Abstract: An objective of the present invention is to provide a rare earth metal-based permanent magnet with improved adhesion properties. A rare earth metal-based permanent magnet of the present invention as a means for achieving the objective has a laminated plating film, and is characterized in that the plating film comprises as an outermost surface layer a SnCu alloy plating film having a film thickness in a range from 0.1 ?m to 2 ?m, the composition of the SnCu alloy plating film is 35 mass % or more but less than 55 mass % of Sn and the rest being Cu, and a base plating film having two or more layers including at least a Ni plating film and a Cu plating film which are formed as the lower layer under the SnCu alloy plating film, and among the base plating film, the Ni plating film is located just below the SnCu alloy plating film.

Abstract: An objective of the present invention is to provide a rare earth metal-based permanent magnet with improved adhesion properties. A rare earth metal-based permanent magnet of the present invention as a means for achieving the objective has a laminated plating film, and is characterized in that the plating film comprises as an outermost surface layer a SnCu alloy plating film having a film thickness in a range from 0.1 ?m to 2 ?m, the composition of the SnCu alloy plating film is 35 mass % or more but less than 55 mass % of Sn and the rest being Cu, and a base plating film having two or more layers including at least a Ni plating film and a Cu plating film which are formed as the lower layer under the SnCu alloy plating film, and among the base plating film, the Ni plating film is located just below the SnCu alloy plating film.

Abstract: [Problem] To provide a process for producing a permanent magnet for use in an automotive IPM motor, which excels in all of corrosion resistance, abrasion resistance, and impact resistance. [Means for Resolution] The production process characterized in that it comprises forming on the surface of an R—Fe—B based permanent magnet a 3 to 15 ?m thick Ni film as a first layer by electroplating method, followed by a 3 to 15 ?m thick Cu or Sn film as a second layer by electroplating method, and a 4 to 7 ?m thick Ni—P alloy film as a third layer by electroless plating method, provided that the third layer has a Vicker's hardness of 2.5 to 4.5 with respect to the Vicker's hardness of the Cu or Sn electroplated film provided as the second layer taken as 1.

Abstract: A corrosion-resistant R-Fe-B type sintered permanent magnet exhibiting deterioration of not more than 5 % from the initial magnetic properties after being tested for 500 hours under the conditions of a temperature of 80.degree. C. and a relative humidity of 90 % is produced by:causing at least one colloidal noble metal selected from the group consisting of Pd, Ag, Pt and Au to be adsorbed in a colloidal state or forming a thin layer thereof through vapor deposition on the surface of the sintered body; applying at least one base metal selected from the group consisting of Ni, Cu, Sn and Co containing P and/or B by electroless plating; and further applying at least one base metal selected from the same group.The noble metal layer is 1-10 nm thick. The electroless plating layer is no more than 10 .mu.m and the electrolytic plating layer 5-60 .mu.m thick.