A preparation method of an aluminum-molybdenum alloy

Abstract

The present invention relates to the technical field of molybdenum-aluminum alloy preparation, and in particular to a method for preparing an aluminum-molybdenum alloy. The method comprises the following steps: mixing molybdenum trioxide, aluminum powder, and calcium oxide to obtain a mixture; igniting a portion of the mixture as a base material to initiate a thermite reaction; and continuously feeding the remaining mixture after the thermite reaction has occurred for 4 to 6 seconds to ensure the continued thermite reaction, thereby obtaining the aluminum-molybdenum alloy. The aluminum-molybdenum alloy produced by this method has stable quality and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of molybdenum-aluminum alloys, and in particular to a method for preparing an aluminum-molybdenum alloy. Background Art

[0002] High-quality intermediate alloys are key raw materials for improving the strength, corrosion resistance and heat resistance of high-strength and tough titanium alloys. With the rapid development of my country's aerospace industry, there is an increasing demand for high-density molybdenum alloys, such as landing gear, aircraft wing spars, beams, trusses, stringers, fasteners and springs and other key components.

[0003] At present, the domestic preparation of aluminum-molybdenum alloys mainly adopts the following methods: Aluminothermic reduction method: using molybdenum source, aluminum source and slag-forming agent as raw materials, loading the furnace into a crucible, igniting and cooling to obtain aluminum-molybdenum alloy ingots. This method cannot produce aluminum-molybdenum alloys with a molybdenum content greater than 75wt%, and the aluminum thermal reaction time is between 20 and 30s, and the temperature is higher than 2620℃ (molybdenum melting point) for 10 to 25s, which cannot fully alloy the reduction product molybdenum with aluminum, resulting in high-density inclusions in the aluminum-molybdenum alloy, affecting the quality of the aluminum-molybdenum alloy and making it impossible to apply to military titanium alloys; smelting method: mixing metal aluminum and molybdenum in proportion and refining them in a medium-frequency furnace to obtain aluminum-molybdenum alloy. The smelting method produces aluminum-molybdenum alloys. Due to the high melting point of metal molybdenum, the aluminum loss rate in the capacity process is high, which affects the alloy content, and the stability of different batches of products is poor. In addition, the smelting time is long, the energy consumption is high, and the price is high. Due to the material of the medium-frequency furnace crucible, aluminum-molybdenum alloys with a molybdenum content greater than 80wt% cannot be produced; powder metallurgy: the main powder making methods are gas atomization, which uses high-pressure inert gas to impact molten metal, and the small metal droplets formed by the impact solidify to form powder. However, this method has the problems of low powder yield and many powder defects. The atomization process adds oxygen by about 0.05wt%, which leads to an increase in powder price. It can be seen from this that there is no stable method suitable for large-scale production of aluminum-molybdenum master alloys in China. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing an aluminum-molybdenum alloy, wherein the aluminum-molybdenum alloy prepared by the preparation method has stable quality and is suitable for large-scale production.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing an aluminum-molybdenum alloy, comprising the following steps:

[0007] mixing molybdenum trioxide, aluminum powder and calcium oxide to obtain a mixture;

[0008] Part of the mixed material is ignited as a base material to carry out a thermite reaction. After the thermite reaction occurs for 4 to 6 seconds, the remaining mixed material is continuously fed to ensure that the thermite reaction continues to proceed, thereby obtaining the aluminum-molybdenum alloy.

[0009] Preferably, the weight ratio of the molybdenum trioxide to the aluminum powder is (1.6-2.3):1.

[0010] Preferably, the mass of the calcium oxide accounts for 5-22% of the total mass of the molybdenum trioxide and aluminum powder.

[0011] Preferably, the mixing is carried out under stirring conditions;

[0012] The stirring speed is 6-15 rpm and the stirring time is 40-60 min.

[0013] Preferably, the mass ratio of the partial mixture to the remaining mixture is (0.2-0.4): (0.6-0.8).

[0014] Preferably, the electric combustion is ignited by a magnesium strip.

