Diamond Composites Research Articles

Formation and Performance of Diamond (111)/Cu Interface from First-Principles Calculation

The interface formation and properties of composite materials are very important for the preparation of composite materials, and the bonding state and charge transfer between atoms in the interface have a particularly significant effect on the interface formation. In this work, the first-principles calculation method was used to study the adsorption behavior and molecular dynamics of copper atoms on the (111) surface of H-terminated diamond, and the adsorption energy and adhesion work of Cu atoms were calculated. The results show that the adsorption of copper atoms is not sensitive to the diamond (111) surface, the adsorption work is very small at the four high symmetry positions, and the adhesion work is the largest at the T4 position and is 0.6106 J/m2. Furthermore, according to the electron localization function (ELF) analysis, there is no compound formation between Cu and H atoms; only a small amount of charge transfer exists, which belongs to physical adsorption. The diamond–copper interface formed by the growth of adsorption sites is a metastable structure without energy stability. This work provides an important theoretical reference for understanding the formation mechanism of copper-based diamond composites.

Effect of nickel-plated graphite on microstructure and properties of matrix for Fe-based diamond tools

Nickel-plated graphite particles and unmodified graphite particles with different contents were added to the Fe-based diamond composites. The basic properties of those specimens were measured, including relative density, hardness, bending strength, abrasion ratio and holding force coefficient. And also, SEM, XRD and EDS were used to carry out microstructure characterization, phase analysis and element distribution of these specimens. The results show that nickel plating effectively improves the surface wettability of graphite particles. And it is determined that an element diffusion zone is formed on the transition interface between the nickel-plated graphite and the matrix materials, effectively enhancing the interfacial bonding strength. Also, the pores and cracks in the matrix generated by adding the graphite particles are reduced after nickel plating. Thus, the loss of basic properties of the specimens is restrained. But it is found the higher the graphite content is, the weaker the positive effect of nickel plating is. In addition, it is revealed that nickel plating plays a conducive part in the formation of graphite lubricants on the working surface, and nickel-plated graphites can slow down the thermal corrosion of the diamond particles inside the high-temperature sintered specimens.

PHASE COMPOSITION AND STRUCTURE OF CARBONADO DIAMOND POLYCRYSTALS AFTER LASER TREATMENT

Synthetic polycrystalline diamonds are mainly composed of inclusions of graphite and a catalyst metal (Me). The presence of these inclusions and their amount significantly affects many of the physical and mechanical properties of diamonds and, ultimately, the performance of diamonds in a tool. Therefore, the study of the quantitative phase composition of synthetic diamonds (SD) is very important. The paper considers the change in the period of the crystal lattice of SD polycrystals and nickel (Ni) impurities after exposure to laser radiation with a wavelength of 1.06 μm. The time of laser irradiation varied from 3 to 60 sec. To determine the crystal lattice period of SA polycrystals, powders with a grain size of 315/250, 200/160, and 100/80 μm were used. A decrease in the crystal lattice period of the studied diamonds was found. We assume that this is due to the diffusion process of ordering of the diamond lattice, when the metal-enriched sections of the diamond-metal-catalyst system are locally heated. The results obtained will make it possible to understand the physical mechanism for increasing the strength of the studied crystals after exposure to laser beams under certain conditions.

Effect of basalt fiber on the thermal conductivity and wear resistance of sintered WC-based diamond composites

Tungsten carbide (WC)-based matrix powder, basalt fiber (BF) and diamond were used as raw materials to prepare WC-based diamond composites by hot-press sintering, and then the sintered samples were tested for thermal conductivity and wear resistance. The surface, fracture surface and wear surface of the samples were observed using scanning electron microscope (SEM), x-ray diffraction (XRD) and energy disperse spectroscopy (EDS). The results showed that the addition of BF significantly weakened the wear resistance of the diamond composites, and the abrasive ratio of the samples was reduced by 34.4% at 5% mass fraction BF addition compared to the samples without BF addition. At the same time, the addition of a moderate amount of BF increased the relative density of the matrix and reduced the number of pores in the matrix material. When 1 wt% BF was added, the WC-based diamond composite had the highest thermal conductivity, reducing the risk of possible thermal damage to the diamond.

