UDC 666.792.34:539.89
V. Z. Turkevich*, M. P. Bezhenar, A. M. Patsyk, D. V. Turkevich
V. M. Bakuly Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*vturk@ism.kiev.ua
Thermodynamic calculation of the phase diagram of the Al–B–N system at pressures up to 9 GPa (pp. 3-9)
Within the framework of phenomenological thermodynamics models, using the Thermo-Calc software package and using interaction parameters from literature data and the equation of state of competing phases, the phase diagram of the aluminum–boron–nitrogen system at pressures from 0.1 MPa to 9 GPa was calculated. Comparison of the calculation results with experimental studies of the phase composition of polycrystalline cubic boron nitride samples sintered at high pressures and temperatures showed their correspondence.
Keywords: phase diagram, high pressure, high-hardness composites.
UDC 621.921.34:544.225.2:539.25
Bin Tian, Wenyang Wang, Yong Xu*, Zhenxing Liu, Ruichao Ge
School of Materials Science & Engineering, Shandong Jianzhu University, Jinan, P.R. China
*xuyong2612@sdjzu.edu.cn
Study of the diamond/metal film interface and analysis of the valence electron structure of diamond growth (pp. 10-16)
The diamond/metal film interface was studied using transmission electron microscopy and electron backscatter diffraction. The properties of this interface are important in the graphite/diamond transition process, when a metal film from the Fe–Ni–C system covers diamond during its growth at high pressure and high temperature. The interface of the metal film is found to consist of γ-(Fe,Ni) and orthorhombic Fe3C, with γ-(Fe,Ni) present in tetragonal forms, the exposed surfaces of which are likely to be (001) crystal surfaces. The valence electron structures of Fe3C, γ-(Fe,Ni) and diamond are calculated, and the difference in relative electron density of diamond growth surfaces is analyzed using the empirical electron theory of solids and molecules. The relative electron density difference of the Fe3C/diamond interfaces is found to be continuous to the first order of approximation, indicating that carbon atoms decomposing from Fe3C can be converted into the diamond structure. The relative electron density difference of γ-(Fe,Ni)/Fe3C is found to be continuous. It is assumed that carbon atoms for diamond growth can arise as a result of Fe3C decomposition, and γ-(Fe,Ni) serves as a catalytic phase that promotes Fe3C decomposition.
Keywords: diamond/film interface, diamond growth, valence electronic structure.
UDC 620.22-621.921.34:539.422.25
B. T. Ratov1, E. Gevorkyan2, V. A. Mechnyk3, *, M. O. Bondarenko3, V. M. Kolodnitsky3, **, T. O. Prikhna3, V. E. Moshchil3, V. P. Nerubatsky4, A. B. Kalzhanova5, R. U. Bayamirov5, A. R. Togasheva5, M. D. Sarbopeeva5
1NAO “Kazakh National Research Technical University named after K. I. Satpayev”, Almaty, Kazakhstan
2University of Life Sciences in Lublin, Lublin, Poland
3Institute of Superhard Materials named after V. M. Bakul, NAS of Ukraine, Kyiv, Ukraine
4Ukrainian State University of Railway Transport, Kharkiv, Ukraine
5Caspian University of Technology and Engineering named after Sh. Yesenov, Aktau, Kazakhstan
*vlad.mechnik2019@gmail.com
**vasylkolod56@gmail.com
The influence of ZrO2 content on the strength characteristics of the matrix material of Salmaz‒(WC‒Co) composites manufactured by spark-plasma sintering (pp. 17-31)
In samples of the matrix material (94WC‒6Co) + ZrO2 of the same structure, differing in the ZrO2 content, used in Salmaz‒(WC‒Co) composite diamond-containing materials formed by spark-plasma sintering, the dependences of the relative density rrel, the compressive strength limits Rcm and bending strength Rbm, the microhardness НV and the fracture toughness KIс on the concentration of zirconium dioxide were established. The addition of 6% (by weight) zirconium dioxide to the composition of the WC‒6Co composite leads to an increase in the relative density from 0.948 to 0.990, an increase in the compressive strength Rcm from 4950±110 to 5600±120 MPa and bending strength Rbm from 1935±80 to 2660±115 MPa, as well as an increase in the fracture toughness KIс from 13.8±0.71 to 16.9±0.76 MPa·m0.5 with a slight decrease in hardness (from 15.9±0.72 to 15.1±0.33 GPa). Such indicators are due to the grinding of grains of the main phase WC and the transformability of the tetragonal phase t-ZrO2 and, accordingly, the strengthening of the role of the transformation strengthening mechanism, as well as the active action of internal mechanical compressive microstresses. With an increase in the ZrO2 addition to 10% in the composition of the WC‒6Co composite, the indicators rrel, Rcm, Rbm and KIc gradually decrease. At the same time, the material at the edge of the indenter imprint begins to collapse and cracks propagate chaotically. It was found that the deterioration of the properties rrel, Rcm, Rbm and KIc in the case of exceeding the concentration of zirconium dioxide nanopowder ZrO2 by more than 6% (by mass) in the composition of the WC‒6Co sample is associated with the formation of agglomerates in the process of mixing the components, their separation during sintering and the formation of micropores and microcracks.
