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C.h. Cooley - One of the best experts on this subject based on the ideXlab platform.

  • Wear-in behaviour of Polycrystalline Diamond thrust bearings
    Wear, 2011
    Co-Authors: C.w. Knuteson, T.n. Sexton, C.h. Cooley
    Abstract:

    Abstract Polycrystalline Diamond (PCD) bearings are designed for use in harsh environments, including process-fluid-lubricated applications such as those in oil and gas drilling turbines. This paper discusses the wear-in behaviour of Polycrystalline Diamond thrust bearings. Laboratory test results are presented that show the roughness, profile, and coefficient of friction of the Polycrystalline Diamond wear pads as the wear-in of the Polycrystalline Diamond bearings progresses. Laboratory test results show a significant decrease in the surface roughness and a change in the profile of the wear pads. Measured values of the coefficients of friction reveal that the lubrication regime of PCD thrust bearings can move from boundary to mixed-mode and may even become hydrodynamic after wearing-in for a period of time under the right conditions. This mechanism can provide extended life for PCD thrust bearings in harsh environments.

  • Polycrystalline Diamond thrust bearings for down hole oil and gas drilling tools
    Wear, 2009
    Co-Authors: T N Sexto, C.h. Cooley
    Abstract:

    Down-hole tools used for drilling oil and gas wells are subjected to harsh environments where abrasive fluids, high loads and speeds, and high temperatures can cause tool components, including thrust bearings, to quickly fail. This paper discusses the advantages that Polycrystalline Diamond can provide when used as a bearing material in down-hole tools. Laboratory test results are presented that can be used to help predict the performance of Polycrystalline Diamond bearings in these down-hole applications. Results from two types of tests are presented including tests that measure bearing capacity and those that evaluate Diamond bearing wear rates. Bearing failures, generated during laboratory testing, are discussed. These failures are very similar to those observed in down-hole drilling tools and indicate that thermal damage to the Polycrystalline Diamond structure is the main cause of bearing failure. Bearing wear rates measured during laboratory testing show that Polycrystalline Diamond thrust bearings can provide a long-lasting bearing solution for down-hole drilling tools.

Hitoshi Sumiya - One of the best experts on this subject based on the ideXlab platform.

  • Cutting Performances of Nano-Polycrystalline Diamond
    Key Engineering Materials, 2012
    Co-Authors: Katsuko Harano, Hitoshi Sumiya, 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.

  • Cutting performance of nano-Polycrystalline Diamond ☆
    Diamond and Related Materials, 2012
    Co-Authors: Katsuko Harano, T. Satoh, Hitoshi Sumiya
    Abstract:

    Abstract Nano-Polycrystalline Diamond (NPD) synthesized by the direct conversion sintering process from graphite under ultra-high pressure and high temperature (15–18 GPa, 2100–2300 °C) has a very fine texture consisting of small Diamond grains (10–50 nm in size) bonded directly without any binder materials. NPD has extremely high hardness, high wear resistance, no anisotropic mechanical properties, no cleavage feature, and high thermal stability, and so has high potential for precise cutting tools. To clarify this potential, we conducted cutting tests for various work materials under different conditions and compared the results with those for conventional Polycrystalline Diamond (PCD) and single crystal Diamond (SCD) tools. The results of the cutting tests were as follows: approximately 10–20 times higher than the PCD tool on turning of Al–Si alloy, 3–5 times higher than the PCD tool on turning of cemented carbide, and more than two times higher than the SCD tool on ultra-precision cutting for binderless cemented carbide. Detailed observations of the cutting edge after the cutting tests indicated that the excellent cutting performance of the tool was the result of its isotropic feature and fine texture without any binder. These results revealed that nano-Polycrystalline Diamond has outstanding potential for various cutting and processing applications.

