UDC 620.22
AND. F. Lysovsky
Institute of Superhard Materials named after IN.N.Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
lisovsky@ism.kiev.ua
Theory and practice of the formation of mesostructures in composite materials. Review (pp. 3‒23)
The scientific foundations of the formation of mesostructures in composite materials have been developed. According to the structural feature, these materials are divided into four classes, each of which has unique features of structure formation. Thermodynamic studies determined the conditions for the formation of equilibrium mesostructures, especially the mass transfer of the liquid phase during the interaction of mesoelements and the matrix, and substantiated the conditions for obtaining mesostructures in nanodispersed composite materials. The peculiarities of obtaining mesocompositions in each of the selected classes are considered. It is shown that the creation of mesostructures in composite materials allows to significantly improve the properties and operational characteristics of these materials and makes a technical breakthrough in various areas of technology.
Keywords: mesostructure, composite material, thermodynamics, mass transfer.
UDC 666.233
IN. Yu. Dolmatov1,*, A. AND. Malygin2, A. AT. Dorokhov3, A. WITH. Kozlov1, V.AND.Marchukov1, V. G. Sushchev1, V. Myllymäki4, A. Vehanen4
1Federal state unitary enterprise “Special design and technological bureau “Technology”, St. Petersburg, Russia
2St. Petersburg State Technological Institute (Technical University), St. Petersburg, Russia
3AO “Plastmass Plant”, Kopeysk, Chelyabinsk Region, Russia
4Carbodeon Ltd. Oy, Mr. Vantaa, Finland
*diamondcentre@mail.ru
Development of the process of obtaining detonation nanodiamonds using tetryl and binary compositions based on it (pp. 24‒38)
The technology for obtaining detonation nanodiamonds (DNA) from individual compounds (tetryl, picric acid) and binary compounds with a tetryl content ≥ 50% (by mass) was developed, the yield of DNA up to 7.5% (by mass) was achieved. The main regularities of the dependence of DNA yield on the content of tetryl with TNT, hexogen, and picric acid were found. The dependence of the DNA content in the diamond charge on the composition of the explosive substance and the pressure in the Chapman-Jouget plane was determined.
Key words: detonation nanodiamonds (DNA), tetryl, picric acid, TNT, hexane, sensitivity to external effects of explosives, binary charges, armoring of the charge, Chapman-Jouget pressure, diffractogram.
UDC 539.234:621.921.34:665.723:661.96:661.939.3
Biao Deng, Qiuping Wei*, Mingkun Yi, Yijie Luo, Liang Li, Kechao Zhou, Li Ma
State Key Laboratory of Powder Metallurgy, School of Powder Metallurgy, Central South University,Changsha, China
*qiupwei@csu.edu.cn
The influence of the interaction of CH4/H2/Ar gas ratios and the distance between the hot filament and the substrate on the growth of nanocrystalline diamond (pp. 39‒50)
Due to the special shape of the cutting or grinding tools used today, the presence of a gap between the hot filament (HGN) and the substrate is usually inevitable in the process of chemical vapor deposition of diamond (HFCVD), which leads to a complex process of deposition of nanocrystalline diamond (NCA). To solve this problem, the influence of the interaction of CH4/H2/Ar gases in various ratios and the distance from the ANN to the substrate on the growth of NCA films was systematically studied. Scanning electron and Raman spectroscopy were used to analyze the surface morphology and phase content of sp3/sp2-diamond films applied to different areas of each sample. The results showed that the optimal increase in the distance between the ANN and the substrate and the concentration of CH4 or Ar stimulates the growth of NCA. At a lower concentration of CH4 or Ar, the deposition of NCA with homogeneously sized grains can also be realized in a certain distance from the ANN to the substrate.The graph demonstrating the growth conditions of MCA, MCA/NCA and NCA was obtained by creatively summarizing deposition parameters and experimental results.A method of applying NCA using the HFCVD method on cutting or grinding tools of a special shape is presented.
Key words: chemical vapor deposition, nanocrystalline diamond, distance from the hot filament to the substrate, grain size.
