CN109231259B - A kind of method for preparing ultrafine ITO powder with metal indium and metal tin - Google Patents

Abstract

The invention discloses a method for preparing ultrafine ITO powder from metal indium and tin. Directly use metal indium ingot and tin ingot as raw materials, after composition design, alloying and pre-melting, gas oxidation is carried out in a hot ball mill at a temperature of 100-300 ° C to generate indium oxide and tin oxide, and the ball milling effect of the ball mill is used at the same time. The newly formed indium oxide and tin oxide are peeled off from the surface of the alloy droplet, and finely ground is completed to finally obtain ITO powder, which is subjected to airflow classification to produce an ITO composite powder product with uniform particle size. Compared with the traditional process, the invention has the advantages of short reaction process, fine product particle size, less reagent consumption, etc., and solves the problem that the direct metal indium and tin generate oxide film during the oxidation process, which makes it difficult to be further oxidized.

Description

A kind of method for preparing ultrafine ITO powder with metal indium and metal tin

technical field

The invention belongs to the field of material metallurgy, and more particularly relates to a method for preparing ultrafine ITO powder by thermal ball milling and oxidation.

Background technique

Indium tin oxide (ITO) has the advantages of high light transmittance, low resistivity, high film hardness, good chemical stability and etching performance, and is widely used in liquid crystal displays, solar cells, thin-film light-emitting devices, sensors and other cutting-edge manufacturing fields. The current preparation method is that indium oxide and tin oxide are separately powdered, and then mixed and then formed and sintered to form an ITO target, which has a long process and high powder production cost. And because metal tin is oxidized to form a stable tin dioxide film, which is insoluble in conventional acids and alkalis, which hinders the further oxidation reaction, so tin oxide powder is mostly prepared by wet chemical method. The common feature is that tin salt precursors are synthesized in solution. The main problems of obtaining tin oxide by calcination or without calcination are long process and large amount of waste water.

Patent CN102923765A "a kind of indium tin oxide (ITO) nano powder and its manufacturing method" uses the soluble salt raw materials of indium and tin, adding organic matter to synthesize ellipsoidal indium oxide and tin oxide powder by combustion; patent CN102417203 "a kind of fuel The method of preparing ultra-fine ITO powder by synthetic method "also uses indium and tin nitrate as raw materials, and obtains ultra-fine ITO powder by reduction combustion. This kind of method consumes large reagents and high product cost. Patent CN105540647A discloses "a kind of ITO powder for preparing rotating target by thermal spraying and its production method and application", using chemical co-precipitation method to obtain ITO co-precipitation powder in one step, and then heat treatment to obtain ITO powder, the process is short, in line with the production concept of short process , and similar methods include hydrothermal method and sol-gel method. The spray oxidation method is also a direct synthesis method, and uses metal indium and tin as raw materials, the process is further simplified, but the investment of spray equipment is large and the process control requirements are high.

From the perspective of simplifying the process, direct oxidation of metal indium and tin is the most direct method to prepare indium oxide and tin oxide, but the problem is that the passivation of the oxide film makes it difficult to further oxidize metals, especially metal tin, once tin oxide is formed After the film, the further progress of the reaction will be blocked. Only by peeling off the oxide layer in time can the oxidation reaction continue to continue, and ball milling can achieve this effect. Therefore, this patent proposes a method for preparing ultrafine ITO powder from metal indium and tin. The metal indium and tin are oxidized by air under heating, and the ball-milling is performed simultaneously to realize the rapid oxidation of indium and tin. The layer peeling and oxidation products are refined and mixed, the process is cost-effective, clean and high-quality, and it is expected to further expand the application field of ultra-fine ITO powder.

SUMMARY OF THE INVENTION

In view of the problems existing in the background technology, the present invention proposes a method for preparing ultrafine ITO powder from metal indium and metal tin. A hot ball mill is used as a reaction device to complete the simultaneous oxidation of metal indium and tin and the simultaneous refinement of oxides, thereby realizing Cost-effective, controllable and stable production of ultrafine indium oxide and tin powders.

