CN111804926A - A kind of method for preparing refractory metal powder - Google Patents

Abstract

The invention relates to a method for preparing refractory metal powder, belonging to the technical field of metal powder preparation. Processing refractory metal raw materials into particles; placing the obtained granular raw materials in an induction coil of electromagnetic suspension refining equipment, introducing protective gas pure Ar, and suspending and melting the metal particles into liquid suspended in the air after switching on a power supply; continuing suspension smelting of suspended metal particles, evaporating liquid metal when the temperature of liquid metal droplets is far higher than the melting temperature of the liquid metal droplets to generate metal powder suspended in protective gas, and collecting condensed powder in the protective gas at a gas outlet after condensation; and drying the condensed powder to prepare the refractory metal powder. The method can solve the problem of preparing the powder of the refractory metal material, and can realize the fast, simple and environment-friendly preparation of the refractory metal powder.

Description

A kind of method for preparing refractory metal powder

technical field

The invention relates to a method for preparing refractory metal powder, and belongs to the technical field of metal powder preparation.

Background technique

Refractory metals play an important role in the development of new materials and the improvement of the properties of existing materials. For new materials with higher precision, the added alloying elements need to meet the requirements of particle size and quality at the same time. At present, the main preparation methods of metal powder are plasma rotating electrode method, gasification atomization method and physical chemical method.

The plasma rotating electrode method is easy to produce spherical powder with good sphericity, but it is not easy to produce powder, and the material utilization rate is not high; the gasification atomization method is divided into traditional atomization technology and new atomization technology. Taking low melting point metal powders such as aluminum, the hot gas atomization method in the new atomization technology can provide a high atomization rate and is widely used in the production of alloy powders such as stainless steel, iron alloys, nickel alloys, magnetic materials, etc., but due to its special heating Nozzle design is rarely researched by institutions; physical chemical method is a mature technology for manufacturing metal powder, but this method is only limited to metal materials that are easy to react with hydrogen and increase brittleness after hydrogen absorption. According to the characteristics of the above methods, at present, the preparation of refractory metal powders has made progress.

Niobium powder is an important element in high-end technology products such as aviation and low temperature superconductivity, which can improve the heat resistance, strength and thermal conductivity of products. At present, the molten salt electrolysis method can be used to prepare niobium powder. Since this method dissolves the graphite anode and the cathode in the molten salt at the same time, the control of the potential in the molten salt, the precipitation of impurities at the cathode, and the side reactions caused by the impurities are all At the same time, the preparation of the method also needs to consume a large amount of time more than 12 hours. CN200610149612 describes a preparation method of niobium powder for powder metallurgy. Finally, niobium powder is obtained. This method can effectively prepare niobium powder, but the whole process takes 7 hours or more.

Titanium powder is widely used in aerospace, medical equipment, metallurgy and other fields, and has the advantages of reducing material weight, improving strength, and acid and alkali corrosion resistance. CN201711022391 describes a method for preparing titanium powder, which comprises: mixing, pressing and sintering titanium material and calcium oxide, mixing and pressing the sintered product with calcium hydride to obtain a pre-reduced billet, and then undergoing vacuum thermal reduction to obtain a crude product, The crude product is acid washed, washed with water and dried to finally obtain titanium powder, but the whole process takes 6 hours or more.

At present, there are existing methods to realize the preparation of refractory metal powder, but these methods all have the problems of complicated equipment, long process route, long consumption time, and pollution to the environment by the by-products or the solvent used.

SUMMARY OF THE INVENTION

Aiming at the above problems and deficiencies in the prior art, the present invention provides a method for preparing refractory metal powder. The method can solve the problem of powder preparation of refractory metal materials, and can realize rapid, simple and environmentally friendly preparation of refractory metal powder.

For solving the technical problem, the present invention adopts the following technical solutions:

A method for preparing refractory metal powder, comprising the following steps:

Step 1: Wire cutting or grinding the refractory metal raw material, and process it into a granular shape, wherein the particle size is about less than 16mm;

Step 2: Place the granular raw material obtained in Step 1 in the induction coil of the electromagnetic suspension refining equipment, pass in the protective gas pure Ar, and control the power supply system: input current 200-400A, input power 3000-4500W, input frequency 180- 450kHz, after the power is turned on, the metal particles are suspended and melted into a liquid suspended in the air;

Step 3: Continue suspending and smelting the metal particles suspended in Step 2. When the temperature of the liquid metal droplet is much greater than its melting temperature, the liquid metal begins to evaporate, and the metal powder is suspended in the protective gas. After condensation, the protective gas is collected at the gas outlet. Condensed powder in;

Step 4: Drying the condensed powder obtained in Step 3 to prepare a refractory metal powder.

