Patent ID: 7164233

Claim:
A lamp assembly, comprising: a sealed envelope of glass; a light emitting element housed within said envelope; at least one lead-in wire passing through said envelope and coupled electrically to said light emitting element and having a predetermined coefficient of thermal expansion over a temperature range from ambient to 520° C.; wherein said sealed envelope is fabricated of barium silica glass that is essentially free of cadmium and which has a coefficient of thermal expansion over the temperature range of ambient to 520° C. which is about the same as that of said lead-in wires so as to preclude a build up of stress, separation, cracking or failure at the interface of said lead-in wires and said envelope during repeated heating and cooling cycles of said lamp assembly; and wherein said at least one lead-in wire has a composition of about 42.5 wt. % nickel, 5.75 wt. % chromium, 0.5 wt. % manganese, 0.25 wt. % silicon, 0.07 wt. % maximum carbon, and the balance essentially iron.