Tribo-charging characteristics of powder in a rotating vessel are investigated under different humilities and temperatures to clarify the effect of atmospheric condition. The sample powder was prepared through coating of ferrite carrier particles with silicone resin.
It is found that the absolute value of the maximum charge of powder and the time constant of charge relaxation decrease with increasing relative humidity and temperature. The contact potential difference of sample powder against the wall of a rotating vessel and the time constant of charge generation are found to be constant, even if relative humidity and temperature vary. Therefore, the dependence on relative humidity and temperature of the maximum charge of powder is caused by the change in time constant of charge relaxation. Furthermore, there are good correlations among absolute humidity, maximum charge of powder and time constant of charge relaxation.
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