Detonation Synthesis Research Articles

Investigation of the Morphology and Atomic Structure of Nanopowder Particles Obtained by Grinding Natural Diamond and by the Method of Detonation Synthesis

By a complex of high-resolution methods, it has been shown that the nanopowder particles obtained by grinding natural diamonds have a wide range of sizes and are predominantly lamellar in contrast to the detonation synthesis nanopowder, which consists mainly of similar in size and isometric particles. The primary particles of the nanopowder obtained by grinding, as well as detonation synthesis nanodiamonds, consist of diamond cores with cubic crystal lattices surrounded by shells with complex structures formed from carbon atoms in the sp2 state and impurities. A noticeable increase in the interatomic distances in nanodispersed diamond crystals is observed compared to those for bulk diamond crystals.

Tritium-Probe Method in a Study of Adsorption Layers of Lysozyme on the Surface of Detonation Nanodiamonds

Tritium-labeled lysozyme was used to determine its adsorption on the surface of nanodiamonds produced by detonation synthesis. It was found that the amount of the adsorbed protein depends on the charge of the nanodiamond surface. A multilayer coating is formed on the originally positively charged nanodiamonds, with the adsorption becoming 4–5 times stronger on negatively charged nanodiamonds produced from the original nanodiamonds via their annealing in air. According to IR spectroscopic data, the adsorption of lysozyme results in that the number of loops and turns in the protein structure decreases in the adsorption on two types of nanodiamonds. The use of a tritium probe did not find any significant difference between the structures of protein molecules in their adsorption on nanodiamonds with different functional surface compositions. The orientation of molecules in the surface layer was found to be the same: Protein parts containing amino acid residues of phenylalanine are contacting with the sorbent, and the amino acid residues of proline, which are contained in the loops, are on the surface of the adsorption layer.

X-Ray Photoelectron Spectroscopy of Nanodiamonds Obtained by Grinding and Detonation Synthesis

The initial composition and chemical state of nanopowder primary particles obtained by grinding natural diamond and detonation synthesis have been studied by X-ray photoelectron spectroscopy. It has been shown that the primary particles of both nanopowders contain mainly carbon and oxygen atoms. The signals from nitrogen, sulfur, chlorine, and metal atoms in the photoelectronic spectrum do not exceed the noise level. It has been discovered that the proportions of carbon atoms are ∼46.5 and ∼67.8% in the state of the sp3 hybridization, ∼26.8 and ∼17.4% in the state of the sp2-hybridization, and ∼26.7 and ∼14.7% in the composition of the oxygen-containing functional groups in the primary particles of the nanopowders obtained by detonation synthesis and by grinding natural diamond, respectively.

Shock focusing effects on silica phase production during cyclotrimethylene trinitramine/2,4,6-trinitrotoluene detonations

Detonation is an increasingly studied method for the synthesis of nanomaterials due to the rapid reaction rate producing extreme pressures and temperatures for short durations, which can result in the production of ultra-hard and high-temperature nanomaterials. The present study shows that phase formation in detonation depends on the distribution of inert additives in the explosive charge. Numerical simulations and experimental validation were conducted on silica powders that were shock loaded by detonation of a 3.8 cm diameter cylindrical explosive charge composed of cyclotrimethylene trinitramine, 2,4,6-trinitrotoluene, and paraffin wax. Silica was incorporated into the explosive in three configurations and at two different starting particle sizes in both simulation and experiments. The detonation residues were purified to concentrate the silica and characterized via x-ray diffraction with Rietveld refinement and optical microscopy. Loading conditions and silica phase morphology were not consistent between the configurations and starting size of silica incorporated into the charge. The implication of these results is that the prediction of phase production in detonation synthesis experiments cannot be based on Chapman–Jouguet steady detonation parameters of the explosive matrix but must also include analysis of shock interaction and heat transfer into the additives incorporated into the explosive.