The object of the present invention is achieved through the following technical solutions:

A method for preparing ultra-fine ITO powder from metal indium and metal tin, using metal indium ingots and metal tin ingots as raw materials, firstly carrying out composition design and alloying premelting, in a hot ball mill at a temperature of 100-300 DEG C and feeding oxidation The thermal ball milling oxidation is carried out under the condition of volatile gas, so that the metal indium and the metal tin are oxidized in the liquid form, and the ball milling is carried out at the same time, and the ultrafine ITO powder is obtained after the thermal ball milling oxidation is completed.

The reaction temperature of the inner chamber of the hot ball mill of the present invention is 100-300° C. The metal indium and tin are easily oxidized by air to generate indium oxide and tin oxide. It can be seen from FIG. 3 that the Gibbs free energy change value of the reaction is It is below -300kJ/mol in the range of 0～1000℃, and increases with the increase of temperature, so the reaction temperature is not easy to be too high, and indium is easier to oxidize than tin. However, the generated indium oxide and tin oxide cover the surface of the metal droplets, hindering the further progress of the oxidation reaction.

Sn+O ₂ (g)=SnO ₂

2In+1.5O ₂ (g)=In ₂ O ₃

The reaction temperature in the method is 100-300°C, the melting point of metal indium is 156.61°C, the melting point of metal tin is 231.89°C, the melting point of indium-tin alloy melt is lower, and the method of the present invention has a superheat degree of 0-150°C, The kinetics of the oxidation reaction of indium tin alloy can be guaranteed. At the same time, the reaction is an exothermic reaction, and an excessively high temperature is unfavorable for the degree of oxidation and increases energy consumption.

In the technical scheme of the present invention, the superfine ITO powder is directly prepared from metal indium and metal tin by means of thermal ball-milling oxidation reaction, and the newly generated indium oxide and tin oxide are ball-milled and refined by ball-milling at the same time of oxidation, and the surface can be peeled off. The oxide layer, and the newly generated indium oxide and tin oxide powders are continuously refined by ball milling, and ultra-fine ITO powders are directly produced.

Preferably, the mass ratio of the metal indium ingot and the metal tin ingot in the composition design is 9.45:1.

Preferably, the temperature of the alloying pre-melting is 250-300 °C, and the metal indium ingot and the metal tin ingot are pre-melted at a temperature of 250-300 °C, so that indium and tin form an alloy melt with uniform composition, Thereby ensuring the uniformity of the oxidation reaction and the uniform distribution of the final oxide;

Preferably, the oxidizing gas is air or oxygen.

Preferably, the linear speed of the oxidizing gas bubbling is 0.1-2 m/s, and the forced oxidizing gas bubbling can speed up the oxidation of indium and tin, and at the same time play a certain role in stirring the molten alloy liquid, and strengthen the oxidation diffusion transmission. quality, the oxidation of indium and tin can be more sufficient; the intrusion linear velocity is more preferably 0.5-1.5 m/s.

Preferably, in the hot ball milling process, the ball milling strength is 30-120 rpm, the filling rate is 10-50%, and the ball-to-material ratio is 3-9. The above parameters can ensure both the ball milling efficiency and the production efficiency; further preferably, The filling rate is 20-40%, and the ball-to-material ratio is 5-8.

In the present invention, the ball milling can play two roles. On the one hand, the indium oxide and tin product layers on the surface of the alloy droplets are continuously peeled off, so that the oxidation reaction can be continuously carried out. On the other hand, the generated indium oxide and tin oxide are immediately Ball-milling oxidation can directly obtain ultra-fine indium oxide and tin oxide. However, the ball milling operation is a high energy consumption process, so it is not suitable to use an excessively high speed.

Preferably, the spherical material medium used in the ball mill is one of zirconia, agate, cemented carbide and corundum, all of which are inert materials and can ensure high temperature stability and product purity; preferably zirconia.

