UDC 669.27
N. V. Novikov, V. P. Bondarenko, V. T. Golovchan (Kyiv)
High-temperature mechanical properties of WC-Co hard alloys (review)
The article presents experimental results of laboratory studies of high-temperature mechanical properties of WC-Co hard alloys depending on the parameters of the structure (cobalt content, average sizes of carbide grains and cobalt interlayers), composition of the binder (content of carbon and cubic carbides) and the nature of the thermal force effect. The effect of high temperatures on deformation characteristics under bending, tension and compression is analyzed. The problems of short-term and long-term strength (heat resistance) and thermomechanical fatigue are discussed. The identified mechanisms of high-temperature deformation are noted.
UDC 544.3:621.762
A. F. Lisovsky (Kyiv)
On the application of thermodynamics for the study of nanoparticles
The analysis of the methods of J. V. Gibbs, L. M. Shcherbakov, T. Hill for the thermodynamic description of the state of nanoparticles is carried out, the applicability limits of each of the considered methods are determined. It is shown that the developed methods allow one to describe the state of nanoparticles in the entire range of their sizes from the lower limit, which corresponds to the size of the nucleus of a new phase, to particles with the properties of a macrophase.
UDC 666.11.01:621.921-419
S. A. Kukharenko, A. E. Shilo, E. K. Bondarev, V.N. Tkach (Kyiv)
Study of diffusion processes in silicate multicomponent systems for creating CBN composites
The main results of the study of diffusion processes in silicate multicomponent systems are presented and summarized.
It is shown that by regulating the processes of interpenetration of ions that develop in glass-forming systems, by varying the compositions and heat treatment modes of multicomponent glasses, it is possible to obtain glass composites for instrumental purposes with the necessary physical and mechanical properties.
UDC 621.922.079
V.I. Kushch, S.A. Ivanov, A.L. Maistrenko, V.P. Pereyaslov (Kyiv)
Study of the mechanism and kinetics of compaction of a porous body during intensive electric sintering. Message 3. Prediction of shrinkage kinetics and comparison with experiment
A theoretical model and software tools for predicting the shrinkage of metal powder blanks both at the stage of cold pressing and during their intensive electric sintering have been developed. The shrinkage model is supplemented with heat transfer equations during electric heating and formulated as an initial-boundary value problem that takes into account the features of the real technological process. The input parameters of the model are pressing pressure and current strength, as well as the electrothermophysical and mechanical properties of the pressed material. A parametric numerical analysis of the model and its comparison with experimental data have been carried out. Based on the results of the study, a simplified model has been proposed that ensures engineering calculations and the optimal choice of technological parameters for the intensive electric sintering process.
UDC 621.923.042
M. N. Sheiko (Kyiv)
On the issue of calculating the instantaneous temperature on the grain in a diamond dressing tool arising during its operation
Taking into account the features of the mechanical and statistical characteristics of the operation of an abrasive-diamond tool and its individual grains, various approaches to calculating the instantaneous temperature on the surface of diamonds for the conditions of dressing abrasive wheels with rollers and bars are proposed and analyzed. At the same time, an original analytical solution to the non-stationary thermal problem, asymptotic in the time of action of the source, is found.
UDC 622
A. L. Maistrenko, M. O. Bondarenko, V. G. Gargin, Ya. V. Kuntsyak, Yu. V. Dublenich, Ya. S. Gavrilov, O. T. Draganchuk, M. M. Yavorsky (Kiev), V. I. Vekerik, R. S. Yaremiychuk (m. Ivano-Frankivsk)
Ways to improve the efficiency of drilling robots to increase the production of oil and gas in Ukraine
The main results of theoretical research and design and industrial developments on the creation and implementation of a complex of technologies, technical features and new materials to improve the efficiency of drilling robots are presented. There is an increase in the production of oil and gas with a way to renovate dead drills, conduct more straight and horizontal drills, and change the drilling quality of drilling holes.
UDC 621.922
A. A. Adamovsky (Kyiv)
Precision dressing of diamond tools
A dressing tool (adhesive-active roller) and a method for dressing diamond wheels with it are proposed. The temperature in the grinding zone was measured and its gradient in the contact zone between the diamond grain and the metal being processed was calculated.
UDC 621.93.026
S. S. Eroshin (Lugansk), G. A. Petasyuk (Kyiv), M. T. Tarashchansky (Lugansk)
The influence of axial rigidity of AKVR diamond cutting wheels on the non-flatness of cut-off plates
An analytical dependence was obtained that relates the axial component of the cutting force and the axial rigidity of a diamond cutting wheel with an internal cutting edge with the non-flatness of the cut-off plates. A qualitative and quantitative analysis of the adequacy of the obtained mathematical model. The results of the check are consistent with the experimental data on the measurement of geometric errors of the cut plates published in the literature.
UDC 519.688:536.2:669.018.25
N. V. Litoshenko (Kiev)
Algorithm for determining the ratio of the thickness of the cobalt layer to the size of the carbide grain based on the results of measurements in the plane of the section