Method for preparing tungsten-silicon alloy based on self-propagating reaction low-temperature sintering
By using the self-propagation reaction of W, WO3 and Si powders and aluminum powder, the problem of high-temperature sintering in the preparation of traditional tungsten silicon alloy powder is solved, and the preparation of high-purity tungsten silicon alloy powder is achieved at low temperature, reducing equipment cost and energy consumption.
Patent Information
- Application Number
- CN202510722736.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-30
- Publication Date
- 2025-08-15
AI Technical Summary
High temperature sintering in traditional tungsten silicon alloy powder preparation methods leads to problems such as high equipment costs, waste of energy and high impurity content.
W, WO3 and Si powders are used as raw materials, and a small amount of active substance aluminum is added to generate heat through self-propagation reaction, reducing the sintering temperature and removing oxides, and pure tungsten silicon alloy powder is prepared.
The sintering temperature of the tungsten silicon alloy powder is reduced, the uniformity and purity of the alloy phase is improved, excessive grain coarseness is avoided, and production costs are reduced.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of alloy material preparation, and in particular to a method for preparing tungsten silicon alloy based on self-propagating reaction low-temperature sintering. Background Art
[0002] With the rapid development of the semiconductor industry, the integration of semiconductor integrated circuits continues to increase, the device size is proportionally reduced, and the critical line width of the integrated circuit continues to decrease, which greatly increases the resistance of the gate and interconnected polysilicon thin layers. Therefore, higher requirements are placed on metal electrodes. On the one hand, they need higher conductive properties, and on the other hand, they need to be resistant to high temperatures and have good interface contact with silicon.
[0003] Tungsten-silicon alloy thin films, characterized by high electrical conductivity, excellent high-temperature resistance, and superior chemical resistance, are widely used in semiconductor integrated circuits. As a transparent conductive layer or back electrode, tungsten-silicon alloy thin films can enhance photoelectric conversion efficiency. Furthermore, as contact layers in LEDs or lasers, they can improve carrier injection efficiency. Their broader applications in photovoltaic and optoelectronic devices are urgently awaited.
[0004] The preparation of tungsten silicon alloy thin films mainly adopts physical vapor deposition (PVD) technology. PVD technology includes sputtering deposition and evaporation. Due to the high melting point of tungsten silicon alloy, sputtering deposition is adopted. This method has the advantages of good repeatability, stable deposition rate, high film adhesion, easy sputtering and cleaning of the substrate, and easy control of film thickness. The performance of the film obtained by target sputtering is closely related to the raw material of tungsten silicon alloy powder. Only when the prepared alloy powder is of high purity and low content of impurities such as oxygen and carbon, the performance of the film obtained by target sputtering will be relatively excellent.
[0005] At present, most tungsten-silicon alloy powders are prepared using tungsten powder and silicon powder as raw materials. After ball milling and mixing, they are sintered at high temperature in a tubular furnace to obtain tungsten-silicon alloy powder. This method has the advantages of simple raw materials and easy operation. However, the temperature required for the reaction of tungsten and silicon powder raw materials to form tungsten-silicon alloy is relatively high. High temperature not only places stringent requirements on sintering equipment, but also requires high-temperature resistant heating elements and insulation materials, which increases equipment cost and maintenance difficulty. In addition, the high-temperature sintering process consumes a lot of energy, resulting in increased production costs. Alternatively, due to the influence of experimental equipment, sintering is performed at a lower temperature. Incomplete reaction of the raw materials will result in more residual tungsten or silicon, which exists in the target material as an impurity phase and has a certain degree of influence on the performance of the target material. Summary of the Invention
[0006] In order to solve the problem of reduced alloy performance due to the presence of oxygen in tungsten silicon alloy in traditional preparation methods, as well as the energy waste caused by high-temperature sintering, the present invention proposes a method for preparing tungsten silicon alloy by low-temperature sintering based on self-propagating reaction. The method uses W, WO3 and Si mixed powder as raw materials, and adds a small amount of active material (such as aluminum, etc.). The self-propagating reaction of tungsten trioxide and the active material releases a large amount of heat in an instant, greatly shortening the time required for the temperature to rise to the reaction temperature, avoiding excessive coarsening of the tungsten silicon alloy grains, and improving the uniformity of the tungsten silicon alloy phase.
