A spliced tungsten alloy crucible and a manufacturing method thereof

Abstract

The application discloses a spliced tungsten alloy crucible and a manufacturing method thereof. The manufacturing method comprises the following steps: firstly, preparing tungsten alloy strips; then, splicing the tungsten alloy strips into the side wall of the crucible by staggered joint; and finally, applying adhesive to the joint gap to obtain the spliced tungsten alloy crucible. The manufacturing method of the tungsten alloy strip comprises the following steps: mixing WO3, SiO2, KCl and Al2O3 to obtain mixed powder; performing two-stage hydrogen reduction on the mixed powder to obtain doped tungsten powder; taking appropriate doped tungsten powder, and performing rubber sleeve powder packaging to obtain tungsten plate blanks by cold isostatic pressing; sintering the tungsten plate blanks in a hydrogen atmosphere to obtain sintered blanks; performing wire cutting on the sintered blanks to obtain tungsten alloy blocks with a desired size; performing bending pressing on the tungsten alloy blocks; and processing grooves and protrusions on the opposite ends of the tungsten alloy blocks after the bending pressing to obtain the tungsten alloy strips. The process steps are simple, the high-temperature performance and density of the prepared tungsten crucible can meet the use requirements, the production cost is low, the size is flexible, and batch production is facilitated.

Description

Technical Field

[0001] This invention relates to the field of high-temperature refractory metal technology, specifically to a spliced ​​tungsten alloy crucible and its manufacturing method. Background Technology

[0002] Tungsten crucibles have the characteristics of high melting point, high electrical conductivity, and good chemical stability, and are widely used in the inner lining of large equipment such as crystal growth furnaces and sintering furnaces.

[0003] Currently, the most widely used tungsten crucibles are pure tungsten crucibles. Pure tungsten crystallizes at temperatures above 1200℃, leading to increased high-temperature deformation, material brittleness, and a shorter service life. Furthermore, the reported methods for preparing large-size tungsten crucibles are mainly integral molding methods such as hot sintering, which require sophisticated equipment, are technically challenging, costly, and inefficient. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a spliced ​​tungsten alloy crucible and its manufacturing method. The manufacturing method involves first preparing tungsten alloy strips, then using several tungsten alloy strips to splice together in a staggered manner to form the sidewall of the crucible, and finally applying an adhesive to the splicing gaps to obtain the spliced ​​tungsten alloy crucible. This process is simple, and the high-temperature performance and density of the prepared tungsten crucible can meet the usage requirements. Moreover, the production cost is low, the size is flexible, and it is convenient for mass production.

[0005] To achieve the above objectives, the specific solution adopted by the present invention is as follows:

[0006] A method for manufacturing a spliced ​​tungsten alloy crucible involves dividing the sidewall of the tungsten alloy crucible into several small alloy strips along the height direction. Each alloy strip has a groove and a protrusion processed at both ends, and then the crucible is spliced ​​together in a staggered manner to achieve integration.

[0007] The manufacturing method specifically includes the following steps:

[0008] Step 1: Mix WO3, SiO2, KCl and Al2O3 to obtain a mixed powder, and perform a two-stage hydrogen reduction on the mixed powder to obtain doped tungsten powder;

[0009] Step 2: Take an appropriate amount of doped tungsten powder, put the powder in a plastic bag, and obtain several tungsten slab blanks by cold isostatic pressing.

[0010] Step 3: Perform medium-frequency sintering on the tungsten slab under a hydrogen atmosphere to obtain a sintered slab;

[0011] Step 4: Wire cut the sintered billet obtained in Step 3 to obtain a tungsten alloy block of the required size;

[0012] Step 5: Bend the tungsten alloy block obtained in Step 4.

[0013] Step six, recesses and protrusions are processed on opposite ends of the bent tungsten alloy block, and a tungsten alloy strip is obtained;

[0014] Step seven, the side wall of the crucible is obtained by splicing several tungsten alloy strips staggered, and the side wall and the bottom are combined into a crucible;

[0015] Step eight, the doped tungsten powder and glycerol are mixed uniformly at a mass ratio of 1:2, and are applied to the gaps of the crucible, thereby obtaining a spliced tungsten alloy crucible.

