Component used for vacuum tube solar heat collector, comprises portion having glass having boron trioxide, sodium oxide, potassium oxide, calcium oxide, magnesium oxide, barium oxide, strontium oxide and silica, and another portion

摘要

A component (1) comprises a primary portion containing glass and a secondary portion containing metal and metal-glass compound (4). The glass comprises 0-3 wt.% boron trioxide, 1-4 wt.% alumina, 8-16 wt.% sodium oxide, 1-9 wt.% potassium oxide, 0-5 wt.% calcium oxide, 0-5 wt.% magnesium oxide, 0-2 wt.% barium oxide, 0-4 wt.% strontium oxide, and remainder of silica, and includes less than 400 ppm iron. The glass and metal are different in thermal expansion coefficient by 10% or less.