Now showing 1 - 4 of 4
  • Publication
    Fracture properties of PCBN as a function of loading rate and temperature
    Polycrystalline Cubic Boron Nitride (PCBN) is a superhard material which is used in machining of hardened steels and other abrasive and aerospace grade alloys. In these applications the tools are subjected to high operating temperatures, abrasive and impact loading. Impact loading can lead to the sudden fracture and hence failure of the tool. In this work the static and dynamic fracture toughness of PCBN is determined via a combined experimental-numerical approach. The results show that the fracture toughness of PCBN varies with loading rate
      307Scopus© Citations 4
  • Publication
    High rate and high temperature fracture behaviour of polycrystalline diamond
    (Trans Tech Publications, 2011-09) ; ;
    Polycrystalline diamond (PCD) materials have a variety of applications, mainly as cutting tools for machining non-ferrous metals and non-metallic materials. A significant application of PCD is in oil and gas industry for rock drilling operations. Other important areas, such as mining, have yet to reach their full potential. These cutters/tools are subjected to high operating temperatures, impact loads and abrasive wear during these operations, which may lead to their sudden failure. An advantage of these materials is that their structure and composition can be engineered to return properties required for specific applications and operations. In this study, the mechanical and fracture properties of two grades of PCD have been determined at dynamic loading rates up to 5 m/s and elevated temperature up to 600°C in laboratory conditions using three point bending (TPB) and split-Hopkinson pressure bar apparatus (SHPB). The results show Young’s modulus to be completely rate insensitive, while fracture toughness changes significantly. Two dominant regions can be observed on the rate scale: one predominated by the conductivity of the material and the other predominated by the rate of fracture where binder degrades locally at the crack tip. This behaviour was related to the material microstructure, where similarities and differences in the fracture of two different grades of PCD are shown examining polished fractured specimens using scanning electron microscopy, revealing mechanisms of fracture over the range of loading rates.
      492Scopus© Citations 4
  • Publication
    The mechanical properties of polycrystalline diamond as a function of strain rate and temperature
    Polycrystalline diamond (PCD) materials are used in various applications, mainly as cutting tools for machining non-ferrous metals and non-metallic materials and for rock drilling operations. A better knowledge of their mechanical properties is of fundamental importance to PCD manufacturers and end users. In order to understand and predict the behaviour and structural integrity of the tools containing PCD, it is first necessary to study the behaviour of the material as a function of loading rate and temperature. In this paper, material behaviour is determined under testing conditions which correspond more closely to those in actual drilling, which is a significant improvement over investigations to date. Young’s modulus determined by four-point bending and a split-Hopkinson pressure bar apparatus was relatively constant with the rate, while a consistent decrease was observed with increase of temperature. The flexural strength was found to increase with the temperature, while decreasing with an increase in rate.
      1794Scopus© Citations 22
  • Publication
    Fracture properties of PCBN as a function of loading rate and temperature
    (Trans Tech Publications, 2010-11) ; ; ;
    Polycrystalline Cubic Boron Nitride (PCBN) is a super-hard material used in some of the most demanding material removal operations today. These include turning of hardened steels, as well as the machining of highly abrasive alloys. In these applications the tools are subjected to high operating temperatures, abrasive and impact loading. This can lead to the brittle fracture of the tool. Accurate determination of the fracture toughness and mechanical properties of PCBN under a wide range of operating conditions is therefore essential in order to evaluate the performance of the tool under these highly demanding conditions. For this study, a laboratory scale three point bend test rig has been used for the fracture tests. The fracture toughness of two different grades of PCBN are measured at a range of loading rates and temperatures corresponding to the actual in-service conditions. The results show the measured properties of these materials vary with both loading rate and temperature. The fracture surfaces of the specimens are examined using scanning electron microscopy to determine dominant fracture mechanisms
      418Scopus© Citations 4