To the 100th anniversary of G.A. Meyerson 70 years from setting up of the chair of less-common metals and powder metallurgy at MISiS
Preface- Strizhko V.S., Libenson G.A., Rakova N.N. To 70 years from setting up of the chair of less-common metals and powder metallurgy
- Klyachko L.I. The reflections about G.A. Meyerson
Lobova T.A. A series of G.A. Meyerson’s works on production of refractory metal powders by electrolytic refining in salt solutions of products from reduction of complex less-common raw materials
A review is given of works made by G.A. Meyerson on development of new technologies of refractory-metal powder production from the products of low-temperature reducing decomposition of titanium-niobium-zirconium concentrates by electrolysis of soluble anodes in salt melts. The paper discusses G.A. Meyerson’s contribution to the theory of thermodynamic calculations of solid-phase reduction reactions of pure refractory metal oxides by carbon, calcium carbide and cyanamide with participation of nitrogen as well as electrochemical extraction of components using soluble anodes made of titanium, niobium, and zirconium carbides, carbonitrides, and silicides.
Medvedev A.S., Rakova N.N. Mechanoactivation in tungsten hydrometallurgy
The paper summarizes the results of researches made by the chair of less-common metals and powder metallurgy of Moscow State Steel and Alloys Institute (Technological University) in the field of tungsten mineral mechanoactivation prior their hydrometallurgical decomposition by soda, alkali, and nitric acid solutions. An outlook of application of planetary centrifugal mills is shown for intensification of production processes.
Voldman G.M. The effect of mixed polyanion formation on separation of molybdenum and tungsten by extraction from subacid solutions
An analysis is made for equilibrium of molybdenum cation-exchange extraction from subacid solutions under conditions of mixed polyanion formation and rate of the process with different limiting stages (decomposition of mixed polyanions with releasing molybdenum, molybdenum diffusion to the aqueous/organic phase interface, reaction along the interface). At high tungsten content, both distribution coefficient and extraction rate are shown to be inversely proportional to tungsten concentration irrespective of the limiting stage.
Medvedev A.S., Molchanov S.A. Sorption refinement of tungsten acid from sodium
The paper represents experimental data on sorption refinement of tungsten acid, isolated from sodium tungstate solution by acidification, from sodium ions. A process flowsheet providing residual Na+ content H2WO4 less than 0,001 % is proposed.
Yermilov A.G., Rakova N.N. On possible mechanism of tungsten carbidizing treatmentThe effect of different factors (activity of initial components of charges, their homogenization degree, carbon/tungsten ration, introduction of oxidant into reaction zone) on the process of tungsten monocarbide formation is considered. On the basis of the researches carried out, a conclusion is made on the process of multistage carbidizing treatment of metalloorganic mixture that contains carbon and tungsten (MOCW): MOCW ®W + C ®WCFCC + C ®W2Chex + C ®WC. It is noted that separation of tungsten carbidizing treatment stages in time furthers the increase in carbon diffusion coefficient and consequently the decrease in process temperature and its duration.
Powder Materials and CoatingsPanov V.S. G.A. Meyerson is an establisher of the production of domestic hard alloys and powder high-speed steelsG.A. Meyerson’s works in the field of scientific bases and the technology of hard alloys and powder high-speed steel are annotated. His role in development of the first domestic hard alloy «Pobedit»as well as refractory metals: tungsten, molybdenum, titanium, and their carbides is noticed. It is shown that owing to the researches made under the direction of G.A. Meyerson, VK8Ta, VK12Ta, T15K6«3K»hard alloys of improved grades and the high-speed steel cutting waste processing were developed.
Narva V.K. Carbidosteels represents a new generation of hard alloys
Different processes of production of carbidosteels and improvement of their properties after sintering have been studied. The carbidosteel coating applying processes onto steel basis by plasma sputtering, electrocontact baking, and diffusion welding under vacuum were studied.
Levinsky Yu.V. Thermodynamics of processes related to producing refractory titanium compounds
Professor G.A. Meyerson’s contribution to development of thermodynamics concerning the processes of production of refractory titanium compounds is discussed. The main achievements in the theory of thermodynamic calculations of the reactions with participation of condensed phases of varying composition and high dispersion ability are considered. The ways of the further development in this field of the thermodynamics are outlined.
Pedos S.I., Pustov Yu.A., Radyuk A.G. The modes of formation of gas-thermal aluminum coatings on copper affect on their operating characteristics
The results of studying the structure and properties of aluminum coatings produced by gaseous metallization on copper basis are given. Improved operating characteristics of the surface composition (hardness, wear resistance, corrosion resistance) can be obtained by homogenizing annealing in the air in the temperature range of 973-1073 K for 2-4 h and the following deformation by rolling in the range of e= 8¸15 % depending on starting coating thickness.
Shelekhov E.V., Pripisnov O.N., Rupacov S.I. Diffusion and phase-formation in mechanoactivated Cr-C, Cr-Si, Cr-B systems
Diffusion behavior of the carbide, silicide, and boride formation mechanism during the processing of Cr-C, Cr-Si, and Cr-B mixtures in the planetary centrifugal mill (activation time of every mixture was 12-43, 9-60, and 6-40 min respectively with ball:material ratio of 20:1) was experimentally proved. The data accord with the conception that a dispersed «roll»is formed during mechanoactivation from intermittent layers of mixture components being about 1000 Å in thickness, that is comparable with the carbon, silicon, and boron diffusion length in chromium at the experimental temperatures. It is noted that the diffusion along the dislocation tubes and grain boundaries, energy of which is about half of that for intra-grain diffusion, can give a significant contribution in the total diffusion constant.
Yermilov A.G., Safonov V.V., Nesterov N.V. Formation of protective nickel coatings on small-size articles produced by powder metallurgy
Substrate thermocycling is shown to enable producing dense coatings under thermal decomposition of metal carbonyls even on a highly developed surface, for example, of articles produced by powder metallurgy. The process parameters optimization of which provides for sufficiently high metal output into the coating: up to 90 % are found. The coating is shown to form not only on the external surface of an article but also on the inner surface of the substrate macrodefects.
Surface engineering. Multifunction films. Corrosion and metal protection
Levashov E.A., Ralchenko V.G., Yasinsky S.A., Vlasov I.I., Spitsyn B.V. Plasmachemical deposition of polycrystalline diamond films on functionally graded diamond-containing materials produced by SHS
Multilayer functionally graded hard composites with TiB2 + TiSi2 or TiC + SiC + Si matrix have been used as substrates for diamond film deposition by microwave plasma enhanced CVD technique. The substrates produced by self-propagating high-temperature synthesis (SHS) contain 8/16 mm HPHT diamond particles of gradually changing concentration to minimize the residual stress in the SHS product. The impregnated diamond particles in the composite carry out several functions: (a) increase the matrix strength, (b) act as nucleation centers upon CVD diamond growth, and (c) improve adhesion of diamond coating because of the anchor effect. The structure of the substrate and coatings were characterized with Raman spectroscopy, SEM, and XRD analysis. Being under thermal (compressive) stress of about 1 GPa the diamond films yet exhibit a good adhesion. No significant difference in growth and properties of diamond films on the composites with different matrix was noted. The diamond-based composites coated with CVD diamond may be of practical interest primarily in tool manufacturing.