Numerical investigations on rock breaking mechanism and parameter influence of torsional percussive drilling with a single PDC cutter

Torsional percussive drilling tool was designed to reduce the risk of stick-slip and improve drilling efficiency, but there are few studies on the influence of torsional impact parameters, including amplitude, frequency, waveform, on the rate of penetration (ROP) while drilling the hard rock. The design of the torsional percussive drilling tool was proposed, and the mathematical model of torsion hammer movement was developed, the Riedel-Hiermaier-Thoma (RHT) rock dynamic material model was applied to analyze the rock-breaking process of the tool. A numerical model of hard rock cutting with a single polycrystalline diamond composite (PDC) bit cutter was established, the influences of amplitude, frequency, time parameters, and waveforms on the penetration depth of the PDC bit cutter were analyzed in the process of torsional percussive drilling. The results showed that the numerical simulation results were in good agreement with the indoor test results, which verified the correctness of the numerical simulation. Compared with conventional drilling, the penetration depth of torsional percussive drilling was increased by 20.0%, and the cutting debris particles were smaller, which was conducive to improving ROP and reducing stick-slip vibration of the bit. With the increase of the peak value of torsional percussive amplitude, the penetration depth of the cutter first increased and then decreased. When the ratio of torsional impact load to axial static load was 1.0, the penetration depth of the drilling cutter reached a maximum. When the torsional impact frequency was 40 Hz–100 Hz, the penetration depth decreased with the increase of the frequency, but the diameter of cuttings became smaller and smaller, which was conducive to cleaning the wellbore with drilling fluid. The latter has the highest rock-breaking efficiency compared with triangular, sine, and rectangular waves. Finally, suggestions are given on how to adjust these parameters by adjusting engineering parameters and tool structure parameters to optimize the efficiency of the torsional percussive drilling tool.

Role of interface on irradiation damage of Cu−diamond composites using classical molecular dynamics simulations

Cu−diamond composites have been proposed as a candidate thermal management material for spacecraft electronics. Nevertheless, irradiation effects on the composites remain poorly understood at present. Here we focus on investigating the influence of Cu−diamond interfaces (CDIs) on energetic displacement cascades using atomistic simulations. Results show that a primary knock-on atom of Cu (PKA-Cu) can induce more significant damage than a PKA-C. Under almost all circumstances, the statistically averaged fraction of surviving interstitials is not only lower than that of vacancies but also no more than 1. Because of the unique nature in the mobility and interactions with CDIs, Cu interstitials exhibit the lowest concentration among all defects in most cases. The high residual rate of displaced defects in diamond makes it relatively difficult to heal. The structural damage is mainly manifested in a short-range disorder of diamond and a long-range disorder of Cu after irradiation. At elevated temperatures, the atomic displacement region may form compact chain-like defects to restrain lattice loosening. Despite the above, CDIs could act as effective sinks to facilitate the recombination and/or annihilation of irradiation-induced defects in all scenarios. This study provides an important insight into the understanding of the microscopic evolution of irradiation defects for the composites.

Polarization Transfer from Optically Pumped Ensembles of N- V Centers to Multinuclear Spin Baths

Nitrogen-vacancy (N-$V$) diamonds have attracted keen interest for nanoscale sensing and spin manipulation. In particular, the nonequilibrium electron spin polarization after optical excitation of single N-$V$ centers has successfully been transferred to nuclear spin baths in the surrounding of defects. However, these experiments need to be extended to N-$V$ ensembles that have promising practical applications in the hyperpolarization of bulk sample volumes for NMR signal enhancement. Here, we use a dense, shallow ensemble of N-$V$ centers to demonstrate polarization transfer to nuclear spins in a well-defined composite diamond sample system. This allows us to address three different types of nuclear spins in different positions with respect to the N-$V$ polarization source: from the close proximity of ${}^{13}\mathrm{C}$ inside the diamond lattice to the self-assembled molecular system consisting of ${}^{1}\mathrm{H}$ and ${}^{19}\mathrm{F}$ spins outside the diamond and over multiple interfaces. We show that ensemble N-$V$ experiments face problems different from single N-$V$ experiments. In particular, using spinlock pulses, the inhomogeneously broadened electron spin resonance line of the N-$V$ ensemble limits the minimal resonance linewidth with which the transfer protocol can occur. Furthermore, we compare the N-$V$ spin-polarization losses and polarization transfer rates to the different nuclear baths and discuss the role of spin diffusion as detrimentally affecting the direct observation of nuclear polarization buildup within the detection volume of nanoscale N-$V$-NMR experiments.

