Diamond Particles Research Articles

О НЕКОРРЕКТНОМ И НЕРЕПРЕЗЕНТАТИВНОМ ЦИТИРОВАНИИ В ОБЗОРЕ S.J. JIA, F. YANG “HIGH THERMAL CONDUCTIVE COPPER/DIAMOND COMPOSITES: STATE OF THE ART” И ДРУГИХ РАБОТАХ

Several papers published in Elsevier and Springer journals in 2020–2021, in which there were numerous violations of standards concerning citation practice in scientific papers, are analyzed. These papers deal with high-thermal-conductive diamond/metal composites. The examples under consideration mainly concern composites prepared via deposition of tungsten coatings onto diamond particles. The revealed errors and distortions in citations are indicated and classed. The examples given may be useful to a wide range of readers (authors, reviewers, editors) as illustrations of the data distortion encountered in scientific publications due to incorrect citation

A general approach to composites containing nonmetallic fillers and liquid gallium.

We report a versatile method to make liquid metal composites by vigorously mixing gallium (Ga) with non-metallic particles of graphene oxide (G-O), graphite, diamond, and silicon carbide that display either paste or putty-like behavior depending on the volume fraction. Unlike Ga, the putty-like mixtures can be kneaded and rolled on any surface without leaving residue. By changing temperature, these materials can be stiffened, softened, and, for the G-O-containing composite, even made porous. The gallium putty (GalP) containing reduced G-O (rG-O) has excellent electromagnetic interference shielding effectiveness. GalP with diamond filler has excellent thermal conductivity and heat transfer superior to a commercial liquid metal-based thermal paste. Composites can also be formed from eutectic alloys of Ga including Ga-In (EGaIn), Ga-Sn (EGaSn), and Ga-In-Sn (EGaInSn or Galinstan). The versatility of our approach allows a variety of fillers to be incorporated in liquid metals, potentially allowing filler-specific "fit for purpose" materials.

Dynamics modeling and analysis of feed drive system for a frame saw machine considering time-varying load

Frame saw machine is one of machine tools that is used to process dimension stone. The velocity fluctuation of traditional feed drive system (FDS) lead to excessive wear of diamond particles. The dynamic performance of the FDS has time-varying characteristics during the processing of stone with a large material removal rate. In this paper, a novel FDS was proposed. Firstly, the dynamic modeling of FDS was set up on account of lumped parameter method (LPM). Then the speed of the new FDS was compared with that of the traditional FDS. Finally, the frequency response characteristics of the system were solved by Lagrange and state space method. Results showed that the new FDS has a faster response feed and less velocity fluctuation. The natural frequency and the amplitude of acceleration increase with decreasing load. With the time-varying load, the range of the second-order natural frequency increased by 50 Hz, which was larger than that of the first-order. The modal test verified that the first two natural frequencies of the saw blade are within the range of the natural frequencies of FDS. The proposed FDS can guide for design, reduce the wear of diamond, and improve processing quality.

Assessment of different surface treatments and shear bond characteristics of poly-ether-ether-ketone: An in vitro SEM analysis.

Aim:The aim of this study is to assess the surface roughness and shear bond characteristics of pol-ether-ether-ketone after different surface treatments.Setting and Design:An in vitro, prospective.Materials and Methods:One hundred and twenty disc-shaped samples of 10 mm diameter and 2 mm thickness were milled and subjected to following surface treatments: 110 μm alumina particles, 98% concentrated sulfuric acid, and 10–20 μm synthetic diamond particles. Surface characteristics of treated sample were studied under SEM with ×500 and ×1000 magnification. Shear bond strength (SBS) with composite resin discs embedded in acrylic blocks after luting with self-etch resin cement and resin-modified glass ionomer cement (RMGIC) was evaluated using the universal testing machine (Instron®, Massachusetts U. S. A).Statistical Analysis Used:The data collected were evaluated using the Analysis of variance and Tukey's honest significant difference post hoc test.Results:Highest SBS and SR were noted with self-etch resin cement in the given order: 98% sulfuric acid (2.106 ± 0.186 μm), followed by alumina particles (1.706 ± 0.160 μm) and synthetic diamond particles (1.101 ± 0.167 μm).Conclusion:The SBS of self-etch resin cement was higher compared to RMGIC for all three surface treatments done on test samples. Hundred percent samples treated by all three surface treatment methods showed mixed type of failure.

