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To improve the lubrication and friction characteristics of diamond thrust bearings and extend their service life, this study took inspiration from the anti-adhesion and wear-resistant properties of a dung beetle body surfaces and used laser processing to create dimples on the surface of a polycrystalline diamond compact (PDC). The spacing, diameter, and depth of the dimples were designed and optimized using an orthogonal experimental method. The wear mechanism of the textured PDC was analyzed using various microscopic characterization methods. The results showed that the bio-inspired dimple-textured PDC exhibited better tribological behavior and was an effective way to enhance the lifetime and reliability of diamond thrust bearings. • Verified that a laser processing method for PDC inspired by dung beetle surface can effectively improve tribological behaviors. • Determined the optimal texture morphology parameters for tribological performance. • Summarized the wear mechanism of textured dung beetle-inspired PDC. [ABSTRACT FROM AUTHOR]

The tribological behaviors of polycrystalline diamond compact (PDC) under alternating high and low temperature conditions in vacuum environment were evaluated by a ball-on-disk tribometer. The wear surface features and chemical composition were measured by FIB-SEM-Raman-TOF-SIMS microanalyzer (SEM, EDS, Raman), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that the coefficient of friction (COF) was pretty low and stable at atmospheric room temperature condition, while it was much higher and fluctuated in vacuum environment with alternating high and low temperature condition. In atmospheric environment with room temperature, the continuous formation of adsorbed films on the contact surface kept the chemical composition of the friction pair virtually unchanged, and the wear mechanism was a combination of mild abrasive wear and oxidative wear. In vacuum environment with alternating high and low temperature condition, the adsorbed film on the contact surface desorbed and could not continue to form, and the adhesion of Si 3 N 4 materials occurred on the wear area and the Si-C bonds were formed. In addition, a combination of high friction heat, localized flash temperature and Co binder led to the graphitization of diamond. The wear mechanism was a combination of abrasive wear and adhesive wear. The above results showed that the adhesion of Si 3 N 4 and the Si-C bonds led to high friction force, while the graphitization phenomenon weakened the bonding force between diamond grains, and made them more likely to be detached during the sliding. These were the mainly reasons for the severe wear under vacuum environment with alternating high and low temperature condition. [Display omitted] • Evaluation of the possibility of polycrystalline diamond compact (PDC) as a potential material for space drilling bits. • The vacuum environment and the fluctuation of temperature led to an increased wear rate of PDC. • The main wear mechanism of PDC under alternating high and low temperatures in vacuum was elucidated. [ABSTRACT FROM AUTHOR]

The fragmentation behavior of mixed diamond particles with different grain sizes under high pressure is important to guide the design of raw material diamond powder ratios and obtain high performance polycrystalline diamond compact (PDC). In this study, five different grain size diamond powders commonly used for the preparation of PDCs were selected, and the single and mixed diamond particles were cold pressed at 7.7 GPa for 60s. The particle size variations of diamond powders with different principal particle sizes and ratios after cold pressing were analyzed by a laser particle size scanner, and the crushing behavior was observed by scanning electron microscopy. The results showed that the larger the initial grain size, the more significant the degree of fragmentation under high pressure. The crushing morphology of fine-grained diamond showed that the majority of grains were locally fractured at the edge, and the peak of the grain size distribution curve was shifted to the left after high pressure. In comparison, the coarse-grained diamond produced a large number of cracks and fractures along the weak grain boundaries under high pressure, which generated a large number of fine grains, and multiple secondary peaks in the particle size distribution curve. The addition of fine-grained diamond as filler particles to coarse-grained diamond could inhibit the crushing phenomenon to some extent. As the proportion of filler particles increased, the crushing of coarse-grained diamond was inhibited more significantly. When the proportion of filler particles was 30 wt%, the crushing under high pressure was greatly limited, especially when the size difference between filler particles and main particles was large. The results of the cold pressing experiments provided preliminary evidence that 30 wt% of filler particles were too high, and that a better ratio should be between 10 wt% and 20 wt%. [ABSTRACT FROM AUTHOR]