Preferably, the time of the hot ball milling reaction process is 1-5 hours, which can ensure sufficient oxidation and fine grinding of indium and tin; more preferably, it is 1-3 hours.

The method for preparing ultrafine ITO powder from metal indium and metal tin according to the present invention specifically includes the following steps:

S1. Composition design: take the metal indium ingot and the metal tin ingot according to a certain mass ratio for accurate weighing;

S2. Alloying pre-melting: the weighed metal ingots and metal tin ingots are pre-melted at a temperature of 250-300 °C, so that indium and tin form an alloy melt with uniform composition;

S3. Alloy melting: add the alloy melt obtained in step S2 into the hot ball mill, turn on the electric heating, and make the inner cavity temperature of the ball mill reach 100-300°C;

S4. Thermal ball milling oxidation: turn on the rotating device, start the thermal ball milling reaction, maintain a certain speed, and at the same time blow oxidizing gas into the inner cavity from the air inlet to start the oxidation reaction and ball milling; during the thermal ball milling oxidation process, the combustion chamber The flue gas is discharged from the flue gas outlet of the fuel chamber, and the flue gas in the reaction chamber is discharged through the flue gas filter outlet installed in the reaction chamber. The filter port is equipped with a ceramic filter plate, which can prevent the material in the ball mill from being carried out;

S5. Cooling and discharging: After a certain time of reaction, stop heating, ball milling and drum oxidizing gas, open the discharge port to release the product ITO powder, and after it is completely cooled to the greenhouse, put it into the silo, and classify to obtain ITO products of different particle sizes.

Relative to the prior art, the beneficial effects of the present invention are:

(1) The method of the present invention creatively uses metal indium and metal tin alloy pre-melting-liquid-phase low-temperature thermal ball milling oxidation to replace the current mainstream process of precursor preparation-calcination and decomposition, greatly improving productivity and simplifying the process. The only auxiliary oxidant uses clean air or Oxygen, reducing reagent consumption, greatly reducing production costs, and realizing green, low-carbon, and efficient ultrafine ITO powder preparation.

(2) The method of the present invention is oxidized at low temperature, and the oxidation temperature is only 100 to 300 ° C. Compared with the high-temperature oxidation process used in the prior art, the method of the present invention reduces equipment requirements, reduces energy consumption, and reduces production at the same time. cost.

(3) The method of the present invention integrates the oxidation of metal indium tin, the stripping and refinement of the oxidation products in one process, and the process is short, clean and efficient, and solves the problem of the oxidation reaction caused by the formation of indium oxide and tin oxide films in the traditional oxidation process. The disadvantage of being difficult to proceed.

(4) The present invention realizes the simultaneous oxidation of indium and tin, and shortens the process of separately powdering indium oxide and tin oxide to produce ultrafine ITO powder in the prior art.

Description of drawings

1 is a schematic diagram of the process flow of the method for preparing ultrafine ITO powder from metal indium and metal tin according to the present invention.

2 is the XRD pattern of the ITO powder obtained in Example 1 of the present invention.

FIG. 3 is a graph showing the relationship between ΔG ^θ -T of the oxidation reaction of metal tin and indium.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

Example 1

In the metal indium ingot as the raw material: In>99.99%, the total amount of impurities <0.01%; in the metal tin ingot: Sn>99.99%, the total amount of impurities <0.01%.

The present embodiment provides a method for preparing ultrafine ITO powder from metal indium and metal tin. The process flow chart is shown in FIG. 1 , and the specific steps are as follows:

S1. Composition design: Take metal indium ingots and metal tin ingots and accurately weigh them according to the mass ratio of 9.45:1, weighing 1000g in total;

S2. Alloying pre-melting: the weighed metal indium ingot and metal tin ingot are pre-melted in a crucible at a temperature of 280°C, so that indium and tin form a uniform alloy melt, and stir several times;

S3. alloy melting: add the alloy melt obtained in step S2 into the hot ball mill, put in a corresponding number of zirconia balls according to the ball-to-material ratio of 5, turn on the electric heating, and make the inner cavity temperature of the ball mill reach 200 ° C;

