Diamond Nanopowder Research Articles

Electrochemical Detection of Melatonin at Nano-Sized Highly Boron-Doped Diamond Electrode

This work investigates the electrochemical oxidation of melatonin at boron-doped diamond electrodes and demonstrates the significant enhancement in the detection of melatonin using highly boron-doped diamond nanopowder (h-BDD). Employing differential pulse voltammetry, Tween-coated h-BDD modified screen-printed electrodes (Tween/h-BDD/SPE) showed two linear response ranges for melatonin: 0.057–10 and 10–200 μM, with sensitivities of 390 ± 36 and 72.2 ± 3.4 μA mM–1, respectively, and a detection limit (3Sb/m) of 0.017 μM. The Tween/h-BDD/SPE demonstrated good selectivity against common interferences such as tryptophan, serotonin, lactate, cytidine, cytosine, and urea. The analytical utility of Tween/h-BDD/SPE was validated by quantifying melatonin in commercial pharmaceutical tablets, achieving close to 100% recoveries.

Development of neutron scattering kernels for cold neutron reflector materials

The newest neutron scattering applications are highly intensity-limited techniques that demand reducing the neutron losses between source and detectors. In addition, the nuclear industry demands more accurate data and procedures for the design and optimization of advanced fission reactors, especially for the treatment of fuel and moderator materials. To meet these demands, it is necessary to improve the existing calculation tools, through the generation of better models that describe the interaction of neutrons with the systems of interest. The Neutron Physics Department at Centro Atomico Bariloche (CNEA, Argentina) has been developing over the time new models for the interaction of slow neutrons with materials, to produce scattering kernels and cross section data in the thermal and cold neutron energy region. Besides the studies carried out on neutron moderators, we have recently begun looking at materials that could serve as efficient neutron reflectors over those energy ranges. In this work we present the results of transmission and scattering experiments on diamond nanopowder and magnesium hydride, carried out simultaneously at the VESUVIO spectrometer (ISIS, UK), and compare them with newly generated cross-section libraries.

КИНЕТИКА РОСТА МДО-ПОКРЫТИЯ ПРИ ВНЕВАННОМ ПРОЦЕССЕ

The authors consider theoretical foundations of the coating formation when using the no-bath method of microarc oxidation (MAO) as applied to a point counter electrode. The relationships between the growth rate of the coating thickness and the electrical, geometric and chemical parameters of the MAO process have been mathematically determined. An algorithm for calculating the productivity of the MAO process, due to the growth rate of the coating thickness has been developed. The off ered methodology for the experimental selection of modes of the no-bath MAO of aluminum alloys with an electrically neutral nozzle was verifi ed to obtain a coating on a small area of a part with a fl at surface. In the experiment, with a constant “Nozzle-Workpiece” distance equal to 10 mm, the distance “Electrode-Workpiece” took the values of 5, 10, 20, 30 mm. As a “fl at” surface, the authors took the end face of a 50 mm rod made of the D16T alloy based on aluminum, and a rod made of the 08Kh18H10T steel with a diameter of 6 mm served as an electrode. Use was made of the composition applied in the bath method which included an electrolyte: 8 g of KOH, 30…35 g of Na2SiO3, 1 g of artifi cial diamond nanopowder per 6 liters of distilled water. The duration of the MAO process was 120 min. It has been experimentally established that an increase in the “Electrode-Workpiece” distance decreases the potential for coating formation, which decreases the current in the electrochemical circuit. The analysis of the MAO coating thickness has revealed that 5…15 mm is the optimal distance from the electrode and nozzle to the workpiece, which ensures a stable coating thickness of more than 100 microns on an area equal to or greater than the cross-sectional area of the nozzle supplying electrolyte. The expediency of using the developed mathematical model and the methodology for selecting the process modes with the no-bath method of microarc oxidation has been experimentally confi rmed. The experimental studies have established that the proposed scheme of the MAO process provides an increase in the productivity (the thickness growth rate) of coating deposition by 20% and a decrease in energy consumption by 25%.

