A wire-drawing method comprises providing a rod comprising a wrapped sheet, wherein the sheet comprises a plurality of copper layers and a plurality of graphene layers; extracting an inner layer of the wrapped sheet from the rod to form a spiral; and forming a wire by feeding the spiral through an opening of a die unit.

In a single-crystal diamond material, a concentration of non-substitutional nitrogen atoms is not more than 200 ppm, a concentration of substitutional nitrogen atoms is lower than the concentration of the non-substitutional nitrogen atoms, and the single-crystal diamond material has a crystal growth main surface having an off angle of not more than 20. A perforated tool includes a single-crystal diamond die, wherein in the single-crystal diamond die, a concentration of non-substitutional nitrogen atoms is not more than 200 ppm, a concentration of substitutional nitrogen atoms is lower than the concentration of the non-substitutional nitrogen atoms, and the single-crystal diamond die has a low-index plane represented by a Miller index of not less than 5 and not more than 5 in an integer, a perpendicular line of the low-index plane having an off angle of not more than 20 relative to an orientation of a hole for wire drawing.

Embodiments of the invention relate to polycrystalline diamond (PCD) exhibiting enhanced diamond-to-diamond bonding. In an embodiment, PCD includes a plurality of diamond grains defining a plurality of interstitial regions. A metal-solvent catalyst occupies at least a portion of the plurality of interstitial regions. The plurality of diamond grains and the metal-solvent catalyst collectively exhibit a coercivity of about 115 Oersteds (Oe) or more and a specific magnetic saturation of about 15 Gauss.Math.cm.sup.3/grams (G.Math.cm.sup.3/g) or less. Other embodiments are directed to polycrystalline diamond compacts (PDCs) employing such PCD, methods of forming PCD and PDCs, and various applications for such PCD and PDCs in rotary drill bits, bearing apparatuses, and wire-drawing dies.

A single-crystal diamond includes a pair of main surfaces facing each other, an impurity concentration being changed along a first direction in each of the main surfaces.

A drawing die made from cemented carbide material is formed of tungsten carbide and a metallic binder. The cemented carbide material includes: tungsten carbide with an average grain size of 0.15-1.3 m, 0.5-5.0 wt.-% (Co+Ni), with a ratio Co/(Co+Ni) of 0.6-0.9; 0.1-1.0 wt.-% Cr, with 0.05Cr/(Co+Ni)0.22; 0.02-0.2 wt.-% Mo; and 0-0.04 wt.-% V. The cemented carbide material is substantially free from -phase.

A drawing die made from cemented carbide material is formed of tungsten carbide and a metallic binder. The cemented carbide material includes: tungsten carbide with an average grain size of 0.15-1.3 m, 0.5-5.0 wt.-% (Co+Ni), with a ratio Co/(Co+Ni) of 0.6-0.9; 0.1-1.0 wt.-% Cr, with 0.05Cr/(Co+Ni)0.22; 0.02-0.2 wt.-% Mo; and 0-0.04 wt.-% V. The cemented carbide material is substantially free from -phase.

Provided are a metal wire rod drawing die that has a longer life than conventional dies and that can prevent damage to a metal wire rod surface and a method for manufacturing the die. In a metal wire rod drawing die (1), a die hole (2) for inserting a metal wire rod is formed. Where Ra1 represents a surface roughness of an inner surface of the die hole from a bearing section (2b) to an approach section (2a) corresponding to an area reduction rate of 30% in an axial direction of the die hole, Ra2 represents a surface roughness of the inner surface of the die hole from the bearing section to the approach section corresponding to the area reduction rate of 30% in a direction orthogonal to the axial direction of the die hole, and Ra3 represents a surface roughness of an inner surface of the bearing section of the die hole in the axial direction of the die hole, the Ra1, the Ra2, and the Ra3 satisfy a relationship represented by 0.14 m>Ra2>Ra1>Ra3.

Provided are a metal wire rod drawing die that has a longer life than conventional dies and that can prevent damage to a metal wire rod surface and a method for manufacturing the die. In a metal wire rod drawing die (1), a die hole (2) for inserting a metal wire rod is formed. Where Ra1 represents a surface roughness of an inner surface of the die hole from a bearing section (2b) to an approach section (2a) corresponding to an area reduction rate of 30% in an axial direction of the die hole, Ra2 represents a surface roughness of the inner surface of the die hole from the bearing section to the approach section corresponding to the area reduction rate of 30% in a direction orthogonal to the axial direction of the die hole, and Ra3 represents a surface roughness of an inner surface of the bearing section of the die hole in the axial direction of the die hole, the Ra1, the Ra2, and the Ra3 satisfy a relationship represented by 0.14 m>Ra2>Ra1>Ra3.

A shaped diamond die includes a polycrystalline diamond, the polycrystalline diamond having a machining hole, wherein a length D of a side of the machining hole is 100 m or less, a corner R is 20 m or less, the shaped diamond die includes a bearing portion, a surface roughness Sa of the bearing portion is 0.05 m or less, and an average grain size of the polycrystalline diamond is 500 nm or less.

A composite sintered body includes a diamond phase and a non-diamond carbon phase. A non-diamond carbon phase occupancy rate is higher than 0% and not higher than 30%. The non-diamond carbon phase occupancy rate is a percentage of an area of the non-diamond carbon phase to a total area of one arbitrarily specified cross section of the composite sintered body. As a result, there is provided a high wear-resistant, high local wear-resistant and high chipping-resistant diamond-containing composite sintered body suitably used as a material for a wear-resistant tool, a cutting tool and the like.