[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is:
[0008] A method for preparing tungsten silicon alloy based on low-temperature sintering via self-propagating reaction, using W, WO3 and Si powders as raw materials, and adding aluminum powder as active material. During the low-temperature sintering process, the self-propagating reaction of tungsten trioxide and the active material is used to release heat to reduce the sintering temperature of the tungsten silicon powder. Finally, the generated active oxides are removed to obtain pure tungsten silicon alloy powder.
[0009] As a preferred technical solution of the present invention, the preparation method specifically comprises the following steps:
[0010] Step 1: Prepare precursor powder: ball-mill W, WO3 and Si powders, then add an appropriate amount of aluminum powder as an active material and mix well to obtain precursor powder;
[0011] Step 2: cold isostatic pressing to form a composite block: the obtained precursor powder is placed in a mold and cold isostatic pressing is used to obtain a composite block;
[0012] Step 3: low-temperature reaction sintering in a tubular furnace: placing the composite block into a tubular furnace and sintering in an argon atmosphere to obtain a tungsten-silicon composite block material;
[0013] Step 4: crushing the bulk material: crush the sintered bulk material into particles, then put it into the air flow mill, and continuously cycle the crushing process until the target particle size of tungsten silicon composite powder is obtained;
[0014] Step 5: Pickling the powder to remove impurities; the tungsten-silicon composite powder is placed in acid to remove active oxides, and then the remaining powder is repeatedly rinsed with deionized water, and then dried to obtain pure WSi2 alloy powder.
[0015] As a further preferred technical solution of the present invention, in the preparation method:
[0016] The tungsten powder used in step 1 has a purity of more than 99.99% and a particle size of 5-13 μm; the tungsten trioxide powder used has a purity of more than 99.99% and a particle size of 100 nm; the Si powder used has a particle size of 6-15 μm; the active material powder used has a purity of 99.99% and a particle size of 5-10 μm; the mass ratio of W, WO3 and Si powder is 10-15:0.5-2.5:4-6, and the amount of active material added is 1-5wt% of the ball-milled powder.
[0017] The ball milling mixing parameters in step 1 are as follows: a carbide ball milling jar is selected, the grinding balls have a diameter of 4 mm, the ball-to-powder ratio is 4:1, and the jar is loaded into a high-performance ball mill and ball milled for 12 hours at a ball milling speed of 300 r / min; after the ball milling is completed, the active substance powder and the ball-milled powder are evenly mixed in an agate mortar.
[0018] The parameters of the cold isostatic pressing in step 2 are as follows: a stainless steel mold with a diameter of 1.5 cm is used, and a punch and a die set are used for compression molding; molybdenum foil is used as a lubricating layer on the mold wall to make the pressed block easy to eject; a pre-press is used to press the powder block at room temperature, and the pressure is uniformly increased to 50 MPa and maintained for 1 minute.
[0019] The process conditions for the low-temperature reaction sintering in the tubular furnace in step three are as follows: in an argon atmosphere, heating from room temperature to 600°C at a heating rate of 5°C / min, holding for 30 minutes, then heating to 950-1000°C at a rate of 3°C / min, and holding for 2 hours.
[0020] The pulverization parameters in step 4 are as follows: adding the preliminarily crushed particles to the air flow mill, setting the air flow pressure to 1 MPa, the gas-solid ratio to 12:1, the nozzle angle to 20°, the spacing to 70 mm, and the rotation speed to 4000 r / min; and cyclically crushing until the target powder particle size is reached.
[0021] The pickling and impurity removal process in step five is as follows: removing active oxides in the composite powder by hydrochloric acid washing, then repeatedly washing the remaining powder with deionized water, and drying to obtain pure tungsten silicon alloy powder.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] 1. The traditional preparation method uses tungsten powder and silicon powder as raw materials, and the sintering temperature to form tungsten silicon alloy is about 1200℃. In the present invention, aluminum is added as an active material to react with tungsten trioxide to release a large amount of heat, which significantly reduces the sintering temperature of tungsten silicon.
