Polycrystalline superhard layer made by electrophoretic deposition

A method of making polycrystalline superhard material 26 by electrophoretically depositing charged superhard particles 22 onto a surface 14 of an electrically conductive substrate 12 to form a pre-sintered body, and sintering the pre-sintered body at a temperature and pressure at which the superhard material is thermodynamically stable, thereby forming polycrystalline superhard material. The substrate 12 forms the cathode of an electrophoretic cell, the superhard particles 22 are positively charged and suspended in a liquid 20 which contacts the cathodic substrate 12 and an anode 16 which opposes said surface of the substrate 12. The particles 22 can be deposited as a series of layers or as discrete three-dimensional structures on un-masked areas of the substrate 12. The material can be polycrystalline diamond or polycrystalline cubic boron nitride. Used for making cutting tools.