Improved vacuum tribological properties of sintered polycrystalline diamond compacts treated by high temperature annealing

The sintered polycrystalline diamond compacts (PDC) can be used in drilling in outer space with its excellent tribological properties such as low friction coefficient and high wear resistance. However, an unsatisfactory adhesion resistance behavior should be brought to the forefront, which may be the main factor resulting in the failure of PDC under vacuum environment. Consequently, we make the first attempt at improving the vacuum tribological behaviors of PDC. The effects of annealing on the vacuum tribological behavior of PDC are discussed in view of experimental studies using complementary analytical techniques (Raman, SEM&EDS, AFM). Raman spectra revealed that the degree of graphitization of PDC was increased with the temperature. The wear mechanism of the PDC under vacuum condition varied from adhesion to the abrasive wear when the annealing temperature was increased from 25 °C (RT) to 700 °C in ambient air. It was found that the friction coefficient of the compacts under vacuum can be minimized to lower than 0.015, while the wear can hardly be seen. Therefore, the vacuum tribological behavior of PDC can be largely improved after annealing treatment.

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