In the step 1, the refractory metal raw material is a metal material with a melting point below 3000K, such as niobium with a melting point of 2750K, titanium with a melting point of 1933K, and nickel with a melting point of 1728K.

In the step 2, the protective gas pure Ar gas flow rate is 0.5-1.5 L/min.

The completion time of collecting the condensed powder in the steps 2 to 3 is 50-120 min.

The electromagnetic levitation refining equipment in the above steps 2 and 3 is shown in Figure 1. The electromagnetic levitation refining equipment includes a temperature measurement system, a power supply system, a main equipment and a filtering system. The top of the main equipment is provided with a triangular prism, and the upper side of the main equipment is provided with a The protective gas is pure Ar inlet, a magnetic induction coil is installed in the middle of the main equipment, and the magnetic induction coil is connected with the power system. The system measures the temperature for the main device.

The principle of this method:

(1) Principle of electromagnetic levitation: When the induction coil is connected to high-frequency alternating current, a Lorentz force opposite to the direction of gravity is generated inside the induction coil. When the Lorentz force is greater than or equal to the gravity of the droplet, the metal material is suspended; at the same time, the high-frequency The alternating current generates a changing magnetic field, which causes the change of the magnetic flux inside the coil, which causes the metal raw material to generate an induced current and generate Joule heat. When the temperature is higher than the melting point of the metal material, the metal material melts from a solid state to a liquid droplet.

(2) Evaporation and powdering principle: When the metal material is melted and heated to a higher temperature, the metal material evaporates and generates steam, and the atoms in the steam and the inert protective gas atoms continue to rub and collide, and the metal vapor condenses, nucleates and crystallizes. The grains grow and form metal powder.

Evaporation can be expressed by the following formula:

where N is the amount of metal evaporated, R is the molar gas constant, t is the evaporation time, T is the metal temperature, s is the evaporation surface area, M is the relative atomic mass of the metal, and p _m is the metal vapor at a temperature of T (K). pressure.

The beneficial effects of the present invention are:

1. This method can realize the preparation of refractory metal powder with high melting point and high activity, and provides a new method for the preparation of refractory metal powder.

2. Compared with the existing technology for preparing metal powder, the method has the advantages of simple and convenient operation, short process and less time-consuming, and can realize rapid preparation of refractory metal powder.

3. Compared with the existing metal powder preparation technology, this method does not use chemical solvents such as leaching solution, avoids the generation of waste residue or harmful by-products, and avoids environmental pollution.

4. This method is completed by electromagnetic suspension refining equipment. In the process of preparing powder, the metal material is not in contact with the crucible, so as to avoid the metal material being polluted, which is beneficial to obtain high-activity and high-quality metal powder. It is uniform and the surface renewal speed is fast, which is conducive to the preparation of refractory metal powder with uniform composition.

Description of drawings

FIG. 1 is a diagram of the electromagnetic suspension refining equipment of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

Example 1

As shown in Figure 1, the method for preparing refractory metal powder includes the following steps:

Step 1: The refractory metal raw material metal niobium is wire-cut and polished, and processed into granules, wherein the particle size is 10mm;

Step 2: Place 3.5g of granular raw material obtained in step 1 in the induction coil of the electromagnetic suspension refining equipment, pass in the protective gas pure Ar (the gas flow rate is 1.0L/min), open the coil cooling water after ventilation for 3 minutes and turn on the electricity , Control power system: input current 400A, input power 4500W, input frequency 400kHz, after the power is turned on, the metal particles are suspended and melted into liquid suspended in the air;

Step 3: Continue suspending and smelting the metal particles suspended in Step 2. When the temperature reaches 2950K, the molten droplets begin to evaporate, resulting in metal powder suspended in the protective gas. After condensation, the condensed powder in the protective gas is collected at the gas outlet;

Step 4: Put the condensed powder obtained in Step 3 into a drying oven, and keep it at 373K for 30min to prepare metal niobium powder.

The completion time of collecting the condensed powder in the steps 2 to 3 is 75 min.

In this example, 2.9 g of metal powder was prepared, and the yield of fine powder reached 82.8%.

