Nano-sized Diamond Research Articles

Bejan number and entropy generation analysis of unsteady MHD non-Newtonian micropolar squeezed trihybrid nanofluid flow

Microscopic particles have incredible thermal conductivity making them essential in nanotechnology, electronics, materials science and heat exchangers. For suitable optimization of thermic engineering structure, thermal transportation has to increased but minimized the entropy generation. One of the basic reasons for the developing interest in tri hybrid nanofluids is its unique ability to increase thermal characteristics, that is very useful in numerous heat exchangers. Three distinct nanosized particles, namely silver, gold and diamond are considered with water as a base liquid. A set of dimensionless ODE’s are solved numerically by Bvp4c technique. The results of prominent parameters are elaborated and graphs are presented for velocity profile, entropy profile, Bejan and temperature profiles. Moreover, present result is compared with the literature and found a good agreement. It is observed that the Bejan number and entropy generation shows the opposite behavior for higher values of Casson and magnetic parameter. Further, it is noted that at the lower disk, squeezed Reynold number increases the skin friction coefficient and opposite trend noted against the upper disk. Temperature profile shows increasing trend for higher values of Eckert number. It is also noted that both velocities, temperature, entropy and Bejan number profiles for tri-hybrid nanofluid flow attains maximum values as compared to bi-hybrid and mono nanoparticles.

Implementation of probe rheology simulation technique in atomistically detailed molecular dynamics simulations

The probe rheology simulation technique is a technique for measuring the viscosity of a fluid by measuring the motion of an inserted probe particle. This approach has the benefit of greater potential accuracy at a lower computational cost than other conventional simulation techniques used for the calculation of mechanical properties, such as the Green-Kubo approach and nonequilibrium molecular dynamics simulations, and the potential to allow for sampling local variations of properties. This approach is implemented and demonstrated for atomistically detailed models. The viscosity of four different simple Newtonian liquids is calculated from both the Brownian motion (passive mode) and the forced motion (active mode) of an embedded probe particle. The probe particle is loosely modeled as a nano-sized diamond particle: a rough sphere cut out of an FCC lattice made of carbon atoms. The viscosities obtained from the motion of the probe particle are compared with those obtained from the periodic perturbation method, and good agreement between the two sets of values is observed once the probe-fluid interaction strength (i.e., in the pair-wise Lennard-Jones interaction) is two times higher than their original values, and the artificial hydrodynamic interactions between the probe particle and its periodic images are accounted for. The success of the proposed model opens new opportunities for applying such a technique in the rheological characterization of local mechanical properties in atomistically detailed molecular dynamics simulations, which can be directly compared with or help guide experiments of similar nature.

Revealing impurity evolution in silicon-doped diamond film via thermal oxidation

The incorporation of impurity atoms into diamonds has been an important issue for the application in the area of electronics, opto-electrics, and quantum optics with color centers. To date, it remains a challenge to explore the impurity distribution in diamond films owing to the low incorporation efficiency. In this work, Si-doped diamond films were deposited in microwave CVD system. Thermal oxidation was employed to selectively etch the non-diamond phase to study the impurity distribution and evolution. For micro-/nano-sized diamond films, the micro-sized grains remain intact, while the diamond nanocrystals are oxidized into porous oxides. The diamond needles exhibit strong silicon-vacancy center optical emission at 738 nm, implying that the Si atoms are incorporated into the lattice. Detailed microstructure characterizations reveal that the porous oxides are crystallized in amorphous state, consisting of silicon, oxygen, and carbon elements. Such abundance of Si in the amorphous porous oxides suggests that the Si atoms segregate at the grain boundaries. Therefore, this work provides a new path to reveal the impurity distribution along diamond crystalline defects. Moreover, the in-situ formed silicon oxide can act as an anti-reflection coating to enhance the optical emission of color centers, which is important for their optical applications.

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.

