| 摘要 |
<p>This invention is directed to transparent photochromic glasses that can darken to a comfort range, i.e., between about 35-60%, or to a dark range, i.e., below 35%, depending upon glass composition, and will exhibit a faded transmittance after five minutes' removal from actinic radiation higher than 70%. The base compositions of the glasses consist essentially, in weight percent, of about SiO2 46-60 MgO 0-3.5 B2O3 16-28 CaO 0-6 Al2O3 4-11 SrO 0-6 ZrO2 2-6 BaO 0-6 Al2O3+ZrO2 6-13 MgO+CaO+SrO+BaO 0-7 Li2O 2-5 P2O5 0-5 Na2O 0-4 TiO2 0-3 K2O 2.5-9 For a comfort glass the photochromic elements consist essentially, as analyzed, of Ag 0.13-0.18 Br 0.08-0.14 Cl 0.16-0.34 CuO 0.001-0.004 For a dark glass the photochromic elements consist essentially, as analyzed, of Ag 0.15-0.3 Br 0.07-0.14 Cl 0.2-0.45 CuO 0.004-0.016</p> |