Example 2

As shown in Figure 1, the method for preparing refractory metal powder includes the following steps:

Step 1: wire-cut and grind the refractory metal raw material titanium, and process it into particles, wherein the particle size is 11mm;

Step 2: Place 2.5g of granular raw material obtained in Step 1 in the induction coil of the electromagnetic suspension refining equipment, pass in the protective gas pure Ar (the gas flow rate is 1.0L/min), open the coil cooling water after ventilating for 3 minutes and turn on the electricity , Control power system: input current 300A, input power 4000W, input frequency 330kHz, after the power is turned on, the metal particles are suspended and melted into liquid suspended in the air;

Step 3: Continue suspending and smelting the metal particles suspended in Step 2, and when the temperature reaches 2133K, the molten droplets begin to evaporate, resulting in metal powder suspended in the protective gas, and the condensed powder in the protective gas is collected at the gas outlet after condensation;

Step 4: Put the condensed powder obtained in Step 3 into a drying box, and keep it at 373K for 30 minutes to prepare titanium metal powder.

The completion time of collecting the condensed powder in the steps 2 to 3 is 115 min.

In this example, 2.2 g of powder was prepared, and the yield of fine powder reached 88%.

Example 3

As shown in Figure 1, the method for preparing refractory metal powder includes the following steps:

Step 1: wire-cut and grind the refractory metal nickel raw material, and process it into particles, wherein the particle size is 10mm;

Step 2: Place 3.2g of the granular raw material obtained in Step 1 in the induction coil of the electromagnetic suspension refining equipment, pass in the protective gas pure Ar (the gas flow rate is 1.5L/min), open the coil cooling water after ventilation for 3 minutes and turn on the electricity , Control power system: input current 280A, input power 3500W, input frequency 220kHz, after the power is turned on, the metal particles are suspended and melted into liquid suspended in the air;

Step 3: Continue suspension smelting of the metal particles suspended in Step 2, and when the temperature reaches 1928K, the molten droplets begin to evaporate, resulting in metal powder suspended in the protective gas, and the condensed powder in the protective gas is collected at the gas outlet after condensation;

Step 4: Put the condensed powder obtained in Step 3 into a drying oven, and keep it at 373K for 30 min to prepare metallic nickel powder.

The completion time of collecting the condensed powder in the steps 2 to 3 is 80 min.

In this example, 2.8 g of powder was prepared, and the yield of fine powder reached 87.5%.

Example 4

As shown in Figure 1, the method for preparing refractory metal powder includes the following steps:

Step 1: wire cutting or grinding the metal copper raw material, and process it into granules, wherein the particle size is 9mm;

Step 2: Place 3.4g of the granular raw material obtained in Step 1 in the induction coil of the electromagnetic suspension refining equipment, pass in the protective gas pure Ar (the gas flow rate is 1.0L/min), open the coil cooling water after ventilating for 3 minutes and turn on the electricity , Control power system: input current 200A, input power 3800W, input frequency 180kHz, after the power is turned on, the metal particles are suspended and melted into liquid suspended in the air;

Step 3: Continue suspending and smelting the metal particles suspended in Step 2. When the temperature reaches 1557K, the molten droplets begin to evaporate, resulting in metal powder suspended in the protective gas. After condensation, the condensed powder in the protective gas is collected at the gas outlet;

Step 4: Put the condensed powder obtained in Step 3 into a drying oven, and keep it at 373K for 30min to prepare metallic copper powder.

The completion time of collecting the condensed powder in the steps 2 to 3 is 95 min.

In this example, 3 g of powder was prepared, and the yield of fine powder reached 88.2%.

The specific embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and can also be made within the scope of knowledge possessed by those of ordinary skill in the art without departing from the spirit of the present invention. Various changes.

Claims (4)

1. A method for preparing refractory metal powder is characterized by comprising the following steps:

step 1: performing linear cutting or grinding on a refractory metal raw material, and processing the refractory metal raw material into particles;

step 2: placing the granular raw materials obtained in the step 1 in an induction coil of electromagnetic suspension refining equipment, introducing protective gas pure Ar, and controlling a power supply system: inputting current of 200-400A, input power of 3000-4500W and input frequency of 180-450 kHz, and suspending and melting metal particles into liquid state suspended in the air after the power supply is switched on;

and step 3: continuing suspension smelting of the metal particles suspended in the step 2, evaporating the liquid metal when the temperature of the liquid metal molten drops is far higher than the melting temperature of the liquid metal molten drops to generate metal powder suspended in the protective gas, and collecting condensed powder in the protective gas at a gas outlet after condensation;

and 4, step 4: and (4) drying the condensed powder obtained in the step (3) to prepare refractory metal powder.

2. The method for producing a refractory metal powder as defined in claim 1, wherein: in the step 1, the refractory metal raw material is a metal material with a melting point below 3000K.

3. The method for producing a refractory metal powder as defined in claim 1, wherein: and in the step 2, the flow speed of the protective gas pure Ar gas is 0.5-1.5L/min.

4. The method for producing a refractory metal powder as defined in claim 1, wherein: and the time for collecting the condensed powder in the steps 2 to 3 is 50-120 min.

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