[0016] As a preferred solution, in step one, the components contained in the mixed powder and the mass fraction of each component are as follows: SiO2 0.05-0.1%, KCl 0.2-0.5%, Al2O3 0.03-0.05%, and the balance is WO3.

[0017] As a preferred solution, in step one, the mixture of SiO2, KCl and Al2O3 is added to WO3 by wet method or spray method, and after mixing uniformly, it is sieved through a 160-200 mesh sieve, thereby obtaining the mixed powder.

[0018] As a preferred solution, in step one, the purity of WO3 is not less than 99.95%, the Fisher particle size is 3.0-4.5 μm, and it is sieved through a 160-200 mesh sieve; SiO2, KCl and Al2O3 are all sieved through a 160-200 mesh sieve.

[0019] As a preferred solution, in step two, after the rubber sleeve is filled with powder and vibrated, it is sealed airtight, and the shape of the rubber sleeve is shaped to ensure that the shape of the pressed blank after cold isostatic pressing is regular.

[0020] As a preferred solution, in step two, the pressure of cold isostatic pressing is 350 MPa-390 MPa, and the pressure holding time is 3-10 min.

[0021] As a preferred solution, in step three, the specific parameters of medium frequency sintering are as follows: first, the temperature is raised to 800℃ at a rate of 3℃ / min, and the temperature is kept for 6h; then the temperature is raised to 900℃ at a rate of 3℃ / min, and the temperature is kept for 1h; then the temperature is raised to 1500℃ at a rate of 10℃ / min, and the temperature is kept for 1h; finally, the temperature is raised to 2200-2400℃ at a rate of 5℃ / min, and the temperature is kept for 12h; after the temperature holding is completed, the furnace is cooled to room temperature.

[0022] As a preferred solution, in step five, the tungsten alloy block is heated to 1400-1500℃ in a hydrogen atmosphere, and the temperature is kept for 60 min, and after the temperature holding is completed, it is taken out and subjected to bending treatment on an oil press with concave and convex molds.

[0023] As a preferred solution, in step seven, the bottom of the crucible is obtained by cutting the sintered blank wire obtained in step three.

[0024] A spliced tungsten alloy crucible is characterized in that it is manufactured by the above method.

[0025] The SiO2 has the effect that: the Si element promotes the powder agglomeration in the sintering process to increase, and the increased agglomeration is more conducive to secondary recrystallization, abnormal grain growth, and formation of coarse-grained sintered slab. The huge grain boundary is tortuous and curved, the grain boundary is interlocked, and the deformation is hindered, which is difficult to deform.

[0026] The KCl has the effect that: the potassium element is not soluble with tungsten metal, and in the high-temperature sintering process, the potassium is gasified to form a potassium bubble. The potassium bubble is pinned on the grain boundary, which inhibits dislocation deformation, so that the alloy has better high-temperature creep resistance.

[0027] The Al2O3 has the effect that: the aluminum element will form dispersedly distributed inclusions in the sintering process, increase the roughness of the grain surface, and make the dislocation blocked on the slip plane, so that the alloy has better high-temperature stability.

[0028] Beneficial effects:

[0029] 1) The process is simple, the ratio of tungsten trioxide powder is changed, the original pure tungsten material is replaced by doped tungsten powder, which to some extent relieves the defects of tungsten high-temperature recrystallization brittleness and short service life, and the splicing cost is much lower than that of integral forming.

[0030] 2) The doped tungsten powder is used in the preparation of the spliced tungsten alloy crucible, the doped tungsten powder uses bubble strengthening, and under the "nailing" effect of the bubbles, the material deformation is difficult, the high-temperature creep resistance is good, and the service life is long.

