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Date submitted2021-10-15
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Date accepted2022-09-06
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Date published2022-11-10
Experimental research on the thermal method of drilling by melting the well in ice mass with simultaneous controlled expansion of its diameter
- Authors:
- Danil V. Serbin
- Andrey N. Dmitriev
During the seasonal work of the 64th Russian Antarctic Expedition in 2018-2019 at the “Vostok” drilling facility named after B.B.Kudryashov (“Vostok” station, Antarctic) specialists of Saint Petersburg Mining University conducted experimental investigations on the process of drilling by melting with simultaneous expansion of wells in the ice mass. A test bench and a full-scale model of a thermohydraulic reamer-drilling tool were developed, manufactured and tested for the research. The first bench tests of the full-scale model proved its efficiency and suitability for experimental drilling with simultaneous expansion of wells in ice mass; its operational capabilities were determined and the drawbacks that will be taken into account in future were found out. The article substantiates the choice of constructive elements for thermohydraulic reamer-drilling tool. It is determined that the technology of full diameter drilling with simultaneous expansion of the well in ice mass can be implemented by combining contact drilling by melting and convective expansion with creation of forced near-bottomhole annular circulation of the heated heat carrier. Dependencies of expansion rate on main technological parameters were determined: active heat power of heating elements in penetrator and circulation system, mechanical drilling rate, pump flow rate. According to the results of investigations, the experimental model of thermohydraulic reamer-drilling tool will be designed and manufactured for testing in conditions of well 5G.
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Date submitted2019-07-11
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Date accepted2019-09-04
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Date published2019-12-24
Recent scientific research on electrothermal metallurgical processes
- Authors:
- E. Baake
- V. A. Shpenst
A wide range of industrial metallurgical heating and melting processes are carried out using electrothermal technologies. The application of electrothermal processes offers many advantages from technological, ecological and economical point of view. Although the technology level of the electro heating and melting installations and processes used in the industry today is very high, there are still potentials for improvement and optimization due to the increasing complexity of the applications and the strong requirements regarding the performance and quality of the products but also regarding the reduction of time and costs for the development of new processes and technologies. In this paper recent applications and future development trends for efficient heating and melting by electrothermal technologies in metallurgical processes are described along selected examples like induction heating for forging or rolling of billets, heat treatment of strips and plates, press-hardening processes, induction surface hardening of complex geometries, induction welding as well as induction melting processes.
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Date submitted2019-01-16
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Date accepted2019-03-07
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Date published2019-06-25
Sintered sorbent utilization for H2S removal from industrial flue gas in the process of smelter slag granulation
- Authors:
- A. B. Lebedev
- V. A. Utkov
- A. A. Khalifa
Authors suggest removing hydrogen sulfide from the hot industrial gas at temperatures 200-300 °C and its subsequent interaction with Fe 2 O 3 . For this purpose the following sorbents have been proposed: a mixture of iron oxide and fly ash; iron oxide and pumice; different samples of red mud (bauxite treatment residues containing iron oxide). To prevent dusting and loss of absorbing capacity, the sorbents were shaped into porous granules with other metallic oxides. Materials utilized in the study were obtained the following way: mixing of Fe 2 O 3 with fly ash; sintering of the mixture with red mud. The blend contains aluminum oxide and silica, which can act as matrix shapers, alkali oxides and fluxing agents that reduce the temperature during metal sintering. After the samples had been saturated with sulfur, they were positioned in a venting reservoir, where under the temperature 600-700 °C desorption to the initial state occurred by means of passing an air flow through the sorbent layer. In the process of this operation, sulfur dioxide was released and reactive metal oxides re-emerged. Desorption also generated a small amount of elemental sulfur and sulfuric acid. Absorbing capacity was assessed at higher temperatures, efficiency of H 2 S removal reached 95-99.9 %. Proposed technology of air cleaning is recommended to use in metallurgic processes with elevated atmospheric pollution, e.g. granulation of melted blast-furnace slag.
