The Influence of the Dimension Factor on the Consolidation Process of Highly Disperse Nickel Powders

摘要

Ultradisperse (UDP) and finely disperse (FDP) nickel powders were investigated, with dimensions of d_p ? 0.1 #mu# m, 1.0 #mu# m and 10.0 #mu# m in the series "starting state - pressing -sintering". It has been established that great changes of physico-chemical structural and technological parameters occur in this series when the grain size is below 1 #mu# m. The influence of the dimension factor on dominating mass transfer mechanisms during sintering is such, that with the increase of the dispersion degree the influence of adhesion, surface diffusion and diffusion on grain boundaries increase, while the influence of volume diffusion decreases. It has been established that for two groups of nickel powders with different grain sizes, recrystallization and mass transfer are processes that occur in parallel during the structure formation process during sintering pressed samples