[0031] 3) The tungsten alloy strip prepared by the method has grooves and protrusions at two ends, and the combination of mortise and tenon and tungsten production process reduces the production difficulty of large-size crucible. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a structure schematic view of the tungsten alloy strip. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be described below in detail with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0034] The present application discloses a spliced tungsten alloy crucible and a manufacturing method thereof. The specific preparation method of the spliced tungsten alloy crucible will be described in detail below. The manufacturing method of the spliced tungsten alloy crucible mainly includes the following steps:

[0035] S1, the side wall of the tungsten alloy crucible is divided into several small size alloy strips from the height direction, and grooves and protrusions are arranged at both ends of each alloy strip respectively, and the specific size of the tungsten alloy strip is determined;

[0036] S2, preparing the bottom and several tungsten alloy strips;

[0037] S21, powdering: adding a mixture of SiO2, KCl and Al2O3 to WO3 by wet method or spray method to obtain a mixed powder, reducing the mixed powder to tungsten dioxide by two-stage hydrogen reduction method, and then reducing to doped tungsten powder;

[0038] S22, compression molding: taking an appropriate amount of doped tungsten powder, and after the powder is vibrated and compacted in a rubber sleeve, the rubber sleeve is sealed, the shape of the rubber sleeve is shaped, and the shape of the compression blank after cold isostatic pressing is ensured to be regular, and the cold isostatic pressing is formed, the cold isostatic pressing pressure is 350MPa-390MPa, the pressure holding time is 3-10 minutes, and several tungsten plate blanks are obtained;

[0039] S23, sintering: under hydrogen atmosphere, first, the temperature is raised to 800℃ at a rate of 3℃ / min, and the temperature is kept for 6h; then the temperature is raised to 900℃ at a rate of 3℃ / min, and the temperature is kept for 1h, so that the low-temperature oxides and contaminants are fully volatilized; then the temperature is raised to 1500℃ at a rate of 10℃ / min, and the temperature is kept for 1h, to remove low-melting-point impurities; finally, the temperature is raised to 2200-2400℃ at a rate of 5℃ / min, and the temperature is kept for 12h; after the temperature holding is finished, the furnace is cooled to room temperature, and a sintered blank is obtained;

[0040] S24, the sintered blank is subjected to wire electrical discharge machining to obtain a tungsten alloy block or a bottom with the required size;

[0041] S25, the alloy tungsten block is heated to 1400-1500℃ under hydrogen atmosphere, and kept for 60min, and then bent on an oil press with concave-convex molds;

[0042] S26, the bent tungsten alloy block obtained in step five is subjected to wire electrical discharge machining, and dovetail grooves and connecting protrusions are machined on the opposite ends respectively, to obtain a tungsten alloy strip;

[0043] S3, the tungsten alloy strips are spliced into the required circular crucible side wall, and the side wall and the bottom are combined into a crucible;

[0044] S4, the doped tungsten powder and glycerol are mixed into a binder at a mass ratio of 1:2, and are applied to the joint gap of the spliced crucible, to obtain a joint tungsten alloy crucible.

[0045] In step S21, the components and mass fraction of each component contained in the mixed powder are as follows: SiO2 0.05-0.1%, KCl 0.2-0.5%, Al2O3 0.03-0.05%, and the balance is WO3. The purity of WO3 is not less than 99.95%, Fisher particle size is 3.0-4.5 um, and the powder is passed through a 160-200 mesh screen. SiO2, KCl and Al2O3 are passed through a 160-200 mesh screen.

[0046] It should be noted that in step S1, the size of each tungsten alloy strip is determined by the prior art. For example, according to the diameter and height of the to-be-manufactured crucible, the crucible is divided into several layers from the height direction, the height of each layer is uniform, the net arc length and the arc of the alloy strip are calculated by the number of alloy strips (usually 16-20) defined in each layer, the size of the alloy strip in each layer is ensured to be the same as possible, and then the alloy strip with grooves and protrusions is drawn by using software. At this time, the center arc length of the alloy strip is equal to the net arc length plus the length of the convex groove, so that the specific size of the alloy strip can be obtained.

[0047] In step S21, the two-stage hydrogen reduction method is used in the present application, that is, WO3 is first reduced to WO2, and then the intermediate product WO2 is reduced to W. The former reaction is reduced by slightly lower temperature and low-purity hydrogen gas, and the latter reaction requires higher temperature and high-purity hydrogen gas. The two-step reaction can accurately control the temperature and purity, avoid the formation of intermediate oxides, and ensure the rationality of the particle size distribution.

[0048] In step S4, the present application adopts the method of mixing doped tungsten powder and glycerol to form a binder. In this method, the doped tungsten powder is filled into the small holes, gaps and uneven parts on the surface of the crucible to smooth the surface and enhance the integrity of the crucible, so as to avoid the influence of poor contact between the crucible strips on the use. Glycerol is a viscous colorless liquid that can enhance the adhesion of wet powder and is easy to apply. On the other hand, glycerol only contains C, H and O elements, which will decompose in a high-temperature environment in a hydrogen atmosphere without producing other impurity elements.

