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: An object of the present invention is to provide a method for producing a surface-modified rare earth metal-based sintered magnet having extremely excellent corrosion resistance even in an environment with fluctuating temperature and humidity and also having excellent magnetic characteristics. The method for producing a surface-modified rare earth metal-based sintered magnet of the present invention as a means for achieving the object is characterized by comprising a step of subjecting a rare earth metal-based sintered magnet to a heat treatment at 200° C. to 600° C. in an atmosphere having an oxygen partial pressure of 1×103 Pa to 1×105 Pa and a water vapor partial pressure of 45 Pa or less with the ratio between the oxygen partial pressure and the water vapor partial pressure (oxygen partial pressure/water vapor partial pressure) being 450 to 20000.

Abstract: An object of the present invention is to provide an R—Fe—B based sintered magnet having on a surface thereof a chemical conversion film with higher corrosion resistance than a conventional chemical conversion film such as a phosphate film, and a method for producing the same. The 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, Nd, fluorine, and oxygen as constituent elements and not containing phosphorus directly on a surface of an R—Fe—B based sintered magnet, wherein R is a rare-earth element including at least Nd.

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: An objective of the present invention is to provide a rare earth metal-based sintered magnet having imparted thereto sufficient corrosion resistance by an oxidative heat treatment, which is resistant even in an environment of fluctuating humidity, while suppressing the deterioration of the magnetic characteristics ascribed to the oxidative heat treatment, and to provide a method for producing the same.

Abstract: In an R—Fe—B based rare-earth sintered magnet according to the present invention, at a depth of 20 ?m under the surface of its magnet body, crystal grains of an R2Fe14B type compound have an (RL1-xRHx)2Fe14B (where 0.2?x?0.75) layer with a thickness of 1 nm to 2 ?m in their outer periphery. In this case, the light rare-earth element RL is at least one of Nd and Pr, and the heavy rare-earth element RH is at least one element selected from the group consisting of Dy, Ho and Tb.

Abstract: An object of the present invention is to provide an R—Fe—B based sintered magnet having on a surface thereof a chemical conversion film with higher corrosion resistance than a conventional chemical conversion film such as a phosphate film, and a method for producing the same. The 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, Nd, fluorine, and oxygen as constituent elements and not containing phosphorus directly on a surface of an R—Fe—B based sintered magnet, wherein R is a rare-earth element including at least Nd.

Abstract: An object of the present invention is to provide an R—Fe—B based sintered magnet having on a surface thereof a chemical conversion film with higher corrosion resistance than a conventional chemical conversion film such as a phosphate film, and a method for producing the same. The 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, Nd, fluorine, and oxygen as constituent elements and not containing phosphorus directly on a surface of an R—Fe—B based sintered magnet, wherein R is a rare-earth element including at least Nd.

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 object of the present invention is to provide a method for producing a surface-modified rare earth metal-based sintered magnet having extremely excellent corrosion resistance even in an environment with fluctuating temperature and humidity and also having excellent magnetic characteristics. The method for producing a surface-modified rare earth metal-based sintered magnet of the present invention as a means for achieving the object is characterized by comprising a step of subjecting a rare earth metal-based sintered magnet to a heat treatment at 200° C. to 600° C. in an atmosphere having an oxygen partial pressure of 1×103 Pa to 1×105 Pa and a water vapor partial pressure of 45 Pa or less with the ratio between the oxygen partial pressure and the water vapor partial pressure (oxygen partial pressure/water vapor partial pressure) being 450 to 20000.

Abstract: An object of the present invention is to provide an R—Fe—B based sintered magnet having on a surface thereof a chemical conversion film with higher corrosion resistance than a conventional chemical conversion film such as a phosphate film, and a method for producing the same. The R—Fe—B based sintered magnet having a chemical conversion film on the surface thereof of the present invention as a means for achieving the object is characterized by comprising a chemical conversion film on a surface of an R—Fe—B based sintered magnet wherein R is a rare-earth element including at least Nd, the chemical conversion film having a laminate structure including at least an inner layer that contains R, fluorine, and oxygen as constituent elements and an outer layer that is amorphous and contains Zr, Fe, and oxygen as constituent elements, provided that no phosphorus is contained in the film.

Abstract: In a method for producing an R—Fe—B based rare-earth sintered magnet according to the present invention, first, provided is an R—Fe—B based rare-earth sintered magnet body including, as a main phase, crystal grains of an R2Fe14B type compound that includes a light rare-earth element RL, which is at least one of Nd and Pr, as a major rare-earth element R. Thereafter, the sintered magnet body is heated while a heavy rare-earth element RH, which is at least one element selected from the group consisting of Dy, Ho and Tb, is supplied to the surface of the sintered magnet body, thereby diffusing the heavy rare-earth element RH into the rare-earth sintered magnet body.

Abstract: In an R—Fe—B based rare-earth sintered magnet according to the present invention, at a depth of 20 ?m under the surface of its magnet body, crystal grains of an R2Fe14B type compound have an (RL1?xRHx)2Fe14B (where 0.2?x?0.75) layer with a thickness of 1 nm to 2 ?m in their outer periphery. In this case, the light rare-earth element RL is at least one of Nd and Pr, and the heavy rare-earth element RH is at least one element selected from the group consisting of Dy, Ho and Tb.

Abstract: In a method for producing an R—Fe—B based rare-earth sintered magnet according to the present invention, first, provided is an R—Fe—B based rare-earth sintered magnet body including, as a main phase, crystal grains of an R2Fe14B type compound that includes a light rare-earth element RL, which is at least one of Nd and Pr, as a major rare-earth element R. Thereafter, the sintered magnet body is heated while a heavy rare-earth element RH, which is at least one element selected from the group consisting of Dy, Ho and Tb, is supplied to the surface of the sintered magnet body, thereby diffusing the heavy rare-earth element RH into the rare-earth sintered magnet body.

Abstract: In an R—Fe—B based rare-earth sintered magnet according to the present invention, at a depth of 20 ?m under the surface of its magnet body, crystal grains of an R2Fe14B type compound have an (RL1-xRHx)2Fe14B (where 0.2?x?0.75) layer with a thickness of 1 nm to 2 ?m in their outer periphery. In this case, the light rare-earth element RL is at least one of Nd and Pr, and the heavy rare-earth element RH is at least one element selected from the group consisting of Dy, Ho and Tb.

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.