The method of producing intermetallic titanium - aluminum in powder form

 

(57) Abstract:

Usage: to obtain a powder of alloys based on titanium metals soluble in the liquid magnesium. The essence of the invention: process for the recovery of titanium tetrachloride lead to the aluminum content in the magnesium 2.1 to 5.7 times from the original, then stop the flow of titanium tetrachloride, load aluminum in the form of granules, pieces (pigs) or liquid form in the molten magnesium, soak in for some time and continue the recovery process. The residual concentration of aluminum (A1) in the melt is determined by the formula , where A is the initial concentration of A1 in magnesium, kg; is the quantity of titanium tetrachloride to time determine (a), kg n and m are constant coefficients obtained from experimental tests for boundary conditions (A/a = 2,1oC 5,7). 2 C.p. f-crystals, 1 table.

The invention relates to ferrous metallurgy, in particular to obtain a powder of alloys based on titanium metals, soluble in liquid magnesium, metallothermic recovery of titanium chloride (IV).

A method of obtaining refractory metals, titanium alloys and master alloys (patent Germany N 1057786, 3.12.59), which consists in recovering a low-melting metal is insoluble, or has limited solubility, binding restored refractory metal other metal component liquid alloy with the formation of ligatures.

The advantage of this method is the possibility of obtaining alloys based on refractory metals with other metals, forming a liquid alloy with the metal-reducing agent, but paulauskasa active reductants, as this metal, and associated with the refractory metal during metallotrejderskogo recovery. In particular, this method is applicable to alloy producing a titanium-aluminum. In the method in practice receive a ligature, heterogeneous in composition, representing a very hard and brittle, spongy material is subjected to further processing.

The known method the Abundant C. A. Gulyanitskii B. C. Kramnik C. Y. and other metallurgy of titanium. M. 1968, S. 325, consisting in metallothermic the recovery of titanium tetrachloride at a temperature of 550-600oC alloy of sodium with zinc. In the recovery of sodium whole formed titanium dissolves in excess of zinc, Paulauskas reducing agent, and after cooling is easily separated from the salt phase with the formation of titanium-zinc alloys.


Exploratory experiments on the joint recovery of the chloride of titanium, aluminum and vanadium with getting alloyed titanium sponge (RMJ 1975 N 2, 2G 173)). In these experiments legious additive is aluminum is introduced into the melt of magnesium, which is loaded into the reactor and lead the process of recovery of titanium tetrachloride at 850 900oC, then the reaction mass is allowed to stand for 1 h at 800 850oC, and carry out the separation process within 30 h at 950oC. Then the sponge is allowed to stand for 1 h at room temperature in argon 20% O2the block is cut and take samples. The obtained alloy sponge contained in the upper part of the block and the annular layer of 40% alloy sponge and 0.7% aluminum, in the annular area of the middle part of the block, respectively 10.4% and 20.0% in the core unit 7.3 and 4.4% and in the lower part of the block 81,6 and 35.5%

This process allows you to get a sponge, suitable for grinding, and in addition, the disadvantage of this method is the following. The execution result of the known methods, and using as a reductant of titanium tetrachloride liquid magnesium-aluminum alloy receive a titanium-aluminum alloys in the form of a block of non-uniform structure on its height. The upper part of the block, composing is luminia to 5% wt. what complicates further processing, which consists in a sequential multi-stage crushing metal with sampling to determine quality indicators. The middle part of the block was grey spongy solid metal and sintered in large pieces, as the upper part, but with slightly higher content of aluminium, nepriimami 10% Recycling of this metal to relatively small pieces dimensions HH mm possible on the independent circuit. The lower part, which constitutes about 10% of the mass of the block, dark grey needs processing on an individual scheme, different from the first two options. It is part closest to the intermetallic titanium-aluminum, but even the lower layers of this ligatures are experiencing the lack of it (25% Al).

Each of these parts of the block ligatures in experimental testing was needed to separate the processing of the individual plan, and 50% of the mass of metal of high hardness (heterogeneity) are not amenable to cutting and arrive at the beginning of the technological cycle of melting, and only 10% ligatures after preliminary grinding can be used in powder metallurgy, not being pure intermetallic TiAl.

Task izobreteniya, as well as reducing the number of returnable metal, aimed at re-production cycle, including the limits of melting, chlorination, recovery, vacuum separation and maganparrott.

This is achieved in that in the method of producing intermetallic titanium-aluminum, comprising preparing a melt of magnesium, aluminum, loading it into the machine recovery, the supply of titanium tetrachloride in the melt with periodic draining of the salt, the separation of the obtained reaction mixture, followed by extraction block obtained intermetallic, what's new is that the recovery process lead to the aluminum content in magnesium 2,1 5,7 times of its original, then stop the flow of titanium tetrachloride, load aluminum in the form of granules, lumps or liquid form in the molten magnesium, maintain and continue the recovery process. In addition, the concentration of aluminum in the melt is determined by the formula

< / BR>
A initial concentration of aluminium in magnesium, kg;

the flow rate of titanium tetrachloride in recovery, kg;

n, m with constant coefficients obtained from experimental tests and mathematical processing.

