UDC 669.017
S. V. Utkin*, V. Z. Kubliy, S. V. Sleptsov, A. A. Bondar, P. P. Levchenko, G. A. Osokin, T. Ya. Velikanova
Institute of Problems of Materials Science named after I. M. Frantsevich, NAS of Ukraine, Kyiv, Ukraine
*instron123@gmail.com
Solidus surface of the Mo–Ni–B system (pp. 3–19)
Alloys of the Mo–Ni–B system with a boron content of up to ~ 41% (at.) were obtained by arc melting, after subsolidus annealing they were studied by X-ray phase and differential thermal analysis, scanning electron microscopy with local X-ray spectral analysis and the melting onset temperature was determined by Pirani-Altertum. Based on our own experimental data and taking into account the literature data, the projection of the solidus surface of the Mo–Ni–B system in the Mo–MoB1.0–NiB~0.8–Ni region was first constructed.
Keywords: B–Mo–Ni, phase diagram, solidus, ternary boride, Mo2NiB2.
UDC 621.762.5
Delong Xie*, Haiqing Qin, Feng Lin, Xiaoyi Pan, Chao Chen, Leyin Xiao, Jiarong Chen, Peicheng Mo
Guangxi Key Laboratory of Superhard Materials, Chinese National Engineering Research Center for Special Mineral Materials, China Nonferrous Metal (Guilin) Geology and Mining Co., Ltd, Guilin, China
*xiedelonghn@foxmail.com
Microstructures and properties of Fe–Co–Cu pre-alloyed powder for geological diamond bits (pp. 20–30)
For geological diamond bits Fe–Co–Cu alloys are the new generation of metal matrix. In this paper, the Fe–Co–Cu pre-alloys with various chemical compositions were synthesized using the co-precipitation method, which were subsequently sintered at different temperatures. The structural, thermal and properties of the powders and its sintered materials were characterized by various techniques. X-ray diffraction studies indicated that solid solutions were formed for the alloys during the co-precipitation process. Microstructures of these pre-alloyed powders exhibited that the sintering process was facilitated by the irregular shapes, interconnected fine particles as well as the large surface areas. The thermal effects of the pre-alloyed powders were explored by differential scanning calorimetry.The optimal sintering temperature for each pre-alloyed powder was determined by the mechanical analysis. Scanning electron microscopic results show that the composition ratio of Fe and Cu had a significant impact on the microstructures of the sintered materials, and the 65%Fe–20%Cu–15%Co alloy reached the best surface coverage over the diamond bits.The drilling performances for various pre-alloyed powders were verified by micro-drilling experiments. Those results suggested that the 65%Fe–20%Cu–15%Co alloy exhibited the optimal performance for application in geological diamond drilling bits.
Keywords: pre-alloyed powder, sintering, co-precipitation method, geological diamond bit.
UDC 661.888.3:539.89:536
Jing Chang1,*, Nina Ge2, Ke Liu1, Xu He3
1College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu, China
2State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang, China
3Chengdu Textile College, Chengdu, China
*changjing0394@163.com
High pressure effects on structural, elastic and thermodynamic properties of tantalum mononitride (pp. 31–44)
The pressure effects on the structural, elastic and thermodynamic properties of tantalum mononitride in WC-type phase (i.e. WC–TaN) are investigated by the first-principles plane wave pseudopotential density functional theory method and the quasi-harmonic Debye model. The obtained equilibrium structure parameters and ground state properties are in excellent agreement with the experimental and other theoretical results. The calculations of the phonon dispersion curve and the density of phonon states verify that the WC–TaN is dynamically stable. A full elastic tensor and anisotropy behavior of the WC–TaN is also evaluated and discussed in the wide pressure range. The results show that WC–TaN is elastic anisotropy and mechanically stable up to 100 GPa, and the compression along c-axis direction is more difficult than along a-axis. The obtained superior mechanical properties show that WC–TaN is a promising candidate structure to be one of the ultra-incompressible and hard materials.Finally, by using the quasi-harmonic approximation model, we predicted the thermodynamic properties of WC–TaN under pressure and temperature. The heat capacity CV, Debye temperature θ, the thermal expansion α and the Grüneisen constant γ are obtained successfully in the ranges of 0–100 GPa and 0–2000 K.