[0024] 2. Compared with the traditional tube furnace sintering, the high temperature self-propagating reaction releases a lot of heat in an instant, which greatly shortens the time required for the temperature to rise to the reaction temperature, avoids the excessive coarsening of the tungsten silicon alloy grains, and improves the uniformity of the tungsten silicon alloy phase.
[0025] 3. Using active material aluminum as raw material, while utilizing its heat release during reaction with tungsten trioxide, it solves the problem of tungsten powder and silicon powder with high surface energy being oxidized in the air, avoids the adverse effects of foreign oxygen elements, and improves the purity of the synthesized tungsten silicon powder. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 EDS diagrams of W and Si element distribution of alloy powders prepared in various embodiments and comparative examples.
[0027] Figure 2 XRD patterns of alloy powders prepared in various embodiments and comparative examples. DETAILED DESCRIPTION
[0028] The preferred embodiments and comparative examples of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.
[0029] Example 1
[0030] The method for preparing tungsten silicon alloy powder in this embodiment is as follows:
[0031] Step 1: Prepare the precursors by ball milling: Tungsten powder with a purity of 99.99% or higher and a particle size of 5-13μm; tungsten trioxide powder with a purity of 99.99% or higher and a particle size of 100nm; Si powder with a particle size of 6-15μm; and active material powder (aluminum) with a purity of 99.99% and a particle size of 5-10μm. The weights of tungsten powder, tungsten trioxide powder, and Si powder are 12.73g, 1.71g, and 5.56g, respectively, for a total of 20g.
[0032] The W, WO3, and Si powders were ball-milled using a carbide milling jar with 4 mm diameter balls and a 4:1 ball-to-powder ratio. The mixture was milled for 12 hours at a speed of 300 rpm in a high-performance ball mill. After milling, 0.4 g of aluminum powder (2 wt%) was mixed with the milled powder in an agate mortar.
[0033] Step 2: Cold isostatic pressing to form a composite block: Use a stainless steel mold with a diameter of 1.5 cm to load the obtained precursor powder into the stainless steel mold, and use a punch and mold assembly for compression molding; use molybdenum foil as a lubricating layer on the mold wall to make the pressed block easy to eject, and use a pre-pressing machine at room temperature to press it into a powder block, and the pressure is evenly increased to 50 MPa and maintained for 1 minute.
[0034] Step 3: low-temperature reaction sintering in a tubular furnace: place the composite block in a tubular furnace. The process conditions for pressureless sintering in an argon atmosphere in a tubular furnace are as follows: under vacuum conditions, heat from room temperature to 600°C at a heating rate of 5°C / min, keep warm for 30 minutes, then heat to 1000°C at a rate of 3°C / min, and keep warm for 2 hours.
[0035] Step 4: Crush the bulk material: Add the preliminarily crushed tungsten silicon composite particles into the air flow mill, set the air flow pressure to 1 MPa, the gas-solid ratio to 12:1, the nozzle angle to 20°, the spacing to 70 mm, and the speed to 4000 r / min; circulate the crushing until the powder particle size reaches the micron level.
[0036] Step 5: Pickling and removing impurities from the powder: The tungsten silicon composite powder is placed in 15% hydrochloric acid to remove aluminum oxide, and then the remaining powder is repeatedly rinsed with deionized water, and then dried to obtain pure tungsten silicon alloy powder.
[0037] Example 2
[0038] The method for preparing tungsten silicon alloy powder in this embodiment is as follows:
[0039] Step 1: Prepare the precursors by ball milling: Tungsten powder with a purity of 99.99% or higher and a particle size of 5-13μm; tungsten trioxide powder with a purity of 99.99% or higher and a particle size of 100nm; Si powder with a particle size of 6-15μm; and active material powder (aluminum) with a purity of 99.99% and a particle size of 5-10μm. The weights of tungsten powder, tungsten trioxide powder, and Si powder are 13.53g, 0.86g, and 5.61g, respectively, for a total of 20g.