  • cutting performance of nano Polycrystalline Diamond
    Diamond and Related Materials, 2012
    Co-Authors: Katsuko Harano, T. Satoh, Hitoshi Sumiya
    Abstract:

    Abstract Nano-Polycrystalline Diamond (NPD) synthesized by the direct conversion sintering process from graphite under ultra-high pressure and high temperature (15–18 GPa, 2100–2300 °C) has a very fine texture consisting of small Diamond grains (10–50 nm in size) bonded directly without any binder materials. NPD has extremely high hardness, high wear resistance, no anisotropic mechanical properties, no cleavage feature, and high thermal stability, and so has high potential for precise cutting tools. To clarify this potential, we conducted cutting tests for various work materials under different conditions and compared the results with those for conventional Polycrystalline Diamond (PCD) and single crystal Diamond (SCD) tools. The results of the cutting tests were as follows: approximately 10–20 times higher than the PCD tool on turning of Al–Si alloy, 3–5 times higher than the PCD tool on turning of cemented carbide, and more than two times higher than the SCD tool on ultra-precision cutting for binderless cemented carbide. Detailed observations of the cutting edge after the cutting tests indicated that the excellent cutting performance of the tool was the result of its isotropic feature and fine texture without any binder. These results revealed that nano-Polycrystalline Diamond has outstanding potential for various cutting and processing applications.

  • Generation of multi-megabar pressure using nano-Polycrystalline Diamond anvils
    Japanese Journal of Applied Physics, 2007
    Co-Authors: Yuki Nakamoto, Tetsuo Irifune, Hitoshi Sumiya, Takahiro Matsuoka, Katsuya Shimizu, Yasuo Ohishi
    Abstract:

    A nano-Polycrystalline Diamond was synthesized from graphite by direct conversion under high pressure. The nano-Polycrystalline Diamond consists of nanosized Diamond grains oriented in random directions and has higher toughness and more isotropic mechanical properties than the single-crystal Diamond. We generated the pressure using a pair of anvils composed of nano-Polycrystalline Diamond particles. The highest generated pressure achieved was 210 GPa. The generated maximum pressure was almost the same as that achieved by the single-crystal Diamond anvils.

  • Correction: Ultrahard Polycrystalline Diamond from graphite
    Nature, 2003
    Co-Authors: Tetsuo Irifune, A. Kurio, Shizue Sakamoto, Toru Inoue, Hitoshi Sumiya
    Abstract:

    Nature 421, 599–600, 2002 In the legend to Fig. 1a of this communication, the diameter of the transparent Polycrystalline Diamond shown is 1 mm, and not 0.1 mm as published; the scale divisions represent 0.1 mm. Also, the first full paragraph in the second column on page 600 should read: “Recent chemical-vapour deposition techniques provided pure Polycrystalline Diamonds, but these Diamonds are not sintered and have poor intergrain adhesion.

T N Sexto - One of the best experts on this subject based on the ideXlab platform.

  • Polycrystalline Diamond thrust bearings for down hole oil and gas drilling tools
    Wear, 2009
    Co-Authors: T N Sexto, C.h. Cooley
    Abstract:

    Down-hole tools used for drilling oil and gas wells are subjected to harsh environments where abrasive fluids, high loads and speeds, and high temperatures can cause tool components, including thrust bearings, to quickly fail. This paper discusses the advantages that Polycrystalline Diamond can provide when used as a bearing material in down-hole tools. Laboratory test results are presented that can be used to help predict the performance of Polycrystalline Diamond bearings in these down-hole applications. Results from two types of tests are presented including tests that measure bearing capacity and those that evaluate Diamond bearing wear rates. Bearing failures, generated during laboratory testing, are discussed. These failures are very similar to those observed in down-hole drilling tools and indicate that thermal damage to the Polycrystalline Diamond structure is the main cause of bearing failure. Bearing wear rates measured during laboratory testing show that Polycrystalline Diamond thrust bearings can provide a long-lasting bearing solution for down-hole drilling tools.

Tetsuo Irifune - One of the best experts on this subject based on the ideXlab platform.

A Klopfer - One of the best experts on this subject based on the ideXlab platform.

  • the wear of Polycrystalline Diamond tools used in the cutting of metal matrix composites
    International Journal of Refractory Metals & Hard Materials, 1999
    Co-Authors: R M Hooper, J L Henshall, A Klopfer
    Abstract:

    Abstract Polycrystalline Diamond (PCD) has been used for some years for the machining of abrasive systems such as aluminium/silicon and glass filled polymeric materials. This paper reports on the machining of the highly abrasive composite system of aluminium reinforced by silicon carbide particles and/or alumina fibres using Polycrystalline Diamond tools. The results indicate that Polycrystalline Diamond tooling offers superior performance over carbide, both in wear resistance and the quality of the surface finish produced. Observations of the morphology of the wear scars on the tools indicate that the wear process involves both adhesive wear and of the build up of defects within the Diamond particles leading to eventual micro- and macro-fracture in a fatigue-like process.