[0049] It should be noted that the manufacturing method of the present application is particularly suitable for the preparation of large-size crucibles (diameter greater than 600 mm, height greater than 800 mm).

[0050] The technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0051] Example 1

[0052] A manufacturing method of a spliced tungsten alloy crucible, the diameter of the crucible is 1430 mm, the height is 1600 mm, and the wall thickness is 30 mm, mainly comprising the following steps:

[0053] S1, according to the diameter and height of the crucible to be manufactured, the side wall of the crucible is divided into 620 small-size tungsten alloy strips, 20 strips per layer, a total of 31 layers, the size of each alloy strip is determined;

[0054] S2, prepare the crucible bottom and several tungsten alloy strips;

[0055] S21, mix the raw materials according to the following mass fraction: WO3 99.07%, SiO2 0.05%, KCl 0.45%, Al2O3 0.03%, and pass through a 200-mesh screen. Then, a two-stage hydrogen reduction treatment is performed using a fifteen-tube reduction furnace to obtain doped tungsten powder;

[0056] S22, the doped tungsten powder is selected and the appropriate size of the rubber sleeve is selected, the alloy powder is loaded into the rubber sleeve, and the rubber sleeve is sealed after being vibrated and compacted. Cold isostatic pressing is performed at a pressure of 390 MPa for 3 min to obtain a tungsten slab blank, and then the tungsten alloy slab blank is ground and shaped;

[0057] S23, sinter the tungsten slab blank in a hydrogen protective atmosphere: first, heat to 800℃ at a heating rate of 3℃ / min, and keep for 6h; then, heat to 900℃ at a heating rate of 3℃ / min, and keep for 1h; then, heat to 1500℃ at a heating rate of 10℃ / min, and keep for 1h; finally, heat to 2300℃ at a heating rate of 5℃ / min, and keep for 12h; after the heat preservation is completed, the furnace is cooled to room temperature, and a sintered blank with a size of 257(0, +6) x 235(0, +6) x 30(±2) mm is obtained;

[0058] S24, cut the sintered blank into a tungsten alloy block with a size of 230.4 x 50 x 30 mm;

[0059] S25, heat the tungsten alloy block to 1500℃ in a hydrogen atmosphere, keep for 60 min, and then take it out. The concave-convex mold is used for bending treatment on the oil press.

[0060] S26, the bent tungsten alloy block obtained in step five is cut by wire electrical discharge machining, and dovetail grooves and connecting protrusions are machined on opposite ends of the tungsten alloy block, respectively, to obtain a tungsten alloy strip;

[0061] S3, a plurality of tungsten alloy strips are sequentially spliced into the required circular crucible side wall, and the side wall and the crucible bottom are combined into a crucible;

[0062] S4, mix the doped tungsten powder and glycerol in a mass ratio of 1:2, and apply it to the joint gap of the spliced crucible to obtain a tungsten alloy crucible.

[0063] Example 2

[0064] The embodiment differs from example 1 only in that: (1) in step S21, the raw materials are mixed uniformly according to the following mass fractions: WO3 99.07%, SiO2 0.1%, KCl 0.45%, Al2O3 0.03%; (2) in step S23, finally heated to 2400℃ at a heating rate of 5℃ / min, and kept for 12h.

[0065] Comparative example 1

[0066] Comparative example 1 differs from example 1 only in that: the raw material is pure tungsten powder, not doped tungsten powder.

[0067] Comparative example 2

[0068] Comparative example 2 differs from example 1 only in that: in S23, directly heated to 2300℃ at a heating rate of 5℃ / min, and kept for 12h.

[0069] Comparative example 3

[0070] Using doped tungsten powder as raw material, a tungsten alloy crucible is prepared by the hot sintering integrated molding method in the prior art (reference: patent with publication number CN104789844A).

[0071] Performance detection

[0072] The performance (including density, hardness and recrystallization temperature) of the crucibles prepared in examples 1-2 and comparative examples 1-3 are detected, and the results are shown in the following table.