Morphology and defect-impurity composition of the Zapolyarnaya pipe diamonds

A representative collection of Zapolyarnaya pipe diamonds of the first batch of industrial production was studied by methods of morphological analysis, IR, FL, and EPR. Diamonds belong to the medium-low-nitrogen, they are the closest to the Daldyn-Alakit area diamonds in terms of their composition and ratios of impurity centers. Typomorphic features for diamonds of Zapolyarnaya pipe are the predominance of curved dodecahedroids, a significant degree of development of the processes of dissolution, etching and plastic deformation, close to the maximum content of IR defects B2, the minimum content of hydrogen, as well as a wide spread of paramagnetic centers W7.

Cerium-doped gadolinium-scandium-aluminum garnet powders: synthesis and use in X-ray luminescent diamond composites

Powders of single-phase solid solutions based on cerium-doped gadolinium-scandium-aluminum garnet were synthesized by coprecipitation from aqueous solutions followed by annealing at 1600 °C. The solubility limit of cerium in gadolinium-scandium-aluminum garnet was determined by X-ray powder diffraction and scanning electron microscopy. It has been demonstrated that the solubility limit of cerium depends not only on the concentration of scandium in the solid solution but also on the fraction of Sc3+ cations in the dodecahedral and octahedral positions of the garnet crystal lattice. Based on the X-ray luminescence spectra of Ce3+ (∼575 nm, 5d→4f transition) in single-phase samples, the composition (Gd2.73Ce0.02Sc0.5Al4.75O12) with the highest X-ray luminescence was determined. A diamond composite “Diamond-GSAG:Ce” with Gd2.73Ce0.02Sc0.5Al4.75O12 particles has been fabricated, which exhibits intense yellow X-ray luminescence, that is visible to the eye. The investigated class of composites is promising for applications in stable detectors and visualizers of high-intensity X-ray radiation in synchrotrons and free-electron lasers.

Effect of diamond layer thickness on tool wear of polycrystalline diamond composites

Well-sintered polycrystalline diamond composite (PDC) is a hard material obtained from WC–Co substrate and diamond using a high-temperature high-pressure (HPHT) process. PDC has immense potential in aerospace, automobile, oil and gas, and tool manufacturing industries. In this study, PDC was formed by sintering diamond powder (average crystal size = 10 μm) and WC–15 wt% Co substrates at HPHT and the diamond layer thickness is 1.2 mm. The thicknesses of the diamond layer on the PDC cutter were varied, and their effects on the PDC cutter wear were examined. Wear experiments and hardness tests were conducted on samples with varying diamond layer thicknesses. They were characterized using scanning electron microscopy, X-ray diffraction, and Hall effect, and these revealed that (1) hardness of the PDC slightly increased with an increase in the thickness of the diamond layer, and (2) the PDC tool's life could be improved by appropriately increasing the thickness of the diamond layer. The findings of this study provide insights for future studies on designing and optimizing the properties of the PDC.

Molecular simulation and curing-forming of ultraviolet/thermal-sensitive resin diamond composites for microstructured polishing tool

Molecular simulation and curing-forming of ultraviolet/thermal-sensitive resin diamond composites for microstructured polishing tool

Influence of Diamond Parameters on Microstructure and Properties of Copper-Based Diamond Composites Manufactured by Fused Deposition Modeling and Sintering (Fdms)

Influence of Diamond Parameters on Microstructure and Properties of Copper-Based Diamond Composites Manufactured by Fused Deposition Modeling and Sintering (Fdms)

Influence of Diamond Parameters on Microstructure and Properties of Copper-Based Diamond Composites Fabricated by Fused Deposition Modeling (Fdms)

Influence of Diamond Parameters on Microstructure and Properties of Copper-Based Diamond Composites Fabricated by Fused Deposition Modeling (Fdms)

Nanoengineered Polycrystalline Diamond Composites with Advanced Wear Resistance and Thermal Stability.