Synthesis and characterization of polyaniline/nanodiamond hybrid nanostructures with various morphologies to enhance the corrosion protection performance of epoxy coating

In this study, nano-sized diamond particles (ND) were functionalized in two consecutive stages. First, dry thermal oxidation was employed to obtain carboxylated ND. In the next step, carboxylated ND was properly surface modified through wet chemistry to acquire aminated-ND (ND-NH2). Then, polyaniline (PANI) was synthesized in the presence of aminated-ND particles at a broad concentration from 1 wt% to 70 wt% to obtain PANI/ND hybrid nanostructures. The chemical structure, morphology, and thermal stability of nanoparticles were comprehensively characterized by different techniques such as FT-IR, UV–visible, TGA, XRD, FESEM, and TEM. It was observed that the morphology of PANI/ND nanostructures varied from nanotube at low concentration of ND to aggregated NDs covered by PANI at high concentration of NDs, namely at 70 wt%. Eventually, the hybrid PANI/ND nanoparticles were incorporated into epoxy coatings in order to improve the corrosion protection performance. The anti-corrosion properties of the coatings were examined carefully by electrochemical impedance spectroscopy (EIS). The results indicated that the morphology of PANI/ND nanohybrid structure dominated greatly the corrosion protection behavior of epoxy coating. Accordingly, it was revealed that PANI/ND5%-epoxy nanocomposite showed improved and synergistic corrosion resistance compared to neat epoxy, ND-epoxy, PANI-epoxy and even PANI/ND50%-epoxy nanocomposites due to better anodic protection as well as greater barrier performance.

Plasma & Microwaves as Greener Options for Nanodiamond Purification: Insight Into Cytocompatibility.

The potential biomedical applications of nanodiamond have been considered over the last few decades. However, there is still uncertainty regarding the extent to which the surface characteristics of this material can influence potential applications. The present study investigated the effects of surface characteristics alongside the prospective of improving nanodiamond production using cold plasma and microwave technologies for the surface tailoring of the nanocarbons. Numerous approaches were applied to purify, refine and modify a group of nanosized diamonds at each step of their production cycle: from the detonation soot as the initial raw material to already certified samples. The degree of surface changes were deliberately performed slowly and kept at different non-diamond carbon presence stages, non-carbon elemental content, and amount converted superficial moieties. In total, 21 treatment procedures and 35 types of nanosize diamond products were investigated. In addition cultures of human fibroblast cells showed enhanced viability in the presence of many of the processed nanodiamonds, indicating the potential for dermal applications of these remarkable nanomaterials.

Simple and Convenient Interface Modification by Nanosized Diamond for Carbon Based All-Inorganic CsPbIBr2 Solar Cells

Simple and Convenient Interface Modification by Nanosized Diamond for Carbon Based All-Inorganic CsPbIBr₂ Solar Cells

Microstructure and Properties of Nickel/Detonated Nanodiamond Composites Fabricated by Powder Metallurgy

Abstract Nickel/detonated nanodiamond composites were prepared using the powder metallurgy technique. Detonated nanosized diamond particles were reinforced in the nickel matrix. The investigated powder was used to prepare homogenous diamond/nickel composite mixtures with different detonated nanodiamond content of weight percentage (0.2, 0.4, 0.6, and 0.8 wt.%). The produced mixtures were cold pressed into a cylindrical die shape under compaction pressure of 400 MPa followed by sintering at 1,000°C for 120 min under a controlled atmosphere of 1:3 hydrogen/nitrogen gas mixture. Phase identification and microstructure of the produced sintered samples were investigated using X-ray diffraction and scanning electron microscope, respectively. The results of the microstructure show a good distribution of the detonated nanodiamond in the nickel matrix, especially in the 0.8 wt% diamond/nickel sintered sample. The densities of the obtained sintered samples were measured by applying the Archimedes principal. As the detonated nanodiamond content was increased in the nickel matrix, the density of the sintered samples was decreased. The thermal expansion, electrical conductivity, and hardness of the produced diamond/nickel composites were measured. The coefficient of thermal expansion and electrical conductivity were decreased, but the hardness was increased by increasing the detonated nanodiamond weight percentage.

