Kinetics of Whisker Growth on Vanadium Pentoxide

摘要

The interplay of three growth mechanisms responsible for the formation of filaments on solid surfaces is analyzed. These are: 'short circuit' diffusion within the filament body, evaporation from and condensation on the tip of the filament. Kinetic expressions for the simultaneous occurrence of the former with the latter processes are developed and typical growth behaviors are characterized. A dislocation core is used as a suitable 'short circuit' path for diffusion. Kinetic evidence is presented to show that whiskers grown on V2O5 crystals follow the derived growth patterns. Detailed rate data are reported for temperatures 500 to 650C in air, steam and vacuum. Observations on growth morphology of V2O5 whiskers are reviewed. Whenever a growing whisker collided with an adjacent crystal, rapid radial growth of the filament resulted. Thus, it is suggested that whisker growth within fine particles or pores of loose aggregates characterizes the first stage of sintering of solid particulate systems. Mathematical expressions for each step of the kinetic sequence from whisker formation to neck growth between sintering particles of vanadium pentoxide are presented. (Author)