UDC 621.921.34-492.2
N. V. Novikov, G. P. Bogatyreva, M. N. Voloshin, M. A. Marinich (Kyiv) V. I. Padalko, Yu. S. Slavinsky (Zhitomir)
Nanostructured porous diamond powders and their surface properties
The article presents the results of the study of the characteristics and surface properties of nanostructured porous diamond powders obtained by crushing compacts from detonation synthesis nanopowders. The prospects of using new micropowders as sorbents are shown.
UDC 621.921.343-492.2:541.128.13
G. P. Bogatyreva, M. A. Marinich, E. V. Ishchenko, V. L. Gvyazdovskaya, G. A. Bazaliy (Kyiv)
Adsorption and catalytic processes on the surface of nanodispersed diamonds
The adsorption and catalytic properties of the original and modified nanodispersed diamonds were studied. The influence of the diamond surface chemistry on the mechanism of the catalytic oxidation of carbon monoxide to dioxide was considered. It was found that heavy metal ions are adsorbed mainly on the hydrophobic surface, and protein molecules – on the hydrophilic one. It was shown that the adsorption properties of nanodispersed diamonds are determined by the active centers of the transition zones of sp3- and sp2-hybridizations. The adsorption centers of the nanodiamond surface are simultaneously the centers of catalytic processes. Electrochemical treatment of nanodiamond surface allows to saturate it with atomic oxygen, which in turn leads to significant intensification of the process of catalytic oxidation of carbon monoxide to dioxide.
UDC 621.793.002:3-419
V. Yu. Dolmatov (St. Petersburg) T. Fujimura (Tokyo) G. K. Burkat, E. A. Orlova (St. Petersburg)
Production of wear-resistant chromium coatings using nanodiamonds of different nature
The process of electrochemical deposition of chromium in the presence of detonation and static synthesis nanodiamonds is considered in comparison. It is shown that in both cases the microhardness of chromium-diamond coatings increases, but more so in the case of using detonation synthesis nanodiamonds. Wear resistance of coatings, on the contrary, is higher in case of using nanodiamonds of static synthesis, however, wear of the counterbody is also significantly higher. It was found that in terms of the set of properties, the use of nanodiamonds of detonation synthesis is preferable in comparison with classical ones of the same size.
UDC 544.778.3
A. P. Voznyakovsky (St. Petersburg) T. Fujimura (Tokyo) V. Yu. Dolmatov, M. V. Veretennikova (St. Petersburg)
Formation and stabilization of nanodiamond suspensions in liquid media
The features of stabilization of dispersion of particles of ultradispersed diamonds of detonation synthesis in aqueous media under the application of an ultrasonic vibration field are considered. The periodicity of the change in the polydispersity curve is demonstrated when ultradispersed diamond particles are in an ultrasound field. The interval of application of the ultrasound field is found, which allows maintaining the initial dispersion for a long time. A method of solid-phase chemical modification of the surface by grafting organosilyl groups is proposed, which allows obtaining highly dispersed suspensions in non-polar organic media.
UDC 621.921.1:621.367
G. P. Bogatyreva, M. A. Marinich, G. A. Bazaliy, N. A. Oleynik, V. L. Gvyazdovskaya, V. S. Shamraeva (Kyiv)
Formation of physicochemical properties of nanodiamond dispersions during their extraction and purification
The results of a study on the formation of optimal physicochemical properties of nanodiamond dispersions during the extraction and purification of ultradispersed diamonds by chemical and electrochemical methods are presented, and a flexible technology for the production of three grades of nanodiamond dispersion products – ASUDO, ASUDCH, UDAG is described. Possible areas of their application are indicated.