To solve the problems of high vibration, low lifespan, and frequent replacement of diamond thrust bearings, the tribological behavior and friction mechanism of cobalt-removed and untreated PDC under different axial loads and rotational speeds were investigated in the WBDFs. The results indicated that the cobalt-removed PDC had lower friction coefficients, smoother friction status, better wettability, and better wear resistance than the untreated PDC. Cobalt-removed PDC could avoid the occurrence of thermal wear in the friction process, and the main forms of surface abrasion were dominated by mechanical wear. This study provides the experimental basis for the use of cobalt-removed PDC as a friction pair material for diamond thrust bearings, which can promote further research and development of downhole drilling tools. • Validation of the possibility of using cobalt-removed polycrystalline diamond compact (PDC) as a friction pair material for diamond thrust bearings. • Cobalt-removed PDC has a better tribological behavior suitable for the working conditions of diamond thrust bearings. • The friction coefficients of cobalt removed PDC and untreated PDC increase with the increase of rotational speed and axial load. • The wettability of the cobalt-removed PDC in contact with water-based drilling fluids (WBDFs) was better than that of untreated PDC. • Elucidated the main wear formats and mechanisms in WBDFs lubrication of cobalt removed PDC. [ABSTRACT FROM AUTHOR]

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]

Polycrystalline diamond compacts (PDC) with three different substrate geometries and trimodal diamond particle formulation were fabricated. The properties of prepared PDC including Vickers hardness, toughness, wear performance, and thermal stability were evaluated. The microscopic features including morphology, elemental and phase composition, and residual stress state were systematically investigated. The optimal substrate contributing to best comprehensive properties of PDC was singled out. Discrepancies in the properties of PDCs with different substrate geometries were mainly in fracture toughness and impact toughness, with maximum and minimum values of 6.54 MPa m1/2/3120 J and 5 MPa m1/2/1680 J, respectively. The best wear performance was 5.88 mm2/60P. The results showed that the tendency of wear performance was consistent with toughness and thermal stability, showing a strong correlation. The substrate geometry affected the morphology and composition of the cobalt transition layer in the interface, which had a significant impact on its toughness. Differences in residual stress states induced by the interfacial geometries were also important determining PDC's impact toughness. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond compact (PDC) with different grain sizes were fabricated and the multi-physical behaviors, including mechanical-, thermal-, and magnetic performances, and the microscopic features were examined to study the grain size dependence of wear behavior while cutting dense granite. The results showed that the coarse grade PDC had higher impact resistance and fracture toughness. However, the fine grade PDC had higher cobalt content, hardness and thermal resistance. Among these properties, the wear resistance changed the same way as thermal expansion properties proving the strong correlation. Moreover, the crack network caused by thermal mismatch, and the peeling/fracture of metallic phases and diamond promoted fracture wear and played the critical roles in the wear of coarse grade PDC. [ABSTRACT FROM AUTHOR]

• The methane hydrate with different saturation is generated in simulated reservoir inside high-pressure reaction vessel. • The effects of different saturations on gas production dynamics during microwave heating hydrate decomposition have been investigated. • The reservoirs with high initial hydrate saturation are more suitable for the application of microwave heating technology for development. Microwave heating technology is an effective method to promote the decomposition of hydrates, with hydrate saturation being an important parameter influencing this process. This study has synthesized natural gas hydrates with different saturations within a high-pressure reaction vessel to conduct experiments on the decomposition of natural gas hydrates by microwave heating. The reservoir temperature, gas production dynamics, and energy utilization rate are investigated for hydrate saturations of 30.26 %, 35.63 %, and 39.61 %, respectively. The results indicate that increasing hydrate saturation enhances the microwave penetration depth, which in turn elevates the reservoir temperature and accelerates hydrate decomposition. When the hydrate saturation increases from 30.26 % to 39.61 %, the gas production time decreases. Simultaneously, both the volume and rate of gas production increase, accompanied by enhanced energy utilization rate. When the hydrate saturation is 39.61 %, the experiment achieves an average gas production rate of 1.17 L/min, a total volume of 19.73 L, and an energy utilization rate of 2.716. The research results can promote the application of microwave heating technology in the development of hydrates. [ABSTRACT FROM AUTHOR]

The nonlinear static and dynamic buckling (snaking motion) analysis of a rotating drilling string laterally constrained in a horizontal well is presented, through a group of fourth-order nonlinear partial differential equations. The analytical approximate solutions to the static and dynamic buckling are obtained via combining Newton linearization with Harmonic Balance Method, and Galerkin's method, respectively. On the basis of the analytical approximate solutions, static post-buckling deformation, critical dynamic buckling load, and two different kinds of snaking motions (i.e. the pipe moves up and down around its static buckling configuration; the pipe moves from one side of the wellbore to the other side) are investigated. Accuracy of the approximate solutions is verified by comparing with numerical solutions. Theoretical results are useful for practical design applications related to calculation of buckling loads and selection of bottom hole-assembly (BHA) elements and pipe rotational speeds. What's more, the solving procedures of accurate analytical approximate solutions to the snaking motions yield rapid convergence with respect to exact numeric solutions. The present results are valid for small as well as large oscillation amplitudes. [ABSTRACT FROM AUTHOR]