Aquasomes Nanocarriers for Delivery of Small Molecules

Aquasomes are nanobiopharmaceutical carrier devices having a polyhydroxyl oligomeric layer surrounding them and a nanocrystalline calcium phosphate or ceramic diamond particle core. Aquasomes are spherical spheres with a diameter of 60-300 nanometers that are used to deliver medications and antigens. Because of qualities such as protection and preservation of delicate biological molecules, conformational integrity, and surface exposure, it was an excellent carrier mechanism delivering bioactive molecules such as peptides, proteins, hormones, antigens, and genes to specific sites. The most common core materials used to manufacture aquasomes are tin oxide, nanocrystalline carbon ceramics (diamonds), and brushite (calcium phosphate dihydrate). Calcium phosphate is the focus of attention due to its natural function in the body. Brushite is an acidic mineral that converts into hydroxyapatite after being stored for a long time. As a consequence, hydroxyapatite seems to be a more powerful centre for aquasome preparation. It’s often used in the design of drug-delivery implants. A putative artificial oxygen-carrying mechanism has been found as hemoglobin-loaded aquasomes with a hydroxyapatite core. Because of their structural integrity, aquasomes have been employed as red blood cell substitutes, vaccines for delivering viral antigen (Epstein-Barr Virus and Human Immunodeficiency Virus) to elicit appropriate antibodies, and a targeted technique for intracellular gene therapy. Due to their enzyme activity and responsiveness to molecular conformation, aquasomes were created as a new carrier for enzymes such as DNAses and pigment/dyes. The challenges of retaining the conformational integrity and biochemical functioning of immobilised surface pairs, as well as the integration of these principles into a single functional composition, are described in this article.

Surface preparation and analysis on fused silica glass substrate with deterministic grinding method

Optical quality of glass components are determined by its surface finish either at lapping stage or at final polished stage. The criticality of optical components is defined by its application. For commercial application its surface finish can be of the order of few microns, whereas for special purpose applications such as aerospace, navigation and laser based sensors its surface finish requires super smooth polish ranging from angstrom to sub angstrom level. In order to achieve such high surface figure, the optical components has to be pre-processed from lapping stage. Two parameters play a major role for obtaining better quality of optical components; they are Surface Roughness (Ra) and Sub Surface Damage (SSD). These parameters have to be monitored from the initial stage of lapping. In this work, Fused Silica glass substrate has been considered and lapped with different deterministic grinding methods, such as Diamond Pellet, Diamond Trizact Tile and Diamond Cup Tools. The abrasives used are pre determined diamond particles embedded in different matrix, such as metal bound, resin bound, ceramic bound and electroplated. The processed samples were characterized for its Average Roughness (Ra) through White Light Interferometry technique and its corresponding depth of SSD was calculated. Images of processed samples were captured through Field Emission Scanning Electron Microscope (FESEM). Process optimization and comparative study between various deterministic lapping processes has been established. Average Surface Roughness (Ra) has been reduced from 274 nm to 3.3 nm and its corresponding depth of SSD values were also reduced from 14.5 µm to 0.151 µm. Earlier, studies determine that SSD depends on grit size of diamond whose relation was given by 0.5d, irrespective of processing parameter or methodology adopted. In this study results have been obtained with one order down with respect to earlier achieved results.

Comparison of diamond nanoparticles captured on the floating and grounded membranes in the hot filament chemical vapor deposition process.

Negatively charged diamond nanoparticles are known to be generated in the gas phase of the hot filament chemical vapor deposition (HFCVD) process. However, the structures of these nanoparticles remain unknown. Also, the effect of charging on the stability of nanodiamond structures has not been studied experimentally. Here, by installing a capturing apparatus in an HFCVD reactor, we succeeded in capturing nanoparticles on the floating and grounded SiO, carbon, and graphene membranes of a copper transmission electron microscope grid during HFCVD. We examined the effect of charge on the crystal structure of nanodiamonds captured for 10 s under various conditions and identified four carbon allotropes, which are i-carbon, hexagonal diamond, n-diamond, and cubic diamond, by analyzing 150 d-spacings of ∼100 nanoparticles for each membrane. Nanoparticles captured on the floating membrane consisted mainly of cubic diamond and n-diamond, whereas those captured on the grounded membrane consisted mainly of i-carbon. Diamond particles deposited for 8 h on the floating silicon (Si) substrate exhibited an octahedron shape with well-developed facets, and a high-intensity 1332 cm−1 Raman peak, whereas diamond particles deposited on the grounded Si substrate showed a spherical shape partially covered with crystalline facets with a broad G-band Raman peak. These results indicate that charging stabilizes the diamond structure.

