UDC 678.044:678.063
V. Yu. Dolmatov (St. Petersburg)
Polymer-diamond composites based on detonation nanodiamonds. Message 2
The effect of diamond-containing charge and detonation nanodiamonds on the physical and mechanical properties of polymer composites based on polyisoprene, butadiene-styrene and polysiloxane rubbers is shown. The introduction of diamond-containing charge provides higher strength properties and greater fatigue endurance of the composites. Cohesive strength increases by 1.3-2.0 times, tear resistance – by ≈ 2 times.
The use of composite nanofillers with diamond-containing charge in polysiloxane leads to an increase in strength parameters by ≈ 1.7 times.
UDC 621.922.079
V. I. Kushch, S. A. Ivanov, A. L. Maistrenko, V. P. Pereyaslov (Kiev)
Study of the Mechanism and Kinetics of Porous Body Compaction during Intensive Electrosintering. Message 1. Laboratory Research
The article presents the results of laboratory research on the identification of the mechanism of porous body consolidation during intensive electrosintering. A computer data acquisition system has been developed to analyze the kinetics of the process, providing for the measurement of voltage, current, and shrinkage of samples in real time. It has been proven that the main mechanism of compaction during intensive electrosintering of powder material blanks in the solid phase is thermally activated plastic deformation. A method for assessing the degree of consolidation of a powder compact is proposed, based on a comparison of experimental data on electrical conductivity with model representations of composite mechanics.
UDC 621.762:544.722
E. K. Sevidova, V. I. Kononenko (Kharkiv)
Assessment of ceramic coatings for bioengineering purposes by the wetting method
The studies of wettability of coatings with saline (0.9 ‰ NaCl), including ceramic ones, promising for use on bioengineering products, were conducted. It was found that all types of the considered coatings increase the wetting angle of the surface compared to the original metal materials (12X18N10T, VT6, Co—Cr—Mo alloy), which serves as a prerequisite for improving the biocompatibility index of implants. The degree of bioinertness increases in the series of coatings: titanium nitride -> diamond carbon films -> aluminum nitride -> titanium oxide (anodic oxide film) -> aluminum nitride (oxidized) -> aluminum oxide -> titanium oxide (anodic spark coating).
UDC 546.26:545.345.67:539.216
T. V. Semikina (Kiev)
Study of diamond formation processes in glow -> spark discharge
The production of diamond microcrystalline particles 1.5-5 μm in size during a discharge with direct current in a hydrogen atmosphere (100 Torr) is described. As a result of studying the Raman spectra of the particles and their structure, it was established that they are diamonds with different habit forms. The obtained particle growth rates (≈ 5 μm/s) are uniquely high. It is shown that the particles do not grow on the substrate, and a hypothesis is put forward about their formation through the liquid phase of carbon. Particles with new features in their spectra near 819, 1063 and 1320 cm-1 are detected. A sharp intense peak near 1320 cm-1 is characteristic of an agglomerate of ultradispersed diamond.
UDC 537.312:553.65:553.612
I. Kh. Abdukadyrova (Tashkent)
Comparative study of the effect of γ-radiation on the electrical parameters of oxide dielectrics
The effect of ionizing radiation on the electrical properties of oxide dielectrics is studied. A comparative analysis of the temperature dependences of electrical conductivity of non-irradiated and irradiated samples of three types of oxide dielectrics was performed: aluminum oxide, silicon dioxide, and corundum ceramics in the temperature range of 200-700 K. The obtained data were compared with the features of thermoradiation modification of the dielectric parameters of oxides. The patterns of change in the dielectric loss tangent and permittivity as a function of temperature and g-radiation dose in a large range were determined. The values of the peak conductivity parameters of ceramic samples were calculated. An assumption was made about the nature of the observed features of the temperature and dose dependences of the electrical properties of oxide dielectrics and a possible mechanism of their conductivity. UDC 621.922.029:661.65
V. S. Ptashnikov (St. Petersburg)
Metal dispersion in the structure of specific grinding work
For the first time, the work of metal dispersion (absolute values and dynamics of its change in the structure of specific grinding work) by a CBN tool on a polymer bond was isolated and quantitatively estimated using a new technique of three experiments. It was found that the specific work of metal dispersion varies in a wide range: from a maximum of more than 50 ‰ of grinding work to a minimum of its smallest part. The work of metal dispersion is easy to control and monitor in accordance with the described technique. Exogenous and endogenous methods for reducing the work of dispersion and improving