Antifriction properties of electrochemical coatings based on carbon materials

As a result of research by the detonation synthesis method, chemically stable nanodiamond particles with a size of up to 100 nm were obtained. Aqueous solutions of the obtained particles can be used as an electrolyte to obtain carbon coatings by the electrochemical method.

In Ukrainian

Development of methods for controlling the change in the functional cover and the energy composition of the surface of detonation synthesis diamond nanopowders is necessary to create stable suspensions and materials from them. The aim of this work is to study changes in the electrokinetic and electrophysical characteristics of the powder as a result of the modification of detonation synthesis diamond nanopowders using a liquid-phase thermochemical treatment. Diamond nanopowders of grades ASUD-75 - ASUD-99 with different sp2-hybridization carbon content, manufactured at the V.I. Bakul National Academy of Sciences of Ukraine from the product of detonation synthesis of diamond from the company "ALIT" (Zhytomyr) investigated. Diamond nanopowders of ASUD-90 grade after their modification by means of liquid-phase thermochemical treatment using: a melt of alkalis, a mixture of nitric and sulfuric acids, a mixture of chromic and sulfuric acids were investigated by electrophoresis using a device "Dzeta-potential-analizer" company "Mikromeritiks". Electrokinetic characteristics of diamond nanopowders: the magnitude and sign of the electrokinetic potential, electrophoretic mobility are determined. The methods were used to study the physicochemical characteristics of nanopowders: electrical resistivity, carbon content of sp2-hybridization, mass fraction of impurities in the form of an incombustible residue, and specific surface area. In this work, it was established by electrophoresis that the value of the electrokinetic potential and electrophoretic mobility of the powder decrease by 2-10 times with a decrease in the mass fraction of sp2-hybridization carbon from 23.6 to 0 wt%. Using the ASUD-90 nanopowder as an example, it is shown that the modification of the nanopowder by the liquid-phase method using thermochemical treatment with mixtures of oxidants leads to a decrease in the values ​​of electrophoretic mobility by 1.1-7.5 times and electrokinetic potential by 1.1-7.3 times. It was found by dielectric measurement that the tangent of the dielectric loss angle of diamond nanopowders of grades ASUD-90 - ASUD-99 is in the range 0.3046 - 0.3146. Modification of the ASUD-90 grade nanopowder using a liquid-phase thermochemical treatment leads to a change in the interval of the dielectric loss tangent, namely 0.2450-0.3249. According to the degree of increase in the ratio of the dielectric loss tangent from 0% humidity to 100% humidity, the methods for modifying nanopowders can be arranged as follows: modifying using a melt of alkalis (ASUD-90-1 sample, S = 12.8%) <mixture of chromic and sulfuric acids (sample ASUD-90-3, S = 13.8%) <mixture of nitric and sulfuric acids (sample ASUD-90-2, S = 20.8 %).

Features of Electron Probe Microanalysis of Nitrogen-Containing Compounds

This work is aimed at development of a method of investigation into the chemical composition of natural and synthetic nitrogen-containing compounds using electron probe microanalysis (EPMA) and its application for identification of the form of inclusion of light elements (C, N, O) in complex anions and cations. The analysis was performed using Kα lines appearing upon electron transfer from valence 2p states to internal 1s states. The characteristic features of Kα spectra of C, N, and O, which affect the correctness of the EPMA results, were revealed, and adjustments accounting for integral line intensity, self-absorption of the nitrogen line, and absorption of background absorption by nitrogen were determined. The procedure is multifunctional: it is intended for analysis of various nitrogen-containing samples, including diamonds produced by detonation synthesis. The surface of such samples is usually coated with a layer of oxygen- and nitrogen-containing functional groups. The experiments are aimed at detection of the optimum conditions of excitation and recording of Kα lines. The applied accelerating voltage is 10 kV; the beam current is 50–120 nA. When analyzing the recording of the signal amplitude in the differential mode, we apply a universal (for all samples) empirical equation describing the curve of background intensity in the area of the nitrogen line. The resistance of samples against the action of the electron beam is improved by the raster mode with linear size of 20–40 μm and movement of sample in the area of ~100 × 100 μm2 (if allowed by sample size). The concentrations of the detected elements were calculated by the PAP program using Henke absorption coefficients. At 80 nA, the detection limits of carbon, oxygen, and nitrogen were 0.33, 0.46, and 0.86 wt %, respectively.

