UDC 548.522:621.921.34-492.2
Tao Zhang1, *, Feng Qin1, **, Lijun Zhang2, ***, Li Gao2, ****, Fanghong Sun3, *****
1Mechanical Institute of Technology, Wuxi Institute of Technology, Wuxi, China
2School of Engineering Science and Technology, Shanghai Ocean University, Shanghai, China
3School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China
*zhangt@wxit.edu.cn
**qinf@wxit.edu.cn
***ljzhang@shou.edu.cn
****lgao@shou.edu.cn
*****sunfanghong@sjtu.edu.cn
HFCVD synthesis of boron-doped microcrystalline diamonds (p. 3–10)
Microcrystalline diamond powders are deposited directly by a HFCVD apparatus with adding amounts of trimethyl borate in the gas mixture. The study establishes the relationship between the boron concentration and growth behaviors of microcrystalline diamond particles. The results present that the addition of boron and oxygen atoms increases the growth rate of diamond crystals by a factor of 1.2–1.7, moreover, does not influence the morphology and grain density of diamond particles significantly.
Keywords: microcrystalline diamond particles, boron doping, growth rate, hot filament CVD.
UDC 669.018.25
M. M. Prokopiv
Institute of Superhard Materials named after V. M. Bakuly, NAS of Ukraine, Kyiv, Ukraine,
keramtex@ukr.net
Formation of a layered structure WC–(Cо,Ni,Al) on the surface of a cutting insert made of hard alloy WC–7(W, Ti)С–10Cо in the contact zone with the Ni3Al melt diamonds (pp. 11–20)
The discovery of a new type of structure on the surface of a cutting insert made of hard alloy WC–7(W, Ti)С–10Cо of the T5K10 brand after contact with the Ni3Al melt at 1530 °C in a vacuum is reported, which includes the outer WC–(Cо,Ni,Al) and the intermediate WC–(W,Ti)С–(Cо,Ni,Al) layers with variable chemical and phase composition in thickness. The maximum content and dimensions of the Co-based phase are characteristic of the structure at the boundary of the outer and transition layers, which are 1.7 and 2 times, respectively, higher than the similar indicators in the main structure of this sample. The formation of such a structure occurs by the release of W, C and a phase based on Co from the volume to the surface of the plate and the counter-absorption of Ni and Al from the Ni3Al melt. It is shown that the layered structure formed on the surface of the plate has residual microporosity, but at a lower level than in the main structure beyond the boundary of the surface layer, which also decreased compared to the level of microporosity in the structure of the original plate.
Keywords: hard alloy, melt, structure, phase, WC, (W,Ti)С, Co, Ni3Al, layer.
UDC 621.762.5:536.421.5
Tülay Yıldız*, Süleyman Aba
Fırat University, Faculty of Technology, Department of Metallurgical and Materials Engineering, Elazığ, Turkey
*tyildiz@firat.edu.tr
The effect of sintering temperature on wear resistance of alloys produced by using hot isostatic pressing method diamonds (p. 21–35)
The present study investigated the effect of the temperature, at which a new matrix material was produced via hot isostatic pressing (HIP) method by adding a certain rate of Co and Ni elements into CuSn (85/15) bronze alloy, and Co and Ni elements wear resistance of the samples produced. One of the major advantages of the HIP method is that heat and pressure are applied simultaneously during the sintering process. Thus, all or almost all of the pores are eliminated during manufacturing and a denser material is obtained. During the study, sintering pressure and sintering time were kept constant as 15 min, and also sintering temperature was selected to be 700 and 800 °C as the variable parameter. The sintering process was carried out under vacuum starting from the first burn. The produced samples were then prepared metallographically and SEM and EDS analyzes were performed for microstructure examinations. Microhardness of the samples was taken to investigate mechanical behaviors of the samples and they were subjected to wear test. Finally, the density test was applied to samples and their experimental and theoretical densities were calculated. In conclusion, it was seen that more homogeneous samples were obtained as the sintering temperature increased. As Co amount and temperature increased in the study, wear resistance increased.
Keywords: hot isostatic pressing, powder metallurgy, microhardness, abrasive wear.
UDC 666.233
IN. Yu. Dolmatov1, *, D. IN. Rudenko1, G. K. Burkat2, A. WITH. Alexandrova2, A. I. Vul3, A. THERE ARE. Aleksenskyi3, A. WITH. Kozlov1, V. Myllymäki4, A. Vehanen4, I.AND. Dyakov5, A. AT. Dorokhov6, M.N.Kiselev6
1 FSUE “Special Design and Technology Bureau “Technology” St. Petersburg, Russia
2St. Petersburg State Technological Institute (Technical University),St. Petersburg, Russia
3Physical and Technical Institute named after AND. F. Ioffe, St. Petersburg, Russia
4Carbodeon Ltd. Oy, Vantaa, Finland
5 Tambov State Technical University, Tambov, Russia
6 JSC “Plant “Plastmass”, Kopeysk, Russia
*diamondcentre@mail.ru
Investigation of the process of electrochemical deposition of gold in citric acid and phosphoric acid electrolyte in the presence of modified of detonating nanodiamonds (p. 36–47)
The use of modified detonation nanodiamonds in the most common gilding electrolytes (citric acid and phosphoric acid) makes it possible to increase microhardness by ~1.2 times and wear resistance by 3.6 times to the wear resistance of an almost non-abrasive coating, while preserving the electrolyte formulation, temperature, and current density that are characteristic of the basic technological process. It is recommended to reduce the coating thickness by 2-3 times.
