An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a sulfur content of 0.1 to 0.5 mass % and an aggregation degree R.sub.Blaine/R.sub.BET of 3.0 to 5.5 wherein R.sub.Blaine is the particle size calculated from the Blaine specific surface area and R.sub.BET is the particle size calculated from the BET specific surface area.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a sulfur content of 0.1 to 0.5 mass % and an aggregation degree R.sub.Blaine/R.sub.BET of 3.0 to 5.5 wherein R.sub.Blaine is the particle size calculated from the Blaine specific surface area and R.sub.BET is the particle size calculated from the BET specific surface area.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has a BET specific surface area of 12.0×10.sup.3 to 25.0×10.sup.3 m.sup.2.Math.kg.sup.−1 and a Blaine specific surface area of 2.0×10.sup.3 to 7.0×10.sup.3 m.sup.2.Math.kg.sup.−1.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has a BET specific surface area of 12.0×10.sup.3 to 25.0×10.sup.3 m.sup.2.Math.kg.sup.−1 and a Blaine specific surface area of 2.0×10.sup.3 to 7.0×10.sup.3 m.sup.2.Math.kg.sup.−1.

Methods for forming a dual-phase magnetic component from an initial component comprising a non-magnetic austenite composition are provided. The method may include: forming a coating on a portion of the surface of the initial component to form a masked area while leaving an unmasked area thereon. Thereafter the initial component may be heated to a treatment temperature such that nitrogen diffuses out of the unmasked area of the initial component to transform the non-magnetic austenite composition to a magnetic phase in the unmasked area. Thereafter, the initial component may be cooled from the treatment temperature to form a dual-phase magnetic component having a magnetic region corresponding to the unmasked area and a non-magnetic region corresponding to the masked area.

A composite material, especially for use in a stator stack and/or rotor stack is disclosed. The composite material includes a first and a second electrical steel strip layer and a polymeric layer arranged in between, wherein the polymeric layer consists of a crosslinked acrylate-based copolymer of high molecular weight and has a layer thickness in the range from 3 to 20 μm.

A composite material, especially for use in a stator stack and/or rotor stack is disclosed. The composite material includes a first and a second electrical steel strip layer and a polymeric layer arranged in between, wherein the polymeric layer consists of a crosslinked acrylate-based copolymer of high molecular weight and has a layer thickness in the range from 3 to 20 μm.

An annealing separator composition for a grain-oriented electrical steel sheet according to an embodiment of the present invention includes: 100 parts by weight of at least one of a magnesium oxide and a magnesium hydroxide; and 30 to 250 parts by weight of a metal hydroxide including at least one of a nickel hydroxide and a cobalt hydroxide, wherein an average particle diameter of the metal hydroxide is 0.01 to 80 μm.

An annealing separator composition for a grain-oriented electrical steel sheet according to an embodiment of the present invention includes: 100 parts by weight of at least one of a magnesium oxide and a magnesium hydroxide; and 30 to 250 parts by weight of a metal hydroxide including at least one of a nickel hydroxide and a cobalt hydroxide, wherein an average particle diameter of the metal hydroxide is 0.01 to 80 μm.

The present invention provides a cast product that can further enhance the stability of an alumina barrier layer and can exhibit further superior oxidation resistance, carburization resistance, nitriding resistance, corrosion resistance, and the like when used under a high-temperature atmosphere. The cast product according to the present invention is a cast product having an alumina barrier layer including an aluminum oxide on a surface of a matrix, and the aluminum oxide is (Al.sub.(1-x)M.sub.(x)).sub.2O.sub.3, where M is at least one of Cr, Ni, Si, and Fe, and x satisfies a relationship 0<x<0.5. Furthermore, the cast product according to the present invention is a cast product having an alumina barrier layer including an aluminum oxide on a surface of a matrix, and at least one of Cr, Ni, Si, and Fe forms a solid solution in the aluminum oxide, and at least one of Cr, Ni, Si, and Fe forming the solid solution with Al is contained so as to satisfy a relationship Al/(Cr+Ni+Si+Fe)≧2.0 in an atomic % ratio.