A production method of a high-uniformity molybdenum-vanadium-aluminum-chromium alloy

Abstract

The present invention provides a method for producing a molybdenum-vanadium-aluminum-chromium alloy with high uniformity. The composition of the molybdenum-vanadium-aluminum-chromium alloy is as follows: Mo 25% - 28%, V 24% - 27%, Cr 28% - 31%, with the balance being Al, O ≤ 0.05%, C ≤ 0.05%, and the segregation of the main content being < 0.6%. It relates to the field of metallurgical technology. The technological steps are as follows: (1) Prepare an ammonium molybdate-ammonium dichromate-ammonium metavanadate precursor by hydrothermal method using sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride; (2) Perform high-temperature treatment on the precursor to obtain a MoO3 / V2O5 / CrO3 composite material; (3) Mix the MoO3 / V2O5 / CrO3 composite material, refined aluminum powder, and calcium oxide in proportion, load them into a furnace and ignite to undergo a thermite reaction to obtain a molybdenum-vanadium-aluminum-chromium alloy ingot. Compared with the molybdenum-vanadium-aluminum-chromium alloy produced by the traditional thermite method, the uniformity of the present invention is greatly improved, and it can be used for the production of titanium alloys such as TB2, TB9, TB15, and TB16.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and particularly relates to a production method of a molybdenum-vanadium-aluminum-chromium alloy with high uniformity. Background Art

[0002] TB2 (Ti-5Mo-5V-8Cr-3Al) is a metastable β-type titanium alloy, including isomorphous β elements Mo: 5%, V: 5%, eutectoid β element Cr: 8%, and α element Al: 3%. TB2 titanium alloy has excellent cold forming performance and welding performance in the solution-treated state, and its high strength and good plasticity provide more possibilities for its application. The semi-finished products of TB2 titanium alloy are mostly in the forms of plates, strips, foils, rods, wires, etc., and can be made into sheet metal, high-pressure containers, rocket engine casings, corrugated and honeycomb structure materials, cold and hot rivets, head bolts after pressing and casting, for manufacturing fasteners below 300°C, and fasteners below 500°C, etc., and are widely used in the aerospace field.

[0003] Commonly, aluminum-chromium alloy, aluminum-molybdenum alloy, aluminum-vanadium alloy are mixed with a titanium source and melted to obtain TB2 titanium alloy. Affected by the production process, the three intermediate alloys of aluminum-chromium alloy, aluminum-molybdenum alloy, and aluminum-vanadium alloy are mostly produced by aluminothermic reaction, and inevitably introduce alumina inclusions. The three alloys have different heats, and the particle sizes of the generated alumina inclusions are different. In TB2 titanium alloy, it causes uneven oxygen content distribution, affecting the toughness and service life of the alloy; the uniformity degrees are different. For example, high-density inclusions are likely to be generated inside the aluminum-molybdenum alloy (Mo≥60%), seriously affecting the quality of the titanium alloy during the melting of TB2 titanium alloy. Therefore, it is necessary to use ternary, quaternary and above intermediate alloys with coexisting molybdenum, vanadium, and chromium for melting production. There are also the same problems with grades such as TB9, TB15, and TB16.

[0004] Currently, at home and abroad, the aluminothermic method is used to produce molybdenum-vanadium-aluminum-chromium alloy. Using chromium oxide green, molybdenum trioxide (molybdenum dioxide), vanadium pentoxide (vanadium trioxide), and slag-forming agent as raw materials, after mixing evenly, an aluminothermic reaction occurs to obtain a molybdenum-vanadium-aluminum-chromium alloy ingot, and the alloy finished product is obtained after post-treatment. However, the molybdenum-vanadium-aluminum-chromium alloy produced by the aluminothermic method has poor uniformity, and the main content segregation is between 1-2.5%. During the production process of TB2 titanium alloy, the three intermediate alloys of aluminum-molybdenum, aluminum-chromium, and aluminum-vanadium have been used. In the medium-frequency furnace melting method, four pure metals of molybdenum, vanadium, aluminum, and chromium are directly melted in a medium-frequency induction furnace. Due to the relatively high melting points of molybdenum and chromium, the alloy segregation phenomenon is more serious, and it cannot be applied to the production process of titanium alloy. Therefore, it is necessary to produce a molybdenum-vanadium-aluminum-chromium alloy with high uniformity by the aluminothermic method. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for producing a molybdenum-vanadium-aluminum-chromium alloy with high uniformity. The preparation method provided by the present invention can prepare a molybdenum-vanadium-aluminum-chromium alloy with high uniformity, and solves the problem of the uniformity of the molybdenum-vanadium-aluminum-chromium alloy produced by the aluminothermic method.