High Temperature Treatment of Diamond Particles Toward Enhancement of Their Quantum Properties

Fluorescence of the negatively charged nitrogen-vacancy (NV-) center of diamond is sensitive to external electromagnetic fields, lattice strain, and temperature due to the unique triplet configuration of its spin states. Their use in particulate diamond allows for the possibility of localized sensing and magnetic-contrast-based differential imaging in complex environments with high fluorescent background. However, current methods of NV(-)production in diamond particles are accompanied by the formation of a large number of parasitic defects and lattice distortions resulting in deterioration of the NV(-)performance. Therefore, there are significant efforts to improve the quantum properties of diamond particles to advance the field. Recently it was shown that rapid thermal annealing (RTA) at temperatures much exceeding the standard temperatures used for NV(-)production can efficiently eliminate parasitic paramagnetic impurities and, as a result, by an order of magnitude improve the degree of hyperpolarization of(13)C via polarization transfer from optically polarized NV(-)centers in micron-sized particles. Here, we demonstrate that RTA also improves the maximum achievable magnetic modulation of NV(-)fluorescence in micron-sized diamond by about 4x over conventionally produced diamond particles endowed with NV-. This advancement can continue to bridge the pathway toward developing nano-sized diamond with improved qualities for quantum sensing and imaging.

Near- and far-field Raman spectroscopic studies of nanodiamond composite films deposited by coaxial arc plasma

Raman spectroscopic studies on nanodiamond composite (NDC) films, comprising nano-sized diamond grains and an amorphous carbon (a-C) matrix, deposited by coaxial arc plasma deposition are challenging because the scattering of the nano-sized diamond grains competes with the strong signal of the a-C matrix. To unravel the nanocomposite structure of NDC films, both far- and near-field Raman spectroscopy were employed. Based on the comparison of visible and ultraviolet far-field Raman data, component spectra based on either nanodiamond or a-C were estimated by a peak-decomposition procedure based on band fitting. Near-field optical resolution achieved via tip-enhanced Raman spectroscopy reveals sharper peaks of both the nanodiamond and the amorphous carbon than the far-field spectra. Consequently, the peak-decomposition procedure is not required, which evidently indicates the effective detection of nanodiamond grains embedded in a-C matrices and is a direct result of the high spatial resolution that limits the number of probed grains. The size of the nanocrystals could additionally be estimated from the profile and position of a diamond peak. This work demonstrates that tip-enhanced Raman spectroscopy is a powerful nondestructive method for nanodiamond composite films, which allows direct access to parameters hitherto only available via average data.

Tribological behaviors of the diamond films sliding against the T800/X850 CFRP laminates

The frictional resistance and hole quality when drilling CFRP laminates are associated with tribological behaviors of drill materials. In the present study, tribological tests are conducted on various diamond coated WC-Co balls sliding against T800/X850 CFRP laminates with [-45/90/45/0]s lay-up, under specific conditions similar to the drilling process. It is firstly found that the coefficient of friction (COF) varies with the sliding direction. The boron-doped micro-crystalline and nano-crystalline composite diamond (BDMC-NCCD) film synthesized by optimized growth durations (9 h for BDMCD and 2.5 h for NCD) presents relatively low COF and wear rate (0.193 and 0.97 × 10−8 mm3/N m, when the sliding velocity and normal load are respectively 1.5 m/s and 5.0 N), as well as high critical load for the film peeling (35 N), owing to the nano-sized diamond grains and low surface roughness (Ra~125.09 nm measured by the confocal microscopy) of the surface NCD layer, and high hardness and favorable adhesion of the underlying BDMCD layer. Besides, influences of the sliding velocity and normal load are clarified, indicating that the COF increases with the load, but decreases with increasing the velocity, while the wear rate increases with either the load or velocity.

Approach for Polishing Diamond Coated Complicated Cutting Tool: Abrasive Flow Machining (AFM)

Lower surface roughness and sharper cutting edge are beneficial for improving the machining quality of the cutting tool, while coatings often deteriorate them. Focusing on the diamond coated WC-Co milling cutter, the abrasive flow machining (AFM) is selected for reducing the surface roughness and sharpening the cutting edge. Comparative cutting tests are conducted on different types of coated cutters before and after AFM, as well as uncoated WC-Co one, demonstrating that the boron-doped microcrystalline and undoped fine-grained composite diamond coated cutter after the AFM (AFM-BDM-UFGCD) is a good choice for the finish milling of the 6063 Al alloy in the present case, because it shows favorable machining quality close to the uncoated one, but much prolonged tool lifetime. Besides, compared with the micro-sized diamond films, it is much more convenient and efficient to finish the BDM-UFGCD coated cutter covered by nano-sized diamond grains, and resharpen its cutting edge by the AFM, owing to the lower initial surface roughness and hardness. Moreover, the boron incorporation and micro-sized grains in the underlying layer can enhance the film-substrate adhesion, avoid the rapid film removal in the machining process, and thus maximize the tool life (1040 m, four times more than the uncoated one). In general, the AFM is firstly proposed and discussed for post-processing the diamond coated complicated cutting tools, which is proved to be feasible for improving the cutting performance