[0015] Preferably, before and during the continuous feeding, backflushing is further performed, and the backflushing gas is argon;

[0016] Before feeding, the blowing flow rate of the argon gas is 20-40 L / min;

[0017] During the feeding process, the blowing flow rate of the argon gas is 30 to 60 L / min.

[0018] Preferably, during the continuous feeding process, the feeding speed is 30 to 60 kg / s.

[0019] Preferably, the thermite reaction is carried out in a furnace;

[0020] The height of the furnace body is 4 to 6 meters, and the distance between the flame height and the top of the furnace body is 0.5 to 1.5 meters.

[0021] Preferably, after the feeding is completed, the backflushing is stopped within 10 to 20 seconds and then cooled.

[0022] The present invention provides a method for preparing an aluminum-molybdenum alloy, comprising the following steps: mixing molybdenum trioxide, aluminum powder, and calcium oxide to obtain a mixture; igniting a portion of the mixture as a base material to initiate a thermite reaction; and continuously feeding the remaining mixture after the thermite reaction has occurred for 4 to 6 seconds to ensure the continued progress of the thermite reaction, thereby obtaining the aluminum-molybdenum alloy. The preparation method of the present invention utilizes a continuous feeding process to extend the thermite reaction time at high temperatures, eliminate high-density inclusions in the alloy, and improve alloy quality. This method addresses the low content, poor quality, and unstable quality of conventional aluminum-molybdenum alloys, providing a promising approach for the preparation of titanium alloys for high-end fighter aircraft in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1Schematic diagram of the preparation method of the aluminum-molybdenum alloy of the present invention. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing an aluminum-molybdenum alloy, comprising the following steps:

[0025] mixing molybdenum trioxide, aluminum powder and calcium oxide to obtain a mixture;

[0026] Part of the mixed material is ignited as a base material to carry out a thermite reaction. After the thermite reaction occurs for 4 to 6 seconds, the remaining mixed material is continuously fed to ensure that the thermite reaction continues to proceed, thereby obtaining the aluminum-molybdenum alloy.

[0027] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0028] The invention mixes molybdenum trioxide, aluminum powder and calcium oxide to obtain a mixture.

[0029] In the present invention, the weight ratio of the molybdenum trioxide to the aluminum powder is preferably (1.6-2.3):1, more preferably (1.7-2.2):1, and most preferably (1.8-2.1):1. In the present invention, the mass of the calcium oxide preferably accounts for 5-22% of the total mass of the molybdenum trioxide and aluminum powder, more preferably 8-16%, and most preferably 10-13%.

[0030] In the present invention, the mixing is preferably carried out under stirring conditions; the stirring speed is preferably 6 to 15 rpm, more preferably 8 to 13 rpm, and most preferably 10 to 12 rpm; the stirring time is preferably 40 to 60 minutes, more preferably 45 to 55 minutes, and most preferably 48 to 52 minutes. In the present invention, during the alloy production process, the total amount of raw materials per furnace is between 2800 and 3600 kg, which is a large amount of material. To ensure uniform mixing of the raw materials, the mixing time needs to be significantly extended during the mixing process.

[0031] In the present invention, adjusting the ratio of the molybdenum trioxide and the aluminum powder can ensure the alloy grade of the aluminum-molybdenum alloy finally prepared.

[0032] In the present invention, the amount of calcium oxide added can ensure that the thermal effect of the reaction unit charge is 750-1000 kJ / kg, thereby preventing the following during the continuous feeding process: 1. The instantaneous heat is too high, the aluminum heat reaction is violent, the flame is violent, and it enters the discharge channel, causing a dangerous reaction of the charge in the pipeline; 2. The reaction heat is prevented from being too low, the reaction rate is slow, affecting the reaction speed during continuous feeding, and affecting the separation effect of the alloy and slag inclusions.

[0033] After obtaining the mixture, the present invention ignites part of the mixture as a base material to carry out thermite reaction. After the thermite reaction occurs for 4 to 6 seconds, the remaining mixture is continuously fed to ensure that the thermite reaction continues to proceed, thereby obtaining the aluminum-molybdenum alloy.

