Aluminum-free borosilicate glass and applications thereof
The fluorescent lamp is made with an aluminum-free borosilicate glass having a composition, in percent by weight, based on oxide content of: SiO 2 , 65-77; B 2 O 3 , 7-20; Li 2 O, 0-2; Na 2 O, 0-4; K 2 O, 3-12; MgO, 0-2; CaO, 0-2; with MgO+CaO, 0-3; BaO, 0-3; ZnO, 0-2; ZrO 2 , 0.8-12; TiO 2 , 0-10; CeO 2 , 0-1; and F − , 0-0.6. Preferred embodiments with more than 1% by weight TiO 2 have especially good UV blocking properties and are especially suitable for lamp glass for backlights. Other embodiments have good sealing properties to tungsten, KOVAR®, and molybdenum and have coefficients of thermal expansion α of 4.7 to 5.3×10 −6 /K, good chemical resistance, and a working point V A of between 990° C. and 1290° C.
1. A fluorescent lamp comprising a lamp glass, said lamp glass consisting of an aluminum-free borosilicate glass, said aluminum-free borosilicate glass having chemical resistance and a composition, in percent by weight, based on oxide content, of:
SiO 2
60-78
B 2 O 3
7-20
Li 2 O
0-2
Na 2 O
0-4
K 2 O
3-12
MgO
0-2
CaO
0-2
with MgO + CaO
0-3
BaO
0-3
ZnO
0-2
ZrO 2
0.8-12
TiO 2
0-10
CeO 2
0-1
F −
0-0.6
and optionally at least one refining agent in a standard amount for refining.
2. The fluorescent lamp as defined in claim 1 and consisting of a miniaturized fluorescent lamp or a backlight.
3. The fluorescent lamp as defined in claim 1 , wherein said aluminum-free borosilicate glass contains greater than 1% by weight of said TiO 2 .
4. The fluorescent lamp as defined in claim 1 , wherein said aluminum-free borosilicate glass has a coefficient of thermal expansion α(20° C.; 300° C.) of 4.7×10 −6 /K and 5.3×10 −6 /K, and said composition, in percent by weight, based on oxide content, comprises said SiO 2 , 70-75; said B 2 O 3 , 15-18; said Li 2 O, 0-1; said Na 2 O, 0-3; said K 2 O, 5-8; said CaO, 0-1; said BaO, 0-1; said TiO 2 , 0-1; said ZrO 2 , 0.8-5; and wherein Li 2 O+Na 2 O+K 2 O is 5.5-10.5.
5. The fluorescent lamp as defined in claim 4 , wherein said lamp glass is sealed to tungsten.
6. The fluorescent lamp as defined in claim 1 , wherein said aluminum-free borosilicate glass has a coefficient of thermal expansion α(20° C.; 300° C.) of 4.7×10 −6 /K and 5.3×10 −6 /K, and said composition, in percent by weight, based on oxide content, comprises said SiO 2 , 67-70; said B 2 O 3 , 15-18; said Li 2 O, 0-1; said Na 2 O, 0-3; said K 2 O, 7-10; said ZnO, 0-1; said ZrO 2 , 0.8-5; and wherein Li 2 O+Na 2 O+K 2 O, 7-12.5.
7. The fluorescent lamp as defined in claim 6 , wherein said lamp glass is sealed to an Fe—Co—Ni alloy or molybdenum.