Fe-Cr-Ni alloy for electron gun electrode

Abstract

An electron gun includes a cathode, a control electrode, a screen electrode arranged in front of the control electrode, at least one focusing electrode arranged in front of the screen electrode to form a pre-focusing lens unit, a final accelerating electrode arranged in front of the focusing electrode(s) to form a main lens unit, and a shield cup electrically connected to the final accelerating electrode. The iron-chromium-nickel alloy for the focusing electrode(s), the final accelerating electrode, and the shield cup contains 18-20% or less by weight of chromium, 8-10% by weight of nickel, 0.03% or less by weight of carbon, 1.00% by weight of silicon, 2.00% or less by weight of manganese, 0.04% or less by weight of phosphorous, 0.03% or less by weight of sulfur, a balance of iron, and a trace of impurities, and has an average granularity of 0.010-0.022 mm. The iron-chromium-nickel alloy for the electrode of an electron gun contains a smaller amount of expensive Ni so that the manufacturing cost of electron guns can be greatly reduced. In addition, an electron gun electrode made of the iron-chromium-nickel alloy steel has effective drawing properties and pressing formability. The iron-chromium-nickel alloy is nonmagnetic, and can prevent focusing and convergence drift properties from deteriorating. Accordingly, more reliable cathode ray tubes can be manufactured with the iron-chromium-nickel alloy.

What is claimed is:  
     
         1 . An iron-chromium-nickel alloy for an electrode of an electron gun which includes a cathode, a control electrode, a screen electrode arranged in front of said control electrode, at least one focusing electrode arranged in front of said screen electrode to form a pre-focusing lens unit, a final accelerating electrode arranged in front of said at least focusing electrode to form a main lens unit, and a shield cup electrically connected to said final accelerating electrode, said iron-chromium-nickel alloy for said at least one focusing electrode, said final accelerating electrode, and said shield cup comprising chromium in a range of 18-20% by weight, nickel in a range of 8-10% by weight, no greater than 0.03% by weight of carbon, no greater than 1.00% by weight of silicon, no greater than 2.00% by weight of manganese, no greater than 0.04% by weight of phosphorous, no greater than 0.03% by weight of sulfur, a balance of iron, and a trace of impurities.  
     
     
         2 . The iron-chromium-nickel alloy of  claim 1 , having a surface roughness Ra in a range of 0.05-0.2 μm and a maximum roughness Rmax in a range of 1.5-2.0 μm.  
     
     
         3 . The iron-chromium-nickel alloy of  claim 2 , wherein the surface roughness originates from a surface pattern of said iron-chromium-nickel alloy formed using an uneven roller.  
     
     
         4 . The iron-chromium-nickel alloy of  claim 3 , wherein the surface pattern is a discontinuous dot pattern parallel to a rolling direction for smaller anisotropy of the iron-chromium-nickel alloy.  
     
     
         5 . The iron-chromium-nickel alloy of  claim 1 , wherein one of said at least one focusing electrode and said final accelerating electrode has a single large electron beam aperture and a height of at least 7 mm.  
     
     
         6 . The iron-chromium-nickel alloy of  claim 5 , having a micro Vickers hardness in a range of 165-180 Hv when used for said at least one focusing electrode and said final accelerating electrode having a single large electron beam aperture.  
     
     
         7 . The iron-chromium-nickel alloy of  claim 1 , wherein said shield cup has a height of at least 7 mm.  
     
     
         8 . The iron-chromium-nickel alloy of  claim 7 , having a micro Vickers hardness in a range of 165-180 Hv when used for said shield cup.  
     
     
         9 . The iron-chromium-nickel alloy of  claim 1 , wherein one of said at least one focusing electrode and said final accelerating electrode has independent small electron beam apertures and a height no greater than 7 mm.  
     
     
         10 . The iron-chromium-nickel alloy of  claim 9 , having a micro Vickers hardness in a range of 160-175 Hv when used for said at least one focusing electrode and said final accelerating electrode having independent small electron beam apertures.  
     
     
         11 . The iron-chromium-nickel alloy of  claim 1 , wherein one of said at least one focusing electrode and said final accelerating electrode includes an inner electrode and has a height no greater than 7 mm.  
     
     
         12 . The iron-chromium-nickel alloy of  claim 11 , having a micro Vickers hardness in a range of 160-175 Hv when used for said at least one focusing electrode and said final accelerating electrode.  
     
     
         13 . The iron-chromium-nickel alloy of  claim 1 , having an average granularity in a range of 0.010-0.022 mm.  
     
     
         14 . The iron-chromium-nickel alloy of  claim 1 , wherein said alloy is processed into a material for said electrode of said electron gun by at least one of primary cold rolling, annealing, acid washing, secondary skin pass rolling and degreasing.  
     
     
         15 . The iron-chromium-nickel alloy of  claim 1 , wherein said alloy is subject to at least one of bright annealing, tension leveling and slitting for wrapping.  
     
     
         16 . An iron-chromium-nickel alloy for an electrode of an electron gun which includes a cathode, a control electrode, a screen electrode arranged in front of said control electrode, at least one focusing electrode arranged in front of said screen electrode to form a pre-focusing lens unit, a final accelerating electrode arranged in front of said at least one focusing electrode to form a main lens unit, and a shield cup electrically connected to said final accelerating electrode, said iron-chromium-nickel alloy for said at least one focusing electrode, said final accelerating electrode, and said shield cup comprising chromium in a range of 18-20% by weight, nickel in a range of 8-10% by weight, no greater than 0.03% by weight of carbon, no greater than 1.00% by weight of silicon, no greater than 2.00% by weight of manganese, no greater than 0.04% by weight of phosphorous, no greater than 0.03% by weight of sulfur, a balance of iron, and a trace of impurities, wherein said iron-chromium-nickel alloy is subjected to annealing at a temperature of no less than 1,000° C. to restore a ferromagnetic martensitic structure formed as a result of cold working into an original non-magnetic ostenitic structure.  
     
     
         17 . The iron-chromium-nickel alloy of  claim 16 , having an average granularity in a range of 0.010-0.022 mm when used for said at least one focusing electrode, said final accelerating electrode, and said shield cup.  
     
     
         18 . The iron-chromium-nickel alloy of  claim 16 , having a surface roughness Ra in a range of 0.05-0.2 μm and a maximum roughness Rmax in a range of 1.5-2.0 μm.  
     
     
         19 . The iron-chromium-nickel alloy of  claim 16 , wherein said alloy is processed into a material for said electrode of said electron gun by at least one of primary cold rolling, annealing, acid washing, secondary skin pass rolling and degreasing.  
     
     
         20 . The iron-chromium-nickel alloy of  claim 16 , wherein said alloy is subject to at least one of bright annealing, tension leveling and slitting for wrapping.