Monolithic seal for sapphire CMH lamp

A ceramic-metal-halide discharge lamp produced by the method comprising the steps of:

• providing a tube made of sapphire;
• providing an end cap made of unsintered polycrystalline alumina, said end cap comprising a main wall defining an annularly-shaped groove axially extending from a side of said main wall;
• heating said end cap until said end cap is presintered to remove binder;
• placing said presintered end cap on an end portion of said tube to form an interface therebetween;
• and
• heating said presintered end cap and said tube until said end cap is sintered onto said tube and said sapphire tube grows into said end cap to form a monolithic seal at the previous interface between said end cap and said tube, said monolithic seal existing at an interface between an outer groove surface of said end cap groove and an outer surface of said tube.

A ceramic-metal-halide discharge lamp produced by the method comprising the steps of:

• providing a tube made of sapphire;
• providing an end cap made of unsintered polycrystalline alumina, said end cap comprising a disc-shaped main wall and a tubularly-shaped extension axially extending from a side of said main wall, and said end cap defines an aperture axially extending through said main wall and said extension;
• heating said end cap until said end cap is presintered to remove binder;
• placing said presintered end cap on an end portion of said tube to form an interface therebetween;
• and
• heating said presintered end cap and said tube until said end cap is sintered onto said tube and said sapphire tube grows into said end cap to form a monolithic seal at the previous interface between said end cap and said tube.

A high-pressure discharge lamp produced by the method comprising the steps of:

• providing a tube made of sapphire;
• providing an end cap made of unsintered polycrystalline alumina, said end cap comprising a disc-shaped main wall and a tubularly-shaped extension axially extending from a side of said main wall, and said end cap defines an aperture axially extending through said main wall and said extension;
• heating said end cap until said end cap is presintered to remove binder;
• placing said presintered end cap on an end portion of said tube to form an interface therebetween;
• and
• heating said presintered end cap and said tube until said end cap is sintered onto said tube and said sapphire tube grows into said end cap to form a monolithic seal at the previous interface between said end cap and said tube.