Rare earth metal-based permanent magent, and process for producing the same

摘要

A rare earth metal-based permanent magnet has a metal oxide film formed on the surface thereof by a sol-gel coating process. The rare earth metal-based permanent magnet is produced by forming a metal oxide film on the surface thereof by a sol-gel coating process. The metal oxide film is thin and dense. The adhesion of the film to the surface of the magnet is excellent. The film exhibits an excellent corrosion resistance. Typical examples of the metal oxide films are Al, Si, Ti and Zr oxide films. An interfacial layer with R (rare earth element) atom chemically bonded with a film forming metal atom through oxygen atom is formed between the metal oxide film and the entire surface of the magnet.