A process for the adjustment of the uv - absorption of glasses and glass ceramics and use of glasses and glass-ceramics

摘要

A method for the preparation of a transparent, uv - block ends of the glass or glass ceramic having a defined uv - edge, wherein the glass compositionthe following components in w -% comprises:Sio₂ 60 – 85 Wt..-%B₂O₃ 0 – 35 Wt..-%Al₂O₃ 0 – 10% By.-%Li₂O 0 – 10% by.-%Na₂O 0 – 20% by.-%K₂O 0 – 20 w -%, wherein theΣ li₂O + na.sub.2₂O + k₂O 0 – 25 w -%, andMgo 0 – 8% by.-%Cao 0 – 20% by.-%Sro 0 – 5% by.-%Bao 0 – 5 w -%, wherein theΣ mgo + cao + sro + bao 0 – 20 w -%, andTio₂ 0,5 – 10% By.-%,characterised in that the glass(a), directly after the melting, a cooling with cooling rates of less than 500 k / min is subjected to, wherein the cooling rate is selected in such a manner that the glass in the comparison to a glass tube, which with cooling rates of 500 k / min is cooled, a displacement of the uv - edge of more than 5, in particular more..