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The particle size and particle size ratio of the raw diamond powder have a great influence on the stacking density, which is critical to the performance of polycrystalline diamond compact (PDC). In this study, diamond powders with five different particle size of 1 μm, 4 μm, 12 μm, 20 μm and 27 μm were selected. High stacking density diamond powder formulations with three filler particle ratios of 10 wt%, 20 wt% and 30 wt% were designed by using 12 μm, 20 μm and 27 μm diamond as the main particles and 1 μm and 4 μm diamond as the filler particles. The different formulations were evaluated by mechanical property tests and microscopic characterization of PDC samples to find out the optimal filler particle size as well as filler ratio in different main particle series. The results showed that the larger the main particle size in the formulation, the worse the wear resistance and the better the impact toughness of PDC. Adding decent number of fine particles with appropriate particle size could effectively improve the comprehensive performance of PDC. But the match between different main particles and filler particles was not consistent, and the three optimal formulations finally derived under the conditions in this paper were 80 wt%12 μm-20 wt%1 μm, 90 wt%20 μm-10 wt%4 μm, and 80 wt%27 μm-20 wt%4 μm. The rock cutting life of PDC with optimal formulations was all improved by 20 passes and the wear resistance was improved by 62%, 53.8% and 40.4%, respectively, compared with the single particle size control group. The impact toughness was improved by 650 J/68.4%, 1200 J/77.4% and 750 J/20%, respectively. The PDC performance variation pattern of different formulations was highly consistent with that of Co content, indicating that the decrease of Co content caused by the increase of stacking density was the main mechanism for performance enhancement of dual-particle size PDC. • PDCs with different dual particle size diamond formulations were fabricated. • The matching of different main particles with filler particles was elucidated. • Optimal diamond powder formulations were derived for three different main particles. • The link between mechanical properties and Co content of PDC with different formulations was elucidated. [ABSTRACT FROM AUTHOR]

In this study, PDC added with tantalum was successfully prepared via high pressure and high temperature (HPHT, 7.7GPa and 1650 °C) with the Cubic-Anvil Press. The effect of tantalum on the mechanical properties and thermal stability was systematically investigated by hardness, abrasion resistance, impact resistance and coefficient of thermal expansion (CTE) tests. The results showed that the hardness, wear ratio, total impact energy and initial expansion temperature increased by 21.7%, 45.5%, 55.2% and 20 °C with the addition of tantalum, respectively. The Ta-PDC material binder phase consisted of Ta-phases (TaC, (Ta,W)C X) and cobalt phase after sintering. In elemental quantification observe that the addition of Ta facilitated cobalt infiltration which was benefit to diamond-diamond bonding. The improvement of mechanical properties and thermal stability can be attributed to the reinforced binder, refined and deagglomerated WC grains at the interface between PCD layer and substrate, and better sintering quality. Further optimization of the Ta additive phase content, mixing methodology, or sintering conditions could be explored to further improve the mechanical properties and thermal stability of this novel PDC material. • Adding Ta can promote the sweeping of cobalt. • Adding Ta greatly refined and de-agglomerated the WC grains at the interface. • Adding Ta enhanced the mechanical properties and thermal stability of PDC. [ABSTRACT FROM AUTHOR]

In this study, fine-grained (0-2 μm) polycrystalline diamond compacts (PDC) doped with 0.5 wt% nano‑vanadium carbide (VC) addition were sintered under high pressure and high temperature (HPHT, 6GPa and 1600 °C). The effect of VC on the phase composition, microstructure and mechanical properties of fine-grained PDC has been systematically studied. The results showed that the hardness and impact resistant energy of the PDC samples doped with VC were 66.65GPa and 160 J, increased by 8.7% and 100%, respectively. The samples exhibited higher wear resistance, and the wear ratio of 5 passes, 10 passes and 15 passes were 60 × 104, 54.3 × 104 and 52.2 × 104，increased by 8.2%, 65.4% and 65.5%, respectively. The enhanced of hardness and wear resistance can be attributed that VC as a harder material occupied the space of cobalt in the polycrystalline diamond table and reduced the cobalt and η-phase Co 3 W 3 C content. At the same time the VC refined the tungsten carbide (WC) gains and made them more homogeneous dispersed in the polycrystalline diamond table. VC and WC formed solid solution dispersed in the binder to produce the pinning effect, which change the fracture mode to improve the impact resistance of PDC. [Display omitted] • Doping VC reduced the content of cobalt and η-phase Co 3 W 3 C in PDC. • Doping VC refined the WC grains in the PDC significantly. • Doping VC enhanced the mechanical properties of fine-grained PDC. • VC and WC formed the solid solution (V,W)C X which changed the fracture mode. [ABSTRACT FROM AUTHOR]