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.

Enhancing metal processing efficiency based on using a lubricating-cooling agent with ultradispersed diamond powder

The present study describes a new technological environment based on ultradispersed diamond graphite powder. The task is to further study effects of lubricating and cooling agent containing diamond nanopowder. The agent is fed into the zone of refinement or polishing of the part while affecting wear and durability of carbide tooling. The impact of the agent on the quality of the surface layer in the processing of heat-resistant steels and alloys is investigated. It also identifies the optimal agent composition when polishing a particular material. Experimental studies established a positive effect of the agent on the treated surface quality and other parameters of clean finishing and polishing of various metals.

Comparison of morphological and structural characteristics of nanopowder particles obtained by natural diamond grinding and detonation synthesis

The study covers specific features of morphological and structural characteristics exhibited by nanopowder particles obtained by grinding a massive natural diamond and the method of detonation synthesis. High-resolution transmission and scanning electron microscopy, small-angle X-ray scattering demonstrated that natural diamond nanopowder particles obtained by grinding have a wider range of sizes and a plated appearance, unlike detonation synthesis nanopowders consisting of similar in size and isometric particles. X-ray diffraction analysis and Raman spectroscopy used in addition to the methods mentioned above showed that the structure of nanodiamond particles obtained from natural diamond is similar to the structure of a detonation synthesis nanodiamond. Each particle of natural nanopowder, as well as detonation synthesis nanodiamond, consists of a diamond core with a crystal lattice related to the cubic system and a shell containing mainly non-diamond carbon forms with sp 2 hybridization having a complex structure. The average particle size of nanopowders obtained from natural diamond and using detonation synthesis studied by three methods including BET showed results that are in satisfactory agreement with each other. The average nanoparticle size is about 24 nm for natural diamond powder and close to 5.6 nm for UDA-S-GO detonation synthesis nanodiamonds produced by the Federal Research and Production Center «Altai». An insignificant increase in the interatomic distances in diamond nanocrystals compared with a massive diamond crystal was shown experimentally. The study and analysis of a numerous images of natural and detonation synthesis diamond nanocrystals obtained by high-resolution transmission electron microscopy made it possible to establish that the most frequent defects in nanodiamonds are dislocations and point defects.

Kinetics of the Surface Oxidation of Diamond Nanopowder, Modified with Tungsten by Chemical Adsorption from a Solution

The oxidation kinetics of the ACM5 0.1/0 statically synthesized diamond nanopowder in the presence of tungsten in the amounts of 1 and 5 wt %, introduced into the sample by wetting it with the (NH4)2WO4 water solution was investigated. It is established that at the chemical modification of a diamond nanopowder with tungsten by adsorption from a solution the inhibitory action of tungsten on the kinetics of the diamond oxidation also shows. This agrees with the suggested kinetic scheme of the reaction, which contains the stage of the diamond interaction with the gaseous tungsten oxide.

Effects of Surface Pretreatment on Nucleation and Growth of Ultra-Nanocrystalline Diamond Films**supported by National Natural Science Foundation of China (No. 11175137) and the Research Fund of Wuhan Institute of Technology, China (No. 11111051)

The effects of different surface pretreatment methods on the nucleation and growth of ultra-nanocrystalline diamond (UNCD) films grown from focused microwave Ar/CH4/H2 (argon-rich) plasma were systematically studied. The surface roughness, nucleation density, microstructure, and crystallinity of the obtained UNCD films were characterized by atomic force microscope (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The results indicate that the nucleation enhancement was found to be sensitive to the different surface pretreatment methods, and a higher initial nucleation density leads to highly smooth UNCD films. When the silicon substrate was pretreated by a two-step method, i.e., plasma treatment followed by ultrasonic vibration with diamond nanopowder, the grain size of the UNCD films was greatly decreased: about 7.5 nm can be achieved. In addition, the grain size of UNCD films depends on the substrate pretreatment methods and roughness, which indicates that the surface of substrate profile has a “genetic characteristic”.

