UDC 678.044:678.063
V. Yu. Dolmatov (St. Petersburg)
Polymer-diamond composites based on detonation nanodiamonds. Message 3
The effect of diamond charge and nanodiamonds on the physicomechanical and physicochemical properties of polymer composites based on polyurethane foam, frost-resistant butadiene-nitrile rubbers, polycarbonates, rubbers resistant to explosive decompression and polymer coatings obtained by gas-plasma application is shown.
The introduction of diamond charge into polyurethanes leads to an increase in compressive strength, and into butadiene-nitrile rubbers – to an improvement in the most important performance characteristics (friction coefficient, wear resistance, elasticity, frost resistance), which ensure high durability. Introduction of diamond charge into rubbers resistant to explosive decompression increases tear resistance (by ≈ 60 &8240;) and abrasion resistance (by ≈ 40 ‰). Introduction of nanodiamonds into polycarbonates leads to an increase in tensile strength, the energy of polymer failure increases significantly.
UDK 546.264:547-304
V. D. Blank, D. V. Batov, B. A. Kulnitskiy, E. V. Polyakov, I. A. Perezhogin (Troitsk, Moscow Region, Russia) D. A. Podgorny, Yu. N. Parkhomenko (Moscow, Russia)
Y-junction bamboo-like CNx nanotubes
The method for the production of multiwall Y-junction bamboo-like CNx nanotubes by the resistive heating of graphite is described. Different branched bamboo-like CNx nanotubes have been observed. A possible mechanism for the formation of branched nanotubes is proposed.
UDC 621.922.079
V. I. Kushch, S. A. Ivanov, A. L. Maistrenko, V. P. Pereyaslov (Kiev)
Study of the mechanism and kinetics of compaction of a porous body during intensive electrosintering. Message 2. Theoretical model of shrinkage and its verification
Theoretical models are proposed to describe the compaction of a porous plastic material during cold pressing and pressing with heating in a process cell. Their experimental verification is carried out, confirming the adequacy of the theoretical model of shrinkage, as well as the reliability of the initial data and properties of the materials used in the calculations. Satisfactory agreement between theoretical and experimental data opens up the possibility of using the modeling results to solve problems of predicting and optimizing the technological parameters of the intensive electrosintering process.
UDC 666.233
V. K. Genchel, A. V. Kucherov, A. I. Sizov, T. M. Zvukova, B. M. Bulychev, V. G. Babaev, M. B. Guseva (Moscow)
Synthesis of Various Carbon Modifications during Thermolysis of Poly(hydrocarbyne)
The conditions for the transformation of poly(hydrocarbyne) into various carbon modifications were studied. It was shown that the activation of the rearrangement of its carbon skeleton by metallic potassium leads to the formation of potassium hydride and carbyne. Submicron diamonds and fcc carbon formed jointly with graphite and glassy carbon were obtained during the thermolysis of poly(hydrocarbyne) under high pressures (3.0–8.0 GPa) and temperatures (900–1500 °C).
UDC 544.3:621.762
A. F. Lisovsky (Kyiv)
Thermodynamics of Particle Consolidation in a Three-Phase System
Using the Gibbs thermodynamic method, thermodynamic functions describing the consolidation process in a three-phase system consisting of particles of phases 1, 2 and mobile phase 3 were obtained, and an expression for the shrinkage pressure arising during the consolidation of particles was obtained. Based on the thermodynamic functions, criteria were proposed that allow predicting the structure of a composite heterophase material.
UDC 661.65:661.55
V. I. Kushch, S. N. Dub, P. M. Litvin (Kyiv)
Determination of Young’s Modulus from the Elastic Section of the Berkovich Indenter Penetration Diagram
A new method for determining the local elastic modulus is proposed, based on a comparison of nanoindentation data with the results of numerical modeling of contact interaction in the indenter-sample system. An atomic force microscope image of the Berkovich indenter imprint in a material with low elastic recovery was obtained and the geometric parameters of the equivalent indenter in the form of a body of revolution were determined, which are necessary for an adequate formulation of the model contact problem. A method for determining Young’s modulus by solving the inverse problem of elasticity theory from the condition of the best agreement between the experimental and calculated penetration diagrams is proposed. The data presented in the paper show that taking into account the real shape of the Berkovich indenter tip provides a higher accuracy of elastic modulus measurements in nanoindentation compared to known methods.
UDC 553.653:538.95
I. Kh. Abdukadirova (Tashkent)
Features of Changes in Optical Spectra of Neutron-Irradiated Leucosapphire Crystals
The dose and temperature dependences of the formation and discoloration of absorption bands in the visible region of the spectrum of leucosapphire single crystals processed in the reactor core are described, reflecting the features of the change in the optical spectra of the material as a function of flow and temperature. When removing the above dependences in the process of high-temperature isochronous annealing of the irradiated The main stages and substages of color bleaching at 460, 570, 620 nm were revealed in the studied crystals, and the occurrence of negative annealing of these bands at some temperatures was detected. The stage-by-stage nature of the defect formation process was established, the activation energies and concentrations of the corresponding centers were determined, and an assumption was made about their nature. A power law was revealed that describes the radiation kinetics of the generation of the 460 nm color center and 540 nm photoluminescence, and a single mechanism of defect formation responsible for the induction of these bands was assumed. The causes influencing the course of the dose dependences of the luminescence intensity as the neutron fluence increases are discussed.
UDC 621. 9.014.8
L. S. Sidorenko (Kiev)
Calculation of the length, height, and edge radius of a build-up adhering to a tool
An analysis of models and formulas for calculating the sizes of contact pads on the front surfaces of a tool, known in the theory of cutting, was carried out. Based on the rheological properties of materials and some laws of cutting theory, a basic mathematical model for determining the size of the build-up has been developed. Two options for calculating the height of the build-up and the edge radius are given depending on the size of the areas under variable cutting conditions, the geometry of the tool, and the mechanical properties of the material. An example of calculating the size of the build-up using new formulas is given, which give an error, in comparison with experimental data, of no more than 23 ‰, which confirms the adequacy of the proposed model.
UDC 621.295.26.724
A. P. Umansky, V. P. Konoval, I. A. Podchernyaeva, A. D. Panasyuk, Ya. N. Gladky, O. N. Makovkin (Kiev)
Wear resistance of tool steel KhVG, hardened with a coating of composite material based on double titanium-chromium carbide
Using an automatic wear measurement system, a study was conducted on the wear resistance of tool steel KhVG, hardened with a coating of composite material based on double titanium-chromium carbide. The effect of application methods (electric spark alloying and plasma spraying) and process modes on the wear resistance of steel with a coating is considered. The composition and structure of the friction surface of the samples are studied. Optimum operating modes of the coatings, as well as the most effective methods of their application for work under experimental conditions are established.
UDC 621.922.34
M. N. Sheiko, V. N. Skok, A. G. Lubnin (Kyiv)
Main characteristics of the abrasive-diamond layer of dressing tools
It is shown that a dressing roller or stone as a single-layer abrasive-diamond tool can be characterized, like a multilayer one, by two independent parameters – grain size (it is sufficient to indicate the upper sieve) and conditional concentration. The remaining characteristics (surface density of the sample, specific number of diamonds) are uniquely determined using these two parameters according to theoretically substantiated and experimentally confirmed dependencies. Limit values of the amount of diamond powder on the surface of a single-layer and multilayer tool are established, differing from the data of other authors.
UDC 661.8…22:539.89
V. L. Solozhenko (Paris) K. Lathe (Hamburg)
On the melting point of B6O