Dielectric and spectroscopic study of nano-sized diamond dispersed ferroelectric liquid crystal

In the present work, a small concentration of nano-sized (d < 10 nm) diamond particles (NSDPs) were dispersed in the ferroelectric liquid crystal (FLC) and the dielectric and optical studies such as UV absorbance and photoluminescence (PL) spectra of pure FLC as well as FLC-NPs composite were performed. The polarizing optical micrographs (POM) show aggregation of NSDPs in the FLC-NPs composite system which also affects the alignment of the FLC slightly. We have found that the dispersion of NSDPs into the FLC material strongly influences the various properties of dispersed systems. Due to NSDPs dispersion, a rapid decrease in relative permittivity, dielectric loss and ac conductivity has been observed for FLC-NPs composite at lower frequencies. The absorbance and PL emission of FLC-NPs composite has been reduced and a blue shift in PL emission was detected. The possible applications of the composite system have also been suggested in this study.

Promising method for determining the concentration of nano-sized diamond powders in water suspensions

Promising method for determining the concentration of nano-sized diamond powders in water suspensions

Effect of surface termination on the reactivity of nano-sized diamond particle surfaces for bio applications

Nanodiamond has displayed some unique physical and chemical properties compared to bulk diamond, which broadens its applications invarious areas. The here presented investigations have focused on the combined effect of diamond surface planes and termination on surface reactivity. Then especially towards adhered important biomolecules for bone regeneration and vascularization. Moreover, a more detailed picture of nanodiamond quantum confinements is still missing from a theoretical point of view. An evaluation of realistic models for nano-diamond (ND) particles of various sizes will here be presented. In addition, the adhesions of various biomolecules, both in vacuum and in a liquid environment, as a function of surface plane and termination, will also be presented.It was shown possible to model nanodiamond particles of size larger than 2 nm with (100) and (111) surface planes. For the situation with biomolecule adhesion to the nanodiamond surfaces, there is a large similarity between the results for the diamond (111) and (100)- 2x1surfaces. For both of these surfaces, even though the water solvation will create much stronger biomolecular adhesion energies, there is a resemblance in order of adhesion energy for the various systems (i.e., solvated vs. non-solvated).

Microwave assisted efficient furfural production using nano-sized surface-sulfonated diamond powder

Sulfonated nano-sized diamond powder (S-DP) was tested in a typical water-CPME (1:3, v/v) biphasic system and heated in a commercial monowave microwave oven to promote the dehydration of D-xylose into furfural as industrial platform molecule. This new heterogeneous catalyst with a propyl linker between the support and the sulfonyl group expressed remarkable sufficient hydrophilicity, affinity for D-xylose and catalytic activity in presence of NaCl. The solid can act as a strong acidic catalyst without detectable exchange between proton exclusively localized on the surface of the catalyst and sodium ion. It was also stable at 200 °C even after severe recycling treatment. The final optimized condition requires 10 wt% of the catalyst for a maximum furfural yield of 76% when the mixture is heated for 50 min in the current biphasic system.

