Method for manufacturing polycrystalline diamond and its manufacturing method, scribe tool, scribe wheel, dresser, rotary tool, orifices for water jet, wire drawing die, cutting tool, electrode and polycrystalline diamond

摘要

To provide a polycrystalline diamond that is coated with a water-insoluble protection film, and can suppress tribo-plasma.SOLUTION: A polycrystalline diamond is composed of a plurality of crystal grains with a diamond single phase as a basic composition, and contains boron, nitrogen, and a silicon compound, with the balance being carbon and trace impurities. The boron is dispersed in the crystal grains at an atom level, and 90 atom% or more thereof is present as an isolated substitutional type. The nitrogen and the silicon compound are present in the crystal grains as an isolated substitutional type or an intrusion type. The silicon compound is at least one selected from the group consisting of silicon oxide, silicon nitride and silicon carbide. The crystal grains have a particle size of 500 nm or less, and a surface of the polycrystalline diamond is coated with a protection film.SELECTED DRAWING: None