PROPERTIES OF FINE SHIRASUBALLOONS

Hollow glass microspheres named Shirasuballoons have been produced fro m glassy volcanic fragment named as Shirasu or Hakudo, Finer Shirasuba lloons are required to increase in physical and chemical properties of conventional Shirasuballoons and glass balloons, Fine Shirasuballoons of mean particle sizes under 20 mu m and bulk densities under 0.5 (10 (3) kg/m(3)) were successfully prepared by rapid heating of milled pow ders using a fluidized bed furnace. Strengths, thermal stabilities and chemical durabilities of fine Shirasuballoons, conventional Shirasuba lloons and glass balloons were measured under the same conditions, Str engths and chemical durabilities of fine and conventional Shirasuballo ons were obviously superier to these of conventional glass balloons, H igher the particle density of fine Shirasuballoons tended to increase in the strength, Fine and conventional Shirasuballoons held their stru cture up to 800 degrees C, approximately 200 degrees C higher than the conventional glass balloons.