UDC 539.89:621.762.5:621.921.34-492.2
A. A. Bochechka (Kyiv)
Properties of polycrystals sintered at high pressures from diamond nanopowders of detonation and static synthesis
The paper presents the physical and mechanical properties and structure of polycrystals sintered from diamond nanopowders of detonation and static synthesis under high pressure and temperature conditions. It is shown that chemical modification of the initial nanopowder in combination with heat treatment in a vacuum and sealing of the working volume helps to reduce the degree of diamond graphitization during sintering, which in turn leads to an increase in the strength and hardness of the obtained polycrystals.
UDC 538.971; 539.124.143
V. M. Maevsky, E. V. Mozdor, V. I. Padalko (Kiev)
EPR of submicro- and nanosized synthetic diamonds
The electron paramagnetic resonance of samples of submicro powders of synthetic diamonds, nanodiamonds and micropowders with a nanostructure was studied. It was shown that a decrease in the size of diamond grains is accompanied by a change in the type, structure and parameters of the electron paramagnetic resonance spectra. The data obtained indicate significant differences in the structure of diamond grains and their surface in powders with different degrees of dispersion. The dimensional effects are associated with the increasing role of the surface in the formation of the properties of synthetic diamond particles as their size decreases.
UDC 621.921.34:543.544.5
B. A. Patel, K. J. Rutt (Brighton, England) V. I. Padalko (Kiev, Ukraine) S. V. Mikhalovsky (Brighton, England)
Use of industrial diamonds in HPLC
High-performance liquid chromatography (HPLC) is a leading technique used for quantitative analysis. Potential applications of a novel porous disperse diamond (PDD) phase in HPLC have been studied. This phase has shown the best separation characteristics in pure water. The PDD column works efficiently in both normal-phase and reverse-phase HPLC systems. This column mainly separates components via hydrogen bonding and weaker hydrophobic interactions. Being superior to any other stationary phase in mechanical strength and being chemically stable within a wide range of pH, porous diamonds have interesting potential for use in HPLC.
UDC 544.6.076.32
G. V. Zhutaeva (Moscow) M. A. Marinich, G. P. Bogatyreva, E. V. Ishchenko (Kiev) I. S. Chernyshova, M. R. Tarasevich (Moscow)
Electrocatalysis on electrodes based on promoted ultradispersed diamond
The surface state of ultradispersed diamond, both initial and heat-treated, was studied using mass spectrometry. Thermal desorption spectra allowed us to estimate the state and amount of oxygen, water, CO and CO2 adsorbed on its surface. An assumption was made about the significant role of ultradispersed diamond in the pyrolysis of porphyrin deposited on it. It is shown that the electrocatalytic properties of promoted ultradispersed diamond in the reaction of oxygen electroreduction make the obtained composite material a promising catalyst for the oxygen electrode of a fuel cell.
UDC 548.33
S. K. Gordeev (St. Petersburg)
Carbon nanocomposite materials from nanodiamond: production and properties
A method for producing carbon composite materials from nanodiamond is considered, the essence of which is that a blank formed from nanodiamond powder is processed in a hydrocarbon medium, thereby synthesizing a pyrocarbon matrix that binds nanodiamond particles into a single carbon nanocomposite. The obtained materials have high porosity, which is capable of adsorbing low-molecular substances (benzene, water). Electrophysical studies have shown that the nanocomposites have a semiconductor nature of conductivity, depending on the pyrocarbon content. The properties of composites during electron emission and adsorption of medicinal systems are presented.
UDC 539.89
V. T. Senyut (Minsk)
Features of joint heat treatment of UDA and non-diamond carbon under various p, T-conditions
Joint heat treatment of ultradispersed diamond with non-diamond carbon (graphite) was performed in a wide range of pressures and temperatures. It was shown that the structure and properties of materials obtained on the basis of ultradispersed diamonds depend on the type of non-diamond carbon, its dispersion, the method of its introduction into the batch and the conditions of heat treatment. The ability of ultradispersed diamonds to activate phase transformations in non-diamond carbon was established and the possibility of obtaining fibers and particles on their basis under conditions of reduced pressures was shown.