Гибридная углерод-углеводородная структура

A new hybrid carbon-hydrocarbon structure was discovered after pumping a gas mixture of methane and hydrogen through 314 – 400 µm synthetic diamond powder. The experiment was carried out on the microwave plasmachemical installation designed for deposition of polycrystalline diamond films. The main parameters during the experiment were the following: the power of the microwave generator 3,5 kW, the flow rate of hydrogen 400 ml/min, methane 20 ml/min, the pressure in the reactor chamber 63 torr. The gas mixture was pumped at pressure drop of 13 torr. The diamond powders were placed in molybdenum cups inserted into a copper pedestal. In the gaps between the diamond particles of the surface layer unidirectional thread-like structures (length 100 – 500 μm, diameter 2 μm) were found, some of which ended in spherical formations (average diameter 18 μm). Such a composition of thread-like structures and spherical formations was called “dandelion” one. Raman spectroscopy was performed to examine the nature of these formations. The thread-like structure was determined as monocrystalline graphite. The surface of the spherical formation was represented by spindle-shaped structures of nanocrystalline graphite (length 2 μm, thickness 200 nm) and nanodiamond grains with trans-polyacetylene chains [C2H2]n.

Compound physical and mechanical effects stimulating metastable diamond formation

Purpose. To synthesize diamond polycrystals in a thermodynamically stable region, and to grow up a single crystal shell under conditions of thermodynamic metastability. To investigate some physical properties and features of the internal structure for synthesized single crystals for the development of new models and hypotheses regarding the issue of diamond genesis. Methodology. Experimental studies using shock-wave effects on a metal alloy containing non-diamond carbon. Methods of infrared and ultraviolet spectroscopy, X-ray phase analysis, electron paramagnetic resonance, isotope analysis, differential thermal analysis, electron microscopy, and others are used. The synthesis of nanocrystalline diamond particles as nuclei for growing single crystals is carried out by the shock-wave method using profiled shock waves. Findings. A complex of physicochemical methods for studying the grown diamond monocrystals has been carried out. The reasons for the discrete growth of diamond and the retention of the central inclusion (a polycrystalline diamond of shock-wave origin) in the process of growth have been established and analyzed. It is shown that the discreteness of diamond formation is characteristic only for thermodynamically metastable conditions. The results of the experiments give grounds to make an assumption about the metastable growth, including of diamonds from primary deposits. Originality. The hypothesis has been developed concerning the origin of diamond nanoparticles in interstellar carbon clouds which refer exclusively to central polycrystalline inclusions in a monocrystal diamond shell. The hypothesis eliminates the scientific contradiction that arises in all cases when attempts are made to interpret the natural discreteness of diamond formation based on the regularities of the graphite-diamond state diagram. Possible causes of discrete diamond formation in nature and the scenario of the formation of diamond nanocrystals in an interstellar cloud of atomic carbon have been considered. Practical value. The value of the experimental research results refers to the development of a non-energy-intensive technology for the growing large diamond monocrystals at temperatures of 5001400 K, and pressures of 105107 Pa.

In English

The paper presents the results of a study of the physical and chemical properties of narrow fractions of diamond nanopowders with a low content of non-diamond carbon grade ASUD-99. Six fractions with different average diameters of diamond particle aggregates from 28.785 to 3.891 μm were obtained by separating a 0.2 % aqueous suspension of the initial powders by the sedimentation method. It has been found that the smallest aggregates consist of larger particles with a smaller specific surface area and a lower interaction energy between them. This conclusion is confirmed by a decrease in the porosity of the obtained aggregates. So, if the pore volume in the largest aggregates of diamond particles is 0.859 ml/g, then in the smallest 0.550 ml/g, while the pore radius of diamond aggregates in different fractions changes insignificantly. Separation in a magnetic field at different currents of diamond nanopowders with a specific magnetic susceptibility of 0.52×10-8 m3 kg, treated with a solution of 5 % iron chloride, made it possible to obtain five fractions that differ from each other in specific magnetic susceptibility (c) – from magnetic fractions with c = 4.30×10-8 m3/kg to diamagnetic – with c = –0.11×10-8 m3/kg. It is shown that the modification of diamond nanopowders with iron ions increases the separation selectivity and makes it possible to isolate diamagnetic powders.