[0040] The W, WO3, and Si powders were ball-milled using a carbide milling jar with 4 mm diameter balls and a 4:1 ball-to-powder ratio. The mixture was milled for 12 hours at a speed of 300 rpm in a high-performance ball mill. After milling, 0.2 g of aluminum powder (1 wt%) was mixed with the milled powder in an agate mortar.
[0041] Step 2: Cold isostatic pressing to form a composite block: Use a stainless steel mold with a diameter of 1.5 cm to load the obtained precursor powder into the stainless steel mold, and use a punch and mold assembly for compression molding; use molybdenum foil as a lubricating layer on the mold wall to make the pressed block easy to eject, and use a pre-pressing machine at room temperature to press it into a powder block, and the pressure is evenly increased to 50 MPa and maintained for 1 minute.
[0042] Step 3: Tubular furnace reaction sintering: Place the composite block in a tubular furnace. The process conditions for pressureless sintering in an argon atmosphere in a tubular furnace are as follows: Under vacuum conditions, heat from room temperature to 600°C at a heating rate of 5°C / min, keep warm for 30 minutes, then heat to 950°C at a rate of 3°C / min, and keep warm for 2 hours.
[0043] Step 4: Crush the bulk material: Add the preliminarily crushed tungsten silicon composite particles into the air flow mill, set the air flow pressure to 1 MPa, the gas-solid ratio to 12:1, the nozzle angle to 20°, the spacing to 70 mm, and the speed to 4000 r / min; circulate the crushing until the powder particle size reaches the micron level.
[0044] Step 5: Pickling and removing impurities from the powder: The tungsten silicon composite powder is placed in 15% hydrochloric acid to remove aluminum oxide, and then the remaining powder is repeatedly rinsed with deionized water, and then dried to obtain pure tungsten silicon alloy powder.
[0045] Comparative Example 1
[0046] The method for preparing tungsten silicon alloy powder in this comparative example is as follows:
[0047] Step 1: Prepare the precursor by ball milling: the purity of the tungsten powder used is above 99.99%, and the particle size is 5-13 μm; the particle size of the Si powder used is 6-15 μm; the masses of the tungsten powder and Si powder are 14.32 g and 5.68 g respectively, for a total of 20 g.
[0048] The ball milling mixing parameters of W powder and Si powder are as follows: a carbide ball milling jar is used, the grinding ball diameter is 4 mm, the ball-to-powder ratio is 4:1, and the powder is loaded into a high-performance ball mill and ball milled for 12 hours at a ball milling speed of 300 r / min.
[0049] Step 2: Cold isostatic pressing to form a composite block: Use a stainless steel mold with a diameter of 1.5 cm to load the obtained precursor powder into the stainless steel mold, and use a punch and mold assembly for compression molding; use molybdenum foil as a lubricating layer on the mold wall to make the pressed block easy to eject, and use a pre-pressing machine at room temperature to press it into a powder block, and the pressure is evenly increased to 50 MPa and maintained for 1 minute.
[0050] Step 3: Reaction sintering in a tubular furnace: Place the composite block in a tubular furnace. The process conditions for pressureless sintering in an argon atmosphere in a tubular furnace are as follows: Under vacuum conditions, heat from room temperature to 600°C at a heating rate of 5°C / min, keep warm for 30 minutes, then heat to 1150°C at a rate of 3°C / min, and keep warm for 2 hours.
[0051] Step 4: Crush the bulk material: Add the preliminarily crushed tungsten silicon composite particles into the air flow mill, set the air flow pressure to 1 MPa, the gas-solid ratio to 12:1, the nozzle angle to 20°, the spacing to 70 mm, and the speed to 4000 r / min; circulate the crushing until the powder particle size reaches the micron level.
[0052] Comparative Example 2
[0053] The only difference from Comparative Example 1 is that the sintering temperature in the tubular furnace in step 3 is 950°C.
[0054] Table 1
[0055]
[0056] Table 1 shows the mass fraction of WSi2 in the samples. It can be seen that with the increase in the proportion of active substances, the purity of the synthesized WSi2 also increases accordingly, and high temperature conditions are also conducive to the synthesis of WSi2.