Keywords: structural properties, elastic properties, thermodynamic properties, first principles; high pressure.
UDC 669.017.3
E. Viswanathan, M. Sundareswari*, S. Krishnaveni, M. Manjula, D. S. Jayalakshmi
Department of Physics (DST-FIST Sponsored), Sathyabama Institute of Science and Technology (Deemed to be University), Tamilnadu, India
*msundare.deanscience@sathyabama.ac.in
Theoretical investigation on the effect of boron on improving the hardness of zincblende-aluminum nitride and its mechanical, thermal and thermoelectric properties (p. 45–59)
In this paper, we present the outcome of ab-initio band structure study carried out on cubic phase ternary BxAl1–xN (x = 0, 0.125, 0.25, 0.5, 0.75, 0.875 and 1.0) alloys in order to analyze the elastic coefficients thereby the structural, thermoelectric, electronic, thermal, mechanical, and optical properties of these alloys. With the aim of enhancing the hardness of aluminum nitride (19 GPa), the present study on the proposed combinations reveal that B0.75Al0.25N (40.5GPa) and B0.875Al0.125N (49.5 GPa) alloys turn out to be superhard materials as their hardness surpasses 40 GPa. Further, B0.875Al0.125N alloy has been identified to serve as a good thermoelectric as it has a high Seebeck coefficient value of 240 μV/K and of melting temperature of 4282 K. Except for the binary compounds AlN and BN, all the other ternary alloys are predicted to be direct band gap materials. The density of states, band structure, charge density plot, various elastic moduli, Debye’s temperature, elastic wave velocity, dielectric constant, Seebeck’s coefficient and other properties of interest are discussed in this paper. The results are compared and found to agree very well with the available literature.
Keywords: III–V nitrides, superhard materials, covalent bonding, brittleness, Seebeck coefficient.
UDC 669.018.8:661.665:544.6
Chao Liu*, Yang Liu, Yunzhu Ma, Wensheng Liu, Yuehui He
State Key Laboratory of Lightweight and High Strength Structural Materials, Central South University, Changsha 410083, China
*mseliuchao@csu.edu.cn
Influence of µ-size WC on the corrosion behavior of ultrafine WC/WC–Co cemented carbides (p. 60–71)
The electrochemical behavior of ultrafine WC/µ–WC–Co alloy with different grain sizes of WC particles was investigated in 1M HCl and 1M NaOH solutions using potentiodynamic polarization and surface analytical techniques. Good linear grain size dependence existed for the corrosion current density (Icorr). Alloys with smaller WC exhibited better corrosion resistance. Addition of µ-size WC particles can weaken the corrosion resistance of ultrafine WC/µ–WC–Co cemented carbide. The corrosion mechanism is discussed based on the SEM and EDS analysis. The predominant dissolution of the Co particles as the binder phase in HCl solution as well as WC matrix remained at the tangent surface. The benefits of Co(OH)2 protective film can only be used in alkaline solution.
Keywords: cemented carbides, electrochemical behavior, corrosion mechanism.
