Coagulation of tungsten nanopowders under annealing in hydrogen

Coagulation of tungsten nanoparticles is investigated under annealing in hydrogen flow at 600–1000°C and duration of holding up to 1 h. It is established that the main mechanism of coagulation is the gasphase transport, and mass carriers are the WO3 · H2O molecules. Evaluative calculations of the coagulation rate are performed and their satisfactory agreement with experimental results is shown. Recommendations for optimization of conditions of thermal treatment of tungsten nanopowders are given.