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Date submitted2018-10-28
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Date accepted2018-12-30
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Date published2019-04-23
Development and research of formation technologies on specialized presses with subsequent sintering of high-density details from iron-based powders
- Authors:
- A. M. Dmitriev
- N. V. Korobov
- A. Zh. Badalyan
Creating shifts of the lyaers in a deforming workpieces improves the quality of the product produced by pressure treatment. qual-channel angular pressing and precipitations of a cylindrical billet with a rotating turnaround were developed by specialists earlier and became basic for scientists engaged in nanotechnology. One of the most modern schemes for creating nanostructures by processing on presses is the «Cyclic Extrusion Compression» scheme (in Russia – «Hourglass»), which has significant drawbacks. To date, research on the creation of layer shifts in compacted metal powders is substantially less than in compaction of compact blanks. The article developed compaction schemes for presses of blanks from iron-based powders that have a certain analogy with the «Hourglass», while lacking the disadvantages inherent in the named scheme and implemented on the created samples of specialized hydraulic presses. The results of the studies of density, strength and microhardness before sintering the samples molded from a number of domestic and imported powders on iron base, including those doped with carbon and other alloying components, are described. It has been established that with the use of the formation schemes for powders providing large shifts between particles, the density of the preforms increases on average by 10-12 %. With an average stress (16.32 MPa) of the transverse section of the molded specimen prior to its sintering, molding with shifts between particles increases this stress by 78 %. The strength after sintering of samples made using the compaction schemes developed by the authors of the article increases approximately by 2 times. Magnetic pulse treatment (MPT) of a molded sample prior to its sintering increases its resistance to shearing before sintering, regardless of the molding pattern. When MPT of both the powder and the molded sample is executed, the most uniform distribution of microhardness in the sample is achieved, and after subsequent sintering, the most uniform distribution of the mechanical characteristics of the product. The results of all studies are described by regression equations.
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Date submitted2009-07-18
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Date accepted2009-09-08
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Date published2010-04-22
Influence of rock disturbance on their rheological properties
Complex investigations have been conducted of rheological properties of undisturbed and disturbed rocks under laboratory conditions in the modes of creeping, relaxation and lateral pressure. It was stated that the rheological properties of disturbed rocks substantially differ from those properties of undisturbed rocks. Recommendations are given for the use of the obtained results in solution of tasks in mining geomechanics.
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Date submitted2009-07-23
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Date accepted2009-09-09
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Date published2010-04-22
Physical modeling of energy exchange in rock mass
- Authors:
- E. V. Lodus
- E. V. Goncharov
The cause of manifestation of dangerous dynamic phenomena, such as rock bursts, earthquakes, etc., appears to be the energy exchange in rock mass. The inaccessibility of rock mass for carrying out the full-scale observations has stimulated to study this problem with using the methods of laboratory modeling. Description is given to the substance of energy exchange in situ, the principles of its physical modeling in the laboratory, to the test equipment as well as to some results of our investigations.