PURPOSE: To attain a diaphragm where characteristics of the specific elastic modulus and etc. are good, by sticking a melt-sprayed material, which has a specific elastic modulus higher than that of a base material and is insoluble in an etching liquid, to the surface of the metallic base material by plasma spray coating to form a melt-sprayed film and melting the base material with the etching liquid to remove it.
CONSTITUTION: A melt-sprayed material 4 consisting of B4C is melt-sprayed to a metallic base material 5, which is formed with aluminum into the shape of a domic diaphragm, by a plasma spray coating device to form a melt-sprayed film 6 on the surface of the metallic base material 5, and a composite material of the metallic base material 5 and the melt-sprayed film 6 is formed. This composite material is immersed in the etching liquid consisting of hydrochloric acid to melt the metallic base material 5. Since B4C is inactive about hydrochloric acid, it is hardly melted. Therefore, only the metallic base material 5 is melted gradually; and after a sufficient time, the metallic base material 5 is removed completely to obtain the diaphragm consisting of only the melt-sprayed film 6. Since B4C has a specific elastic modulus higher than that of the metallic base material 5, the diaphragm has a high specific elastic modulus.
IDO TAKEO
MOMIYAMA KIMIO
Next Patent: JPS5917796