A method of obtaining a fine powder of an alloy of rhenium and molybdenum

 

(57) Abstract:

The invention relates to a method for producing fine powder (3 to 5 m) of the alloy of rhenium and molybdenum in the ratio of 1 : 1. The inventive process is conducted using a two-stage heat treatment bimetallic alloxanic composition ReOMoO(OCH3)7. The first stage of the heat - decomposition of the complex in air at 250 - Z00oWith over 1 to 2 h, and the second restoration of the amorphous phase in the atmosphere of hydrogen at 800 - 900oC for 2 - 3 hours, the Obtained powder of the alloy identified according to x-ray analysis and electron microscopy.

The invention relates to the metallurgy of rare metals and can be used to produce refractory alloy of rhenium and molybdenum.

Known methods for producing similar alloys;

the alloying powders of pure metals in a vacuum at a temperature of 2400oC for 1 h (the ratio of Re:Mo=1:1) [1]. The disadvantage of this method is the need to maintain vacuum and high temperature process;

sintering of powders of pure metals (ratio Re:Mo from 1:19 to 19:1), mixed on a ball mill in the continuation of 72 h at room temperature [2]. The t mode, theC - 100 hours In all cases according to x-ray phase analysis of the formation of alloys was full. The disadvantages of this method are the duration of the process, high temperatures and the need to use high-purity metal powders;

hydrogen reduction of a mixture of hexafloride metals (MoF6, ReF6in the gas phase at a temperature of 1540 - 140oC in the reactor special design [3] . This has resulted in powders of alloys with a specific surface area of 1.6-14 m2/, a Byproduct of the reaction is hydrogen fluoride. The disadvantage of this method is hard and extremely high chemical activity of the source hexafloride metals, requiring the use of special designs and materials of the reactor.

Closest to the proposed method is a method of obtaining powder of an alloy of Re and Mo, which are used as initial reagents joint aqueous solutions of molybdate and ammonium perrhenate [4]. As a first stage of processing carried out their evaporation to dryness prior to the formation of powder of dry salts. The second stage is the restoration of this powder in an atmosphere of hydrogen (H2) at 800-1000oC. Third stage audie powder, subjected to grinding, is sprayed through a high temperature plasma (>2000oC) to melt the particles and make them homogeneity.

The disadvantage of this method of obtaining powder of the alloy are uneven originally formed particles of alloy composition and size, and will require additional stages of grinding and homogenization at high temperature with the use of special equipment and high energy consumption.

The technical result consists in the simplification of the process (temperature decrease and the decrease in the number of stages).

This result is achieved by the fact that compounds of rhenium and molybdenum is taken bimetallic methylate rhenium and molybdenum, ReOMoO(OCH3)7[5] before the restoration is subjected to heat treatment in air at 250 to 300oC for 1-2 hours you get a black x-ray amorphous powder, which is then reactivated by hydrogen at 800-900oC for 2-3 h

Example 1. Bi-metal methylate rhenium and molybdenum decompose in air at a temperature of 250oC for 2. The resulting powder was restored in an atmosphere of hydrogen at a temperature of 800oC for 3 hours Get the Chi is otlozhenii carried out at 300oC for 1 h Recovery obtained x-ray amorphous powder in hydrogen atmosphere is carried out at 900oC for 2. Get pure alloy of rhenium and molybdenum composition of 1:1. The particle size of the product is 3 - 5 m .

Example 3. The decomposition of a complex of rhenium and molybdenum is carried out at a temperature of 275oC for 2.5 hours Get clean intermetallide rhenium and molybdenum composition of 1:1. The particle size of the product is 3-5 m .

Example 4. The decomposition of a complex of rhenium and molybdenum is carried out at a temperature of 225oC. the resulting powder according to the XRD contains a residual amount of the original complex. With further restoration in the atmosphere of hydrogen occurs the separation of components and the education does not alloy, and the individual metal powders.

Example 5. The decomposition of a complex of rhenium and molybdenum are similar to example 1. The restoration of the obtained powder of lead in the atmosphere of hydrogen at a temperature of 750oC for 1.5 h the resulting product is a mixture of solid solution ReO2-MoO2[6] and alloy of rhenium and molybdenum (1:1).

The use of higher decomposition temperatures (>300oC) the original complex of rhenium and molybdenum leads to the separation of the individual is at high temperatures (>900oC) seems inappropriate, as it does not affect the characteristics of the obtained product, but increases the energy consumption.

Thus, the comparison of the known technical solutions [4] and developed method of producing an alloy of rhenium and molybdenum proves that the proposed method allows to obtain highly dispersed and almost monodisperse (particle size of 3-5 m) powder alloy of rhenium and molybdenum, to achieve chemical homogeneity of the powder of the alloy, to reduce the temperature of the process of obtaining intermetallic and to reduce the number of stages of the process from 4 to 2, without using special equipment and high energy consumption.

Sources of information

1. Mc Horgue C. G., H. J. Maynor Metals, 1953, V. 5, P. 1382.

2. Sawicki, E. M., Talkin M. A., Povarov K. B. J. norgan. chemistry, 1959, So 4. Vol.2. S. 424.

3. Smiley S. H. US Patent, US 3341320, 1967.

4. Kopatz N. E., W. A. Johnson, J. Ritsko E. U.S. Patent, US 4731111, 1988.

5. Kessler V. C., A. V. Shevelkov, Khvorykh G. V., Seisenbaeva G. A. Chem. Commun., 1995, p. 1779.

6. Savborg O., Mat. Res. Bull., 1976, V. 11, P. 275.

A method of obtaining a fine powder of an alloy of rhenium and molybdenum compounds of rhenium and molybdenum, including recovery in hydrogen atmosphere is Eilat rhenium and molybdenum ReOMoO(OCH3)7before restoring it is subjected to heat treatment in air at 250 - 300oC for 1 to 2 h, and recovery in an atmosphere of hydrogen should be performed within 2 - 3 hours

 

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