Abstract: An object of the present invention is to provide a novel method for forming an electrolytic copper plating film having excellent adhesion on the surface of a rare earth metal-based permanent magnet. The method of the present invention as a means for achieving the object is characterized in that after a magnet is immersed in a plating solution, a cathode current density of 0.05 A/dm2 to 4.0 A/dm2 for performing an electrolytic copper plating treatment is applied thereto over 10 seconds to 180 seconds to start the treatment.

Abstract: An object of the present invention is to provide a novel method for forming an electrolytic copper plating film having excellent adhesion on the surface of a rare earth metal-based permanent magnet. The method of the present invention as a means for achieving the object is characterized in that after a magnet is immersed in a plating solution, a cathode current density of 0.05 A/dm2 to 4.0 A/dm2 for performing an electrolytic copper plating treatment is applied thereto over 10 seconds to 180 seconds to start the treatment.

Abstract: A sintered R-TM-B magnet comprising 24.5-34.5% by mass of R, wherein R is at least one selected from rare earth elements including Y, 0.92-1.15% by mass of B, less than 0.1% by mass of Ni, 0.07-0.5% by mass of Ga, 0-0.4% by mass of Cu, and inevitable impurities, the balance being Fe; the amounts (% by mass) of Ga and Cu being in a region of a pentagon defined by a point A (0.5, 0.0), a point B (0.5, 0.4), a point C? (0.1, 0.4), a point D? (0.1, 0.1) and a point E (0.2, 0.0), on an X-Y plane in which the X-axis represents the amount of Ga, and the Y-axis represents the amount of Cu.

Abstract: A sintered R-TM-B magnet comprising 24.5-34.5% by mass of R, which is at least one selected from rare earth elements including Y, 0.85-1.15% by mass of B, less than 0.1% by mass of Co, 0.07-0.5% by mass of Ga, and 0-0.4% by mass of Cu, the balance being Fe and inevitable impurities; the amounts (% by mass) of Ga and Cu being in a region of a pentagon defined by a point A (0.5, 0.0), a point B (0.5, 0.4), a point C (0.07, 0.4), a point D (0.07, 0.1) and a point E (0.2, 0.0), on an X-Y plane in which the X-axis represents the amount of Ga, and the Y-axis represents the amount of Cu.

Abstract: A method for removing rare earth impurities from a nickel-electroplating solution by adding a rare earth compound to the nickel-electroplating solution containing rare earth impurities, keeping the electroplating solution at 60° C. or higher for a certain period of time, and then removing precipitate generated by the heating from the nickel-electroplating solution together with the added rare earth compound by sedimentation and/or filtration.

Abstract: A method for removing rare earth impurities from a nickel-electroplating solution by keeping a nickel-electroplating solution containing rare earth impurities and having pH of 4.0-5.1 at 60° C. or higher for a certain period of time, and then removing precipitate generated by the heating from the nickel-electroplating solution by sedimentation and/or filtration.

Abstract: [Object] When rare earth magnets are plated, components of the rare earth magnets are dissolved in the plating solution, causing plating defects. Thus, an easy method for removing rare earth impurities has been necessary. [Means for Solution] A nickel-electroplating solution containing rare earth impurities is kept at 60° C. or higher for a predetermined period of time to precipitate rare earth impurities for separation by sedimentation or filtration. Rare earth impurities can be precipitated further efficiently by adding precipitate to the nickel-electroplating solution, or by concentrating the nickel-electroplating solution by heating.

Abstract: An object of the present invention is to provide an R—Fe—B based sintered magnet that exhibits excellent corrosion resistance and maintains excellent adhesion strength to an adherend even under severe conditions, and a method for producing the same. A corrosion-resistant magnet of the present invention as a means for achieving the object is characterized by comprising a chemical conversion film containing at least Zr, V, Al, fluorine, and oxygen as constituent elements and not containing phosphorus over a surface of an R—Fe—B based sintered magnet with a film made of Al or an alloy thereof therebetween.

Abstract: An object of the present invention is to provide a production method for an R—Fe—B based sintered magnet having a plating film excellent in adhesiveness on the surface thereof, by conducting a series of processes of acid cleaning and smut removal as pretreatments of an R—Fe—B based sintered magnet, and the subsequent plating treatment effectively without causing trouble. The production method of the present invention includes a series of processes of acid cleaning and smut removal of a magnet as pretreatments, and the subsequent plating treatment is conducted consistently with a state, in which the magnet is placed in a barrel made of synthetic resin. The smut removal is conducted by ultrasonic cleaning of the magnet with rotating the barrel in water in which the dissolved oxygen amount is set to 0.1 ppm to 6 ppm by degassing.

