There is provided a cobalt-based alloy material comprising: in mass %, 0.08-0.25% C; 0.003-0.2% N, the total amount of C and N being 0.083-0.28%; 0.1% or less B; 10-30% Cr; 5% or less Fe and 30% or less Ni, the total amount of Fe and Ni being 30% or less; W and/or Mo, the total amount of W and Mo being 5-12%; Al and/or Si, at least one of Al and Si being more than 0.5% and 3% or less, and the total amount of Al and Si being more than 0.5% and 4% or less; 0.5% or less Mn; 0.5-4% of an M component being a transition metal other than W and Mo and having an atomic radius of more than 130 pm; and the balance being Co and impurities. There is also provided a product formed from the cobalt-based alloy material.

There is provided a cobalt-based alloy material comprising: in mass %, 0.08-0.25% C; 0.003-0.2% N, the total amount of C and N being 0.083-0.28%; 0.1% or less B; 10-30% Cr; 5% or less Fe and 30% or less Ni, the total amount of Fe and Ni being 30% or less; W and/or Mo, the total amount of W and Mo being 5-12%; Al and/or Si, at least one of Al and Si being more than 0.5% and 3% or less, and the total amount of Al and Si being more than 0.5% and 4% or less; 0.5% or less Mn; 0.5-4% of an M component being a transition metal other than W and Mo and having an atomic radius of more than 130 pm; and the balance being Co and impurities. There is also provided a product formed from the cobalt-based alloy material.

The present invention provides a powder for forming a black light-shielding film having a specific surface area of 20 to 90 m.sup.2/g, which is measured by the BET method, comprising zirconium nitride as a main component, and containing magnesium and/or aluminum. If containing the magnesium, the content of the magnesium is 0.01 to 1.0% by mass relative to 100% by mass of the powder for forming a black light-shielding film, and if containing the aluminum, the content of the aluminum is 0.01 to 1.0% by mass relative to 100% by mass of the powder for forming the black light-shielding film.

To provide a magnetic core having a high permeability and a high voltage resistance while having a small variation in the voltage resistance.

The magnetic core includes the magnetic powder. A total area ratio of particles of the magnetic powder in a cross section of the magnetic core is 75% or more and 90% or less. An average circularity of large size particles is 0.70 or more when the large size particles are particles extracted from the particles of the magnetic powder in the cross section of the magnetic core in the order of size from the largest size until a cumulative area ratio of the extracted particles reaches a smallest area ratio exceeding 20% of the total area ratio of the particles of the magnetic powder.

To provide a magnetic core having a high permeability and a high voltage resistance while having a small variation in the voltage resistance.

The magnetic core includes the magnetic powder. A total area ratio of particles of the magnetic powder in a cross section of the magnetic core is 75% or more and 90% or less. An average circularity of large size particles is 0.70 or more when the large size particles are particles extracted from the particles of the magnetic powder in the cross section of the magnetic core in the order of size from the largest size until a cumulative area ratio of the extracted particles reaches a smallest area ratio exceeding 20% of the total area ratio of the particles of the magnetic powder.

A metal powder producing apparatus comprising a melted metal supplying part discharging a melted metal, a cylinder body provided below the melted metal supplying part, and a cooling liquid layer forming part forming a flow of a cooling liquid for cooling the melted metal discharged from the melted metal supplying part along an inner circumference face of the cylinder body, wherein the cooling liquid layer forming part has a primary pressure reservoir, and the primary pressure reservoir is provided on an outer circumference part of the cylinder body.

A metal powder producing apparatus comprising a melted metal supplying part discharging a melted metal, a cylinder body provided below the melted metal supplying part, and a cooling liquid layer forming part forming a flow of a cooling liquid for cooling the melted metal discharged from the melted metal supplying part along an inner circumference face of the cylinder body, wherein the cooling liquid layer forming part has a primary pressure reservoir, and the primary pressure reservoir is provided on an outer circumference part of the cylinder body.

It is possible to provide an iron-based sintered sliding material excellent in the sliding performance. Provided is an iron-based sintered sliding material including, a base containing, by mass, 3 to 15% of S, 0.2 to 6% in a total amount of at least one selected from the group consisting of Cr, Ca, V, Ti, and Mg, and a remainder of Fe and inevitable impurities, sulfide particles containing at least one selected from the group consisting of Cr, Ca, V, Ti, and Mg being dispersed in the base, and pores.

It is possible to provide an iron-based sintered sliding material excellent in the sliding performance. Provided is an iron-based sintered sliding material including, a base containing, by mass, 3 to 15% of S, 0.2 to 6% in a total amount of at least one selected from the group consisting of Cr, Ca, V, Ti, and Mg, and a remainder of Fe and inevitable impurities, sulfide particles containing at least one selected from the group consisting of Cr, Ca, V, Ti, and Mg being dispersed in the base, and pores.

A cubic boron nitride sintered material comprises 30% by volume or more and 99.9% by volume or less of cubic boron nitride grains and 0.1% by volume or more and 70% by volume or less of a binder phase, the cubic boron nitride grain having a carbon content of 0.08% by mass or less, the cubic boron nitride sintered material being free of free carbon.