Mechanical Properties of 2Y-TZP Fabricated from Detonation Synthesized Powder

Yttria stabilized zirconia (Y-TZP) is frequently used in dental and engineering applications due to its high strength and fracture resistance. In this study, 2Y-TZP samples were manufactured from commercially available powder produced by detonation synthesis. Tests of the mechanical properties exhibited an unusual combination of both very high strength and toughness. The materials show a very weak correlation between toughness and grain size. The transformability, measurable by XRD, cannot explain the high toughness. Fractographic analysis revealed a broad transformation affected zone with secondary cracks and shear bands on the tensile side of bending bars which can be made responsible for the high toughness and non-linear stress–strain curves.

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.

Рентгеновская фотоэлектронная спектроскопия наноалмазов, полученных измельчением и детонационным синтезом

The chemical composition and surface state of nanopowder particles prepared by milling natural diamond and detonation synthesis were studied by the method of X-ray photoelectron spectroscopy. It has been shown that the primary particles of both nanopowders contain mainly carbon and oxygen atoms. The signals in the photoelectronic spectrum from atoms of nitrogen, sulfur, chlorine and metals do not exceed the noise level. It was found that in primary particles of detonation synthesis nanodiamond and nanopowder obtained by grinding natural diamond, the proportions of carbon atoms in the sp3 hybridization state are ~ 46.5 and ~ 67.8%, sp2 hybridization is ~ 26.8 and ~ 17.4% and in the composition of oxygen-containing functional groups ~ 26.7 and ~ 14.7%, respectively.

Size and nitrogen inhomogeneity in detonation and laser synthesized primary nanodiamond particles revealed via salt-assisted deaggregation

Detonation nanodiamonds (DND), their properties and deaggregation remain an active field of research. Here we innovated the salt-assisted ultrasonic deaggregation (SAUD) by employing NaHCO3 (a milling agent with relatively low solubility) followed by dialysis (a purification step) and processed two DND and one laser-synthesized (LND) commercial powders. The obtained ND colloids were separated to single-digit supernatant with the yield of 57–65% and sediment fractions by centrifugation and analyzed separately. By thermal analysis we evidenced chemical sensitization of the SAUD-processed DNDs manifested by significantly lower combustion temperatures. By correlation of spectroscopic, microscopic, and thermal analysis techniques we revealed a size and shape inhomogeneity of primary DND particles, also affecting strength of aggregation. By elemental analysis of the fractions we also show that nitrogen content is systematically higher in the smaller primary DND particles. Those features are inherent to all the three ND samples. The provided analyses highlight the need for better understanding of relations between detonation synthesis parameters and properties of the synthesized DNDs in terms of DND primary particle size, aggregation and nitrogen incorporation.

Detonation synthesis of ZrO2 by means of an ammonium nitrate-based explosive emulsion

A zirconium (IV) oxide powder was successfully synthesized from the detonation of an explosive emulsion previously mixed with zirconium sulfate tetrahydrate salt (Zr(SO4)2·4H2O) as a ceramic precursor. After detonation of the energetic mixture in a detonation tank, the as-synthesized ceramic material was purified and characterized by X-ray diffraction, transmission and scanning electron microscopy techniques, nitrogen physisorption and dynamic light scattering. The ceramic powder is made of crystalline nanosized particles exhibiting a homogeneous sphere-like morphology. An attempt to explain the oxide ceramic synthetic mechanism is discussed. The detonation synthetic route implementing high temperatures and high pressures in a short time may be seen as an encouraging method for large-scale production of nanopowder.

