Flowability and infrared interference properties of modified graphite flake with hydrophobic nano-silica

To research the dispersion properties and infrared (IR) interference efficiency of graphite flake particulates modified by hydrophobic nano-silica, the flowability of graphite flake particles before and after modification was measured by a powder property tester. The smoke was formed by dispersing the graphite flake particles into the smoke box using air flow dispersion way. The mass concentration and IR spectrum transmission of the smoke were measured. On the basis of stir settlement model, the settling velocity of smoke was calculated. Results show that the Carr's flowability index of graphite flake particulates modified with hydrophobic nano-silica in mass ratio of 4.0% is the highest, reaching 61 and at the same time, the settling velocity decreases from 2.288×10^-3 m·s^-1 before modification to 1.125×10^-3 m·s^-1 after modification. Average IR spectrum transmission of the smoke formed in the wave band range of 3-5 μm and 8-12 μm decreases from 0.3895% and 0.7288% to 0.072% and 0.176%. The physical modification of hydrophobic nano-SiO₂ on graphite flake surface effectively improves the flowability and dispersion properties and significantly increases the duration of the smoke formed by graphite flake particles and IR interference performance.