Commemorating the accomplishments of the late Dr. Masatoshi Okochi, the Okochi Prize, one of the most prestigious prizes in Japan, is awarded annually to an outstanding achievement in the fields of production engineering and advanced production technologies in Japan. The award ceremony will be held on Wednesday, March 26 at the Industry Club of Japan Hall in Marunouchi, Tokyo.
The 60th Okochi Memorial Technology Prize
Honoring: The development of nano-polycrystalline diamond synthesis technology and applied products
||Chief Engineer/Fellow, Advanced Materials R&D Laboratories
Manager, Inorganic Materials R&D Department
||Senior Manager, Inorganic Materials R&D Department, Advanced Materials R&D Laboratories
||Assistant Manager, Inorganic Materials R&D Department, Advanced Materials R&D Laboratories
3．Backdrop to the Development
The conventional materials used for diamond cutting and molding tools used to be monocrystal and sintered diamonds. The drawbacks of these diamonds were short tool life resulting from partial wear and cleavage*1 of monocrystal diamonds, which are dependent on crystal orientation, and degraded mechanical properties and heat resistance due to the binder contained in sintered diamond, making the tool prone to damage. Furthermore, the synthesis of monocrystal diamond involved crystal growth requiring several tens of hours, posing cost and productivity challenges.
Sumitomo Electric developed the innovative nano-polycrystalline diamond to address the problems of conventional diamond materials. It features a single-phase nano-polycrystalline body of highly densely structured diamond produced through direct conversion of graphite under ultrahigh pressure, higher than 15 GPa, and at high temperatures of over 2000ºC. This new hard material is an ideal tool material since it is harder than single-crystal diamond and extremely tough, as well as free of cleavage and anisotropic mechanical properties, plus highly heat resistant. Using it at the tip, Sumitomo Electric commercialized a family of cutting tools, Sumidia™ Binderless in 2012. This product has been the focus of close attention as an epoch-making tool product that enables the cutting of conventionally difficult-to-machine cemented-carbide and other hard brittle materials with substantially improved efficiency.
4．Outline of Award-Winning Technology
The prize was awarded for the development of advanced and novel production technologies such as ultrahigh-pressure manufacturing technology and new product-machining engineering, which served as the basis for commercializing the nano-polycrystalline diamond. Our nano-polycrystalline diamond synthesis technology directly converts graphite to diamond under ultrahigh-pressure and high-temperature conditions of over 15 GPa and 2000ºC. The combination of this technology with our precision cutting-edge preparation technology makes it possible to accurately cut cemented-carbide and ultrahard brittle materials and substantially reduces machining time.
For the nano-crystalline diamond synthesis technology, the development of ultrahigh-pressure mold materials, the introduction of a new pressurization system and the establishment of a high-precision pressure and temperature control technology enabled the world’s first successful industrial use of ultrahigh pressure (over 15 GPa), more than three times higher than that used in conventional diamond synthesis. The direct conversion of graphite for nano-polycrystalline diamond synthesis is substantially faster than conventional monocrystal diamond fabrication.
Moreover, the development of a special processing method has enabled highly accurate and fast cutting-edge preparation and successful commercialization of nano-polycrystalline diamond tools for ultraprecision and micromachining applications.
Using these technological developments, Sumitomo Electric developed the world’s first mass-production technology for synthetic nano-polycrystalline diamond, combined it with high-precision cutting-edge preparation technology, and commercialized tools for the precision cutting of cemented-carbide and ultrahard brittle materials. These tool products can be used in a new range of applications that conventional diamond materials are not suitable for, improve manufacturing technologies and reduce manufacturing costs in the engineering, electronic and automotive industries, and therefore make a valuable industrial and social contribution.
*1 Cleavage：Splitting along certain crystalline planes unique to monocrystals