S4. Thermal ball milling oxidation: turn on the rotating device, start the thermal ball milling reaction, maintain the speed of 100rpm, and at the same time blow air from the air inlet to the inner cavity at a linear speed of 0.5m/s to start the oxidation reaction and ball milling; the oxidation process of thermal ball milling In the process, the flue gas of the combustion chamber is discharged from the flue gas outlet of the fuel chamber, and the flue gas in the reaction cavity is discharged through the flue gas filter outlet installed in the reaction chamber. material is brought out;

S5. Cooling and discharging: After 2 hours of reaction, stop heating, ball milling and air blasting, open the discharge port to release the product ITO powder, cool it naturally to the greenhouse and put it into the silo.

The oxygen content of the product ITO composite powder was analyzed and tested, and it was found that the oxidation degree of indium tin (In ₂ O ₃ +SnO ₂ )> 96.9%, the particle size range of the laser particle size analyzer was between 0.40 and 8.4 μm, and the average particle size was 4.33 μm, of which -5.0 μm accounted for 76%. The XRD pattern is shown in Figure 2. It can be seen from the figure that the ITO composite powder has high diffraction peak intensity and good crystallinity; the product has high purity, all of which are indium oxide and tin oxide.

Example 2

The metallic indium ingots and metallic tin ingots used as raw materials are the same as those in Example 1.

The present embodiment provides a method for preparing ultrafine ITO powder from metal indium and metal tin. The process flow chart is shown in FIG. 1 , and the specific steps are as follows:

S1. Composition design: Take metal indium ingots and metal tin ingots and accurately weigh them according to the mass ratio of 9.45:1, weighing 1000g in total;

S2. Alloying pre-melting: The weighed metal indium ingot and metal tin ingot are pre-melted in a crucible at a temperature of 300 ℃, so that indium and tin form an alloy melt with uniform composition, and stir several times;

S3. alloy melting: add the alloy melt obtained in step S2 into the hot ball mill, put in a corresponding number of corundum balls according to the ball-to-material ratio of 9, turn on the electric heating, and make the inner cavity temperature of the ball mill reach 120 ° C;

S4. Thermal ball milling oxidation: turn on the rotating device, start the thermal ball milling reaction, maintain the speed of 120 rpm, and at the same time blow air from the air inlet to the inner cavity at a linear speed of 1.0m/s to start the oxidation reaction and ball milling; the oxidation process of thermal ball milling In the process, the flue gas of the combustion chamber is discharged from the flue gas outlet of the fuel chamber, and the flue gas in the reaction cavity is discharged through the flue gas filter outlet installed in the reaction chamber. material is brought out;

S5. Cooling and discharging: After 1 hour of reaction, stop heating, ball milling and air blowing, open the discharge port to release the product ITO powder, cool it naturally to the greenhouse and put it into the silo.

The oxygen content of the product ITO composite powder was analyzed and tested, and it was found that the oxidation degree of indium tin (In ₂ O ₃ +SnO ₂ )> 99.86%. The particle size range of the laser particle analyzer was between 0.58 and 10.2 μm, and the average particle size was 5.18 μm, of which -5.0 μm accounted for 63%.

Example 3

The metallic indium ingots and metallic tin ingots used as raw materials are the same as those in Example 1.

The present embodiment provides a method for preparing ultrafine ITO powder from metal indium and metal tin. The process flow chart is shown in FIG. 1 , and the specific steps are as follows:

S1. Composition design: Take metal indium ingots and metal tin ingots and accurately weigh them according to the mass ratio of 9.45:1, weighing 1000g in total;

S2. Alloying pre-melting: The weighed metal indium ingots and metal tin ingots are pre-melted in a crucible at a temperature of 250 ° C, so that indium and tin form a uniform alloy melt, and stir several times;

S3. Alloy melting: add the alloy melt obtained in step S2 into the hot ball mill, put in a corresponding number of zirconia balls according to the ball-to-material ratio of 3, turn on the electric heating, and make the inner cavity temperature of the ball mill reach 280 ° C;

