Method for producing powders of molybdenum or its composites with tungsten

FIELD: powder metallurgy, possibly production of finely dispersed powder of molybdenum, its composites with tungsten, namely for producing hard alloy materials on base of molybdenum and tungsten.

SUBSTANCE: method provides production of molybdenum and its composites with tungsten at temperature no more than 900°C and also production of materials in the form of finely dispersed powders. Method comprises steps of reducing compounds of molybdenum and tungsten (MoO3 and WO3) by metallic magnesium in medium of melt chlorides such NaCl, KCl or carbonates such as Na2CO3, K2CO3 or their binary mixtures such as NaCl - KCl, Na2CO3 - K2CO3, NaCl - Na2CO3, KCl - K2CO3 at temperature 770 -890°C. According to results of fineness analysis produced powder of molybdenum represents homogenous material having 80% of particles with fraction size 2.2 - 3 micrometers. Composition material depending upon Mo content includes particles with fraction size 5 - 15 micrometers.

EFFECT: enhanced efficiency of method.

1 tbl, 3 ex

 

The invention relates to powder metallurgy can be used to obtain a fine powder of molybdenum or its composites with tungsten and in the production of sintered materials based on molybdenum and tungsten.

The known method of producing metal powder of molybdenum restore it from oxide (Moo3) hydrogen in a tube furnace. Recovery occurs with gradual heating from 700 to 1100° [1]. The disadvantages of hydrogen recovery should be attributed to the low productivity and high risk process.

Powder of molybdenum receive as a result of reactions in the gas medium between the regenerating gas, such as hydrogen and vapors of chlorides, fluorides, molybdenum at 900-1200°C [2].

A method of obtaining powders of molybdenum and tungsten restore their highest chlorides, fluorides at high temperature (above 2000° (C) a stream of hydrogen or a mixture of argon with hydrogen [3].

The disadvantages of methods for recovering metals from their halides should include increased toxicity, highly corrosive environment at a temperature process, high consumption of reagents, the complexity of the hardware design.

The known process of electrolytic deposition of tungsten and molybdenum from molten salts NaCl-KCl, KCl-KF on the cathodes of the various m is materials: molybdenum, graphite, silicon carbide, chromium, tungsten [4].

The disadvantages include high energy density, relatively low productivity and speed the process.

Closest to the proposed to the technical essence and the achieved result is a method of obtaining a composite material of tungsten-containing mineral raw materials [5], which receive molybdenum and tungsten-bearing materials - W-Co-Mo, W-Ni-Mo by aluminothermic recovery SelidovUgol concentrate with additives of oxides of molybdenum, cobalt, Nickel. In addition, the composition of the charge injected thermite additive (NaNO3), which increases the specific heat effect of the reaction, and the flux (CaF2, CaO), improving the conditions of forming the alloy into a compact form. In the melting process develops a temperature of more than 2400°C. the Final products are obtained in the form of compact ingots of metal and slag.

The disadvantages of this method include high temperature process (>2400° (C)determining the use of special heat-resistant reactor, the use of a multicomponent mixture (aluminum, alloy and thermite supplements, fluxes), raising costs.

The basis of the invention is to develop a method ensuring receipt of molybdenum or composite materials with tungsten at tempera is ur not higher than 900° C. a Very important task is to obtain materials in the form of fine powders.

The task is solved by the fact that in the method of obtaining powders of molybdenum or its composites with tungsten according to the invention the oxygen-containing compounds of molybdenum and tungsten (YPA3and WO3) retrieve a metal magnesium in an environment of molten salts: NaCl, KCl, Na2CO3, Na2CO3-K2CO3, Na2CO3NaCl, K2CO3-KCl at a temperature of 770-890°not exceeding their melting temperature for 20-30°C. tungsten contribute to the melt in relation to the molybdenum oxide mass parts within (0.2 to 0.8):1. The magnesium metal powder charge in an amount corresponding to the calculated reaction 1,2):

1. Moo3+3Mg=Mo+3MgO

2. WO3+3Mg=W+3MgO.

The advantage of the proposed solution is that in the framework of the one-stage process provides the materials (Mo, Mo-W) at lower, in comparison with the known method, the temperature, with lower costs of raw materials.

