Abstract: Fe-B-R type permanent magnet is produced by: forming an anticorrosive coating film layer on a Fe-B-R base permanent magnet material body by means of vapor deposition to thereby improve the corrosion resistance thereof.The anticorrosive thin film is formed of metal, oxides, nitrides, carbides, borides, silicides, composite compositions thereof, or a mixture thereof. Additionally blasting, shot peening, heat treatment for forming an interdiffusion layer, and/or resin impregnation may be applied.

Abstract: Fe-B-R type permanent magnet is produced by forming an anticorrosive coating film layer on a Fe-B-R base permanent magnet material body by means of vapor deposition to thereby improve the corrosion resistance thereof.The anticorrosive thin film is formed of metal, oxides, nitrides, carbides, borides, silicides, composite compositions thereof, or a mixture thereof. Additionally blasting, shot peening, heat treatment for forming an interdiffusion layer, and/or resin impregnation may be applied.

Abstract: To obtain an anticorrosive Fe-B-R type permanent magnet; in particular, to reduce deterioration rate of the initial magnetic properties below 10% after the magnet has been kept at 80.degree. C. in 90% relative humidity for 500 hours, the surface of the sintered permanent magnet is coated with metallic coating film layers of at least one noble metal layer and at least one base metal layer disposed on the noble metal layer. Diffusion heat treatment further improves the adhesiveness of the coating film layers.

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.

Abstract: To obtain an anticorrosive Fe-B-R type permanent magnet; in particular, to reduce deterioration rate of the initial magnetic properties below 10% after the magnet has been kept at 80.degree. C. in 90% relative humidity for 500 hours, the surface of the sintered permanent magnet is coated with metallic coating film layers of at least one noble metal layer and at least one base metal layer disposed on the noble metal layer. Diffusion heat treatment further improves the adhesiveness of the coating film layers.

Abstract: A rare earth alloy for producing permanent magnet comprised of: 15-65 atomic % R.sub.1, 35-83 atomic % Fe, and 0-15 atomic % B, where R.sub.1 represents at least one of heavy rare earth elements Gd, Tb, Dy, Ho, Er, Tm and Yb. This alloy is produced by reducing a mixture of corresponding rare earth oxides, Fe, and a boron containing material by Ca, contacting the reduced mass with water, and treating the resultant slurry with water. Using this alloy, Fe-B-R base magnets wherein R.sub.1 is substituted for part of R (R representing lanthanide and/or Y) having a high performance are produced with a reduced cost.

Abstract: Fe-B-R type permanent magnet is produced by: forming an anticorrosive coating film layer on a Fe-B-R base permanent magnet material body by means of vapor deposition to thereby improve the corrosion resistance thereof.The anticorrosive thin film is formed of metal, oxides, nitrides, carbides, borides, silicides, composite compositions thereof, or a mixture thereof. Additionally blasting, shot peening, heat treatment for forming an interdiffusion layer, and/or resin impregnation may be applied.

Abstract: A rare earth-iron-boron alloy powder which consists essentially of:12.5 to 20 at % R wherein R.sub.1 is 0.05 to 5 at %, 4 to 20 at % B, and 60 to 83.5 at % Fe,wherein R.sub.1 is at least one heavy rare earth element selected from the group consisting of Gd, Tb, Dy, Ho, Er, Tm and Yb, 80 to 100 at % of R.sub.2 consists of Nd and/or Pr, the balance in the R.sub.2 being at least one element selected from the group consisting of rare earth elements including Y and except for R.sub.1, and R=R.sub.1 =R.sub.2 by atomic %, wherein a major phase of at least 80 vol % of the entire alloy coinsists of a tetragonal structure, and wherein oxygen does not exceed 10,000 ppm, carbon does not exceed 1000 ppm and calcium does not exceed 2000 ppm. The alloy powder is produced by directly reducing a mixture comprising rare earth oxide, iron and other ingredients or oxide thereof with a reducing agent Ca and CaCl.sub.2, putting the reduced product into water, then treating with water. Up to 35 at % Co may be substituted for Fe.

Abstract: A rare earth alloy for producing permanent magnet comprised of: 15-65 atomic % R.sub.1, 35-83 atomic % Fe, and 0-15 atomic % B, where R.sub.1 represents at least one of heavy rare earth elements Gd, Tb, Dy, Ho, Er, Tm and Yb. This alloy is produced by reducing a mixture of correspoding rare earth oxides, Fe, and a boron containing material by Ca, contacting the reduced mass with water, and treating the resultant slurry with water. Using this alloy, Fe-B-R base magnets wherein R.sub.1 is substituted for part of R (R representing lanthanide and/or Y) having a high performance are produced with a reduced cost.

Abstract: A rare earth-iron-boron alloy powder which consists essentially of:12.5 to 20 at % R wherein R.sub.1 is 0.05 to 5 at %, 4 to 20 at % B, and 60 to 83.5 at % Fe,wherein R.sub.1 is at least one heavy rare earth element selected from the group consisting of Gd, Tb, Dy, Ho, Er, Tm, and Yb, 80 to 100 at % of R.sub.2 consists of Nd and/or Pr, the balance in the R.sub.2 being at least one element selected from the group consisting of rare earth elements including Y and except for R.sub.1, and R=R.sub.1 +R.sub.2 by atomic %, wherein a major phase of at least 80 vol % of the entire alloy coinsists of a tetragonal structure, and wherein oxygen does not exceed 10,000 ppm, carbon does not exceed 1000 ppm and calcium does not exceed 2000 ppm. The alloy powder is produced by directly reducing a mixture comprising rare earth oxide, iron and other ingredients or oxide thereof with a reducing agent Ca and CaCl.sub.2, putting the reduced product into water, then treating with water. Up to 35 at % Co may be substituted for Fe.

Abstract: In the production of a casting syrup, useful in a continuous casting process for manufacture of cast plates, by partial polymerization of methyl methacrylate or its mixture with at least one unsaturated vinyl compound copolymerizable therewith in an amount of not more than about 20% by weight based on methyl methacrylate, an improved method wherein the partial polymerization is carried out in the presence of a thiodicarboxylic acid ester of the formula:R.sub.3 OOCR.sub.1 --S--R.sub.2 COOR.sub.4wherein R.sub.1 and R.sub.2 are each an alkylene group having 1 to 6 carbon atoms and R.sub.3 and R.sub.4 are each an alkyl group having 1 to 24 carbon atoms as a stabilizer using an azo compound as a polymerization initiator, whereby a casting syrup having a suitable viscosity with a good workability on casting and affording a cast plate of high thermal stability on completion of the polymerization is obtainable.