| abstract |
(EN) Provided is a glass ball which is lightweight, has an insulating property, and has sufficient strength, while being relatively easy to process and manufacture and to reduce the manufacturing cost. Density is 2.3 to 3.2 g / cm 3 , Young's modulus is 60 to 150 GPa, average coefficient of thermal expansion at 50 ° C. to 350 ° C. is 40 × 10 −7 to 120 × 10 −7 / ° C., oxide-based moles. In terms of percentage, SiO 2 is 30 to 75 mol%, Al 2 O 3 is 2 to 30 mol%, and R 2 O (where R is at least one selected from Li, Na and K) is 5 to 5. A glass ball formed of a glass material containing 25 mol% and having a compressive stress layer on the surface thereof. |