On the disperse acicular ferrite formation in the structure of cold-resistant joints under temperatures up to –70°С in MMA welding of 10KhSND steel. Part 1

The article presents an analysis of the metallurgical techniques that provide high quality electrodes for manual arc welding of low-carbon low-alloyed cold-resistant steels. It is shown that it is possible to improve technological and operational properties of welded joints at very low climatic temperatures up to –70°C implementing micro-alloying of the weld metal with nitrogen, titanium, cerium oxide and diamond nanopowder produced by detonation synthesis. The composition introduced into the electrode coating modifier mixture is identified. The cumulative effect of its components on the weld impact strength under temperature testing within the range from –20 up to –70°C was established. The matrix of the weld metal is composed mainly of disperse acicular ferrite, hardened by nanoparticles allegedly nitrides and carbonitrides of titanium and aluminum. It is shown that the centers for the crystallization of acicular ferrite are micro-sized non-metallic inclusions formed on ultrafine titanium nitrides. It was revealed that the toughness of the weld metal at low climatic temperatures is higher than toughness of joints welded by massively imported Japanese KOBELCO electrodes LB-52U. The results of the study make it possible to increase the cold resistance of welded structures for petrochemical plants and other facilities located in the Extreme North of the Russian Federation.Part 2 of the article will be devoted to the study of the welding and technological properties of coated electrodes.

Comparison of Morphological and Structural Characteristics of Nanopowder Particles Fabricated by Grinding Natural Diamond and Detonation Synthesis

Comparison of Morphological and Structural Characteristics of Nanopowder Particles Fabricated by Grinding Natural Diamond and Detonation Synthesis

Development of the Detonation Nanodiamond Synthesis from Tetryl Based Ternary Mixtures

The process of detonation synthesis of nanodiamonds from ternary systems was developed with conversion tetryl as their main component. The dependence of the yield of detonation nanodiamonds and their content in the diamond blend on the tetryl content in the ternary composition was shown as well as that of the yield of detonation nanodiamonds on the oxygen balance of the blend. The conditions and composition of the explosive were found to determine the maximum yield of detonation nanodiamonds, 8.2 wt %, based on which it is possible to develop a more economical and efficient industrial technology for the production of detonation nanodiamonds: the use of explosive compositions containing 50 wt % or more conversion tetryl, respectively, a decrease in the content of expensive and scarce RDX; high content of nanodiamond in the diamond blend, which reduces the cost of chemical cleaning; the possibility of a simple selection of the required oxygen balance of the explosive composition.

Study on phase transformation mechanism of various carbon sources in detonation synthesis of diamond

In this paper, the phase transformation mechanism of various carbon sources in the synthesis of diamond by direct detonation method was studied. Through designing comparison experiment and the X-ray diffraction (XRD) characterization technique, an experimental study was conducted on the detonation process with the external of the combined carbon source and free carbon source, and without the participation of the external carbon source. The laws of phase transformation of the various carbon sources are obtained, in which the surplus carbon in the explosives participates in the formation of diamonds through the collision growth of droplet-like carbon, the added bonded carbon does not participate in the synthesis of diamond, and the added free carbon forms diamonds through the Martensitic transformation.

Core–Shell Composites Based on Partially Oxidized Blend of Detonation Synthesis Nanodiamonds

The results of a study on the production of graphite–diamond nanocompositions by partial oxidation of a detonation synthesis blend in aqueous solutions of nitric acid under pressure in the temperature range 120–230°C are presented. A part of the graphite shell was subjected to selective oxidation. According to the results of kinetic studies in a 400 mL autoclave, an oxidation process scheme is proposed, which is based on a radical chain reaction involving nitrogen dioxide and carbon of graphite/graphene shell on the surface of the particles. The synthesis conditions for the main types of graphite–diamond nanocomposites of various oxidation states are determined. On a pilot installation in a swinging titanium autoclave of a 12 L capacity, experimental batches of the product were accumulated, which made it possible to assess the possibility of scaling the developed laboratory process.

