| 摘要 |
PURPOSE:To improve the level of sound pressure in a high frequency area by forming a metal thin film on a substrate with vapor growth method and processing the metal thin film under high temperature and high pressure. CONSTITUTION:On the opposite face of a vessel 21 such as a Fe made, ceramic layers 25 and 27 are provided and the metal thin film of prescribed thickness 29 formed by ion-plating is interposed between the ceramic layers 25 and 27. Then the end parts 31 and 33 at the opposite face of the vessel 21 are fixed each other by welding. In this state, the vessel 21 is installed in a prescribed pressure chamber and left one hour in the temperature of 1050 deg.C, 150MPa and gaseous argon. Then the level of the sound pressure in the high frequency area of 2000Hz or above can be raised as shown by a figure. |
