UDC 539.216:621.762
AT. N.Kaidash*, V. WITH. Turkevich, V. IN.Ivzhenko, P.P.Itsenko, V.N.Weaver
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*ivv@ism.kiev.ua
the influence of in situ formed TiB2–VB2 borides on the structure and properties of the hot-pressed ceramic system B4C–(TiH2–VC) (p. 3-13)
Composites of the B4C–(5–15%)(TiH2–VC) system were obtained using the reaction hot pressing method, their structural features were established, and their physical and mechanical parameters were measured. The resulting dense dispersion-strengthened materials with a high bending strength (Rbm = 420–580 MPa) and increased crack resistance (KIs = 4.1–4.8 MPa·m1/2) while maintaining a hardness of HKN = 19–20 GPa are promising for use in harsh abrasive wear conditions.
Key words: composite material, B4C, TiH2, VC, bending strength, Knoop hardness, crack resistance.
UDC 536.42:669.297
Yahya Al-Khatatbeh1,*, Khaldoun Tarawneh1, Hussein Al-Taani2, Kanani K. M. Lee3
1Department of Basic Sciences, Princess Sumaya University for Technology, Amman, Jordan
2School of Basic Sciences and Humanities, German Jordanian University, Amman, Jordan
3Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA
*y.alkhatatbeh@psut.edu.jo
Theoretical and experimental evidence for a post-cotunnite phase transition in hafnia at high pressures (p. 14-25)
Using first-principles density-functional theory (DFT) computations, we have predicted a new post-cotunnite (OII) phase of hafnia (HfO2) at high pressures. Our computations, using the generalized gradient approximation (GGA), predict a phase transition from OII to a Fe2P-type structure at ~ 120 GPa (~ 140 GPa) with a slight volume collapse at the transition pressure of ~ 0.2% (~ 0.1%) between the two phases using the second- (third-) order Birch-Murnaghan equation of state, respectively. The prediction of the new phase is consistent with recent experiments and computations performed on similar dioxides titania (TiO2) and zirconia (ZrO2) at extreme pressure-temperature conditions. Importantly, our theoretical prediction for the OII® Fe2P transition in HfO2 is experimentally supported by the re-analysis of X-ray diffraction patterns of HfO2 at extreme pressure-temperature (p, T) conditions. Additionally, the equation of state and hardness of the predicted phase have been computed and show that the Fe2P-type phase while less compressible than the OII phase is nearly identical in hardness, indicating that none of the HfO2 phases qualify as superhard.
Keywords: phase transitions, equation of state, hardness, first-principles, x-ray diffraction, phase stability.
UDC 620.178
P.IN.Kaplun1, E.B.Soroka2, *, A.IN.Snozik1
1Khmelnytskyi National University,Khmelnytskyi, Ukraine
2Institute of strength problems named after G. WITH. Pisarenko of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
*rym40a@gmail.com
The influence of hydrogen-free ionic nitriding on the physical, mechanical and operational characteristics of T5K10, T15K6 hard alloys (pp. 26-35)
It is shown that ionic nitriding of hard alloys in a hydrogen-free environment leads to an increase in the average value of microhardness to 20.1 GPa and a 15% increase in the breaking load during cantilever bending. When turning steels with nitrided plates, the friction coefficient and cutting force decrease to 10% of their values before nitriding, the intensity of wear is reduced by a factor of 2. The effectiveness of nitriding is confirmed by production tests during finishing and rough processing.
Key words: hydrogen-free ion nitriding, hard alloy, microhardness, cantilever bending, cutting force, thermo-EMF, coefficient of friction, intensity of wear.
UDC 66.091:661.888.2
Liangbiao Wang, Qianli Shen, Hengfei Qin, Dejian Zhao, Weiqiao Liu, Jianhua Sun, Binglong Zhu, Quanfa Zhou
*Jiangsu Key Laboratory of Precious Metals Chemistry and Engineering, School of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou, P. R. China
*lbwang@jsut.edu.cn
**labzqf@jsut.edu.cn
Chemical synthesis of niobium diboride nanosheets by a solid-state reaction route (p. 36-40)
A new process was developed to synthesize niobium diboride (NbB2) nanosheets with the dimension of about 500 nm and thickness of about 10 nm by using metal niobium, iodine and sodium borohydride as starting materials in a stainless steel autoclave at 700°C.Iodine was used to facilitate the exothermic reaction between metal niobium and sodium borohydride and the formation of NbB2.X-ray powder diffraction pattern indicated that the obtained product is hexagonal phase NbB2 with the calculated lattice constants a = 110 Å and c = 3.2929 Å. The obtained product was also studied by thermogravimetric analysis. It had good oxidation resistance below 400°C in air.
Keywords: solid state route, X-ray diffraction, niobium diboride, nanosheets, chemical synthesis.
UDC 621.9.025.7:661.657.5
Michał Ociepa*, Mariusz Jenek, Eugene Feldshtein Institute of Machine Building and Operation, University of Zielona Gora, Zielona Gora, Poland
*M.Ociepa@ibem.uz.zgora.pl
On the wear comparative analysis of cutting tools made of composite materials based on polycrystalline cubic boron nitride when finish turning of AISI D2 (EN X153CrMoV12) steel (p. 41-49)
This study presents the results of research on the condition of low content polycrystalline cubic boron nitride cutting tools (cBN-L) when finish turning of hardened AISI D2 tool steel. The least changes in the condition of wedges throughout the investigated turning feeds were observed for the composite cBN020, whereas the highest wear intensity was found for the composite cBN200. For all researched cutting materials, abrasive wear, as well as intense adhesion were observed.