Fluorinated grains of micrometer size diamonds overcoated with nanodiamond particles were used as a feedstock for high-pressure, high-temperature synthesis of new polycrystalline diamond composites (PDCs). Such a nanoengineering approach for exploring the interfacial chemistry of diamonds has been implemented in two methods: (i) infiltration of Co from the WC-Co layer into a fluorinated diamond layer with added Al and (ii) sintering of fluorinated micro- and nanosize diamond homogeneous mixtures with added Al and Co. We found that unlike commercial PDCs made with a metallic Co binder for drilling tools, the binding phase in new composites comprises only intermetallic compound AlCo or ternary carbide AlCo3C. As a result, composites made from homogeneous mixtures showed greater promise for improving the thermal stability, while the two-layer experimental composites during granite turning tests have demonstrated >2 times higher wear resistance than leached commercial PDCs.

A Dual Approach of an Oil-Membrane Composite and Boron-Doped Diamond Electrode to Mitigate Biofluid Interferences.

Electrochemical biosensors promise a simple method to measure analytes for both point-of-care diagnostics and continuous, wearable biomarker monitors. In a liquid environment, detecting the analyte of interest must compete with other solutes that impact the background current, such as redox-active molecules, conductivity changes in the biofluid, water electrolysis, and electrode fouling. Multiple methods exist to overcome a few of these challenges, but not a comprehensive solution. Presented here is a combined boron-doped diamond electrode and oil–membrane protection approach that broadly mitigates the impact of biofluid interferents without a biorecognition element. The oil–membrane blocks the majority of interferents in biofluids that are hydrophilic while permitting passage of important hydrophobic analytes such as hormones and drugs. The boron-doped diamond then suppresses water electrolysis current and maintains peak electrochemical performance due to the foulant-mitigation benefits of the oil–membrane protection. Results show up to a 365-fold reduction in detection limits using the boron-doped diamond electrode material alone compared with traditional gold in the buffer. Combining the boron-doped diamond material with the oil–membrane protection scheme maintained these detection limits while exposed to human serum for 18 h.

A perspective on diamond composites and their electrochemical applications

Diamond composites have gained increasing interests because of their outstanding properties (e.g. robust mechanical properties, high conductivity and activity, good chemical and thermal stability, as well as excellent electrochemical properties) and their promising applications in a wide range of different fields. In this perspective, recent advances on the synthesis of diamond composites are summarized together with state-of-the-art progress in their electrochemical applications. Metal-diamond, alloy–diamond, oxide/carbide/nitride-diamond, sp2 carbon/sp3 diamond, and organic-diamond composites are covered in the context of enhancing their performance of electrocatalysis, sensing, water treatment, supercapacitor, and photoelectrochemistry. Ongoing challenges and future perspectives of the synthesis and electrochemical applications of diamond composites are outlined and discussed.

Bioinspired diamond composites and their dynamic shock performance

The design of high-strength and high-toughness materials that can sustain high shock-wave loadings is crucial for both armor and civil applications. We propose a bioinspired diamond composite that mimics the brick-and-mortar arrangement of nacre from mollusk shells and evaluate its performance for different diamond brick contents using lattice-spring model. In this work, we present a systematic investigation elucidating the effects of volume fraction of diamond brick, on the shock compression response of bioinspired diamond composites. By comparing the nacre-like diamond composite with traditional diamond composite, it was found that the nacre-like diamond composite can reduce damage degree in diamond composite, and improve dynamic strength of diamond composite. More importantly, the damage evolution analysis of the impacted nacre-like diamond composite indicated that there is large-scale crack deflection, which is only cause slight damage to the diamond brick. The obtained numerical results may provide valuable insights into the preparation of superhard composites for numerous engineering applications.