Abstract: A method for removing rare earth impurities from a nickel-electroplating solution by keeping a nickel-electroplating solution containing rare earth impurities and having pH of 4.0-5.1 at 60° C. or higher for a certain period of time, and then removing precipitate generated by the heating from the nickel-electroplating solution by sedimentation and/or filtration.

Abstract: A method for removing rare earth impurities from a nickel-electroplating solution by adding a rare earth compound to the nickel-electroplating solution containing rare earth impurities, keeping the electroplating solution at 60° C. or higher for a certain period of time, and then removing precipitate generated by the heating from the nickel-electroplating solution together with the added rare earth compound by sedimentation and/or filtration.

Abstract: [Object] When rare earth magnets are plated, components of the rare earth magnets are dissolved in the plating solution, causing plating defects. Thus, an easy method for removing rare earth impurities has been necessary. [Means for Solution] A nickel-electroplating solution containing rare earth impurities is kept at 60° C. or higher for a predetermined period of time to precipitate rare earth impurities for separation by sedimentation or filtration. Rare earth impurities can be precipitated further efficiently by adding precipitate to the nickel-electroplating solution, or by concentrating the nickel-electroplating solution by heating.

Abstract: An object of the present invention is to provide a production method for an R—Fe—B based sintered magnet having a plating film excellent in adhesiveness on the surface thereof, by conducting a series of processes of acid cleaning and smut removal as pretreatments of a plating treatment of an R—Fe—B based sintered magnet, and the subsequent plating treatment, effectively without requiring troubles. The production method for an R—Fe—B based sintered magnet having a plating film on the surface thereof of the present invention, as a solution method therefor, is characterized in that a series of processes of acid cleaning and smut removal of a magnet as pretreatments of a plating treatment, and the subsequent plating treatment is conducted consistently with a state, in which the magnet is placed in a barrel made of synthetic resin, and that the smut removal is conducted by ultrasonic cleaning of the magnet with rotating the barrel in water in which the dissolved oxygen amount is set to 0.

Abstract: An object of the present invention is to provide a novel method for forming an electrolytic copper plating film having excellent adhesion on the surface of a rare earth metal-based permanent magnet. The method of the present invention as a means for achieving the object is characterized in that after a magnet is immersed in a plating solution, a cathode current density of 0.05 A/dm2 to 4.0 A/dm2 for performing an electrolytic copper plating treatment is applied thereto over 10 seconds to 180 seconds to start the treatment.

Abstract: An R—Fe—B sinlered magnet having on the surface thereof a vapor deposited film of aluminum or an alloy thereof and a method for producing the same. The vapor deposited film of aluminum or an alloy thereof comprises a columnar crystalline structure grown broader from the surface of the R—Fe—B sintered magnet body outward to the outer surface, which has a part within a region defined in the thickness direction of the film as taken from the surface of the R—Fe—B sintered magnet to ? of the film thickness, 5 to 30 intercrystalline gaps of 0.01 ?m to 1 ?m in width as counted per 10 ?m length in the lateral direction of the film. The method comprises controlling the average film formation rate such that it is slower up to a predetermined point and then is speeded up later thereon.

Abstract: An object of the present invention is to provide an R—Fe—B based sintered magnet that exhibits excellent corrosion resistance and maintains excellent adhesion strength to an adherend even under severe conditions, and a method for producing the same. A corrosion-resistant magnet of the present invention as a means for achieving the object is characterized by comprising a chemical conversion film containing at least Zr, V, Al, fluorine, and oxygen as constituent elements and not containing phosphorus over a surface of an R—Fe—B based sintered magnet with a film made of Al or an alloy thereof therebetween.

Abstract: An objective of the present invention is to provide an R—Fe—B based sintered magnet having on the surface thereof a vapor deposited film of aluminum or an alloy thereof, which maintains excellent adhesion strength with the adhered object even after subjecting it to a severe heat cycle test, and a method for producing the same. As a means for solving the problems, an R—Fe—B based sintered magnet having on the surface thereof a vapor deposited film of aluminum or an alloy thereof of the present invention is characterized in that the vapor deposited film of aluminum or an alloy thereof comprises a columnar crystalline structure grown broader from the surface of the bulk magnet body outward to the outer surface, which has a part within a region defined in the thickness direction of the film as taken from the surface of the bulk magnet body to ? of the film thickness, 5 to 30 intercrystalline gaps of 0.01 ?m to 1 ?m in width as counted per 10 ?m length in the lateral direction of the film are existing at the part.