Highlights: [•] A topochemical reaction method was studied for shale oil and gas extraction. [•] The mechanism of topochemical reaction was proposed and well demonstrated. [•] The oxygen is a crucial factor for this chemical heat-enhanced procedure. [•] There were five distinct reaction identified in entire process. [ABSTRACT FROM AUTHOR]

A modified cerium seal PEO pretreatment was developed on 2A14 alloy and combined with an epoxy coating (EP) to form a duplex coating system. The PEO coating was effectively sealed by cerium hydroxides and oxides, and also acted as a controlled release vessel for the cerium salt corrosion inhibitor, and significantly improved the adhesive strength of the EP. The results of electrochemical tests and immersion experiments show that the coating system pretreated with the modified cerium seal PEO exhibits excellent long-term corrosion resistance and active protection. This is attributed to the physical barrier of insoluble cerium-based compounds and sensitive pH-responsive deposition. • A modified Ce-sealed PEO pretreatment was developed for use as an intermediate layer in coating systems. • The PEO coating is effectively sealed and used as a container to store Ce salt inhibitors. • Modified Ce-sealed PEO pretreatment significantly improves the physical barrier effect of the overall coating system. • Ce-sealed PEO coating systems provide effective active corrosion protection for substrates in the event of damage. [ABSTRACT FROM AUTHOR]

• Basalt and carbon fiber in oil well cement were considered. • Mechanical properties of cement was evaluated by compressive and splitting tensile testing. • SEM analysis shows that the basalt and carbon fiber arrest cracking at different levels. In order to study the hybrid effect of basalt fiber and carbon fiber on the mechanical properties of oil well cement, the response surface design method was adopted to optimize the mixed content of basalt fiber and carbon fiber in oil well cement. With the help of X-ray diffraction (XRD) and scanning electron microscope (SEM) characterization, the crushed samples of oil well cement mixed basalt fiber and carbon fiber was micro-analyzed, and the enhancement mechanism of basalt fiber and carbon fiber on the compressive strength and splitting tensile strength of oil well cement was explored. The research results showed that basalt fiber and carbon fiber mixed can significantly increase the compressive strength and splitting tensile strength of oil well cement. Compared with oil well cement without fiber, the maximum compressive strength of oil well cement with mixed fiber for the curing time of 3 days, 7 days and 28 days was increased by 48.94%, 24.05% and 25.68%, respectively. The maximum splitting tensile strength of oil well cement with mixed fiber for curing time of 3 days, 7 days and 28 days was increased by 151.14%, 68.01% and 46.28%, respectively. Moreover, addition of 0.55 wt% basalt fibers and 0.09 wt% carbon fibers in oil well cement leads to more ductile behavior with higher peak compressive strength after 3 days curing time. Addition of 0.29 wt% basalt fibers and 0.32 wt% carbon fibers in oil well cement leads to more ductile behavior with higher peak splitting tensile strength after 3 days curing time. The addition of carbon fiber and basalt fiber does not change the hydrates of oil well cement after oil well cement hydration. The improvement of the mechanical properties of fiber-reinforced oil well cement mainly depends on the fiber bridging, crack deflection and fiber pulling out or breaking. Based on the theory of linear elastic fracture mechanics, a fiber oil well cement crack resistance model was constructed. The results of this study provide a certain reference for the application of fiber-reinforced oil well cement with requirements for tensile and crack resistance in oil and gas well cementing projects. [ABSTRACT FROM AUTHOR]