[0006] It should be noted that the present invention prepares an ammonium molybdate-ammonium dichromate-ammonium metavanadate precursor by a hydrothermal method, and further subjects the precursor to high-temperature treatment in an industrial tube furnace to decompose the precursor at high temperature to form an in-situ grown MoO 3 / V 2 O 5 / CrO 3 composite material. Then, the MoO 3 / V 2 O 5 / CrO 3 composite material, refined aluminum powder, and slag-forming agent are mixed and ignited to obtain a molybdenum-vanadium-aluminum-chromium alloy with high uniformity, which solves the factors affecting the alloy quality due to the mixing uniformity and heat unevenness, and provides a molybdenum-vanadium-aluminum-chromium alloy with high uniformity for the production of titanium alloys of grades such as TB2, TB9, TB15, and TB16.

[0007] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0008] A method for producing a molybdenum-vanadium-aluminum-chromium alloy with high uniformity, comprising the following steps:

[0009] 1. Preparation of MoO 3 / V 2 O 5 / CrO 3 composite material:

[0010] Deionized water, sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride are mixed in a stirring kettle according to a ratio, stirring is started, the above reactants are stirred evenly, dilute nitric acid is added, after adjusting the pH of the solution, the solution is transferred to a high-pressure reaction kettle and reacted at high temperature to obtain a suspension.

[0011] After the above suspension is transferred to a cooling kettle for cooling, the suspension is filtered through a plate-and-frame filter press, washed with deionized water, and then the filter cake is transferred to a blast drying kiln for drying treatment to obtain an ammonium molybdate-ammonium dichromate-ammonium metavanadate precursor.

[0012] The precursor is transferred to a tube furnace, high-purity nitrogen is introduced, and after heating, holding, and cooling according to a program, MoO 3 / V 2 O 5 / CrO 3 composite material.

[0013] 2. Preparation of molybdenum-vanadium-aluminum-chromium alloy:

[0014] Mix MoO 3 / V 2 O 5 / CrO 3 Composite materials, refined aluminum powder, and calcium oxide powder are mixed evenly in a mixer according to a ratio, loaded into a melting pool, ignited with a magnesium strip to undergo an aluminothermic reaction, and after cooling and temperature reduction, a molybdenum-vanadium-aluminum-chromium alloy ingot is obtained.

[0015] Preferably, the mass ratio of sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride is (5.15 - 6):(5.74 - 6.7):(4.36 - 4.83):(10.6 - 12.2), and the mass ratio of deionized water to the above mixture is 10:(2 - 3).

[0016] Preferably, the deionized water, sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride are heated to 38 - 45 °C in a dissolving kettle and stirred for 30 - 90 min to ensure that all the above substances are dissolved.

[0017] Preferably, the concentration of dilute nitric acid is 1.5 - 5 mol / l, while ensuring the concentrations of sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride in the solution, the acidity of the solution is adjusted.

[0018] Preferably, the pH range adjusted by the dilute nitric acid is 1.2 - 2.2. By adjusting the pH, an acidic environment for generating the corresponding ammonium salts is provided, which is beneficial to the precipitation of metal oxide ammonium salts.

[0019] Preferably, the reaction conditions in the mixed solution are to react at 160 - 220 °C for 24 - 42 h to ensure that sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride react fully to form an ammonium molybdate-ammonium dichromate-ammonium metavanadate precursor.

[0020] Preferably, the suspension is cooled by the water cooling method in a cooling kettle. After cooling to 10 - 40 °C, it is subjected to pressure filtration to prevent the suspension temperature from being too high and affecting the filter cloth and service life of the plate and frame filter press.