Mud pulser is the most commonly used Measurement While Drilling(MWD) instrument for downhole data transmission to the surface. The rotor of the key component of the mud pulser is made of cemented carbide material. Under the action of high speed mud erosion containing solid phase, the rotor will produce erosion wear and reduce the quality of signal transmission. To explore the erosion wear mechanism of rotor carbide in mud containing solid phase particles, the influences of different erosion angles and different erosion abrasive sizes on the erosion wear properties of cemented carbides were studied by taking quartz sand as erosion abrasive. By means of surface profilometer, scanning electron microscope (SEM) and energy spectrum analysis (EDS), the erosion wear mechanism of cemented carbide was revealed. The experimental results show that the erosion wear rate increases gradually with the increase of erosion angle. When the erosion angle is 90°, the maximum average erosion rate of WC-5Co, WC-6Co and WC-10Co cemented carbides is 2.39%, 2.42% and 3.22%, respectively. With the increase of the abrasive particle size, the erosion wear rate of the material increases first and then decreases. When 100–200 um, the maximum average erosion rates of WC-5Co, WC-6Co and WC-10Co are 1.84%, 1.98% and 2.48%, showing a significant "particle size effect". At low erosion angle, the wear mechanism is furrow and cutting mark, while at high erosion angle, the wear mechanism is pit. The erosion wear mechanism of small particle size abrasives is that a large area of surface layer falls off in the erosion area. The erosion wear mechanism of large particle size abrasive is the material loss in the erosion pit in the erosion area. • The mass loss at low erosion angle is mainly the removal of Co due to plastic deformation. • The mass loss at high erosion angle is mainly the removal of Co and the pits caused by the removal of WC. • The erosion rate of cemented carbide increases first and then decreases with the increase of abrasive particle size. [ABSTRACT FROM AUTHOR]

Ti-coated diamond and cBN with TiCN as the binder were used to fabricate the TDBN-TiCN series PDC with improved heat resistance, wear resistance and impact toughness by a China-type cubic high-pressure apparatus (5.5–6.5 GPa, 1450–1650 °C) for drilling. Under high temperature and high pressure conditions, the Co in the cemented carbide substrate penetrated into the PCD layer and the binder TiCN to form a metal-ceramic binder system. It can promote the formation of polycrystalline cubic boron nitride (PcBN) from cubic boron nitride particles at the grain boundaries, and promote the TDBN-TiCN series PDC to have the performance of PCD and PcBN. Compared with the TDBN series PDC developed by our former research, the wear resistance of TDBN-TiCN series PDC increased by 17% and the impact toughness increased by 26%. In the TDBN-TiCN series PDC, some heat resistant phases, such as PcBN, TiB 2 and TiN, were formed so as to enhance the initial graphitization and oxidizing temperatures to 958 °C, which was 8 °C higher than the TDBN series PDC (950 °C) and 178 °C higher than conventional PDC (780 °C). • The Co in the cemented carbide substrate penetrated into the PCD layer and TiCN to form a metal-ceramic binder system. • The polycrystalline cubic boron nitride (PcBN) from cubic boron nitride particles at the grain boundaries. • PcBN, TiB 2 and TiN, were formed so as to enhance the initial graphitization and oxidizing temperatures to 958°C. [ABSTRACT FROM AUTHOR]

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]

Diamond/WC-Fe-Ni composite is a potential composition for impregnated diamond drill bits. It is necessary to avoid the graphitization of the diamond from Fe and Ni under the powder metallurgy process. Boron carbide (B 4 C) was coated on diamond, and diamond/WC-Fe-Ni composites were consolidated by hot pressing at different temperatures. The influences of sintering temperature and interfacial structure on bending strength and wear behavior were investigated. The bending strength for diamond/WC-Fe-Ni composite was dependent on matrix densification and interfacial graphitization. Un-coated diamond was eroded by Fe-Ni matrix and partially converted to graphite during the sintering process at all sintering temperatures. In opposite, B 4 C coating was beneficial to matrix densification at a lower sintering temperature, and delayed the appearance of graphitization to around 1300 °C. Therefore, the diamond/WC-Fe-Ni composites with B 4 C coating exhibited larger bending strength and better wear behavior at a relative low sintering temperature. • B 4 C coating is benefit to matrix densification, and delay the diamond graphitization. • B 4 C coating contributes to enhancement bending strength for diamond/WC-Fe-Ni composite (up to 644 MPa). • B 4 C coating contributes to improvement in abrasive ratio (up to 2417), increased by 6 times. [ABSTRACT FROM AUTHOR]