S4. Thermal ball milling oxidation: turn on the rotating device, start the thermal ball milling reaction, maintain the rotation speed at 40 rpm, and at the same time blow air from the air inlet to the inner cavity at a linear speed of 0.4m/s to start the oxidation reaction and ball milling; the oxidation process of thermal ball milling In the process, the flue gas of the combustion chamber is discharged from the flue gas outlet of the fuel chamber, and the flue gas in the reaction cavity is discharged through the flue gas filter outlet installed in the reaction chamber. material is brought out;

S5. Cooling and discharging: After 3 hours of reaction, stop heating, ball milling and air blowing, open the discharge port to release the product ITO powder, cool it naturally to the greenhouse and put it into the silo.

The oxygen content of the product ITO composite powder was analyzed and tested, and it was found that the oxidation degree of indium tin (In ₂ O ₃ +SnO ₂ )> 92.10%, the particle size range of the laser particle size analyzer was between 1.43 and 18.27 μm, and the average particle size was 8.06 μm, of which -5.0 μm accounted for 34%.

Example 4

The metallic indium ingots and metallic tin ingots used as raw materials are the same as those in Example 1.

The present embodiment provides a method for preparing ultrafine ITO powder from metal indium and metal tin. The process flow chart is shown in FIG. 1 , and the specific steps are as follows:

S1. Composition design: Take metal indium ingots and metal tin ingots and accurately weigh them according to the mass ratio of 9.45:1, weighing 1000g in total;

S2. Alloying pre-melting: the weighed metal indium ingot and metal tin ingot are pre-melted in a crucible at a temperature of 270°C, so that indium and tin form an alloy melt with uniform composition, and stir several times;

S3. alloy melting: add the alloy melt obtained in step S2 into the hot ball mill, put in a corresponding number of agate balls according to the ball-to-material ratio of 7, turn on the electric heating, and make the inner cavity temperature of the ball mill reach 250 ° C;

S4. Thermal ball milling oxidation: turn on the rotating device, start the thermal ball milling reaction, maintain the speed of 120 rpm, and at the same time blow air from the air inlet to the inner cavity at a linear speed of 1.0m/s to start the oxidation reaction and ball milling; the oxidation process of thermal ball milling In the process, the flue gas of the combustion chamber is discharged from the flue gas outlet of the fuel chamber, and the flue gas in the reaction cavity is discharged through the flue gas filter outlet installed in the reaction chamber. material is brought out;

S5. Cooling and discharging: After 2 hours of reaction, stop heating, ball milling and air blasting, open the discharge port to release the product ITO powder, cool it naturally to the greenhouse and put it into the silo.

The oxygen content of the product ITO composite powder was analyzed and tested, and it was found that the oxidation degree of indium tin (In ₂ O ₃ +SnO ₂ )> 99.80%, the particle size range of the laser particle analyzer was between 0.02 and 4.6 μm, and the average particle size was 1.37 μm, of which -5.0 μm accounts for 100%.

Example 5

The metallic indium ingots and metallic tin ingots used as raw materials are the same as those in Example 1.

The present embodiment provides a method for preparing ultrafine ITO powder from metal indium and metal tin. The process flow chart is shown in FIG. 1 , and the specific steps are as follows:

S1. Composition design: Take metal indium ingots and metal tin ingots and accurately weigh them according to the mass ratio of 9.45:1, weighing 5000g in total;

S2. Alloying pre-melting: The weighed metal indium ingot and metal tin ingot are pre-melted in a crucible at a temperature of 300 ℃, so that indium and tin form an alloy melt with uniform composition, and stir several times;

S3. alloy melting: add the alloy melt obtained in step S2 into the hot ball mill, put in a corresponding number of zirconia balls according to the ball-to-material ratio of 7, turn on the electric heating, and make the inner cavity temperature of the ball mill reach 220 ° C;