[0021] Preferably, the plate and frame pressure in the plate and frame filter press for the suspension is 3 - 6 kg to ensure the water content of the filter cake.

[0022] Preferably, the filter cake is washed with deionized water in the plate and frame filter press until the pH of the effluent is 5.8 - 7.2 to complete the washing and wash away the excess ammonium salts.

[0023] Preferably, the water content in the filter cake accounts for 20 - 45% of the total weight. The drying temperature in a blast drying kiln is 65 - 75 °C, and the drying time is 8 - 12 h to increase the fluffiness of the dried product and prevent the dried product of the filter cake from caking.

[0024] Preferably, the nitrogen content in the tubular furnace is higher than 98%, and the gas flow rate is 5-15 l / min.

[0025] Preferably, the temperature rising program of the dried product in the tubular furnace is room temperature - (160-200°C) - (450-650°C), and the temperature is raised in layers to achieve the purpose of removing water and generating chromium trioxide, vanadium pentoxide, and molybdenum trioxide.

[0026] Preferably, during the temperature rising process of the tubular furnace, the temperature rising rate from room temperature to (160-200°C) is 1-2°C / min, and the heat preservation time is 50-80 min; the temperature rising rate from (160-200°C) to (450-650°C) is 4-8°C / min, and the heat preservation time is 40-60 min. By controlling the temperature rising rate, the generation rate of chromium trioxide, vanadium pentoxide, and molybdenum trioxide is ensured.

[0027] Preferably, the mass ratio of the refined aluminum powder to the MoO 3 / V 2 O 5 / CrO 3 composite material is (1-2):(2-5). By controlling the feeding ratio, a molybdenum-vanadium-aluminum-chromium alloy that meets the usage requirements is produced.

[0028] Preferably, the feeding amount of calcium oxide accounts for 6-12% of the total weight of the materials to adjust the heat of the thermite reaction and the viscosity of the slag.

[0029] Preferably, the particle size of the refined aluminum powder is <0.2 cm to maintain the uniformity of the heat preservation alloy.

[0030] It should be noted that in the present invention, the in-situ grown MoO 3 / V 2 O 5 / CrO 3 composite material is used as the raw material for the thermite process to replace the traditional molybdenum trioxide, flaky vanadium pentoxide (diameter about 0.2-5 cm), and chromium oxide green raw materials, solving the problems of uneven mixing during the mixing process with aluminum powder, uneven heat during the thermite reaction resulting in furnace spraying, inclusion (aluminum oxide), and segregation of the main elements; while the in-situ grown MoO 3 / V 2 O 5 / CrO 3 composite material ensures the uniformity of mixing and the stability of heat in each part of the thermite process, significantly improving the quality of the alloy ingot.

[0031] Through the above technical solutions, it can be seen that compared with the prior art, the present invention provides a production method of a high-uniformity molybdenum-vanadium-aluminum-chromium alloy, having the following excellent effects:

[0032] Through the present invention, a molybdenum-vanadium-aluminum-chromium alloy with high uniformity can be produced. The precursor material is prepared by a hydrothermal method and the MoO 3 / V 2 O 5 / CrO 3 composite material is obtained. Using the composite material, refined aluminum powder, and calcium oxide as raw materials, the molybdenum-vanadium-aluminum-chromium alloy is produced. The present invention solves the problem of the uniformity of the molybdenum-vanadium-aluminum-chromium alloy, greatly improves the quality of the high molybdenum-vanadium-aluminum-chromium alloy, and provides an excellent intermediate alloy additive for related titanium alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0034] Attached Figure 1 is the sampling diagram of the molybdenum-vanadium-aluminum-chromium alloy ingot of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will combine the embodiments of the present invention and the drawings of the specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0036] The embodiments of the present invention disclose a method for producing a molybdenum-vanadium-aluminum-chromium alloy with high uniformity.

[0037] To better understand the present invention, the following further specifically elaborates on the present invention through the following embodiments. However, it should not be construed as a limitation of the present invention. For some non-essential improvements and adjustments made by those skilled in the art based on the above invention content, they are also considered to fall within the protection scope of the present invention.

[0038] The following will further illustrate the technical solutions of the present invention in combination with specific embodiments.