Reduced interlayer defects of diamond/copper composite doped with holmium (III) oxide

ABSTRACT The interlayer defects of diamond/copper (Cr) composite have been eliminated by adding holmium (III) oxide through Spark Plasma Sintering (SPS) method. The effects of Ho2O3 addition of diamond–copper interlayer on the microstructure and phase composition are investigated. The total density of states (DOS) and partial density of states (PDOS) are investigated by the first-principles calculations. It is revealed that the addition of Ho2O3 has a distinct modification effect on diamond–copper (Cr) interlayer. Obvious cracks around the diamond outer surface are hardly found, and the diamond particles are enfolded by the copper matrix. The Cr2C phase that beneficial to reduce interlayer defects and improve interlayer bonding was generated under the effect of adding Ho2O3. The thermal conductivity of diamond/copper (Cr-Ho2O3) is 686 W/(m·K). The possible reasons for doping Ho2O3 to eliminate interlayer defects and improve the thermal conductivity were discussed.

Shock compression of diamonds in silicon carbide matrix up to 110 GPa

We have synthesized the well-performance bulk diamond–SiC composite by the high-temperature and high-pressure method and employed the light gas gun launched flyer plates to investigate shock compression response of the diamond–SiC composite. The plots of shock velocity vs particle velocity demonstrate the presence of double elastic waves in the diamond–SiC composite under shock compression. The first elastic wave travels at 13.1∼13.6km/s and leads to yielding at ∼12.75GPa. The second elastic wave propagates at 12.8∼13.0km/s and does not display the yielding up to ∼110GPa. Such a Hugoniot elastic limit is apparently higher than that of the single crystal diamond. The strengthening mechanism underlying the diamond–SiC composite has been discussed. By simulations of the lattice-spring model, the results revealed that under shock compression, the silicon carbide matrix yields first in the composite, resulting in damage to the substructure surrounding the diamond particles. This damage releases the intense shear stress and protects the diamond from severe crushing. Due to diamonds being hydrostatically confined by the silicon carbide matrix, both dislocation migration and slip band sliding are suppressed significantly, which enhances the strength of diamonds.

Stimulated Raman scattering in suspension of submicron diamond particles

We report on the first experimental observation of stimulated Raman scattering (SRS), stimulated low-frequency Raman scattering and multiphoton excited negatively-charged single nitrogen-vacancy (NV-) centers luminescence in ethanol suspension of submicron diamond particles obtained at high pressures and temperatures (HPHT). The Stokes and anti-Stokes SRS components with a frequency shift of 1332 cm−1, corresponding to the fundamental optical mode of diamond crystal were observed. The spectral characteristics and energy thresholds of the studied processes were determined.

Wear and tribofilm characterization of bamboo CNT (B-CNT)-peek composite with incremental blending of submicron synthetic diamond particles

Wear characteristics modified on high functionality tribo poly-ether-ether-ketone (PEEK) composite fabricated through the spatial distribution of bamboo Carbon NanoTube (B-CNT) with incrementally blended networks of sub-micron high thermal conductivity synthetic diamond (SD) particles were studied. The composites were developed by the hot press sintering route and were characterized for their mechanical, thermal stability, chemical state, and tribological properties. On the addition of reinforcement particles, the hardness of the composite was increased by 25%, and thermal stability improved by about 25 °C due to the strengthening effect of diamond particles. FTIR reveals the existence of the chemical compatibility of reinforcements in the matrix. XRD results reveal that the addition of reinforcements in the matrix does not alter the structure of PEEK. Wear characteristics of PEEK composite were investigated by varying applied pressures. The coefficient of friction reduced to 30% for 0.5%SD & 0.75%B-CNT sample, and the specific wear rate was reduced to 39% for 1%SD & 1%B-CNT sample compared to neat PEEK, at maximum loading condition. The coefficient of friction and specific wear rate were reduced to a larger extent due to transfer film consisting of ferric oxide film confirmed by XPS oxygen region peak 531.85 eV and distorted polymer rings was confirmed by Raman spectroscopy.

Influence of diamond content and milling duration on microstructure and thermal conductivity of Ti-coated diamond/copper composite coating on copper substrate

In the present work, Ti-coated diamond/copper composite coatings were effectively deposited on T2 Cu matrix via mechanical alloying method. Influences of diamond content and milling time upon the coatings were studied. The results stated that it could promote the wettability between copper and diamond through diamond surface modification with Ti powder by mechanical alloying. It was also a pre-refinement process of diamond particles, which was beneficial to obtain coatings with uniform diamond distributions and promoted properties. Coatings with excellent microstructures and mechanical properties were obtained with the diamond volume fraction of 40% and the milling time of 7 h. Heat treatment was greatly significant to the thermal performance. And the sample was exhibited excellent thermal conductivity of 409W/mK after annealing at 800 °C for 1 h.

