| 摘要 |
PROBLEM TO BE SOLVED: To obtain an R-TM-B-based permanent magnet whose magnetic characteristic is improved and whose reliability is enhanced by a structure wherein a layer in which both R and 0 are concentrated is provided directly under the surface of the R-TM-B- based permanent magnet whose composition ratio is specific and an Ni-plated layer is provided on the surface. SOLUTION: An R-TM-B-based permanent magnet piece is created in such a way that it is composed of 4 to 40% of R (R represents one kind of, or a combination of two or more kinds, of rare-earth elements including Y, of 50 to 90% of TM (TM represents a transition metal mainly by Fe and Co or the transition metal one part of which is replaced by other metal elements or nonmetal elements) and of 0.2 to 8% of B (boron) in terms of a weight %. It is heat-treated, the component of R in the interior is sweated to a part near its surface so as to be oxidized in an argon gas atmosphere, and a layer in which both R and O are concentrated is formed. After that, it is pretreated with acetic acid, and it is electrolytically plated with N in a Watts bath. Thereby, the magnetic characteristic of an obtained sample is nearly identical to that immediately after the sample is cut off before its plating treatment, and the result of a vapor pressurization test is good. |