[0039] Example 1

[0040] Mix 670 kg of deionized water, 54.7 kg of sodium molybdate, 59.4 kg of sodium metavanadate, 46 kg of sodium dichromate, and 112 kg of ammonium chloride in a dissolution kettle. Turn on the steam heating and stir for 70 min at 40°C. Add 22.4 kg of 3 mol / l dilute nitric acid, adjust the pH of the solution to 1.5, transfer the solution to a high-pressure reaction kettle, close the high-pressure reaction kettle, and electrically heat to 195°C for reaction for 30 h to obtain a suspension. Transfer the suspension to a cooling kettle, cool it down to 29°C by water cooling, filter the suspension through a plate-and-frame filter press with a plate-and-frame pressure of 5.5 kg, wash it with 2600 kg of deionized water, and the pH of the effluent is 6.4 to obtain 229 kg of filter cake. Transfer the filter cake to a blast drying kiln and dry it at 66°C for 10 h.

[0041] Transfer 155 kg of the dried product to a tubular furnace, pass nitrogen (98.5%), with a flow rate of 8 l / min, heat up, raise the temperature from room temperature to 180°C at a heating rate of 1.5°C / min, keep the temperature at 180°C for 60 min, raise the temperature from 180°C to 550°C at a heating rate of 5°C / min, and keep the temperature at 550°C for 40 min to obtain MoO 3 / V 2 O 5 / CrO 3 composite material 121.5 kg. Transfer 121.5 kg of MoO 3 / V 2 O 5 / CrO 3 composite material, 70 kg of refined aluminum powder with a particle size < 0.2 cm, and 15 kg of calcium oxide powder are mixed evenly in a mixer according to the proportion, loaded into a melting pool, ignited with a magnesium strip to cause an aluminothermic reaction, and after cooling down, 94.2 kg of molybdenum-vanadium-aluminum-chromium alloy ingot is obtained.

[0042] Take samples of the molybdenum-vanadium-aluminum-chromium alloy ingot, such as Figure 1 and conduct tests. The content is shown in Table 1.

[0043] Table 1 Data table of multi-point sampling of molybdenum-vanadium-aluminum-chromium master alloy

[0044]

[0045] Example 2

[0046] Mix 800 kg of deionized water, 52.8 kg of sodium molybdate, 63 kg of sodium metavanadate, 47 kg of sodium dichromate, and 114 kg of ammonium chloride in a dissolution kettle. Turn on the steam heating and stir at 40 °C for 70 min. Add 29.5 kg of 3 mol / l dilute nitric acid and adjust the pH of the solution to 1.35. Transfer the solution to a high-pressure reaction kettle, close the high-pressure reaction kettle, and electrically heat it to 200 °C for reaction for 26 h to obtain a suspension. Transfer the above suspension to a cooling kettle, cool it to 26 °C with water cooling, filter the suspension through a plate-and-frame filter press with a plate-and-frame pressure of 3.3 kg, wash it with 2200 kg of deionized water, and the pH of the effluent is 6.4 to obtain 266.5 kg of filter cake. Transfer the filter cake to a blast drying kiln and dry it at 75 °C for 12 h.

[0047] Transfer 180 kg of the dried product to a tubular furnace, introduce nitrogen (98.5%), with a flow rate of 8.2 l / min, heat up, the heating rate from room temperature to 180 °C is 1.5 °C / min, the holding time at 180 °C is 65 min, the heating rate from 180 °C to 550 °C is 5 °C / min, and the holding time at 550 °C is 48 min to obtain MoO 3 / V 2 O 5 / CrO 3 composite material 121.5 kg. Transfer the MoO 3 / V 2 O 5 / CrO 3 composite material 126 kg, refined aluminum powder with a particle size < 0.2 cm, 71.6 kg, and calcium oxide powder 17.8 kg are mixed evenly in a mixer, loaded into a melting pool, ignited with a magnesium strip, and after the aluminothermic reaction and cooling, 95.2 kg of molybdenum-vanadium-aluminum-chromium alloy ingot is obtained. The detected data is shown in Table 2

[0048] Table 2 Data table of multi-point sampling of molybdenum-vanadium-aluminum-chromium master alloy

[0049]

[0050] Control example

[0051] Mix 72 kg of aluminum powder, 44.3 kg of flaky vanadium pentoxide, 38.3 kg of molybdenum trioxide, 43.2 kg of chromium oxide green, and 15 kg of calcium fluoride in a mixer, load it into a reaction melting pool, ignite it with a magnesium strip and cool it to obtain a molybdenum-vanadium-aluminum-chromium alloy ingot, as Figure 1 After sampling and testing, Table 3 is obtained.