Nano- and micron-sized diamond genesis in nature: An overview

There are four main types of natural diamonds and related formation processes. The first type comprises the interstellar nanodiamond particles. The second group includes crustal nano- and micron-scale diamonds associated with coals, sediments and metamorphic rocks. The third one includes nanodiamonds and microndiamonds associated with secondary alteration and replacing of mafic and ultramafic rocks. The fourth one includes macro-, micron- and nano-sized mantle diamonds which are associated with kimberlites, mantle peridotites and eclogites. Each diamond type has its specific characteristics. Nano-sized diamond particles of lowest nanometers in size crystallize from abiotic organic matter at lower pressures and temperatures in space during the stages of protoplanetary disk formation. Nano-sized diamonds are formed from organic matter at P-T exceeding conditions of catagenesis stage of lithogenesis. Micron-sized diamonds are formed from fluids at P-T exceeding supercritical water stability. Macrosized diamonds are formed from metal-carbon and silicate-carbonate melts and fluids at P-T exceeding 1150 °C and 4.5 GPa. Nitrogen and hydrocarbons play an important role in diamond formation. Their role in the formation processes increases from macro-sized to nano-sized diamond particles. Introduction of nitrogen atoms into the diamond structure leads to the stabilization of micron- and nano-sized diamonds in the field of graphite stability.

Evaluation of boron-doped-microcrystalline/nanocrystalline diamond composite coatings in drilling of CFRP

The drilling performance of four typical types of single-layer diamond coated drills and two-layer boron-doped-microcrystalline/nanocrystalline diamond (BDMC-NCD) composite coated drill is compared, and the growth duration ratio of the NCD layer to the BDMCD layer (N/B) is optimized. It is demonstrated that the BDMC-NCD film synthesized using proper N/B shows nice adhesion, moderate diamond quality and a smooth surface mostly composed of nano-sized diamond grains, so it shows the best comprehensive performance, including the thrust force reduction, the improvement of the hole quality, the slowing of the tool wear and coating peeling, and the elongation of the tool lifetime. Taking the time of the coating peeling into consideration, 3/9 is the optimum N/B for the BDMC-NCD coated drill, and such the drill also performs the longest lifetime using delamination factors (Fd) of 1.2 or 1.3 as the failure criteria. Moreover, the failure mode of the diamond coated drill is the flank wear when using Fd=1.1 or 1.2 as the failure criteria, while the tool failure should be related to the coating peeling when Fd=1.3.

Pressure-Temperature-Induced Transformations of Hydrocarbon- Fluorocarbon Mixtures into Nano- and Micron-Size Diamonds

Studies of thermal transformations of naphthalene (С10Н8), fluorographite (CF1.1) and octafluoronaphthalene (С10F8) and their binary mixtures (С10Н8 – CF1.1, С10Н8 – C10F8) under pressure of 8 GPa have been undertaken as models for gaining understanding of processes of carbonization, graphitization and diamond formation in pure hydrocarbon, fluorocarbon and carbon-hydrogen-fluorine-containing systems under high pressures. The studies found a significant reduction in the initiation temperature thresholds for all major thermal transformation processes in case of binary mixtures with respect to thresholds for pure hydrocarbon and fluorocarbon compounds. Another distinctive feature of the transformations of binary mixtures with respect to diamond formation stage of the transformations of pure hydrocarbons, has been the presence of massive quantity of nanosize (10–60 nm) diamond fraction in the products from binary mixtures along with the micron-size (5–20 μm) diamond fraction, typically observed in the transformations of pure hydrocarbons. The origin of nanodiamond was related to the specifics of carbonization of fluorocarbon compounds under pressure, which at 800–1000 °С produces, along with submicron particles of graphite-like material, a significant amount of closed shell 2–5 layer carbon nanoparticles of 5–15 nm size. These onion-like carbon nanoparticles act as precursors for formation of nano size diamond fractions in the transformations of binary mixtures of hydrocarbon and fluorocarbon compounds. These results potentially open a new direction for metal catalyst-free synthesis of pure and doped diamonds for broad applications. The present article gives an overview of this emerging area of rese arch.

Vertically aligned diamond-graphite hybrid nanorod arrays with superior field electron emission properties

A “patterned-seeding technique” in combination with a “nanodiamond masked reactive ion etching process” is demonstrated for fabricating vertically aligned diamond-graphite hybrid (DGH) nanorod arrays. The DGH nanorod arrays possess superior field electron emission (FEE) behavior with a low turn-on field, long lifetime stability, and large field enhancement factor. Such an enhanced FEE is attributed to the nanocomposite nature of the DGH nanorods, which contain sp2-graphitic phases in the boundaries of nano-sized diamond grains. The simplicity in the nanorod fabrication process renders the DGH nanorods of greater potential for the applications as cathodes in field emission displays and microplasma display devices.