[0034] In the present invention, the mass ratio of the partial mixture to the remaining mixture is preferably (0.2-0.4): (0.6-0.8), more preferably (0.25-0.35): (0.65-0.75), and most preferably (0.28-0.32): (0.68-0.72).

[0035] In the present invention, controlling the ratio of the partial mixed material and the remaining mixed material can prevent excessive base material from causing violent reactions, causing the materials in the aisle to react, and at the same time prevent insufficient base material from causing rapid reactions, resulting in interruption of continuous feeding reactions.

[0036] In the present invention, part of the mixed material is placed in the molten pool as the base material, and the remaining mixed material is placed in the silo, and the base material in the molten pool is ignited by a magnesium rod. In the present invention, the material of the molten pool is preferably corundum, which can prevent the molten pool from breaking under continuous high temperature reaction, causing the alloy melt to flow out and affect the alloy quality (such as Figure 1 shown).

[0037] In the present invention, before and during the continuous feeding, it is also preferred to include continuous backflushing, and the backflushing gas is preferably argon, and the volume proportion of impurity gases in the argon is preferably ≤10% (the purity of the nitrogen can prevent the gas from reacting with the alloy during the backflushing process to oxidize and nitride, thereby affecting the quality of the alloy); before feeding, the blowing flow rate of the argon is preferably 20-40 L / min, more preferably 25-35 L / min, and most preferably 28-32 L / min; during the feeding, the blowing flow rate of the argon is preferably 30-60 L / min, more preferably 35-55 L / min, and most preferably 40-50 L / min. In the present invention, the start time of the backflushing is preferably 4-6 seconds after the thermite reaction occurs; the start time of the backflushing can ensure that after the base material has fully started to react, continuous feeding is started to maintain the optimal reaction state, thereby accelerating the separation of tungsten oxide slag inclusions in the alloy. During the feeding process, the blowing flow rate of the argon gas can prevent the gas flow rate from being too large during ignition, which may cause the thermite reaction to be interrupted.

[0038] In the present invention, during the continuous charging process, the charging rate is preferably 30-60 kg / s, more preferably 35-55 kg / s, and most preferably 40-50 kg / s. In the present invention, the thermite reaction is preferably carried out within the furnace body; the furnace body height is preferably 4-6 m, more preferably 4.5-5.5 m, and most preferably 4.8-5.2 m; the distance between the flame height and the furnace body top is preferably 0.5-1.5 m, more preferably 0.7-1.3 m, and most preferably 0.8-1.1 m. In the present invention, the air flow rate and the distance between the flame height and the furnace body top prevent the flame from entering the discharge pipe during the thermite reaction, causing a chain reaction; prevent the charge from reacting during the falling process, resulting in a loss of control of the reaction state, ensure that the charge is poured into the molten pool for the thermite reaction, and increase the controllability of the reaction. The furnace body height ensures that the continuous charging reaction is safe and controllable. The charging rate ensures that the continuous charging process does not cause violent reactions while ensuring a smooth and continuous reaction.

[0039] In the present invention, after the feeding is completed, the backflushing is stopped within 10 to 20 seconds and then cooled. In the present invention, the cooling is preferably natural cooling; and the natural cooling time is preferably 30 to 48 hours.

[0040] In the present invention, the weight of the aluminum-molybdenum alloy ingot produced by the continuous feeding method is preferably 1 to 1.5 t. Under this ingot weight, the reaction is most complete and the state is highly controllable. If the ingot weight is too low, the total heat of reaction is too low and the alloy ingot is prone to stratification. If the ingot weight is too large, the alloy post-processing is difficult.

[0041] The preparation method of the aluminum-molybdenum alloy provided by the present invention is described in detail below with reference to the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] 1845kg of molybdenum trioxide, 962kg of aluminum powder and 420kg of calcium oxide were added to the mixer in sequence and stirred at 10rpm for 50min. 1000kg of the mixture was added to the corundum molten pool as the base material. The remaining materials were placed in the storage bin as the silo material and loaded into the furnace. The furnace body was 5.5m high and the theoretical unit charge heat effect was 872.4kJ / kg.