Inorganic Pyrophosphatase-Nanodiamond Conjugates Hydrolyze Pyrophosphate in Human Synovial Fluid.

The present work is focused on testing enzyme-based agents for the partial dissolution of calcium pyrophosphate (CaPPi) deposits in the cartilages and synovial fluid of patients with pyrophosphate arthropathy (CPPD disease). Previously, we suggested that inorganic pyrophosphatases (PPases) immobilized on nanodiamonds of detonation synthesis (NDs) could be appropriate for this purpose. We synthesized and characterized conjugates of NDs and PPases from Escherichia coli and Mycobacterium tuberculosis. The conjugates showed high enzymatic activity and resistance to inhibition by calcium and fluoride. Here, we tested the effectiveness of pyrophosphate (PPi) hydrolysis by the conjugates in an in vitro model system simulating the ionic composition of the synovial fluid and in the samples of synovial fluid of patients with CPPD via NMR spectroscopy. The conjugates of both PPases efficiently hydrolyzed triclinic crystalline calcium pyrophosphate (t-CPPD) in the model system. We evaluated the number of phosphorus-containing compounds in the synovial fluid, showed the possibility of PPi detection in it, and estimated the hydrolytic activity of the PPase conjugates. The soluble and immobilized PPases were able to hydrolyze a significant amount of PPi (1 mM) in the synovial fluid in short periods of time (24 h). The maximum activity was demonstrated for Mt-PPase immobilized on ND–NH–(CH2)6–NH2 (2.24 U mg–1).

Synthesis of Inorganic Pyrophosphatase-Nanodiamond Conjugates Resistant to Calcium and Fluoride.

Pyrophosphate arthropathy is the mineralization defect in humans caused by the deposition of microcrystals of calcium pyrophosphate dihydrate in joint tissues. As a potential therapeutic strategy for the treatment of pyrophosphate arthropathy, delivery of exogenous pyrophosphate-hydrolyzing enzymes, inorganic pyrophosphatases (PPases), to the synovial fluid has been suggested. Previously, we synthesized the conjugates of Escherichia coli PPase (Ec-PPase) with detonation synthesis nanodiamonds (NDs) as a delivery platform, obtaining the hybrid biomaterial retaining high pyrophosphate-hydrolyzing activity in vitro. However, most known PPases including Ec-PPase in the soluble form are strongly inhibited by Ca2+ ions. Because synovial fluid contains up to millimolar concentrations of soluble calcium, this inhibition might limit the in vivo application of Ec-PPase-based material in joint tissues. In this work, we proposed other bacterial PPases from Mycobacterium tuberculosis (Mt-PPase), which are resistant to the inhibition by Ca2+ ions, as an active PPi-hydrolyzing agent. We synthesized conjugates of Mt-PPase with NDs and tested their activity under various conditions. Unexpectedly, conjugates of both Ec-PPase and Mt-PPase with aminated NDs retained significant hydrolytic activity in the presence of well-known mechanism-based PPase inhibitors, fluoride or calcium. The incomplete inhibition of PPases by fluoride or calcium was found for the first time.

Surface Modification of Ultradisperse Diamonds by Vacuum Heat Treatment

The effect of vacuum annealing temperature at 10–2 Pa on the surface structure and functionality of ultradisperse diamond (UDD) produced by detonation synthesis was studied using Raman scattering, IR absorption, x-ray diffraction, and electron paramagnetic resonance techniques. Vacuum annealing at ≤750oC did not affect the structure of diamond nanoparticles although amorphous sp2-hybridized carbon began to form on the particle surfaces at higher temperatures. The UDD surface was completely graphitized and the diamond structure of the particle nucleus was preserved after annealing at 1050oC. Very few functional groups were observed on the UDD surface after annealing at 660–750oC so that the surface remained highly active.