Properties of Hollow Glass Microspheres Obtained in a Propane-Air Torch

Hollow glass microspheres were obtained from soda-borosilicate glass by a high-temperature method, weight content, %: 10 Na2O; 8 CaO; 0.3 MgO; 0.2 Al2O3 ; 9 B2O3 ; 0.5 SO3 ; 72 SiO2 . It was ascertained that the maximum yield of microspheres, up to 87%, is observed on use of a propane-air torch with the following characteristics: air/propane ratio 1.3; maximum temperature on the flame axis 1900 & DEG;C; opening angle about 15 & DEG;; and, flow rate of carrier gas 0.2 g/sec. The hollow glass microspheres obtained in this regime are characterized by median diameter 60 & mu;m, average wall thickness 1.3 & mu;m, bulk density 260 kg/m(3), and calculated strength 50 MPa.