Wear resistance and thermal stability enhancement of PDC sintered with Ti-coated diamond and cBN.

Ti-coated diamond with different particle sizes and proper amounts of cubic boron nitride (cBN) was used to fabricate polycrystalline diamond composite (PDC) with improved wear resistance and thermal stability under high temperature and high pressure (5.5–6.5GPa, 1500–1650 °C). The ratio of Ti-coated diamond powder, cBN powder and normal diamond powder was W 30 – 50 : W 4 – 8 : W 0 – 1 = 70: 15: 15. Cobalt (Co) was used as a binder, and cemented tungsten carbide was used as a substrate to sinter a new high-performance PDC. Ti and TiC on the surface of Ti-coated diamond reacted with cBN under high temperature and high pressure to generate new ceramic phases such as TiB 2 , TiN and TiN 0.3 , which have high hardness and good wear resistance. Compared with the conventional PDC, the impact toughness and wear resistance of PDC with Ti-coated diamond and cBN addition were enhanced by 19% and 28%, respectively. The ceramic phase acts as a protective barrier, which enhances the initial graphitization and oxidizing temperature to 942–950 °C, which were 162–170 °C higher than the conventional PDC. The new ceramic barrier wrapped around the surface of the diamond and Co after the formation of the D-D (diamond-diamond) bonding will give priority to the oxidation reaction of Co and diamond with oxygen, which prohibits cobalt-catalytic graphitization of diamond, meeting the needs of PDC thermal stability and wear resistance in the field of drilling. • A new type of PDC was HPHT sintered with Ti-coated diamond and cBN. • Thermal and wear resistant ceramics such as TiB 2 , TiN and TiN 0.3 was generated during HPHT sintering. • The initial oxidizing temperature of the new PDC was about 950 °C. • The impact toughness and wear resistance of new PDC increased by 19% and 28, respectively. [ABSTRACT FROM AUTHOR]