Keywords: cBN-L, hardened steel, finish turning, wear, cBN coatings.
UDC 621.9.025.77:615.46:616.728
S. V. Sokhan*, A. L. Maistrenko, V. G. Sorochenko, V. V. Vozny, V. G. Kulych, M. P. Gamanyuk, E. M. Zubanev
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*svsokh@gmail.com
The influence of the processing mode on the diamond grinding performance of silicon carbide ceramic balls (pp. 50-64)
The results of an experimental study of the influence of the processing mode on the diamond grinding process of silicon carbide ceramic balls are presented, the indicators of which are the rate of reduction in the diameter of the balls, the rate of change (decrease/increase) of the deviation from the spherical shape and the rate of change in the size of the diameter of the balls in the batch. To isolate the fraction caused by the actual influence of the processing mode, the method of graphical approximation of the change in time of the average values of the accuracy indicators of the balls in the batch was applied. It was established that the isolated fractions can change both in the direction of increase and decrease depending on the values of the processing mode parameters, such as: the feed of the diamond wheel for cutting, the frequency of the wheel feed and the speed of rotation of the table with balls. As a result of conducting full factorial experiments of type 23, the most effective combination of the studied factors for correcting the shape of the balls was determined, which is different for three ranges of change of this deviation, namely: above 300 μm, within 150–300 μm, below 150 μm.
Keywords: ceramic silicon carbide balls, diamond grinding, diamond wheel feed for cutting, wheel feed frequency, table rotation speed with balls, diameter and deviation from spherical shape of balls, different sizes of ball diameters in a batch.
UDC 621.921.34–492.544.023.5:539.215
G. A. Petasyuk1, *, V. I. Lavrinenko1, **, Yu. V. Syrota1, ***, D. G. Muzychka2
1V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2Dnipro State Technical University, Kamianske, Ukraine
*petasyuk@ukr.net
**lavrinenko@ism.kiev.ua
***yatoris@gmail.com
Study of the trend and degree of change in the morphometric characteristics of standard synthetic diamond grinding powders of a continuous series of their grades and grain sizes (pp. 65-77)
A large array of experimental data obtained by the authors on the static strength and morphometric characteristics of standard synthetic diamond grinding powders according to DSTU 3292–95 was analyzed. Trends and the degree of change in the morphometric characteristics of such powders in a wide range of their grades and grain sizes were identified. A literature review on this topic was conducted, which confirmed the originality of the adopted statement of the problem under consideration. Directions for further development of such studies and their applied significance were formulated.
Key words: synthetic diamond, grinding powder, grade, grain size, morphometric characteristics, static strength.
UDC 621.9.02
AND. WITH. Manokhin1, *, S. AND. Klymenko1, S. An. Klymenko1, V. M. Beresnev2
1Institute of superhard materials named after V.N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
2 Kharkiv National University named after IN. N. Karazina MES of Ukraine, Kharkiv, Ukraine
*the.manokhin@gmail.com
Prospective types of coatings for tools equipped with polycrystalline KNB (p. 78-88)
Trends in the development of new types of wear-resistant coatings, including nanostructured ones, applied to tools made of polycrystalline KNB are considered. The main approaches to the creation of nanostructured coatings of high hardness, which are developing at the present time, are presented. On the basis of the analysis of the features of the wear of tools made of polycrystalline KNB, new approaches to the creation of promising wear-resistant coated systems have been identified: the selection of structural components of the coating, which act as a solid lubricant, which effectively reduces the intensity of tool wear; the introduction into the composition of the coating of compounds that are inhibitors of chemical interaction reactions in the treatment zone; reduction of the coefficient of friction and contact loads on the contact surfaces due to solid lubricants and working layers of the coating;ensuring the required structural condition of the coating.
Key words: wear-resistant coatings, PCNB, coating application, turning, tool wear.
UDC 666.3:539.5
I. P. Fesenko1,*, L. V. Viduta2, V. I. Chasnyk3, V. B. Nechytaylo2, D. V. Butenko2, V. M. Tkach1, V. Z. Turkevich1, O. A. Marchenko2, I. I. Zelenska2, O. M. Kaydash1, T. B. Serbeniuk1, T. M. Belyaeva1, E. F. Kuzmenko1, P. M. Tomchuk21V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2Institute of Physics, NAS of Ukraine, Kyiv, Ukraine
3State Enterprise “Orion Research Institute”, Kyiv, Ukraine
*igorfesenko@ukr.net
Structure and current-voltage characteristics of gold island films on highly thermally conductive free-sintered AlN ceramics (pp. 89-91)
The structure and electrophysical properties of gold island films on the surface of aluminum nitride are reported.
Keywords: free sintering, aluminum nitride, gold, island film, current-voltage characteristics.
UDK 544.65 : 539.233
A. A. Shulzhenko1, *, L. Yavorska2, **, A. N. Sokolov1, ***, L. A. Romanko1, V. G. Gargin1, N. N. Belyavina3, V. N. Tkach1, AND. P. Obstruction 1
1Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
2The Institute of Advanced Manufacturing Technology, Krakow, Poland
3Kyiv National University named after Taras Shevchenko, Kyiv, Ukraine
*alexshulzhenko35@gmail.com
**lucyna.jaworska@ios.krakow.pl
***kybor@ism.kiev.ua
Structure and electrophysical properties of the diamond–graphene–silicon carbide composite (pp. 92-96)
The influence of the addition of n-layer graphene Gn(4) and silicon nanocarbide during sintering under conditions of high pressure and high temperature with impregnation of the charge with silicon on the structure and electrophysical properties of the diamond composite was studied.
Key words: diamond, graphene, composite, structure, electrical resistance.