Interval decrease in the concentration of aluminum in the liquid alloy (2.1 igenii its contents in reducing the alloy, it found a lack of alloying metal in the melt promotes the formation of "poor" aluminum alloy Ti-Al. Experiments have shown that aluminum from the recovery of the alloy becomes solid ligature almost the same amount that the magnesium used for the recovery of titanium from titanium tetrachloride. Because the aluminum content in the reducing agent is small there is a "depletion" of the alloy, and then the obtained product alloying metal. It was established experimentally that when more than the 5.7-fold decrease in the Al content from the source, is formed ligature representing a solid spongy mass. It is not suitable for recycling and made it difficult cutting an entire block of aluminide titanium.

The process of downloading the aluminum at less than 2.1 a brief reduction of its content in reducing the alloy, it is possible, but not economically feasible. So when is 2.1-fold reduction in the aluminum content in the reducing alloy and the next intermediate loading uniformity of aluminide titanium to increase failed. However, frequent opening of the device for loading solid or liquid aluminum create additional work and increase the likelihood of oxidation and contamination of Reaiah for intermediate load contributes to the rapid melting and mixing of the injected metal in the volume of the melt. Granular aluminum melts when it enters the melt, and then, gradually falling from the upper layers, mixed with magnesium. The melting of large pieces or whole pigs aluminum occurs during their fall to the bottom of the unit or on the surface of the partially formed of a block of intermetallic. Uniform mixture of aluminum with magnesium is achieved through intensive circulation of the liquid alloy, caused by the temperature gradient between the top and bottom layers of the melt. The result of convective mixing liquid alloy for 10 to 30 minutes to achieve high uniformity environment conducive to the formation of homogeneous powder aluminide titanium.

Molten aluminum when loaded into the device behaves as follows. He descends into the lower layers of the melt, which is accompanied by its heat and wipe over the heated metal in the upper layers. Leads to intensive mixing of the liquid alloy. After 10 to 30 min exposure is uniform distribution of aluminum by volume of the melt.

For the experience of preparing a magnesium alloy brand "MA" in a steel crucible, set in oven CMT-2. In preheated 100oC pot load aluminum in the form of chulucanas alloy contains not more than 10% aluminum. Assembled and tested for tightness machine rotor with lid, bottom drain device and a false bottom, set in the shaft furnace. Otakuminopera and filled with argon apparatus is heated to 780 800oC. In the empty apparatus is poured from the ladle 1000 kg of magnesium-aluminum alloy and 800 820oC start the flow of titanium tetrachloride brand OCT-0-1, STF-05-01-243-88. After the filing of 150 kg TiCl4produce a flow of molten magnesium chloride by means of the discharge device in the empty box. Visual observation showed that the jet of the melt were no traces of liquid metal. Subsequent portions of the accumulated salt away after every 200 filed kg of titanium tetrachloride. Every hour of filing TiCl4take samples restorative alloy to determine changes in the content of aluminum and magnesium by means of Express-analysis. By reducing the aluminum content in the metal alloy 2.1 5.7 times from the source it loads 44oC 68 kg of aluminium in the form of granules or pigs, or molten form (GOST 11069-74), then maintain the melt at 780 - 820oC for 10 to 30 minutes After mixing of the aluminum in liquid magnesium on the surface of a homogeneous magnesium-aluminum melt who is holding aluminum close the flow of titanium tetrachloride, produce plums of magnesium chloride and incubated the reaction mixture into the remaining liquid alloy for one hour.

The residual concentration of (a) the alloying metal in the alloy reductant determine, based on the flow rate of titanium tetrachloride by the formula

< / BR>
A source concentration of Al in the rehabilitation alloy, kg;

the quantity of titanium tetrachloride to time determine (a), kg;

n and m with constant coefficients obtained from experimental tests for the claimed boundary values of the ratio (A/and 2.1oC 5,7), respectively equal to n 0,0692; m 0,766.

Then the resulting reaction mass is subjected to vacuum separation of the well-known scheme, cooled and then removed from the retort. It was porous weakly sintered material is dark gray in color, formed in the block. Pieces of intermetallic easily pulverized in the hands to a fine powder with a metallic luster. The height of the block are selected based on three samples for chemical analysis for determination of aluminum, titanium and major impurities. The results of intermetallic obtained during the implementation of boundary conditions in the described experiments are shown in the table.

The table shows that the content is terminalling phase TiAl, existing data Luchinsky, P. Chemistry of Titan. M. 1971, S. 202) in the range of 48 to 59% (34 of 45 wt.), having a form of a powder material suitable for extrusion and coating.

Experiments were filed 720 1212 kg of titanium tetrachloride used 20 33.6% of magnesium obtained 324oC 471 kg powder aluminide titanium composition TiAl under the conditions: initial concentration of aluminum in reducing the alloy is not more than 10% and intermediate loading of aluminium by reducing the content of 2.1 to 5.7 times the original.

1. The method of producing intermetallic titanium-aluminum in powder form, comprising preparing a melt of magnesium, aluminum, loading it into the machine recovery, the supply of titanium tetrachloride in the melt with periodic draining of the salt, the separation of the obtained reaction mixture, followed by extraction block obtained intermetallic, characterized in that the recovery process lead to the aluminum content in magnesium 2,1 5,7 times of its original, then stop the flow of titanium tetrachloride, immerse the aluminum in the molten magnesium, maintain and continue the recovery process.

2. The method according to p. 1, characterized in that the aluminum is dipped in molten magnesium in the form of powder and/or a large piece is in the molten magnesium is determined by the formula

< / BR>
where A is the initial concentration of aluminum in magnesium, kg;

the flow rate of titanium tetrachloride recovery, kg;

n and m with constant coefficients.

 

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