. Owing to individual interactions of in-flight particles with thermal plasma and co-flight of spherical W micro-powders and W nanoparticles, nanoparticle dispersed spheroidized micro-powder was in-situ synthesized. 3 dimension architecture of the synthesized nanoparticle dispersed micro-powder was revealed by ultrasonic detachment.