[0044] A magnesium rod is used to ignite the bottom material in the molten pool to cause thermite reaction. After 4 seconds of the thermite reaction, the backflush valve is opened, and argon with a purity of 98% is used as the gas source. The gas flow rate is 30 L / min, and the thermite reaction flame is 1 to 1.3 m away from the top of the furnace body. The bin conveyor is opened, the solenoid valve of the feeding pipeline is opened, the feeding speed is controlled to 50 kg / s, and the argon flow rate is increased to 55 L / min. At this time, the thermite reaction flame is 1.2 to 1.4 m away from the top of the furnace body. The backflush valve is closed 15 seconds after the bin material is exhausted, and the temperature is naturally lowered for 42 hours to obtain a 1450 kg aluminum-molybdenum alloy ingot (molybdenum: 81.9 wt%, iron: 0.098 wt%, silicon: 0.097 wt%, oxygen: 0.022 wt%, nitrogen: 0.015 wt% and the remainder of aluminum).

[0045] Example 2

[0046] 1721kg of molybdenum trioxide, 847kg of aluminum powder and 308kg of calcium oxide were added to the mixer in sequence and stirred at 10rpm for 45min. 850kg of the mixture was added to the corundum molten pool as the base material. The remaining materials were placed in the storage bin as the silo material and loaded into the furnace. The furnace body was 5.5m high and the theoretical unit charge heat effect was 912.8kJ / kg.

[0047] A magnesium rod is used to ignite the bottom material in the molten pool to cause thermite reaction. After 4 seconds of the thermite reaction, the backflush valve is opened, and argon with a purity of 98% is used as the gas source. The gas flow rate is 40 L / min, and the height of the thermite reaction flame is 0.8 to 1.2 m. The bin conveyor is opened, the solenoid valve of the feeding pipeline is opened, the feeding speed is controlled to 40 kg / s, and the argon flow rate is increased to 50 L / min. At this time, the thermite reaction flame is 1 to 1.3 m away from the top of the furnace body. The backflush valve is closed 12 seconds after the bin material is exhausted, and the temperature is naturally lowered for 35 hours to obtain 1270 kg of aluminum-molybdenum alloy ingots (molybdenum: 85.9 wt%, iron: 0.108 wt%, silicon: 0.099 wt%, oxygen: 0.019 wt%, nitrogen: 0.024 wt% and the remainder of aluminum).

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum-molybdenum alloy, characterized in that: It consists of the following steps: mixing molybdenum trioxide, aluminum powder and calcium oxide to obtain a mixture; Ignite a portion of the mixed material as a base material to carry out a thermite reaction, and continue to feed the remaining mixed material after the thermite reaction occurs for 4 to 6 seconds to ensure that the thermite reaction continues, thereby obtaining the aluminum-molybdenum alloy; The mass ratio of the partial mixture to the remaining mixture is (0.2-0.4): (0.6-0.8); Before and during the continuous feeding, backflushing is also continued, and the backflushing gas is argon; Before feeding, the blowing flow rate of the argon gas is 20-40 L / min; During the feeding process, the blowing flow rate of the argon gas is 30 to 60 L / min; The thermite reaction is carried out in the furnace body; The height of the furnace body is 4 to 6 meters, and the distance between the flame height and the top of the furnace body is 0.5 to 1.5 meters.

2. The preparation method according to claim 1, wherein The weight ratio of the molybdenum trioxide to the aluminum powder is (1.6-2.3):

1.

3. The preparation method according to claim 1 or 2, wherein The mass of the calcium oxide accounts for 5-22% of the total mass of the molybdenum trioxide and the aluminum powder.

4. The preparation method according to claim 1, wherein The mixing is carried out under stirring conditions; The stirring speed is 6-15 rpm and the stirring time is 40-60 min.

5. The preparation method according to claim 1, wherein The ignition is carried out using a magnesium rod.

6. The preparation method according to claim 1, wherein During the continuous feeding process, the feeding speed is 30-60 kg / s.

7. The preparation method according to claim 1, wherein After the feeding is completed, the backflushing is stopped within 10 to 20 seconds and then cooled.

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