| 摘要 |
<p>PROBLEM TO BE SOLVED: To heighten compressive strength of a seal part so as to prevent the seal part from being damaged, deformed and fixed to a metallic annular gasket by applying positive electrode oxidation coating treatment other than sulfuric acid positive electrode oxidation coating treatment to the seal part of the internal wall of an annular space for interposing the metallic annular gasket. SOLUTION: In a high vacuum valve, a plurality of ports 13A, 13B are formed to be communicated with a valve chamber 11 of a valve body 10 through pipe parts 12A, 12B, and a valve seat 14 is formed in a passage connecting the valve chamber 11 to one pipe part 12B. A valve element 18 is brought into contact with the valve seat 14 to close the passage and the valve element 18 is separated from the valve seat 14 to open the passage. Annular spaces 33 for interposing metallic annular gaskets 28 are formed at the end parts of pipe parts 12A, 12B made of an aluminium alloy, forming the ports 13A, 13B. Seal parts are formed at the internal walls of the annular spaces 33. Oxalic acid positive electrode oxidation coating treatment is applied to the whole of the seal part and valve body 10. Compressive strength of the seal part is thereby heightened so as to prevent the seal part from being damaged, deformed and fixed to the metallic annular gasket.</p> |
