简介 |
PROBLEM TO BE SOLVED : To obtain superior corrosion resistance and adhesion by forming a Zr-oxide coating film on the surface of a rare-earth based permanent magnet. SOLUTION : Casting ingots are ground and pulverized, and the pulverized material is shaped, sintered, heat treated, and surface worked to manufacture a sample piece of a magnet of specified Nd-Pr-Fe-B composition. For this sample piece, a toluene solution of zirconium octylate is prepared as a processing solution. On the sample piece surface, which has been cleaned by shot blasting and solvent degreasing, the processing solution is coated by a dip-coating method with a specified pull-up rate, and a heat treatment is applied. The processing solution coating and the heat treatment are repeated four times to form a Zr-oxide coating film on the sample piece surface. The film thickness of the resultant Zr-oxide coating film (ZrOx coating film : 0
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