Patent ID: 8178451

Claim:
A glass-metal bond in a tube collector of a solar energy collection apparatus, said glass-metal bond comprising a glass tube and a metal component bonded to the glass tube, wherein said glass tube has a glass composition comprising: SiO 2 73-77 wt. % B 2 O 3 6-<8 wt. % Al 2 O 3 6-6.5 wt. % Na 2 O 5.5-7 wt. % K 2 O 1-3 wt. % CaO 2-3.2 wt. % MgO 0-2 wt. % Fe 2 O 3 50-400 ppm TiO 2 0-<100 ppm, wherein a ratio of a total amount of B 2 O 3 , in mol %, to a sum of the total amount of the B 2 O 3 , in mol %, plus a sum of respective amounts of the Na 2 O and the K 2 O, in mol %, is <0.50; wherein a ratio of a sum of respective amounts of alkaline-earth metal oxides, in mol %, in the glass composition to a sum of respective amounts of alkali metal oxides, in mol %, is ≦0.6; and wherein said glass composition has a thermal expansion coefficient of >5.3×10 −6 /K to 5.8×10 −6 /K, a glass transformation temperature of at most 580° C., a processing temperature of at most 1215° C., a water-resistance class of HGB 1 according to DIN ISO 719, an acid-resistance class of S1 according to DIN 12116, an alkali-resistance class of S2 according to DIN ISO 695, and a solar transmission of >92% for wavelengths from 300 to 2500 nm.