PREPARATION OF MONOLAYER PARTICLE COATED POWDER BY THE DRY IMPACT BLENDING PROCESS UTILIZING MECHANOCHEMICAL TREATMENT

Spherical silica particles 0.3, 0.6 and 0.9 mum in diameter, and spherical polyethylene particles 5.2 and 11.9 mum in diameter were used as coating and core materials respectively. Scanning electron microscopy revealed that the silica particles were fixed on the surface of the polyethylene particles, and a monolayer particle coated powder was formed by a dry impact blending preparation method when the ratios of the coating and core particle sizes were 0.3/11.9, 0.6/11.9, 0.9/11.9 and 0.3/5.2. In the dry impact blending of a binary powder mixture which contains two different sizes, it was shown that the ratio of the core and coating particle sizes, the particle sizes themselves and the action of impulsive forces during the operation were important factors in the effective preparation of the monolayer particle coated powder. The binding energies were calculated on the assumption that the Coulomb and London-van der Waals interactions were the basis of adhesion for these monolayer particle coated polyethylene powders. Consequently, it was found that the Coulomb interaction between particles with different electric charges was not always advantageous for the formation of the monolayer particle coated powder.