| 摘要 |
PURPOSE:To obtain a metal bellows on whose surface rust is hardly generated even in a high humidity and in a high density of corrosive gas by covering the atmospheric side surface of the metal bellows with a silicon rubber membrane. CONSTITUTION:The inner side surface of a metal bellows 12, or the atmospheric side surface, is coated with a vinylsilicon rubber which is made by replacing a part of the methyl radical of dimethylsilicon rubber whose side chain is all the methyl radicals, or silicon rubber fluoride which is made by introducing alkylfluoride radical to the side chain of the above vinylsilicon rubber, to form a membrane 13. By using the silicon rubber as the surface coating material, no crack is generated on the membrane at the area transferring from the waveform bending to the straight line of the bellows-form section where the form is liable to vary especially at the expansion and contraction of the metal bellows 12 following the movement of a movable contact maker 9, and moreover, by the heat resisting and medicine-resisting properties of the silicon rubber, the surface of the metal bellows is shielded practically perfectly from the corrosive gas. A vacuum bulb with a long service life even in the corrosive gas can be obtained. |