[0052] Table 3 Data table of multi-point sampling of molybdenum-vanadium-aluminum-chromium master alloy in comparative experiment

[0053]

[0054] Using the alloy grade matching ratio materials in Example 1 and observing Table 3, it is found that the molybdenum-vanadium-aluminum-chromium alloy produced from metal oxides has a higher segregation of main elements compared to Example 1, a higher oxygen element content, and a poorer alloy quality.

[0055] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A production method of a high-uniformity molybdenum-vanadium-aluminum-chromium alloy, characterized in that, it includes the following steps: I Preparation of MoO 3 / V 2 O 5 / CrO 3 Composite material: (a) Stir and mix deionized water, sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride in proportion. After mixing evenly, add dilute nitric acid to adjust the pH of the solution. Then react the mixed solution at high temperature to obtain a suspension; (b) Cool the suspension and then filter it, wash it with deionized water, and then dry the filter cake to obtain an ammonium molybdate-ammonium dichromate-ammonium metavanadate precursor; (c) Subject the ammonium molybdate-ammonium dichromate-ammonium metavanadate precursor to high-temperature treatment, introduce high-purity nitrogen, heat, hold, and cool according to a program to obtain MoO 3 / V 2 O 5 / CrO 3 composite material; II. Prepare the molybdenum-vanadium-aluminum-chromium alloy: Mix the MoO 3 / V 2 O 5 / CrO 3 composite material, refined aluminum powder, and calcium oxide powder in proportion, load them into the molten bath, ignite with a magnesium strip to initiate an aluminothermic reaction, and cool down to obtain a molybdenum-vanadium-aluminum-chromium alloy ingot; The mass ratio of the sodium molybdate, sodium metavanadate, sodium dichromate, and ammonium chloride is (5.15 - 6):(5.74 - 6.7):(4.36 - 4.83):(10.6 - 12.2), and the mass ratio of deionized water to the mixed reactants is 10:(2 - 3); The stirring and mixing temperature in step I (a) is 38 - 45 °C, and the stirring and mixing time is 30 - 90 min; moreover, the concentration of the added dilute nitric acid is 1.5 - 5 mol / l, and the pH range adjusted by the dilute nitric acid is 1.2 - 2.2; the reaction conditions in the mixed solution are to react at 160 - 220 °C for 24 - 42 h; The suspension is cooled by the water-cooling method in a cooling kettle and filtered under pressure after being cooled to 10 - 40 °C; and the plate-frame pressure in the filter press is 3 - 6 kg. After the filter cake is washed with deionized water in the filter press until the pH of the effluent is 5.8 - 7.2, the washing is completed; the water content in the filter cake accounts for 20 - 45% of the total weight, the drying temperature is 65 - 75 °C, and the drying time is 8 - 12 h; The heating program of the ammonium molybdate-ammonium dichromate-ammonium metavanadate precursor in the high-temperature treatment is room temperature - (160 - 200 °C) - (450 - 650 °C), specifically as follows: During the heating process, the heating rate from room temperature to (160 - 200 °C) is 1 - 2 °C / min, and the holding time is 50 - 80 min; the heating rate from (160 - 200 °C) to (450 - 650 °C) is 4 - 8 °C / min, and the holding time is 20 - 40 min.

2. The production method of the high-uniformity molybdenum-vanadium-aluminum-chromium alloy according to claim 1, characterized in that, Refined aluminum powder and MoO 3 / V 2 O 5 / CrO 3 The mass ratio of the composite material is (1 - 2):(2 - 5), and the feeding amount of calcium oxide accounts for 6 - 12% of the total weight of the materials; among them, the particle size of the refined aluminum powder is < 0.2 cm.

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