| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a vortex detection part of a vortex flow meter capable of improving sensor life. SOLUTION: A damaged layer existing in an inside a component cover and/or a part of an elastic matrix is removed by buffing. Alternatively, the damaged layer is reduced. Large irregularity in the surface roughness is made into small irregularity by the buffing so that the surface area to be oxidized is reduced. When heating treatment is performed in an oxygen atmospheric environment, uniform protective film is formed on the inside of the component cover and/or a part of the elastic matrix. The formed protective film is a stable oxidized film, wherein a stable/dense Cr<SB>2</SB>O<SB>3</SB>film is formed. According to the oxidized film, the oxidation from a metal surface under a high-temperature use environment is suppressed. When the oxidation is suppressed, the time is prolonged until adverse effect on a piezoelectric element is caused by reduction of the oxygen concentration. COPYRIGHT: (C)2008,JPO&INPIT
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