Preparation and characterization of coated abrasives with domed pyramid thermosetting polyurethane/epoxy/diamond composites by roller embossing: Wear performance

To improve the durability and self-sharpening ability of traditional coated abrasives for efficient automated manufacturing, structured patterns and super hard materials were utilized for the fabrication of coated tools. In this study, the polymer matrix was synthesized by 50 wt% polyurethane and 50 wt% epoxy, the tensile strength and elongation at break is 53.6 MPa and 36.8%, respectively. Then the thermosetting PU/EP diamond composites were prepared by roller embossing successfully. The wear performance tests of the composites were performed with the difficult-to-machine material 304 stainless steel. The maximum height of the summit of the 400# and 800# diamond composite grits declined by 13.6% and 8.2%, respectively after wear tests. Also, the composite grits could retain material removal ability and renew themselves due to the domed pyramid structure. The surface roughness of the workpiece decreased to 0.405 μm by 80% after the first wear test for 400# diamond and eventually approached 0.036 μm. The improvement on the surface of the workpiece could be accomplished in no more than 90 s.

A comparison of traditional orthodontic polishing systems with composite polishing systems following orthodontic debonding

IntroductionAt the completion of treatment, the orthodontic practitioner’s goal is to effectively remove all traces of adhesive and return enamel to its initial state. With the advent of new polishing systems being released each year, there may be one product that is superior to others. AimThe purpose of this study is to determine the efficacy of new polishing systems (in the last 5–10 years) used in general dentistry on enamel surface roughness following debond utilizing profilometery and scanning electron microscopy and compare them to established orthodontic polishing systems results. MethodsFifty-two mandibular incisors were randomly assigned to one of five test groups (N = 10) and two incisors (untreated enamel) were used for profilometer and scanning electron microscopy analysis at the end of testing. After bracket removal, the teeth were polished using traditional polishing products (Komet H48L bur, Reliance ‘Renew’ point) and newer polishing products (Coltene Spiral Composite Plus Polisher, Ultradent Jiffy Composite Polishing Spiral or 3M Sof-Lex™ Diamond Polishing System). The results were evaluated using a profilometer and scanning electron microscopy images. ResultsThe results of a one-way analysis of variance (ANOVA) determined that the mean change in enamel surface roughness was not statistically different both in the traditional and novel groups. Tukey’s Honestly Significant Difference (HSD) test found that there was no statistically significant difference in the change in enamel surface roughness between instrument groups. ConclusionsThere was no statistically significant difference in enamel surface roughness after polishing between traditional orthodontic polishing systems and the selected novel polishing systems. SEM analysis revealed similar findings. This supports previous research suggesting that a wide variety of polishing systems or none at all, may be used to restore enamel smoothness after removal of orthodontic appliances.

Ultra-precision grinding of 4H-SiC wafer by PAV/PF composite sol-gel diamond wheel

To eliminate the deep scratches on the 4H-SiC wafer surface in the grinding process, a PVA/PF composite sol-gel diamond wheel was proposed. Diamond and fillers are sheared and dispersed in the polyvinyl alcohol-phenolic resin composite sol glue, repeatedly frozen at a low temperature of −20°C to gel, then 180°C sintering to obtain the diamond wheel. Study shows that the molecular chain of polyvinyl alcohol-phenolic resin is physically cross-linked to form gel under low-temperature conditions. Tested by mechanical property testing machines, microhardness tester, and SEM. The results show that micromorphology is more uniform, the strength of the sol-gel diamond wheel is higher, the hardness uniformity is better than that of the hot pressing diamond wheel. Grinding experiments of 4H-SiC wafer were carried out with the prepared sol-gel diamond wheel. The influence of grinding speed, feed rate, and grinding depth on the surface roughness was investigated. The results showed that by using the sol-gel diamond wheel, the surface quality of 4H-SiC wafer with an average surface roughness Ra 6.42 nm was obtained under grinding wheel speed 7000 r/min, grinding feed rate 6 µm/min, and grinding depth 15 µm, the surface quality was better than that of using hot pressing diamond wheel.