This study investigated the effect of short carbon fiber (C f) on the oxidation behavior of ZrB 2 –SiC composites with fiber volume fractions in the range of 0–20%. Precisely, highly dense composite compacts were manufactured by hot-press process at 2000 °C and 30 MPa for 60min. The addition of C f increased the relative density of sintered composite The oxidation treatment at 1600 °C in air tube furnace for 0.5 h revealed that oxidation rate of ZrB 2 –SiC-C f composites decreased from 292.4 μm/h to 77.6 μm/h (almost 73.5% decline), when the content of C f changed from 0 to 20%. Moreover, C f played important roles in blocking and deflecting oxygen diffusion during the oxidation process, which provided a local reduction environment of oxidation products. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond compact (PDC) cutters are used widely for mining and drilling in soft to medium hard rock formations. During drilling in very hard and strong rock formations, the rapid wear of the polycrystalline diamond layer results in a low service life of drilling bits. To improve the performance of PDC cutters, we adopted a high-temperature, high-pressure (HTHP) sintering method (5.5–6.0 GPa and 1350–1500 °C) in the current research by adding a certain amount of graphene to raw materials, and we successfully prepared a new type of high-performance diamond composite PDC-G (graphene was added to PDC). We investigated the microstructure, residual stress, hardness, wear resistance, thermal conductivity, and electrical conductivity of the as-synthesized PDC-G. Compared with PDC without graphene, the hardness and wear resistance of PDC-G with 0.1 wt% graphene addition were enhanced by 75% and 33%, respectively. Moreover, the electrical conductivity of PDC prepared by graphene strengthening was improved 42-fold. The strengthening mechanism of PDC-G mainly occurred as a result of the lubricating effect of graphene between diamond particles; hence, a more dense and uniform structure was formed in the polycrystalline diamond layer after HTHP sintering. [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]

• Factors affecting methane hydrate decomposition under microwave heating are studied. • Hydrate decomposition time decreased with increase in microwave power. • Heating cycle invovled 5 min of microwave stimulation and 1 min of no stimulation. • This intermittent microwave heating improved the efficiency ratio by 59.32%. Microwave stimulation is a new method for natural gas hydrate exploitation. In this study, methane hydrate was synthesized in quartz sand with a particle size of 106–150 μm, and the decomposition characteristics were investigated using continuous and intermittent microwave heating. During the initial stage of continuous microwave heating, methane hydrate decomposed immediately due to microwave stimulation. Subsequently, due to a decrease in microwave penetration depth, microwaves did not affect the areas further away from the microwave source and macroscopic heat transfer became the main heat source for hydrate decomposition. The microwave power used during the study ranged from 200 W to 500 W. The results indicated that hydrate decomposition time decreased as power increased, and the average gas production rate increased at the same time. However, the energy efficiency ratio did not vary with the microwave power. The maximum energy efficiency ratio was 1.320 at a microwave power of 400 W under continuous microwave heating. Compared with continuous microwave heating, intermittent microwave heating improved the efficiency ratio by 59.32 %, with a heating cycle involving microwave stimulation for 5 min (Microwave ON time) and no stimulation for 1 min (Microwave OFF period). As microwaves provide heat for hydrate decomposition, a high-speed gas production can be obtained. Heat reservoirs were utilized to maintain hydrate decomposition during the OFF period, which also resulted in energy saving. Although intermittent microwave heating reduced the average gas production rate slightly, it improved the energy efficiency significantly. Therefore, the number of heating cycles and microwave heating periods should be carefully considered to obtain high hydrate exploitation efficiency. Intermittent microwave heating is recommended for hydrate exploitation to improve extraction efficiency and save energy. [ABSTRACT FROM AUTHOR]

• Reinforcing oil well cement using a hybrid of nano-silica (NS) and nano-hexagonal boron nitride (h-BN). • NS is a cement thickener, h-BN has little effect on rheology properties. • A hybrid of NS and h-BN can significantly improve the mechanical properties in the early stages. • The modification mechanisms of hybrid NS and h-BN in cement are discussed. The purpose of this study was to investigate the effect of the content of hybrid nano-silica (NS) and nano-hexagonal boron nitride (h-BN) on the rheological properties and early mechanical strength of oil-well cement using response surface methodology (RSM). Based on the microstructures revealed by X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy, the modification mechanism of cement mixed with a hybrid of NS and h-BN in the early stage of hydration was studied. It was found that the rheological properties of fresh oil-well cement slurries with added NS and h-BN conformed to those of Bingham fluids. An increase in NS content worsened the fluidity of the cement, whereas the h-BN content did not affect its fluidity. The early compressive, flexural, and splitting tensile strengths at the end of the 3-day curing time increased by 12.33 MPa/47.24 %, 1.88 MPa/29.01 % and 1.24 MPa/53.22 %, respectively. The pozzolanic reaction of NS begins to occur in the early stages of cement hydration. The synergistic effect of the added NS and h-BN increased the density of the early hydration product of the cement. The h-BN mainly enabled the bridging, filling, and crack-resistant effects in the early oil-well cement. [ABSTRACT FROM AUTHOR]

