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Metal coated metal-halide pellets Disclosure Number: IPCOM000020232D
Publication Date: 2003-Nov-04
Document File: 1 page(s) / 22K

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The Prior Art Database


ID699947 & ID699413

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ID699947 & 699413

Metal coated metal-halide pellets

Mercury free metal-halide lamps often suffer of severe (re)ignition problems, caused by formation of free iodine. The free iodine is formed by reaction of the metal-halide lamp-filling with absorbed water. The water is absorbed during the many handling steps the metal-halide pellets have to undergo prior to their dosing in the lamp. In ordinary metal halide lamps the free iodine is being fixed by the excess of metallic mercury. In mercury free lamps, however, there is no metallic compound like mercury and thus, the free iodine will remain free, causing (re)ignition problems. Dosing another metal, like zinc, tin, indium, gallium, etcetera, does work and significantly improves the (re)ignition behaviour of the lamps.

Reliably dosing extreme small amounts of metal (0.1- 100µg) causes severe difficulties for the (existing) lamp-make process. Mixing the metal with the metal-halide is not possible due to the poor solubility of the metal in the liquid halide.

Proposed is to coat the metal-halide pellet with the desired metal. The coating process will be paning by mechanically mixing the pellets with nano-sized metal powder, allowing the tiny metal particles to stick on the surface of the pellets.

Alternatively the process will be vapour deposition like Chemical Vapor Deposition, evaporation, Physical Vapor Deposition (like sputtering), or other techniques for applying coatings.

One embodiment is spherical metal halide pellets of...