Hydrophobicity and Adhesion of Aggregated Diamond Particles

Diamond powders with high hydrophobicity are prepared by etching graphite plates using a hydrogen/argon (H2/Ar) plasma. The morphology and size of the diamond powders are found to vary with the proportion of Ar in H2 from 0% to 50%. Wettability is measured using water contact angle (WCA) measurements giving values between 129.7° and 146.9°. The high hydrophobicity can be ascribed to the aggregated structure of the as‐grown diamond powders. To check this assumption, the aggregated diamond powders are separated into individual particles by mechanical grinding; then, the WCAs of separated as‐grown diamond powders and commercial dispersed diamond powders are compared. The separated diamond surfaces show the lower WCAs of 99.68° and 96.96°. The surface of the aggregated diamond powders also exhibits high adhesion to water. The diamond surface grown in 2% Ar suspends 40 μL of water under a tilt angle of 180°. Such aggregated diamond powders are promising for no‐loss liquid transportation.

A Thermomechanical Model of Retention of a Diamond Particle in Matrices Based on Fe

The aim of this paper was to determine the influence of the mechanical and thermal parameters of the matrix materials on their retentive properties. The term ‘matrix retention’ denotes the capacity of a metallic matrix material to retain diamond particles at the surface of a diamond tool during working. The bonding is obtained during cooling after the hot pressing process. Proper mechanical bonding depends on elastic and plastic properties of the matrix. The model of a diamond particle embedded in a metallic matrix was created using Abaqus software. The analysis has indicated the mechanical parameters that are responsible for the retention of diamond particles in a matrix.

A base-line study of the wear of burs used for chairside milling of ceramic crowns of different hardness: effect on internal fit and surface roughness

INTRODUCTION: Wear of milling burs may affect the internal fit and surface roughness of the milled crown. AIM: To assess the wear of diamond and tungsten carbide (TC) burs from milling ceramic materials and the effect on internal fit and surface roughness. METHODS: Thirty crowns of each of the two materials were milled from the same standard preparation. Diamond burs were used for a feldspathic ceramic and TC burs for zirconia. Before and after the 10th, 20th and 30th milling, diamond particle loss was counted and cutting blade changes of the TC burs measured. Internal fit was measured using a silicone replica technique and surface roughness by 3D laser microscope. RESULTS: An average 26% loss of diamond particles occurred after 30 crowns, resulting in a 6% decrease in internal luting space and a 21% decrease in surface roughness. Wear of the TC burs resulted in a 13% decrease in the luting space, and a 16% increase in surface roughness. CONCLUSION: The wear of milling burs reduces the luting space, and the milling parameters must be adjusted to compensate for this. Surface roughness is affected by bur type: with diamond burs it decreased, and increased with TC burs.

Rapid Measurement and Control of Nitrogen-Vacancy Center-Axial Orientation in Diamond Particles* *Supported by the National Key R&D Program of China (Grant No. 2017YFB0403602), the Nature Science Foundation of Jiangsu Province (Grant No. SBK2020041231), and the Suqian Sci&Tech Program (Grant No. K201912).

Determination and control of nitrogen-vacancy (NV) centers play an important role in sensing the vector field by using their quantum information. To measure orientation of NV centers in a diamond particle attached to a tapered fiber rapidly, we propose a new method to establish the direction cosine matrix between the lab frame and the NV body frame. In this method, only four groups of the ODMR spectrum peaks shift data need to be collected, and the magnetic field along ± Z and ± Y in the lab frame is applied in the meantime. We can also control any NV axis to rotate to the X, Y, Z axes in the lab frame according to the elements of this matrix. The demonstration of the DC and microwave magnetic field vector sensing is presented. Finally, the proposed method can help us to perform vector magnetic field sensing more conveniently and rapidly.

The growth of agglomerates in the conditions of detonation synthesis of diamond

The conditions of detonation synthesis of nanodiamonds do not affect the size of diamond microcrystallites too much, as was shown in numerous experimental studies. This is because microcrystallites are formed almost instantly at the moment of explosive detonation, when conditions are created for crystallization of the diamond carbon phase. Further expansion of detonation products only leads to the creation and enlargement of particle agglomerates. The product of detonation synthesis is always a powder consisting of agglomerates of carbon particles of diamond and non-diamond phases with impurities. The size, density and specific surface area of the agglomerates can be different depending on the synthesis conditions. These product characteristics are of great importance for further technological applications. Meanwhile, the processes of agglomerate formation under conditions of expansion of detonation products have not yet been considered. In this paper, we theoretically consider this process. The dependences of the size and specific surface of carbon agglomerates on the conditions of detonation synthesis were obtained, and comparison with experimental data was made.