METHOD OF PASSIVATING FINE ALUMINIUM POWDER Russian patent published in 2010 - IPC B22F1/02 

FIELD: process engineering.

SUBSTANCE: invention relates to powder metallurgy, particularly to aluminium powder passivating by forming oxide film of the surface of particles. Proposed method comprises thermal treatment of powder in nitrogen-acid medium in the presence of moisture and oxygen content of 6-8 vol. %, 0.4-1 vol. % of moisture, and at 350-450°C , and powder cooling. Note here that aluminium powder with specific surface of at least 0.50 m²/g is subjected to passivating. Thermal treatment is performed together with intensive mixing. After cooling down, aluminium powder is subjected to blending in the mixer in nitrogen-acid medium containing oxygen in amount of at least 8 vol. % for 2-4 h.

EFFECT: complete aluminium powder passivating, formation of γ-AL₂O₃ film on particles surface, long storage in warm and humid ambient conditions.

5 cl, 1 tbl