Keywords: density, compressive and flexural strength, hardness, viscosity of ing, composite, tungsten carbide, cobalt, zirconium dioxide, spark-plasma sintering.
UDC 621.762
A. M. Stepanchuk1, *, I. V. Andreyev2, S. Yu. Teslya1
1National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”,
Institute of Materials Science and Welding named after E. O. Paton, Kyiv, Ukraine
2Institute of Superhard Materials named after V. M. Bakul, NAS of Ukraine, Kyiv, Ukraine
*anstepanchuk6@gmail.com
Features of obtaining molten tungsten carbide in low-temperature plasma under gas pressure and its properties (pp. 32-43)
The conditions for obtaining molten tungsten carbide in an arc furnace using a consumable electrode under different (up to 9 MPa) gas pressures in the working chamber were investigated. It is shown that during melting, tungsten carbide decomposes to obtain a product containing WC and W2C phases and free carbon. The results of the study of integral microhardness, grain crushing strength, wear resistance and abrasiveness are presented, which increase for carbides obtained at higher gas pressures. It is shown that by changing the melting conditions of tungsten carbide, the composition of the product and thus its properties can be regulated. The interpretation of the obtained results is given and a mechanism for the formation of the composition, structure and properties of tungsten monocarbide melted in low-temperature plasma is proposed from the point of view of the behavior of refractory compounds at supermelting temperatures.
Keywords: tungsten carbide, melting, gas pressure, abrasive properties, dissociation
UDC 675.92.026.79:621.921.34:541.124.7
Baoyan Liang, Yitong Luo, Wangxi Zhang, Jizhou Zhang, Mingli Jiao*
Materials and Chemical Engineering School, Zhongyuan University of Technology, Zhengzhou, P.R. China
*zwxlby@126.com
**357827404@qq.com
Spraying of a coating onto the surface of diamond particles at high temperature resulting from a thermal explosion reaction (pp. 44-52)
A new method for coating diamond particles is proposed, which consists in using the high temperature resulting from a thermal explosion reaction to induce the sublimation of volatile substances in the starting material with their subsequent deposition on the surface of diamond particles to form a coating using the example of a thermal explosion reaction of the Mo/Al/B2O3 system. It is shown that the high temperature resulting from the thermal explosion reaction can cause the evaporation of a certain amount of Al, which is deposited on the surface of diamond particles and reacts with a small amount of ambient oxygen to form Al2O3, and it is in this way that an Al–Al2O3 composite was deposited on the surface of diamond particles.
Keywords: coating, diamond, thermal explosion reaction, high temperature, sublimation.
UDC 621.793:661.882
S. A. Klymenko1, *, S. V. Lytovchenko2, S. An. Klymenko1, A. S. Manokhin1, M. Yu. Kopeikina1, A. O. Chumak1, Yu. O. Melniychuk1
1V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2V. N. Karazin Kharkiv National University, Kharkiv, Ukraine
*atmu@meta.ua
Properties of TiCN system carbonitride coatings obtained by vacuum arc deposition method (pp. 53-62)
The results of studies on the influence of the conditions for the formation of TiCN system vacuum arc coatings (shear potential applied to the substrate, partial pressure of nitrogen, composition of the gas mixture С2Н2, N) on their chemical composition, structure and its indicators (lattice parameter, texture indicator and its orientation, size of the OCR, level of microdeformations), mechanical properties (microhardness, adhesion strength indicators, friction coefficient) are considered. The obtained research results indicate that the coatings are mainly polycrystalline and have a cubic B1-NaCl structure with characteristic visible diffraction, peaks in the 2θ region from 30° to 80°, corresponding to reflections (111), (200), (220) and (222); depending on the С2Н2 concentration, the TiN lattice parameter increases from 0.4291 to 0.4301 nm, at the same time, the texture coefficient also increases from 5.91 to 5.97; depending on the С/N ratio, the hardness of the coatings at the shear potential Uzs = –200 V varies from 31.7 to 33.9 GPa; depending on the elemental composition of the coatings, the adhesion strength varies, and the fracture corresponds to the load F = 62.1 N, the friction coefficient µ = 0.45.