UDC 669.018.841
Xiaoqiang Li1, Minai Zhang1, 2,*, Xiaojian Xia1, Ting Cao1, Liang Liang1, Huiyun Li3
1Guangdong Key Laboratory for Advanced Metallic Materials Fabrication and Forming, South China University of Technology, Guangzhou, China
2Chemical Engineering and Materials Science, University of California, Irvine, United States of America
3Dongguan hyperpowder Co. Ltd., Dongguan, China
*zhang.ma@hotmail.com
Corrosion behavior of WC–10 wt % Ni3Al composite in acidic media (p. 72–83)
The room temperature corrosion behavior of WC–10 wt% Ni3Al composite and WC–8 wt% Co hardmetal in various acidic solutions (1 M H2SO4, 1 M HCl and 1 M HNO3) were compared and investigated utilizing immersion test, electrochemical measurement and surface analytical techniques. The results show that in H2SO4 solution WC–10Ni3Al composite has a nobler free corrosion potential, lower corrosion current density (Icorr) values and intrinsically better corrosion resistance than WC–8Co. Notably, pseudopassivity was observed in the polarization curves of WC–10Ni3Al in both HCl and H2SO4 solutions. In addition, although WC–10Ni3Al is corroded much faster in HNO3 solution than in the other two mediums, it exhibits a superior corrosion resistance compared to WC–8Co. The corrosion mechanism of WC–10Ni3Al composites is dominated by Ni dissolution.
Keywords: WC–10Ni3Al composite, intermetallics, corrosion, polarization, pseudopassivity.
UDC 666.233
IN. Yu. Dolmatov1*, V. Myllymäki2, A. Vehanen2, A. AT. Dorokhov3, M.N.Kiselev3
1Federal State Unitary Enterprise “Special Design and Technology Bureau
“Technologist”, St. Petersburg, Russia
2″Carbodeon Ltd. Oy”, Vaanta, Finland
3 JSC “Plant “Plastmass”, Kopeysk, village Sovetov, Russia
*diamondcentre@mail.ru
Dependence of the yield of detonation nanodiamonds on the parameters of the detonation process (pp. 84–89)
To determine the dependence of the output of detonation nanodiamonds on the power of the explosives used, a new concept was introduced – the specific power of explosives (which is related to the speed of detonation and the pressure of gases in the Chapman-Jouget plane), which is equal to the ratio of the heat of explosion to a unit of mass and time. The dependence of the yield of detonation nanodiamonds on the detonation speed and pressure in the Chapman-Jouget plane was found. The optimal (> 5% (by mass)) yield of detonation nanodiamonds occurs at the value specific power of explosives 30000–60000 kJ/(kg×μs), detonation velocity 7250–8000 m/s, pressure in the Chapman-Jouget plane 21–28 GPa.
Keywords: detonation nanodiamonds, power of explosives, pressure in the Chapman-Jouget plane, yield of nanodiamonds, detonation velocity, heat of explosion, composition of explosive charges.
UDC 621.9: 621.923
V. I. Lavrinenko
Institute of Superhard Materials named after V.M. Bakul, NAS of Ukraine, Kyiv, Ukraine
lavrinenko@ism.kiev.ua
Porosity and water absorption of composites for instrumental purposes as factors for increasing the wear resistance of grinding wheels with NTM. Communication 3. Ceramic cutting composites (pp. 90–94)
It is shown for the first time that the presence of porous space in tool ceramics allows, due to water absorption, to influence the process of diamond processing of such ceramics, primarily to improve their machinability. It was established that for oxide-carbide ceramics the effective period of preliminary impregnation with water is 48 hours. For less porous ceramics the period of impregnation increases, for example, for oxide ceramics it is 96 hours, and for metal ceramics – 192 hours.
Keywords: oxide-carbide ceramics, oxide ceramics, water absorption effect, porous space, wear resistance.
UDC 621.762
V. P. Bondarenko, N. V. Lytoshenko
Institute of Superhard Materials named after V. M. Bakul, NAS of Ukraine, Kyiv, Ukraine
lytnat@ukr.net
Residual thermal stresses in a three-phase metal-ceramic composite with a layered structure of the refractory component (pp. 95–100)
The residual thermal stresses in a three-phase metal-ceramic composite with a layered structure of the refractory component (SiC grains covered with WC) were investigated using analytical methods. It was found that the level of residual thermal stresses in the considered alloys significantly depends on the composition and volume content of the interlayer phases and the bond. The results obtained for alloys with a high content of the binding phase are in good agreement with the data calculated using another numerical model.
Keywords: residual thermal stresses, three-phase metal-ceramic composite, phase composition, layered grain structure.