나노다이아몬드 첨가 윤활제가 디젤엔진의 성능에 미치는 영향

Many research works have been conducted to improve a lubrication performance on diesel engines working in severe conditions. In this study the lubricant containing diamond nano-powder is applied on a diesel engine, and the engine performance is analyzed. The concentration of nano-diamond lubricant fabricated by the matrix synthesis dispersion method is varied. The test results with the nano lubricants are compared with the base oil. The result shows the improvement of efficiency with friction reduction and exhaust emissions reduction of CO, smoke and so on.

다이아몬드 나노분말을 적용한 상용 열교환 유체의 열전도도 특성

Nanofluids, suspending nano-particles of various materials, have a good heat transfer characteristics compared with pure base fluids. For the reason, nanofluids have been considered as one of the measure to improve energy efficiency, and studied to apply on a working fluid of a high performance heat exchanger. This study tested thermal conductivities of nanofluids applying diamond nano-powder on DI water, ethylene glycol, and ethyl alcohol. Nanofluids are fabricated by matrix synthetic method, and the volume percent of diamond nano-powder contained in the base fluid are 0.1, 0.3, 0.5, and 1vol%. As a result, thermal conductivities are enhanced with applying diamond nano-power. Especially, the conductivity is highly increased up to 23% at 1vol% nanofluid applying diamond nano-powder on DI water.

Analysis of the interactions in the Cu-Ti-diamond and Co-W-diamond systems in wetting diamond polycrystals and infiltration of UDD diamond nanopowder at high pressure and temperature

The regularities of the diamond-metal alloy interaction of the copper-titanium and cobalt-tungsten systems under diamond thermodynamic stability conditions have been considered. The possibility has been studied of the metallization of diamond polycrystals and composites when sintered in a high-pressure apparatus.

Genotoxic and mutagenic activity of diamond nanoparticles in human peripheral lymphocytes in vitro

Carbon nanomaterials have the numerous applications in biomedical sciences and nanotechnology-based industries. Nanodiamonds due to their unique physico-chemical properties compared to other carbon nanomaterials are suggested to be better drug carriers or implant coating. Nevertheless, little is known about their short- and long-term toxicological effects on humans, other biological systems and surrounding environment. In the present study, we evaluated genotoxic and mutagenic potential of nanodiamond (particle size <10nm) in human lymphocytes in vitro. Starting from concentration of 50μg/ml, diamond nanopowder was cytotoxic, inhibited cell proliferation and induced apoptotic cell death. Nanodiamond-associated oxidative stress was revealed, the effect was dose-dependent and statistically significant. Nanodiamond-mediated DNA oxidative damage (8-oxoG level) and changes in chromatin stability was observed even at as low as 1μg/ml concentration, which was especially seen for DNA single strand breaks estimated with alkaline comet assay. In contrast, no induction of DNA double strand breaks (neutral comet assay) was documented after nanodiamond treatment. Nanodiamond at concentration of 10μg/ml was able to stimulate micronuclei production. Centromeric signals found in nanodiamond-induced micronuclei may be due to aneugenic activity of diamond nanopowder. Taken together, we showed that nanodiamond-mediated oxidative stress may contribute to DNA damage limiting nanodiamond biocompatibility.

Functionalized diamond nanopowder for phosphopeptides enrichment from complex biological fluids

Diamond is known for its high affinity and biocompatibility towards biomolecules and is used exclusively in separation sciences and life science research. In present study, diamond nanopowder is derivatized as Immobilized Metal Ion Affinity Chromatographic (IMAC) material for the phosphopeptides enrichment and as Reversed Phase (C-18) media for the desalting of complex mixtures and human serum profiling through MALDI-TOF-MS. Functionalized diamond nanopowder is characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Diamond-IMAC is applied to the standard protein (β-casein), spiked human serum, egg yolk and non-fat milk for the phosphopeptides enrichment. Results show the selectivity of synthesized IMAC-diamond immobilized with Fe3+ and La3+ ions. To comprehend the elaborated use, diamond-IMAC is also applied to the serum samples from gall bladder carcinoma for the potential biomarkers. Database search is carried out by the Mascot program (www.matrixscience.com) for the assignment of phosphorylation sites. Diamond nanopowder is thus a separation media with multifunctional use and can be applied to cancer protein profiling for the diagnosis and biomarker identification.