Key words: electrochemistry, gold, citric acid electrolyte, phosphoric acid electrolyte, modified detonation nanodiamonds, phosphorus, monocrystalline nanodiamonds.
UDC 621.941
N. THERE ARE. Stakhnyv, L. N. Devin*
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*ldevin@ism.kiev.ua
Effect of cutting speed on temperature and force during finishing turning of non-ferrous alloys with cutters with round diamond carbide plates (pages 48–56)
The regularities of changes in temperature, cutting force, and roughness of the machined surface for different cutting speeds during finish turning of aluminum and brass alloys with a cutter with a diamond-hard alloy plate are established.
Key words: turning, aluminum alloys, brass, diamond-hard alloy plates, cutting temperature, cutting force, roughness.
UDC 621.9: 621.923
IN. AND. Lavrinenko
Institute of Superhard Materials named after V.M. Bakulya National Academy of Sciences of Ukraine, m. Kyiv, Ukraine
lavrinenko@ism.kiev.ua
Porosity and water absorption of tool composites as factors for increasing the wear resistance of NTM grinding wheels. Communication 2. Freezing of water in the porous space of NTM composites diamonds (pp. 57–61)
The conditions for using the porosity of abrasive composites from superhard materials in the process of water absorption and subsequent freezing of water in the composite are determined for the first time. It is shown how the physical and mechanical properties (hardness, strength indicators, electrical conductivity) of such composites change in this case. The peculiarities of the change in the wear resistance of the grinding tool during freezing are studied.
Keywords: abrasive composites with NTM, water absorption effect, porous space, freezing, wear resistance.
UCD 548.7:621.921.1
Y. Chen1, 2,*,X. Chen3, L. AIOuarab3,T. Opoz3,X. P. Xu2, G. Yu4
1College of Mechanical Engineering and Automation, Huaqiao University, Xiamen, PR China
2Ministry of Education Engineering Research Center for Brittle Materials Machining, Huaqiao University, Xiamen, PR China
3Faculty of Engineering and Technology, Liverpool John Moores University, Liverpool, UK
4Roll forging institute, Jilin University, Changchun, PR China
*42371502@qq.com
Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale diamonds (p. 62–76)
Distribution characterization of geometry shape and size of abrasive grits with high quality in tight size band and exact pattern is crucial for modern tool manufacturer to make fine powder abrasive tool and other powder tools, but complex to be classified and evaluated accurately due to the lack of scientific method. In contrast to industrial methods with sieving mesh size or simplified projection criteria with circumscribed (inscribed or escribed) circle or rectangle, a set of new systemic criteria is developed and validated by measuring three representative grits samples in micron scale under 2D/3D microscopy platform. The features of micron abrasive grits under morphology classification include a total of four groups, six sub-groups and eighteen sub-types in consideration of spatial geometry and statistical size distribution. For grinding performance analysis and simulation, it would be better to use a set of dominant volumetric geometries rather than use a single simple geometry. Furthermore, the significance of abrasive grit geometries in grinding performance is discussed.
Keywords: super abrasive grit, morphology analysis, characteristics categorization, microscopy technique, size distribution.
UDC 621.921.34–492.544.023.5:539.215
G. AND. Petasyuk
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
petasyuk@ukr.net
Methodological and applied features of indirect analytical determination of the thickness of the coating of grains of metallized powders of superhard materials diamonds (pp. 77–89)
A review of publications on the determination of the thickness of the coating of grains of metallized grinding powders of superhard materials was carried out. The approaches to the formulation of this problem were analyzed, and the methodological features of its solution were studied. The conducted studies showed that in the case when the actual 3D shape of the grain is a priori unknown, the most advanced approach is based on the use of the external specific surface in calculating the coating thickness. For the first time, it was proposed to use an extrapolation-affine 3D grain model in this calculation scheme. The advantage of such a 3D model compared to a 3D model in the form of a sphere or cube is proven using the example of the grinding powder AC125 400/315. The use of extrapolation-affine 3D grain models allow finding the thickness of the coating of grains of metallized diamond powders with a smaller error. The method proposed on the basis of such a methodological innovation can also be used for powders of other abrasive materials.
Keywords: metallization, coating thickness, indirect analytical methods, 3D grain model, external specific surface area, pycnometric ratio, volume additivity.
UDC 666.3:539.53
A. V. Kozyrev
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
artem.v.kozyrev@gmail.com
Mechanical properties of superconducting materials based on MgB2 diamonds (pp. 90–94)
The results of the study of the structure and mechanical properties of consolidated superconducting materials based on MgB2 obtained under conditions of high pressures and temperatures and hot pressing are presented. It was found that the formation of inclusions of higher borides phases with a stoichiometry close to MgB12 significantly affects the level of critical current density and mechanical properties of superconducting materials, in particular, leads to an increase in microhardness. The presence of Ti and SiC additives (10%), which positively affect the level of superconducting properties, is accompanied by a change in the mechanical properties of the materials, which indicates the influence of additives on the formation of MgB12 inclusions.
Keywords: magnesium diboride MgB2, higher magnesium borides, mechanical properties.