[0057] pass Figure 1 It can be seen that the W and Si elements in the alloy powders prepared in Examples 1 and 2 are uniformly distributed, have good dispersion effects, and have no obvious single element agglomeration phenomenon.
[0058] pass Figure 2 It can be seen that the target product WSi2 is generated only in the two examples in which the active substance aluminum is added, that is, the addition of the active substance has a greater effect on lowering the reaction temperature.
[0059] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.
Claims
1. A method for preparing tungsten silicon alloy based on self-propagating reaction low temperature sintering, characterized in that: Using W, WO3 and Si powders as raw materials, and adding aluminum powder as active material, the self-propagating reaction of tungsten trioxide and active material is used to release heat during the low-temperature sintering process to reduce the sintering temperature of tungsten silicon powder. Finally, the generated active oxides are removed to obtain pure tungsten silicon alloy powder.
2. The method according to claim 1, wherein The specific steps include: Step 1: Prepare precursor powder: ball-mill W, WO3 and Si powders, then add an appropriate amount of aluminum powder as an active material and mix well to obtain precursor powder; Step 2: cold isostatic pressing to form a composite block: the obtained precursor powder is placed in a mold and cold isostatic pressing is used to obtain a composite block; Step 3: low-temperature reaction sintering in a tubular furnace: placing the composite block into a tubular furnace and sintering in an argon atmosphere to obtain a tungsten-silicon composite block material; Step 4: Crushing the bulk material: crush the sintered bulk material into particles, then put it into the airflow mill, and continuously cycle the crushing process until the target particle size of tungsten silicon composite powder is obtained; Step 5: Pickling the powder to remove impurities; the tungsten-silicon composite powder is placed in acid to remove active oxides, and then the remaining powder is repeatedly rinsed with deionized water, and then dried to obtain pure WSi2 alloy powder.
3. The method according to claim 2, wherein The tungsten powder used in step 1 has a purity of more than 99.99% and a particle size of 5-13 μm; the tungsten trioxide powder used has a purity of more than 99.99% and a particle size of 100 nm; the Si powder used has a particle size of 6-15 μm; the active material powder used has a purity of 99.99% and a particle size of 5-10 μm; the mass ratio of W, WO3 and Si powder is 10-15:0.5-2.5:4-6, and the amount of active material added is 1-5wt% of the ball-milled powder.
4. The method according to claim 2, wherein The ball milling mixing parameters in step 1 are as follows: a carbide ball milling jar is selected, the grinding balls have a diameter of 4 mm, the ball-to-powder ratio is 4:1, and the jar is loaded into a high-performance ball mill and ball milled for 12 hours at a ball milling speed of 300 r / min; after the ball milling is completed, the active substance powder and the ball-milled powder are evenly mixed in an agate mortar.
5. The method according to claim 2, wherein The parameters of the cold isostatic pressing in step 2 are as follows: a stainless steel mold with a diameter of 1.5 cm is used, and a punch and a die set are used for compression molding; molybdenum foil is used as a lubricating layer on the mold wall to make the pressed block easy to eject; a pre-press is used to press the powder block at room temperature, and the pressure is uniformly increased to 50 MPa and maintained for 1 minute.
6. The method according to claim 2, wherein The process conditions for the low-temperature reaction sintering in the tubular furnace in step three are as follows: in an argon atmosphere, heating from room temperature to 600°C at a heating rate of 5°C / min, holding for 30 minutes, then heating to 950-1000°C at a rate of 3°C / min, and holding for 2 hours.
7. The method according to claim 2, wherein The pulverization parameters in step 4 are as follows: adding the preliminarily crushed particles to the air flow mill, setting the air flow pressure to 1 MPa, the gas-solid ratio to 12:1, the nozzle angle to 20°, the spacing to 70 mm, and the rotation speed to 4000 r / min; and cyclically crushing until the target powder particle size is reached.
8. The method according to claim 2, wherein The pickling and impurity removal process in step five is as follows: removing active oxides in the composite powder by hydrochloric acid washing, then repeatedly washing the remaining powder with deionized water, and drying to obtain pure tungsten silicon alloy powder.