Keywords: vacuum-arc coating of TiCN, forming conditions, structure, microhardness, adhesion strength, friction coefficient.
UDC 621.923.7
Yu. D. Filatov
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
filatov2045@gmail.com
Material removal rate in the case of polishing parts made of polymethyl methacrylate (pp. 63-72)
As a result of the study of the mechanism of polishing polymethyl methacrylate using dispersed systems of micro- and nano-particles of polishing powders, it was found that the formation of particles of sludge of the processed material occurs as a result of the Förster resonant energy transfer between the energy levels of the particles of the polishing powder and the processed material, which occurs in an open microresonator formed by the surfaces of the processed of material and particles of polishing powder, in multimode mode. It is shown that the material removal rate during polishing of polymethyl methacrylate is determined by the total coefficients of volumetric wear and the total lifetime of the excited state of the clusters of the treated surface and the resulting Q factor of the resonator at all allowed frequencies of the discrete spectrum. It is established that the results of the theoretical calculation of the material removal rate during polishing of polymethyl methacrylate are in good agreement with the data of the experimental determination of the polishing productivity with a deviation of 1–3%.
Keywords: polishing, resonant energy transfer, material removal rate.
UDC 666.762.5:621.914.1
Jinpeng He1, Xiang Cheng1, *, Junfeng Zhang2, Chuanzhi Luo3, Guangming Zheng1, Yang Li1, Mingze Tang1
1School of Mechanical Engineering, Shandong University of Technology, Zibo, P.R. China
2Shandong Yishui Machine Tool Co., Ltd., Linyi, P.R. China
3Histrong Ceramics Co., Ltd., Zibo, P.R. China
*chengxsdut@163.com
Helix milling of small holes in fully sintered zirconia ceramics with PCD tools (pp. 73-93)
Fully sintered zirconia ceramics (ZrO2) are a typical difficult-to-machine material, and it remains a challenge to machine small holes in this material with high precision. PCD tools were used in the helix milling process to investigate this problem. A finite element model was created and a variable thickness cutting simulation was performed to identify the effect of axial depth of cut on cutting force and surface quality. A range of milling parameters for single-factor experiments was previously determined. With the milling force F as the evaluation index, single-factor experiments of helical milling of small holes using a PCD tool were conducted to determine the range of milling parameters (spindle speed n, feed per tooth fz, and axial depth of cut ap) for orthogonal experiments. Orthogonal experiments were conducted, where the surface roughness of the inner hole Ra and the crack width at the entrance to the hole Δw were taken as evaluation indices of machining efficiency. The estimated wear indicators of the PCD milling cutter were the width of the wear band of the front surface VA and the width of the wear band of the side surface VB. Using nonlinear regression analysis and range analysis, nonlinear models were constructed and the patterns of the influence of milling parameters on the estimated indicators Ra, Δw, VA and VB were obtained. The optimal combination of parameters obtained as a result of the analysis was analyzed for experiments on the optimization of small holes, which allowed to obtain better values of Ra, narrower Δw and longer tool life. The obtained results can be technical recommendations for milling small holes in fully sintered zirconia ceramics with PCD tools.
Keywords: screw milling, ceramics, small holes, surface roughness, crack width, tool wear.
UDC 621.923
V. I. Lavrinenko1, *, V. G. Poltoratsky1, O. O. Pasichny1, V. Yu. Solod2, **
1V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2Dnipro State Technical University, Dnipro, Ukraine
*lavrinen52@gmail.com
**v_solod@ukr.net
Application of diamond grinding powders with combined coatings on the surface of diamond grains in grinding tools (pp. 94-101)
A technological process has been developed for the formation of coatings on the surface of diamond grains from two and three components: soluble oxide B2O3 and insoluble oxide Al2O3 or insoluble carbide (B4C, SiC, TiC). It has been established that in order to achieve a guaranteed increase in the wear resistance of diamond wheels when grinding hard alloys, it is necessary to apply a coating of boron oxide and carbide (B2O3 + B4C) to the surface of diamond grains. The positive effect of such a coating of the surface of diamond grains is more pronounced at increased force and thermal loads in the grinding zone. The holding capacity of the processed rough surface according to the parameter of the t50 support surface curve is better in the case of coating the surface of the grains of diamond grinding powders AC6 125/100 with a mixture of B2O3 + B4C. That is, for diamond grains, both taking into account the wear resistance of diamond wheels and the indicators of the rough surface, it is recommended to use diamond grains with a coating of their surface with a mixture of B2O3 + B4C in the wheels when grinding hard alloys.
Keywords: combined protective coating, diamond grinding powders, surface of diamond grains, wear resistance of diamond wheels, roughness of the treated surface.