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Section 5. Materials Science
Rasulov Alisher Khakimovich, Tashkent State Technical University, Senior scientific researcher, the Faculty of Mechanics and Machine building E-mail: [email protected]
Bakhadirov Kudratkhon Gayratovich, Tashkent State Technical University, Senior scientific researcher, the Faculty of Mechanics and Machine building E-mail: [email protected]
Umarov Erkin Adilovich, Tashkent State Technical University, Associate professor, the Faculty of Mechanics and Machine building
Khodjakhonov Yunus Bayram ugli, Bachelor student, the Faculty of Oil and Gas
Implementation of technology production of composite tools of super-hard materials
Abstract: In the article provided information on super-hard materials composite tools production technology. Based on powder metallurgy result of research works created superhard composite of diamond material intended to equip the tool for various purposes is operated in conditions of intense abrasive effect and significant dynamic loads. Keywords: super-hard materials, diamond, powder materials, hard alloy cutting and shaping tools.
Introduction
Scientific and technical progress, increasing of labor productivity, improve product quality, reduce production costs, save labor and material resources to a large extent depends on the use of composite materials containing synthetic super-hard materials in combination with metals and alloys.
As a result of research works created superhard composite of diamond material intended to equip the tool for various purposes is operated in conditions of intense abrasive effect and significant dynamic loads. The materials in this class are tvesal — is a composition of fine powders of synthetic diamond, orderly distributed in the tungsten carbide group - based material.
Objects and methods of research
Super-hard composite of diamond tool material manufactured by powder metallurgy. This method has broad possibilities for the formation of specific, predetermined properties. Manufacturers super-hard composite materials of diamond tools for different purposes a lot of attention is paid to the preparation and processing of diamond raw material, preparing a powder charge, the patterns of distribution of diamonds since the volume of the cutting element, the consolidation of the structural elements to form lasting contacts between them. Typical, a solid diamond grains. Robust single crystals of synthetic diamonds are selected when they are sorted according to their magnetic properties and are classified according to the shape and roughness of the surface.
Synthetic diamonds are sorted, using the flotation separation of grains containing less than 0.2 % impurities. Also, there sonica-tion in molten salts, which are destroyed thermally unstable grains.
The process of preparing the diamond grains comprises degreasing the surface and applying to them the metal coating. A method for carburizing coatings to incomplete saturation.
For the production of super-hard composite of diamond content tool material mixture used carbide powders with alloying elements. Prepare batch mixers in a system such as "drunken" barrel.
Used to form the blend of the non-working items super-hard composite of diamond content tool material, granulated. For this carbide mixture is mixed in a screw mixer with a 12 % a solution of synthetic rubber in gasoline. Prepared charge after drying rubbed over the net on the shaker.
For obtaining products of super-hard composite tool material of diamond content predetermined configuration and dimensions using graphite mold. Graphite form largely determine the complexity of manufacturing tools and the stability of its properties. The use of graphite due to its high strength and production of super-hard composite of diamond instrumental material used graphite brand EG-0.
Molding is the charge on the sample packaging, consistent filling them in the mold and cold pressing.
The sintering process carried out in a hydrogen environment, a two-zone furnace with a graphite heater. The temperature and duration of heating should exclude complete carburization of tungsten carbide to the stoichiometric composition.
The principal difference between super-hard composite materials of diamond content of diamond tools is that the destruction of the material is due to the simultaneous action of both diamond and carbide matrix. Carbide forming crimped "bed", promoting diamonds with stand heavy dynamic loads.
Section 5. Materials Science
Planned studies will be used to study the method of powder metallurgy to create super-hard composite of diamond content tool material, which can not only be used directly powder metallurgy method by which to obtain a wear-resistant, shock-resistant structure that will make it possible to use this method:
• Industry;
• Mechanical engineering.
The purpose of the study of the theoretical foundations of the possibility of creating composite super-hard of diamond content tool material for cutting tools by powder metallurgy.
Scientific results and their analysis
A compound in a single composition on the properties of two different tool materials makes possible entrainment tool life — 32 times in working conditions of intensive wear and considerable dynamic loads.
The reliability and performance of cutting tools are determined, mainly, the state of the cutting part is the most wear out quickly. Increased durability of the cutting elements of tools is one of the basic and effective ways to increase resource performance. This would improve the quality of the tools is guaranteed, and at the same time, the need to cover the industry of the Republic of Uzbekistan due to increased longevity.
Scientific work is provided to analyze and develop the creation of super-hard composite of diamond content tool material by powder metallurgy for metal-cutting tools, unparalleled in practice. It is, first of all, it is necessary for the machine-building industry of the Republic of Uzbekistan.
The basic idea is presented, proved at appropriate scientific conferences and publications. However, its specific solutions require analytical work on the improvement of progress suggested in the patent applications and publications on this topic.
Proposed project, which includes innovative investment solutions and production and economic issues the engineering industry in the use of new methods of obtaining metal-cutting tools.
The results can be applied to other fields of industry for the production of any requiring increase hardness and wear resistance of tools.
To accomplish this work there is a good reason: a number of completed and protected at conferences of scientific papers on the subject. This line of work has no analogues in the near and far abroad.