Following the discovery of high-entropy alloys, high-entropy oxides have gained considerable interest due to their unconventional structural characteristics and versatile functional properties for promising applications. Via synchrotron radial x-ray diffraction in a diamond anvil cell, the mechanical strength and deformation behavior of a typic high-entropy oxide (Mg,Co,Ni,Cu,Zn)O with a rock-salt structure under extreme compression has been investigated in situ. This compound in a polycrystalline state shows a large elastic anisotropy at the initial compression stage and then gradually becomes isotropic at around 21.4 GPa, similar with the behavior of MgO. Based on the lattice strain order conversion and texture evolution under compression, a dominant slip system transition from {100}<011> to {110}<1–10> is proposed in this high-entropy oxide. This work deepens our understanding on the role of chemical disorder in the mechanical properties of entropy-stabilized oxides, which would be indispensable to the design of advanced structural ceramics with optimal strength-to-ductility ratio. [Display omitted] [ABSTRACT FROM AUTHOR]

A WC-bronze-based matrix and an impregnated diamond composite (IDC) reinforced by nano-NbC were fabricated through powder metallurgy to improve the lifespan of drilling bits. The density, hardness, bending strength, and wear resistance of the matrix and IDC were studied. The microscopic features were examined by scanning electron microscopy and X-ray diffraction. The results showed that when the nano-NbC content was 5 wt%, the hardness and bending strength of matrix were 43 HRC and 1085 MPa, increased by 26% and 28%, respectively. The IDC exhibited higher bending strength and the highest wear resistance, and the grinding ratio was 1150, which was approximately 2.4 times higher than that of IDC without the addition of nano-NbC. The indoor drilling tests showed that the drilling bit life expectancy was 78 m, improved by 70%. The enhanced compactness characteristics, grain refinement, and dispersion strengthening were the main reasons behind the enhanced properties. [Display omitted] • Nano-NbC reinforced WC-bronze-based impregnated diamond composites were fabricated. • The composites reinforced by nano-NbC exhibited better mechanical properties. • The life expectancy of drilling bits improved obviously via nano-NbC addition. • The microstructures and phase composition of composites were analysed in detail. • The strengthening mechanisms of nano-NbC were clarified. [ABSTRACT FROM AUTHOR]

The increases in power density and energy consumption of 5G telecommunication base stations make operation reliability and energy-efficiency more important. In this paper, a novel type of rack-level hybrid cooling system which combines a thermosyphon loop with a mechanical refrigeration loop was developed and applied in two parallel cabinets installed different operating powers of the communication equipment. Its performance was tested on-site in a real 5G telecommunication base station in transitional season at Wuhan city, China. Thermal safety and energy consumption under the normal and urgent operation modes were evaluated. The results showed that under the normal daily operation mode 1, communication equipment can be cooled effectively, but the power usage effectiveness value reached 1.59. Under the urgent mode 7, communication equipment can maintain safe operation for over 20 min. In view of this, five novel energy-saving operation modes 2–6 were proposed and tested. The cooling effect and energy consumption under different modes were analyzed and compared. Under the thermosyphon mode 6, the cooling system can only meet the cooling demand for one side of the cabinet when the outdoor temperature is around 20 °C. Compared to mode 1, mode 5 was recommended due to the 7–9 °C lower operating temperature and 27.3% decrease of energy consumption. • A novel hybrid cooling system was developed. • The operating thermal performance and energy consumption of the system applied in a real 5G TBS were investigated. • The performance of the cooling system was compared and analyzed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A TiO 2 coating on SCF is using for designing an interface to separated it from Al 4 C 3. • Interface is stable at the high temperature exposure by self-regulation reaction. • Evolution of fracture mode is dependent on the coating thickness. To better develop the potential properties of the short carbon fiber reinforced aluminum alloy 2024 composite in high-temperature environments, TiO 2 coating was introduced. The composites were fabricated through powder metallurgy and extrusion. The effects on the tensile strength and elongation ratio of composites were investigated by the coating thickness and testing temperature. The yield strength of AA2024 was improved by the short carbon fiber addition at all testing temperatures, and the ultimate tensile strength was strengthened by short carbon fiber with proper coating thickness. Short carbon fiber with 100 nm thickness can improve both tensile strength and elongation ratio of the composites compared with that with uncoated short carbon fiber. The interphase component and fracture surfaces were investigated, and the self-regulating mechanism and fracture mechanism were discussed. The interfacial products are mainly composed of TiO 2 , MgO, and TiC, resulting in a self-regulation interface, that transforms the fracture mechanism from fiber shear failure to fiber pulled-out. [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]