Use of Niobium Oxide as a Binder in the Production of Diamond Nanostructured Composites

The sintering of nanodiamond powders is of interest for both applied engineering of tool materials and fundamental materials science of nanodisperse covalent-type ceramic materials. It is a accept as a general notion that the driving force for sintering of monophase particles is determined by the level of the surface energy. In the case of diamond nanopowder, this level must be significantly higher which makes sintering a difficult process. This difficulty of sintering is connected with the low diffusive mobility of carbon causing the formation of a graphite structure onto surface of the diamond crystals. From this point of view the use of niobium oxide as a binder could be a solution. In an attempt to inhibit the diamonds graphitization process, Nb2O5 and small amounts of amorphous carbon were introduced in the reaction zone. Sintering process was conducted at 6.0 GPa of pressure and 1100-1400oC for a processing time of 30 seconds. At the end of the process, the samples were cleaned, and prepared to be characterized by X-ray diffraction, scanning electron microscopy, density and porosity. From these results it was proposed a densification mechanism based on the consolidation of the particle by diffusion and coalescence of clusters.

The Nucleation and Growth of Nanocrystalline Diamond Films in Millimeter-Wave CVD Reactor

The article was devoted to the research of nanocrystalline diamond (NCD) films deposition in a novel microwave plasma-assisted CVD reactor. In this work, the seeding of silicon substrate by the spin-coating method was optimized. Hydrosol suspensions of diamond nanopowder of two types, namely, with particles having the average size of 50nm (sizes ranging from 20 to 100 nm) and 5nm (mono-dispersed powder), were used. NCD films several hundred nanometers thick were grown on prepared substrates of one and three inches in diameter. The high-density plasma in the novel reactor was generated by the gyrotron radiation at the frequency of 30 GHz. Characteristics of grown diamond films were studied by SEM, AFM and Raman spectroscopy.

Electro-Optical Properties of Carbon Nanotubes Obtained by High Density Plasma Chemical Vapor Deposition

In this work, we studied the electro-optical properties of high-aligned carbon nanotubes deposited at room temperature. For this, we used the High Density Plasma Chemical Vapor Deposition system. This system uses a new concept of plasma generation: a planar coil is coupled to an RF system for plasma generation. This was used together with an electrostatic shield, for plasma densification, thereby obtaining high-density plasmas. The carbon nanotubes were deposited using pure methane plasmas. Three methods were used for the surface modification of the sample: reference substrate (silicon wafer only submitted to a chemical cleaning), silicon wafer with surface roughness generated by plasma etching, silicon wafer with a thin iron film and silicon wafer with diamond nano powder used as precursor materials. For each kind of silicon wafer surface, the carbon nanotubes were deposited with two different deposition times (two and three hours). The carbon nanotubes structural characteristics were analyzed by Atomic Force Microscope and Scanning Electronic Microscope. The carbon nanotubes electrical characteristics were observed by Raman Spectroscopy and the carbon nanotubes electro-optical properties were analyzed by current vs voltage electrical measurements and photo-luminescence spectroscopy measurements. The photoelectric effect in the carbon nanotubes were determined by photo-induced current measurements. In this work, we obtained carbon nanotubes with semiconductor properties and carbon nanotubes with metallic properties. The electro-optical effects depend strongly on the substrate preparation and the deposition parameters of the carbon nanotubes. The carbon nanotubes are high aligned and show singular properties that can be used for many applications.

