Abstract A coated coil emissive electrode of the type utilized in fluorescent lamps and a method for making such an electrode. The electrode includes a tungsten coil, a bonding layer of an emissive form of barium tungstate coating said tungsten coil, and a layer of porous barium oxide coating said barium tungstate, said barium tungstate bonding said barium oxide to said tungsten coil. The electrode is made by coating said tungsten coil wuth a mixture of barium peroxide, cellulose nitrate and butyl cellosolve and heating said coated coil to the exothermal decomposition temperature of said cellulose nitrate. The exothermal decompositon of said cellulose nitrate raises the temperature of the barium peroxide to its exothermal decomposition temperature thereby forming said bonding layer of the emissive form of barium tungstate and releasing bubbles of oxygen causing the pores in said barium oxide.
The method according to claim 1 wherein the alkaline earth peroxide is selected from the group consisting of barium peroxide, calcium peroxide and strontium peroxide.
Claim 2
Dependent Claim
14 words
The method according to claim 1 wherein the alkaline earth peroxide is barium peroxide.
Claim 3
Dependent Claim
22 words
The method according to claim 3 including the step of adding zirconium dioxide to the barium peroxide prior to preparing the suspension.
Claim 4
Dependent Claim
33 words
The method according to claim 1 wherein said heating includes the step of flowing a heated inert gas over the dried suspension to cause said exothermal reaction and remove the gaseous byproducts therefrom.
Claim 5
Independent Claim
133 words
A method of providing improved emissive coatings for long life gas discharge lamps comprising: a. preparing a suspension of 50 g of barium peroxide powder in a 100 cc solution of cellulose nitrate binder and cellosolve solvent; b. coating the suspension onto the surface of tungsten metal cathodes; c. evaporating the cellosolve from the suspension coated on said cathodes to form a dried suspension thereof; and d. heating said cathodes coated with the dried suspension of barium peroxide and cellulose nitrate by means of a heated stream of argon gas to a temperature range of 400*-500* C to form an exothermal reaction between the barium peroxide and the cellulose nitrate in said dried suspension resulting in a fused and porous coating of air stable barium oxide on the surface of said tungsten cathode.