The method is implemented as follows.

Example No. 1.

100 g of KCl or NaCl, or a mixture of KCl-NaCl (1:1) is melted at a temperature of 770-820°C. a transparent melt contribute 10 g of molybdenum oxide and 10 g of a mixture of molybdenum oxide and tungsten oxide. The ratio of the oxide mo is ebden to the oxide of tungsten in the range of 1:(0.2 to 0.8). Then in the molten salt make a powder of magnesium in the amount of 3.2-5, the result is a fine powder of molybdenum or of a composite material molybdenum-tungsten, deposited on the bottom of the reactor. Melt stand 15-20 minutes to complete deposition of powders. Then the liquid is drained from the sediment, the powder is washed from the remainder of the salt water. The finished product is examined using the methods of physical chemistry.

Example No. 2.

100 g of Na2CO3or a mixture of Na2CO3-K2CO3(1:1) is melted at a temperature of 870-890°With, contribute to the melt 10 g of molybdenum oxide and 10 g of a mixture of oxide, molybdenum oxide, tungsten 1:(0.2 to 0.8). In the melt make a powder of magnesium in the amount of 3.2-5, the Resulting powder of molybdenum or the composite tungsten is deposited on the bottom of the reactor. The melt can stand up to full deposition of powders (=20 min), is drained from the sediment. Precipitation of powders washed with water from the remnants of salts.

Example No. 3.

100 g of a mixture of KCl-K2CO3or NaCl-Na2CO3(1:1) melt when 820-870°C. contribute To the melt 10 g of molybdenum oxide and 10 g of a mixture of oxides of molybdenum and tungsten 1:(0.2 to 0.8). In solution in the melt, make a powder of magnesium 3,2-5, the Formed molybdenum or its composite with tungsten deposited on the bottom of the reactor in the form of fine powders. The melt can stand up to full deposition of powders, decanted, precipitation washed water is.

X-ray phase analysis on the diffractometer "DRONE ZM" found that the obtained powder materials are molybdenum in the metal phase and the composites of molybdenum and tungsten in the metal phase.

Elemental analysis shows the following composition:

Name of materialsThe content of elements, wt.%
Powder of molybdenumMoFeCuWNb
98.40.30.30.50.5
Powder composite material Mo-WMoWCuFe-
74.520.30.40.3-
17.180.20.60.5-

According to the results of granulometric analysis of the obtained powder of molybdenum is a homogeneous material, 80% of which consists of particles with a size of 2.5-3 μm. Composite material Mo-W depending on the content of Mo has a particle size of 5-15 microns.

Sources of information

1. Usanov, Amocillin. Technology and properties of sintered hard alloys and the products of them. M. MRS., 2001, s.

2. Ruhlamat, Yevsukov, Ala. Superfine powders of tungsten and molybdenum. M. Metallurgy. 1988, p.7-10.

3. Umorale, Whistler. Recovery of fluorides of refractory metals with hydrogen. M. Metallurgy. 1981, p.184.

4. Bracewell, Auvelais, Vigorelli. The choice of cathode materials for refining tungsten and molybdenum halide melts. Non-ferrous metallurgy. 1988, No. 3, p.53-55.

5. Patent of Russia №2098232. The method of obtaining a composite material of tungsten-bearing minerals. Registered December 10, 1997

Method of producing metal powder of molybdenum or its composites with tungsten from their oxygen compounds, which consists in the fact that the conduct of the melting of the parent compounds, thermal restore them to the metals, followed by the separation of the metal phase from the reaction mass, and the recovery of lead magnesium in the melt of sodium chloride or potassium (NaCl, KCl), or carbonates of sodium or potassium (Na2CO3To2CO3), or their binary mixtures (NaCl-KCl, Na2CO3-K2CO3NaCl-Na2CO3, KCl-K2CO3) at a temperature of 770-890°C.



 

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