Choice of a target with metal coating for laser-induced transfer of ultradispersed materials

The ejection of ultradispersed diamond from a metallised target surface irradiated by nano- and subnanosecond laser pulses is experimentally investigated. Several targets with different transparent bases (quartz, polymethylmethacrylate) and absorbing metal coatings (titanium, aluminium) are investigated. The effect of the metal layer thickness and pulse width on the range of energy densities in which the ejection of diamond nanopowder is due to the transverse strain of metal layer is analysed. The heating of the target rear surface from which transfer occurs, in dependence of the target and laser pulse parameters, is estimated.

Development of ultrananocrystalline diamond (UNCD) coatings for multipurpose mechanical pump seals

The reliability and performance of silicon carbide (SiC) shaft seals on multipurpose mechanical pumps are improved by applying a protective coating of ultrananocrystalline diamond (UNCD). UNCD exhibits extreme hardness (97 GPa), low friction (0.1 in air) and outstanding chemical resistance. Consequently, the application of UNCD coatings to multipurpose mechanical pump seals can reduce frictional energy losses and eliminate the downtime and hazardous emissions from seal failure and leakage. In this study, UNCD films were prepared by microwave plasma chemical vapor deposition utilizing an argon/methane gas mixture. Prior to coating, the SiC seals were subjected to mechanical polishing using different grades of micron-sized diamond powder to produce different starting surfaces with well-controlled surface roughnesses. Following this roughening process, the seals were seeded by mechanical abrasion with diamond nanopowder, and subsequently coated with UNCD. The coated seals were subjected to dynamic wear testing performed at 3600 RPM and 100 psi for up to 10 days during which the seals were periodically removed and inspected. The UNCD-coated seals were examined using Raman microanalysis, scanning electron microscopy, optical profilometry, and adhesion testing before and after the wear testing. These analyses revealed that delamination of the UNCD films was prevented when the initial SiC seal surface had an initial roughness >0.1 μm. In addition, the UNCD surfaces showed no measurable wear as compared to approximately 0.2 μm of wear for the untreated SiC surfaces.

Shadowgraphic imaging of laser transfer driven by metal film blistering

A time-resolved shadowgraphic technique was used to investigate local transfer of diamond nanopowder from a thin titanium film on a silica support under irradiation by 450-fs or 50-ps laser pulses. Clean powder ejection driven by blistering of the metal film remaining on the target surface was found possible in a limited fluence range, but the metal film was removed from the target together with the powder when higher laser fluences were applied. The velocity of the powder ejection demonstrates an approximately linear rise in a wide range of the incident fluences, while the slope of the velocity curve decreases for thicker metal layers. The maximum ejection velocity achievable in the blistering regime was evaluated as ∼100 m/s independently of the metal thickness and pulse width.

Purification and Functionalization of Diamond Nanopowders

AbstractPurification of diamond nanopowder (DNP) was conducted in a less-destructive mild polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5). The wide-angle X-ray diffraction (XRD) showed that the intensity of the characteristic diamond d-spacing (111) at 2.07 Å from purified DNP (PDNP) was fairly increased compared to pristine DNP, indicating that significant amount of carbonaceous impurities were removed. Chemical modification of pristine DNP and PDNP with 4-ethylbenzoic acid was carried out to afford 4-ethylbenzoyl-functionalized DNP (EBA-g-DNP) and PDNP (EBA-g-PDNP). The morphologies of EBA-g-DNP and EBA-g-PDNP from scanning electron microscopy (SEM) were further affirmed the feasibility of chemical modification. The results suggested that the reaction condition was indeed viable for the one-pot purification and functionalization of DNP. The resultant functionalized DNP could be useful for nanoscale additives. Hence, EBA-g-DNP and EBA-g-PDNP was brominated by using N-bromosuccinimide (NBS). The resultant N-brominated DNP and PDNP could be used as initiator for the atom transfer radical polymerization (ATRP) to introduce many polymers onto the surface of functionalized DNP and PDNP.