| 摘要 |
PROBLEM TO BE SOLVED: To improve the bonding strength of a magnetostrictive thin film by forming a magnetostrictive shaft of a cylindrical shaft base material, which is made of the non-magnetic metal material, and a thin film, which is made of the magnetostrictive material and which is formed in the peripheral surface of the shaft base material over the full circumference thereof, and increasing the surface roughness of the shaft base material. SOLUTION: Shot blasting is performed to a surface of a shaft base material 22 made of the austenite group metal material such as steel for non-magnetic hot working die so as to increase the surface roughness to 130μm or more of mean crest-to-crest space Sm and to 5.5μm or more of mean roughness of center line Ra. Magnetic powder material made of aluminium group alloy is thermally sprayed to the peripheral surface of the shaft base material 22 by plasma spraying, and full circumference thereof is formed with a magnetostrictive thin film 23 at 400μm of film thickness, and the surface of the thin film 23 is scraped to 200μm of film thickness. Furthermore, a slit 24 is mechanically formed so as to form a magnetic anisotropic part in the surface of the thin film 23, and held at 700-1100 deg.C for one hour or more, and thereafter, cooled in the oil liquid for magnetic annealing. Bonding strength of a magnetostrictive thin film is thereby improved, and peeling thereof can be restricted.
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