UDC 621.315
IN.AND. Chasnyk1, D.IN. Chasnyk2, I.P. Fesenko3, O.M. Kaidash3
1State Enterprise “Orion” Research Institute, Kyiv, Ukraine
2Ukrainian Research Institute of Special Equipment and Forensic Examinations of the Security Service of Ukraine, Kyiv, Ukraine
3V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
igorfesenko@ukr.net
Study of Thermal Conductivity, Resistivity and Microwave Radiation Absorption of Freely Sintered AlN–Y2O3–Mo and AlN–Y2O3–TiN Composites (pp. 51‒65)
The compositions of highly thermally conductive AlN–Y2O3–Mo, AlN–Y2O3–TiN composites intended for bulk microwave energy absorbers in deceleration systems were selected. The thermal conductivity, resistivity and electromagnetic energy absorption of freely sintered AlN–Y2O3–Mo and AlN–Y2O3–TiN composites were determined.
of AlN composites with different volume contents of conductive Mo and TiN particles.
Keywords: free sintering, aluminum nitride, molybdenum, titanium nitride, thermal conductivity, electrical resistance, absorption of electromagnetic energy, retarding system, volumetric absorber of microwave energy.
UDC 546.26-162:620.178.152.341.4
S. M. Sichkar
Institute of Metallography named after G. V. Kurdyumov, NAS of Ukraine, Kyiv, Ukraine
stmj@ism.kiev.ua
Pressure-induced metallization of diamond at room temperature (pp. 66‒82)
Four different methods were used to test the hypothesis of a possible numerical equivalence between diamond hardness and critical metallization pressure. The initial calculation of the external pressure during modeling of crystal distortion under uniaxial tension gives the lower limit of the critical pressure value Pm(1) = 213 GPa. This value was compared with semi-empirical results obtained on the basis of Penn’s dielectric model, Pm(2) = 187.67 GPa. The Vickers hardness Hv(1) = 92 GPa was experimentally determined, and a semi-empirical approach was used for comparison. Within the Penn model, the theoretical value of diamond hardness is Hv(2) = 92.22 GPa.
Keywords: diamond, metallization, hardness, critical pressure, Penn model.
UDC 534.631:539.32
L. N. Devin*, N. P. Bezhenar, S. IN. Rychev, Ya. M. Romanenko
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*ldevin350@gmail.com
The effect of charge granularity on the impact strength and damping characteristics of BN–Al composites (pp. 83‒93)
The impact strength and damping characteristics of the cBN–Al system composites depending on the specific surface area (granularity) of cubic boron nitride powders were investigated. A correlation was established between the damping characteristics of the composite and its phase composition. The dependence of the phase composition of the composite on the specific surface area of the initial cBN powders is shown. Composites with a two-phase structure and the highest density and hardness for such a structure have the maximum impact strength.
Keywords: polycrystalline superhard materials, cubic boron nitride, dynamic strength, specific surface of the initial charge, acoustic emission, damping characteristics.
UDC 621.921.34-492.2:621.793.6:544.023.5:539.215
G. A. Petasyuk, O. O. Bochechka*, V. I. Lavrinenko, V. G. Poltoratsky, V. P. Bilochenko, D. V. Sokolyuk
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*petasyuk@ukr.net
**bochechka@ism.kiev.ua
Pycnometric-additive method for determining the degree of coverage of grinding powders of superhard materials using an extrapolation-affine 3D grain model (pp. 94‒99)
The methodological components of determining the degree of coverage of grinding powders of synthetic diamond are analyzed. It is noted that the most common weight method for determining this characteristic has its own prerequisites and cannot be applied to all coating methods. As an alternative to the weight method, a pycnometric-additive method for determining the degree of coating of grinding powders of superhard materials using an extrapolation-affine 3D grain model and additional sieve separation is proposed. The results of applying the proposed method to determine the degree of coating of grains of synthetic diamond grinding powders with boron oxide and tungsten are shown.
Keywords: coating, degree of coating, volume, grinding powder, 3D grain model, pycnometric ratio, additive property.