Improvements in or relating to the production of glass or glass-like compositions permeable to ultra-violet rays

摘要

631,865. Glass. NUSSBAUM, A., and FRIEDMANN, Z. June 12, 1945, No. 14858. [Class 56] A glass-like composition which is highly permeable to light waves of shorter length and ultra-violet rays is produced by fusing phosphoric acid with a material consisting wholly of aluminium chloride or at least 15 per cent aluminium chloride with at least one of the oxides or chlorides of Ba, Ca, Sr, Mg, Be, Th, or Zr. The aluminium chloride preferably comprises more than 40 per cent of the mixture, but may be less if a softer glass is required, and is mixed with the other oxides or chlorides, then the stoichiometric equivalent or slight excess of phosphoric acid is added and the whole heated to about 1400‹ C. Two examples are: (1) aluminium chloride 3.00 gm. mols., barium chloride 1.39 gm. mols., strontium oxide 1.93 gm. mols., and calcium chloride 0.901 gm. mols.; (2) aluminium chloride 4.50 gm. mols., barium chloride 0.927 gm. mols., MgCl 2 .6H 2 O 0.492 gm. mols, calcium chloride 0.901 gm. mols. As the proportion of aluminium chloride increases the glass becomes tougher, has a higher softening point, and a greater resistance to atmospheric influences.