S4. Thermal ball milling oxidation: turn on the rotating device, start the thermal ball milling reaction, maintain the rotational speed at 90 rpm, and at the same time blow air from the air inlet to the inner cavity at a linear speed of 0.7m/s to start the oxidation reaction and ball milling; the oxidation process of thermal ball milling In the process, the flue gas of the combustion chamber is discharged from the flue gas outlet of the fuel chamber, and the flue gas in the reaction cavity is discharged through the flue gas filter outlet installed in the reaction chamber. material is brought out;

S5. Cooling and discharging: After the reaction for 2.5 hours, stop heating, ball milling and air blowing, open the discharge port to release the product ITO powder, cool it naturally to the greenhouse and put it into the silo.

The oxygen content of the product ITO composite powder was analyzed and tested, and it was found that the oxidation degree of indium tin (In ₂ O ₃ +SnO ₂ )> 99.20%, the particle size range of the laser particle analyzer was between 0.35 and 9.42 μm, and the average particle size was 4.72 μm, of which -5.0 μm accounted for 69%.

Claims (12)

1. a method for preparing ultra-fine ITO powder with metal indium and metal tin, it is characterized in that, with metal indium ingot and metal tin ingot as raw material, first carry out composition design and alloying premelting, in a hot ball mill at a temperature of 100 ~ Perform thermal ball milling oxidation at 300°C under the condition of introducing oxidizing gas, so that metal indium and metal tin are oxidized in liquid form, and ball milling is performed at the same time, and ultra-fine ITO powder is obtained after the thermal ball milling oxidation is completed; Wherein, the temperature of the alloying premelting is 250-300°C. 2 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 1 , wherein the mass ratio of metal indium ingots and metal tin ingots in the composition design is 9.45:1. 3 . 3 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 1 , wherein the oxidizing gas is air or oxygen. 4 . 4 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 1 , wherein the oxidizing gas is blown in at a linear velocity of 0.1 to 2 m/s. 5 . 5 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 4 , wherein the oxidizing gas is blown in at a linear velocity of 0.5 to 1.5 m/s. 6 . 6. the method for preparing ultrafine ITO powder according to the described metal indium and metal tin of claim 1, it is characterized in that, in the described hot ball milling process, the ball milling strength is 30～120rpm, the filling rate is 10～50%, and the quality of the ball material is 30～120rpm. The ratio is 3~9. 7 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 6 , wherein the filling rate is 20-40%, and the mass ratio of ball to material is 5-8. 8 . 8 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 1 , wherein the spherical material medium used in the ball milling is one of zirconia balls, corundum balls and agate balls. 9 . 9 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 8 , wherein the spherical material medium used in the ball milling is zirconia. 10 . 10 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 1 , wherein the time of the hot ball milling reaction process is 1 to 5 hours. 11 . 11 . The method for preparing ultrafine ITO powder from metal indium and metal tin according to claim 10 , wherein the time of the hot ball milling reaction process is 1 to 3 hours. 12 . 12. The method for preparing ultrafine ITO powder according to metal indium and metal tin according to any one of claims 1 to 11, characterized in that, the method specifically comprises the following steps: S1. Composition design: Take metal indium ingots and metal tin ingots and accurately weigh them according to a certain mass ratio; S2. Alloying pre-melting: the weighed metal indium ingot and metal tin ingot are pre-melted at a temperature of 250~300 ℃, so that indium and tin form an alloy melt with uniform composition; S3. alloy melting: add the alloy melt obtained in step S2 into the hot ball mill, turn on the electric heating, and make the inner cavity temperature of the ball mill reach 100~300°C; S4. Thermal ball milling oxidation: turn on the rotating device, start the thermal ball milling reaction, maintain a certain speed, and at the same time blow oxidizing gas into the inner cavity from the air inlet to start the oxidation reaction and ball milling; S5. Cooling and discharging: After a certain time of reaction, stop heating, ball milling and drum oxidizing gas, open the discharge port to release the product ITO powder, and after it is completely cooled to the greenhouse, put it into the silo, and classify to obtain ITO powder of different particle sizes.

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