| 摘要 |
PURPOSE: To dissolve problems with conventional techniques and provide such a cathode ray tube as being capable for holding desired property by controlling a linsing time to leave a certain amount of carbon on the surfaces of metal parts and metal members. CONSTITUTION: A shadow mask 5 to control the electron beam B of a cathode ray tube is formed by machining an invar material containing metal elements in the following ratio: S; less than 0.005wt.%, P and C; less than 0.015wt.% Al; less than 0.07wt.%, Cr; less than 0.15wt.%, Si; less than 0.25wt.%, Mn; 0.20-0.45wt.% and Ni; 35.3-37.7wt.% and including Fe, for the rest. Then, various hot treatments are given thereto in the state that 10<-4> g/2μm<2> -10<-8> g/2μm<2> C is deposited to be left on the surface and in grains and in grain boundaries in electron beam through-holes.
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