| 摘要 |
<p>664,769. Glass compositions. PHILIPS ELECTRICAL, Ltd. March 11, 1949 [March 15, 1948], No. 6741/49. Class 56 [Also in Group XL (a)] The support of the luminescent screen for a cathode-ray tube is made of cerium glass which does not contain more than one per cent by weight of the oxides of lead, antimony and arsenic which yields little discoloration by electron bombardment. The proportion of sodium oxide in the hard or soft glass preferably should not exceed 15 per cent by weight, and the content of the specified oxides should be correspondingly reduced when the content of sodium oxide, and consequent electrolysis, is increased. A glass which gives no discoloration contains the following proportions : SiO 2 -66, Na 2 O-5, K 2 O-10, B 2 O 3 -2, BaO-15, CeO 2 -2 per cent. Alternatively K,O may be eliminated and Na 2 O increased to 15 per cent to give discoloration which is just visible. The following glass gives slight discoloration-SiO 2 -65, Na 2 O-15, B 2 O 3 , -2, BaO-15, CeO 2 -2, PbO-1 per cent.</p> |