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Date submitted2017-10-31
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Date accepted2018-01-01
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Date published2018-04-24
Peculiarities of formation and growth of nanodispersed intermetallic strengthening inclusions in rapidly-solidified alloys of Al–Mg–Zr–X-system
- Authors:
- D. I. Budelovskii
- S. Yu. Petrovich
- V. A. Lipin
The paper is devoted to the influence of the fourth element on the microstructure of the rapidly-solidified alloys of the Al–Mg–Zr-system. Alloys were additionally doped with high-melting-point metals Ti, Hf, W, and Nb. In the structure of all samples in the immediate area of the cooled surface, uniformly distributed intermetallic inclusions of several nanometers in size were detected. Such a structure can be represented as a dispersion-strengthened composite. A quantitative metallographic analysis was carried out to quantitatively describe the structure of the obtained particles of the cooled melt. The obtained rapidly-solidified alloys can be described as dispersion-strengthened composite materials with the aluminum-magnesium alloy matrix and the intermetallic particles strengthener. Depending on the alloying component, these particles differ in shape (spheres, plates, agglomerates) and in size (from 200 nm when alloying with Hf and W up to 1.2-1.5 μm with Ti and Nb alloying). The X-ray phase analysis (XPA) showed that in the studied alloys of the Al–5Mg–1.2Zr–(0.5÷2.0)X-system, high cooling rates of melts lead to the formation of new intermetallic compounds that are absent in equilibrium systems. The example of an alloy with hafnium additive shows that an increase in the content of the alloying component (from 0.5 to 2 % by mass) leads to an increase in the volume ratio of intermetallic inclusions (from 5 to 12.8 %). At the same time, their shape and average size remain unchanged. The additional alloying component will improve the mechanical characteristics of aluminum alloys by increasing the recrystallization threshold of a rapidly-solidified alloy.
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Date submitted2015-12-13
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Date accepted2016-02-23
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Date published2016-12-23
Properties isotropy of magnesium alloy strip workpieces
- Authors:
- R. Kavalla
- V. Yu. Bazhin
The paper discusses the issue of obtaining high quality cast workpieces of magnesium alloys produced by strip roll-casting. Producing strips of magnesium alloys by combining the processes of casting and rolling when liquid melt is fed continuously to fast rolls is quite promising and economic. In the process of sheet stamping considerable losses of metal occur on festoons formed due to anisotropy of properties of foil workpiece, as defined by the macro- and microstructure and modes of rolling and annealing. The principal causes of anisotropic mechanical properties of metal strips produced by the combined casting and rolling technique are the character of distribution of intermetallic compounds in the strip, orientation of phases of metal defects and the residual tensions. One of the tasks in increasing the output of fit products during stamping operations consists in minimizing the amount of defects. To lower the level of anisotropy in mechanical properties various ways of treating the melt during casting are suggested. Designing the technology of producing strips of magnesium alloys opens a possibility of using them in automobile industry to manufacture light-weight body elements instead of those made of steel.
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Date submitted2014-10-15
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Date accepted2014-12-14
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Date published2015-08-25
Formiing of structure and properties of sheet strips from magnesium alloys in the conditions of twin roll casting process
- Authors:
- R. Kavalla
- V. Yu. Bazhin
In this article the problem of receiving high-quality cast strips from the magnesium alloys received by units of twin roll casting process in the combined methods is discussed. Production of sheets from magnesium alloys combination of casting and rolling at continuous giving of liquid melt to the rotating rolls is perspective and more economic method. Features of crystallization of magnesium alloys of AZ31 and AZ61 in a gap of rolls crystallizers depending on heat exchange conditions at change of technological parameters are considered. Due to impact on melt in forming system it is possible to provide formation of equal fine-grained structure of sheet hire without superficial defects. Development of the production technology of sheets from magnesium alloys creates possibility of their use of automobile branch as the facilitated details of bodies instead of the knots made of steel.