Papers by Author: Daisuke Murakami

Abstract: Single-phase (binder-less) nano-polycrystalline diamond (NPD) has been synthesized by direct conversion sintering from graphite under high pressure and high temperature. NPD is characterized by extremely high hardness compared with single crystal diamond (SCD), even at high temperature. In addition, NPD has high wear resistance, no anisotropic mechanical properties, no cleavages, and high thermal stability. These characteristics suggest that NPD has high potential for use in precision cutting tools for various hard works. In order to evaluate the cutting performance of NPD, cutting tests for various cemented carbides were conducted under various conditions and the results compared with those of single crystal diamond (SCD) and conventional polycrystalline diamond containing metal binder (PCD). The results revealed that NPD has outstanding potential for precision cutting and processing of diverse hard and brittle materials.

Abstract: Cutting tools have been improved to endure severe environments in cutting operations. Especially, ceramic film coating technologies are important. Recently, film structure is optimized and tensile stress in film is controlled, as a result new tools which have the newest coating achieved double the tool life and 1.5 times higher efficiency compared with conventional tools. In tool design, progressive molding and sintering techniques allow more complicated tool shapes which have high rake angles to reduce cutting force, higher accuracy equivalent to grinding class tools and more excellent performance.