To perform the work on this direction has the necessary conditions: the scientific and technical personnel, material-technical base of the Faculty of Mechanics at the Tashkent State Technical University, the necessary office equipment, communication with the scientific schools in the near and far abroad.
Analysis of the results showed that the component life is increased by 2-3 times.
Thus, at this point the following practical results were obtained:
- theoretical analysis of the process of formation in particles super-hard composite of diamond content tool material;
- enter improvements in plasma-chemical plant by the use of a new type of reactor, resulting in improved performance. The morphology and structure of ultrafine tungsten powders. It is shown that powders of ultrafine micro distorted levels 2-3 times higher than standard;
- researched effect of annealing temperature on the hydrogen and vacuum structure and phase composition ofpow-ders and their subsequent reactivity. Proposed thermal treatment regimes for passivation powders;
- questions of structural dynamics, realogy and macro kinetics sintering of fine particles;
- proposed pressing and sintering carbide mixtures modes and tools, made on the basis of super-hard composite of diamond content instrumental material. The objective is to create a diamond-bearing material allowing expand the range of its application by varying its composition and properties, such as strength, hardness, wear resistance and other mechanical properties, as well as the method makes it relatively easy to obtain such material.
Catalytic synthesis method at high static pressures and temperatures of the hexagonal graphite phase (C) (fig. 1) small particles of synthetic diamond cubic phase were obtained (fig. 2).
Fig. 1. Graphite hexagonal
Fig. 2. Nitride crystal lattice
Color from black to white. Depending on the manufacturing technology synthetic diamond can be translucent or opaque. For the same boron and nitrogen technology is received modification of boron nitride BN, on the structure and properties resembling synthetic diamond. The crystal lattice — cubic, hardness is slightly lower than that of diamond, but still very high: 40-45 GPa., i.e. more than twice higher than that of hard alloys, and almost twice as high hardness cutting ceramics... Polycrystalline cubic boron nitride (PCBN) is sometimes called "Borazon" "cubanite", "Borazon". Modulus boron nitride at E = 700-800 GPa., compressive strength approximately same as that of hard alloys: b = 2.5 -5 GPa. and lower than that of hard alloys and polycrystalline diamond, tensile strength bending: s bend = 0.6-0.8 GPa.
Heat stability of cubic boron nitride is much higher than that of synthetic and natural diamonds: about 1000-1100 °C. For this reason, and also in connection with less chemical affinity to carbon, cubic boron nitride is more effective than diamond and hard alloys for finishing machining steel, especially of hardened steels at cutting of high hardness and small sections of the shear layer.
From diamond micro powder brand ACM 28/20 (GOST 9206-80) preparing the charge. To this end, diamond powder binder is added — 20-25 % alcohol solution of phenol formaldehyde resin brand SF-010-A (GOST 18094-80) in an amount of 2-4 wt. % dry resin of the mass of diamond powder. The charge was thoroughly mixed and triturated twice through a sieve of 0.25-0.30 mm. cell.
Forming sample 20-25 mm. in diameter and 2.3 mm. high compression is performed using a batch test portions of the metal mold. A weighed sample is placed in a mold and molded at room temperature with a force of 40-45 kN. Forming removed further from the mold and allowed to stand in air at room temperature for 10 hours and then dried at 70 °C for 1 hour and claim at 150 °C for 1 hour. The thus obtained preform comprises 98 mas. % of diamond and has a porosity of 47 vol. %.
The heat treatment is carried out blank in a vacuum (pressure — 0.1 mm. Hg.), 1550-1600 °C at temperature for 4 min. Such heat treatment conditions allow graphitize diamond particles of 14 wt. %.
The impregnation is carried out semi silicon alloy — titanium, containing 12 wt. % Titanium. The impregnation is carried out by melting the alloy on the surface of said semi-finished product when 1550-1600 °C.
The result is a product, a tablet diameter and 20-25 mm. in height of 2-3 mm. of diamond material, wherein the diamond grains linked matrix comprising silicon carbide, titanium carbide and silicon alloy — titanium (titanium silicide).
Comparative testing of samples for wear treatment ofAPC-dia-mond wheel 150 x 20 x 32 without coolant showed that the samples have a wear resistance substantially equal to the wear resistance of the samples is similar, but which used to impregnate the pure silicon (the known technical solution). The flexural strength of the material obtained, measured by a biaxial flexure 15-20 % above known material not containing titanium compounds.
Thus, the implementation of the claimed method makes it relatively easy to obtain diamond-bearing materials in the form of complex parts and large size. The use of silicon alloys provides an intensification of the process semi-impregnation. Thus, due to the introduction of the additional material of other compounds formed during the implementation of the method, the materials obtained have wider field of use by allowing for selection of optimal formulations erosion and abrasion resistance. Furthermore, the presence of material adhesively-active metal soldering facilitates the manufacture of the tool, and increases the durability of the tools in two times in comparison with analogues.
A comparative study of the mechanical properties of tools for different purposes, made from standard powders and mixes with super-hard composite diamond content instrumental material.
Calculations showed that the expected economic benefit from the implementation of instruments made with super-hard composite diamond content tool material is 400 million sum per year.
References:
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