A method for producing a sintered component, in particular an annular sintered component, with a toothing, having teeth with tooth roots, tooth tips and tooth flanks, includes the steps of pressing a powder to form a green compact, sintering the green compact, and hardening the sintered component, wherein after sintering, the tooth flanks and possibly the tooth tips are post-compacted and subsequently undergo post-processing by machining, and wherein a transition region between the tooth flanks and the tooth roots has an undercut design, and post-compaction of the tooth flanks is carried out only up to this transition region.

A method for producing a sintered component, in particular an annular sintered component, with a toothing, having teeth with tooth roots, tooth tips and tooth flanks, includes the steps of pressing a powder to form a green compact, sintering the green compact, and hardening the sintered component, wherein after sintering, the tooth flanks and possibly the tooth tips are post-compacted and subsequently undergo post-processing by machining, and wherein a transition region between the tooth flanks and the tooth roots has an undercut design, and post-compaction of the tooth flanks is carried out only up to this transition region.

The present invention provides a nitriding treatment method for forming a compound layer of ε phase (Fe.sub.2-3N) and γ′ phase (Fe.sub.4N) iron nitride excellent in wear durability in a steel material, from which a sliding member is formed, by short treatment, with a high thermal efficiency, with a reduced amount of used nitriding gas, and with a low environmental load. The nitriding treatment method of the present invention includes heating a sliding member made of a steel material at a temperature of 600° C. to 700° C. for a time of 1 to 25 minutes under an atmosphere of nitriding gas through high frequency induction heating or resistive heating, to form a compound layer of ε phase (Fe.sub.2-3N) and γ′ phase (Fe.sub.4N) iron nitride, the compound layer having a nitrogen content of higher than 4.5%, in a surface layer portion of the sliding member.

The present invention provides a nitriding treatment method for forming a compound layer of ε phase (Fe.sub.2-3N) and γ′ phase (Fe.sub.4N) iron nitride excellent in wear durability in a steel material, from which a sliding member is formed, by short treatment, with a high thermal efficiency, with a reduced amount of used nitriding gas, and with a low environmental load. The nitriding treatment method of the present invention includes heating a sliding member made of a steel material at a temperature of 600° C. to 700° C. for a time of 1 to 25 minutes under an atmosphere of nitriding gas through high frequency induction heating or resistive heating, to form a compound layer of ε phase (Fe.sub.2-3N) and γ′ phase (Fe.sub.4N) iron nitride, the compound layer having a nitrogen content of higher than 4.5%, in a surface layer portion of the sliding member.

Techniques are disclosed for milling an iron-containing raw material in the presence of a nitrogen source to generate anisotropically shaped particles that include iron nitride and have an aspect ratio of at least 1.4. Techniques for nitridizing an anisotropic particle including iron, and annealing an anisotropic particle including iron nitride to form at least one α″-Fe.sub.16N.sub.2 phase domain within the anisotropic particle including iron nitride also are disclosed. In addition, techniques for aligning and joining anisotropic particles to form a bulk material including iron nitride, such as a bulk permanent magnet including at least one α″-Fe.sub.16N.sub.2 phase domain, are described. Milling apparatuses utilizing elongated bars, an electric field, and a magnetic field also are disclosed.

Techniques are disclosed for milling an iron-containing raw material in the presence of a nitrogen source to generate anisotropically shaped particles that include iron nitride and have an aspect ratio of at least 1.4. Techniques for nitridizing an anisotropic particle including iron, and annealing an anisotropic particle including iron nitride to form at least one α″-Fe.sub.16N.sub.2 phase domain within the anisotropic particle including iron nitride also are disclosed. In addition, techniques for aligning and joining anisotropic particles to form a bulk material including iron nitride, such as a bulk permanent magnet including at least one α″-Fe.sub.16N.sub.2 phase domain, are described. Milling apparatuses utilizing elongated bars, an electric field, and a magnetic field also are disclosed.

To provide a piston ring excellent in thermal setting resistance, and also excellent in side surface wear resistance even under such a high-temperature high-pressure environment as to be more than 300° C. and up to 400° C., the base metal of the piston ring is a steel containing, by mass %, C: 0.30 to 0.65%, Si: 0.80 to 1.20%, Mn: 0.20 to 0.60%, Cr: 4.50 to 5.70%, Cu: 0.01 to 0.5%, and at least one of Mo, V, W, and Co: 0.2 to 5.4%.

An annealing separator for an oriented electrical steel sheet includes: a first component including a Mg oxide or a Mg hydroxide; and a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof.

An annealing separator for an oriented electrical steel sheet includes: a first component including a Mg oxide or a Mg hydroxide; and a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof.

A method for low-temperature interstitial case formation on a self-passivating metal workpiece includes exposing the workpiece in a heated gaseous environment comprising oxygen to pyrolysis products of a nonpolymeric reagent comprising nitrogen and carbon.