| 摘要 |
Electrostatographic carrier materials having low bulk densities and high magnetic permeabilities are obtained by providing an alumino-boro-silicate glass particle containing from between about 10 to about 15 molar percent Fe2O3 in which superparamagnetic ferrite crystallites having an average particle size of up to about 500A have been precipitated by heat treatment. The magnetic behavior of the glass carrier particles which is dependent on the number present and size of the ferrite crystallites can be closely controlled by heat treatment at temperatures in the range of between about 600 DEG C and 800 DEG C. When mixed with toner particles, these magnetic glass carrier materials experience significantly reduced toner impaction levels.
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