Production of Fine Copper Powder by Disproportionation Reaction of Cuprous Sulfate Solution (3rd Report). Formation Mechanism of Fine Copper Powder by Disproportionation Reaction.

Acidic cupric sulfate solution, equilibrated with copper at 220°C, was injected into the same solution which was already placed in a large stainless reservoir.From the observation of the solution and the measurement of light transmittance through the solution, it was found that the solution was clear for a short while after injection and suddenly became turbid. The fact suggests that the homogeneous nucleation of copper take place after some induction period.The particle numbers formed per unit volume (N) could be approximately expressed as a function of supersaturation degree (S)N=S2.05×108.7From the observation of internal structure with TEM and SEM, it was found that copper particles were polycrystals which had radial internal structures.