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Scandium Powder for Lamps

#3243


Development of the Technology of Producing Scandium Metal Powder to Fill Low-Wattage Metal Halide Lamps

Tech Area / Field

  • MAT-ALL/High Performance Metals and Alloys/Materials
  • CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry

Status
3 Approved without Funding

Registration date
06.04.2005

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Supporting institutes

  • VNIIKhT (Chemical Technology), Russia, Moscow

Collaborators

  • Colorado State University, USA, CO, Fort Collins

Project summary

A proposed Project is aimed at developing a technology of producing scandium metal powder by hydriding/dehydriding technique and subsequent application of such powder as a low-wattage metal halide lamp filling component.

Metal halide lamps with emitting additives are widely used both for indoor and outdoor lighting. Lamps of less than 175W are referred to low-wattage metal halide lamps. Decrease in lamp power complicates a dosage of lesser and lesser quantities of emitting additives into quartz arc envelopes of a metal halide lamp. Therefore, efficient loading of low-wattage metal halide lamp arc envelopes requires the dosage of filling components that have a shape of monodisperse pellets (particles) with a mass varying within ±10% of a preset rated value.

A mixture of two emitting additives – scandium triiodide and sodium iodide - is used in scandium metal halide lamps. Filling of low-wattage metal halide lamps requires introducing 0.05-0.5mg of scandium metal into a quartz arc envelope of one lamp. This type of filling rests on engineering solutions known from the patent references and is based on application of a triple mixture composition:

  1. fine monodisperse metal scandium particles;
  2. mercury diiodide pellets;
  3. sodium iodide pellets.

Such method of lamp filling with emitting additives ensures production of needed quantities of anhydrous scandium iodide directly in the quartz arc envelopes at first metal halide lamp turn-on via chemical exchange reaction:

2Sc(sol.)+3HgI2(gas)2ScI3(gas)+3Hg(gas)

A triple mixture “Sc (discrete particles) + HgI2 (pellets) + NaI (pellets)” is a potential substitute as a scandium metal halide lamp filling for a pelleted highly hygroscopic double mixture ScI3+ NaI.

Hydriding/dehydriding technique is one of the most powerful for producing metal powder that constitute a category of hydride-forming metals. At that, chips, sponge, ingots or coarse metal powder (scandium in this case) can be transformed into fine-disperse metal powder.

This technique has been already used to produce commercial titanium, zirconium and uranium powders. A similar workflow for producing fine-disperse and monodisperse scandium powders is to be developed in the process of implementing the Working Plan of a proposed ISTC Project. Hence, development of the technology of producing scandium metal powder by hydriding/dehydriding technique and subsequent application of resultant fine-disperse powder as one of the filling components of low-wattage scandium metal halide lamps in pilot and serial lamp production is an objective of this Project.

Development of the technology for producing scandium metal powder by hydriding/dehydriding technique to provide commercial scandium powder deliveries to the Russian and foreign manufacturers of low-wattage scandium metal halide lamps is a predicted outcome of the effort.


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