Abstract
Polycrystalline diamond compact (PDC) bits have been increasing their application drilling many formations in the past 20+ years. However, their performance in drilling very hard, abrasive and interbedded formations still needs improvement. The main weak point comes from their primary cutting elements, PDC cutters, which still need improvements of wear resistance, impact resistance, and thermal stability. During the traditional manufacturing of the PDC cutters, cobalt catalyst has to be used to lower the pressure and temperature. In this study, we developed an ultra high pressure and high temperature (UHPHT) technology to make the PDC cutters without metallic catalyst into reality. Through this development, we can generate pressures of 14 GPa-35 GPa, which is three to seven times of that in the traditional PDC cutter manufacturing technology. In addition, the extreme high temperatures ranging from 1,900 °C to 2,300 °C are achieved, which is 500-900 °C higher than that in traditional process. Using this UHPHT technology, we successfully processed ultra-strong and catalyst-free PDC materials with two high pressures at 14 GPa and 16 GPa, respectively, to study the different responses of the material properties from different processing parameters. The new process applied industry available micro-sized synthetic diamond powders as starting material to eliminate the large volume shrinkage in phase transformation from graphite to diamond which is typically experienced in traditional manufacturing process. The hardness of the 14-GPa CFPCD materials reaches the top limit of the single crystal diamond, more than double that of the traditional PDC cutters. The material also possesses the near-metallic fracture toughness – more than two times of the traditional PDC cutters. Furthermore, the 16-GPa CFPCD material breaks all four single crystal diamond indenters in Vickers hardness tester, an indication of the world's hardest material in the family of diamonds. As a result, the material exhibits industry-recorded wear resistance and thermal stability. The combination of these breakthrough properties of the new CFPCD materials activates the goal in the effort of "One-Run-To-TD" in drilling operation, after the implementation of CFPCD materials as PDC cutters for PDC drill bits.
Wear resistance of nano-polycrystalline diamond with various hexagonal diamond contents
