| 摘要 |
Elements e.g. microspheres having improved combination of crushing strength, index of refraction, and, especially in some formulations, chemical resistance comprise to an extent of at least 85% by weight of the glass composition 5-60 B2O3, 20-50TiO2, 10-35 BaO/SrO, 0-15 Na2O/K2O and 0-40 SiO2. The microspheres are especially adapted for use as retroreflective elements in pavement markings. |
