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DEVELOPMENT OF PERSPECTIVE RESEARCHES OF OBTAINING TECHNOLOGY
OF LIGHT AND HEAT-RESISTING ALLOYS, THEIR APPLICATIONS AS COATINGS AND
UTILIZATION OF THEIR INDASTRIAL WASTES
Krasikov S.A., Doct. Sci. (Eng.), Gelchinski B.R., Doct. Sci. (Ph.-Mat.), Prof.
Institute of Metallurgy of Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia,
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On the example of researches at the Institute of metallurgy of Ural Branch of the Russian Academy of Sciences it is considered prospects of development of metallothermal technology obtaining of light heat-resisting alloys on aluminum - the nickel intermetallic basis, alloyed by refractory rare metals, and also to use of these alloys as coatings and utilization of their industrial wastes, in cooperation with the international scientific community.
3In the last decade in technologies of aircraft and space equipment development of processing light heat-resisting alloys on the refractory aluminum-titan-nickel intermetallic basis which have to compete on chemical and physic-mechanical properties with heavier Ni-superalloys is very demanded. The profile international conferences testifies that works on rational ways of obtaining such alloys, their use as coatings and utilization of their waste are carried out both in Russia and to others industrial countries (Germany, USA, Japan, China, Belarus).
Traditional ways of obtaining multicomponent heat - resisting alloys on a nickel basis provide briquetting of mechanical mixes of pure metals powders and further remelting of briquettes in vacuum or the inert atmosphere. Naturally, use of pure non-ferrous and rare metals assumes application of difficult multistage technologies for their production and leads to increase in cost of final materials. The preliminary variant of obtaining a semi-product of multicomponent alloys by joint metallothermal reduction of metals from their oxides in controlled temperature conditions can be more perspective and cheaper.
Development of an offered way was approved on the obtaining the two-component Al-alloys (50-60%) Ti and Al-(50-60%) Zr
a b
Fig. 1. Type of ingots of an alloy of Ti-Al and slag after melting in the resistance furnace (a) and the two-electrode arc electric furnace (b)
Similar examples of obtaining are available also on Zr-Al alloy
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5 а б
Fig. 2. Products of zirconium dioxide reduction by aluminum after melting in the resistance furnace (a) and in the induction furnace GM
16 440 of 15 kW (b)
6Patent of the Russian Federation N 2485194
7The regularities of obtaining two-component alloys were used at obtaining an alloy of (36-54%) Al-(16-22%) Ti-(26-39%) Ni by joint aluminotermic reduction of titanium and nickel oxides. Rather low (less than 0.1%) the content of oxygen and nitrogen is recorded In three-component alloys that can testify to insignificant presence at metal of nonmetallic oxide and nitride inclusions. Extraction in an alloy of Ni and Ti was, respectively, 93-99 and 80-90%.
Fig. 3. Slag and ingot of an alloy of Al-Ti-Ni after aluminotermic melting
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Fig. 4. Samples with Ti-Al-Ni covering on a steel substrate after a plasma spraying
Rather uniform layer of coverings of Ti-Al-Ni of 50-100 microns thick on all area of steel sheets is obtained. Researches of microhardness of coatings showed that their values were 700-1000 HV that in 5-7 times exceeded the microhardness of the main material of a steel basis. Tests of corrosion resistance of coatings samples in the camera of a salt fog showed their resistance to destruction within more than 2000 hours.
9Now the main direction of researches and technological developments on obtaining pure non-ferrous and rare metals and their compounds is connected with their extraction from raw materials. As a rule it is rather expensive multistage technologies being accompanied emissions of harmful substances in environment. When processing metal wastes (for example, rhenium-containing alloys on the nickel basis used for production of turbine shovels of aircraft engines), differing high durability, the developments connected with dissolution of these materials by a method of electrolysis in solutions of acids is known.
At the Institute of Metallurgy of UB RAS versions of anode dissolution of wastes of a heat-resisting alloy on the nickel basis, containing Cr, Co, Mo, W, Al, Ta, Nb, Re in solutions of nitric and sulfuric acids were approved. By results of experiences distribution of valuable elements between the main products of process – solution and slime was revealed. The executed research can form a scientific basis for development of perspective technology of processing of metal wastes of the heat-resisting alloys, allowing to extract valuable rare metals and to obtain the rhenium product suitable for production of catalysts.
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CONCLUSION
Development and increase of the efficiency of researches executed at the Institute of Metallurgy of UB RAS on creation of scientific and technological bases of obtaining the light and heat-resisting alloys on aluminum - nickel intermetallic basis, alloyed by refractory rare metals, and also use of these alloys in technology of the coatings put by a plasma method and processing of industrial wastes of rare metals alloys can be undoubtedly realized more effectively within the international scientific cooperation. The work was performed with financial support of the RFFI on the project 13-08-12111 ofi_m
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