[0073] Table 1 Performance detection results

[0074] Density (g / cm 3 )]]> Vickers hardness Recrystallization temperature / °C Example 1 18.0 320 1500 Example 2 17.8 315 1450 Comparative Example 1 18.2 290 1100 Comparative Example 2 17.4 300 1500 Comparative Example 3 18.0 320 1500

[0075] As can be seen from table 1, the crucible prepared in the application is difficult to deform, and the service life is longer. In addition, according to the feedback of our customers, the high temperature creep resistance of the crucible manufactured by this method is better.

[0076] The above description is only a preferred embodiment of the application, and does not limit the application in any form. Any equivalent transformation or modification according to the essence of the application should be covered within the protection scope of the application.

Claims

1. A method for manufacturing a spliced ​​tungsten alloy crucible, characterized in that, The sidewall of the tungsten alloy crucible is divided into several small alloy strips along the height direction. Each alloy strip has grooves and protrusions at both ends, and then they are spliced ​​together in a staggered manner to achieve a whole. The manufacturing method specifically includes the following steps: Step 1: Mix WO3, SiO2, KCl and Al2O3 to obtain a mixed powder, and perform a two-stage hydrogen reduction on the mixed powder to obtain doped tungsten powder; Step 2: Take an appropriate amount of doped tungsten powder, put the powder in a plastic bag, and obtain several tungsten slab blanks by cold isostatic pressing. Step 3: Perform medium-frequency sintering on the tungsten slab under a hydrogen atmosphere to obtain a sintered slab; Step 4: Wire cut the sintered billet obtained in Step 3 to obtain a tungsten alloy block of the required size; Step 5: Bend the tungsten alloy block obtained in Step 4. Step 6: Machining grooves and protrusions at opposite ends of the bent tungsten alloy block to obtain tungsten alloy strips; Step 7: Join several tungsten alloy strips together in a staggered pattern to form the side wall of the crucible, and combine the side wall and the bottom of the crucible to form the crucible. Step 8: Mix the doped tungsten powder and glycerol at a mass ratio of 1:2 evenly, and apply the mixture to all the gaps in the crucible to obtain the spliced ​​tungsten alloy crucible. In step one, the mixed powder contains the following components and their mass fractions: SiO2 0.05-0.1%, KCl 0.2-0.5%, Al2O3 0.03-0.05%, with the balance being WO3. The mixed powder is prepared by adding a mixture of SiO2, KCl, and Al2O3 to WO3 using a wetting or spraying method, mixing it evenly, and then passing it through a 160-200 mesh sieve to obtain the mixed powder. In step three, the specific parameters for medium-frequency sintering are as follows: first, heat to 800℃ at a heating rate of 3℃ / min and hold for 6 hours; then heat to 900℃ at a heating rate of 3℃ / min and hold for 1 hour; then heat to 1500℃ at a heating rate of 10℃ / min and hold for 1 hour; finally, heat to 2200-2400℃ at a heating rate of 5℃ / min and hold for 12 hours; after the holding period, cool to room temperature with the furnace.

2. The method for manufacturing a spliced ​​tungsten alloy crucible according to claim 1, characterized in that, In step one, the purity of WO3 is not less than 99.95%, the Fisher particle size is 3.0-4.5μm, and it passes through a 160-200 mesh sieve; SiO2, KCl and Al2O3 also pass through a 160-200 mesh sieve.

3. The method for manufacturing a spliced ​​tungsten alloy crucible according to claim 1, characterized in that, In step two, after the rubber sleeve is compacted by vibration, it is degassed and sealed, and the shape of the rubber sleeve is shaped to ensure that the pressed blank has a regular shape after cold isostatic pressing.

4. The method for manufacturing a spliced ​​tungsten alloy crucible according to claim 1, characterized in that, In step two, the pressure of cold isostatic pressing is 350MPa-390MPa, and the holding time is 3-10min.

5. The method for manufacturing a spliced ​​tungsten alloy crucible according to claim 1, characterized in that, In step five, the tungsten alloy block is heated to 1400-1500℃ in a hydrogen atmosphere and held for 60 minutes. After the holding period, it is taken out and bent using a convex and concave die on a hydraulic press.

6. The method for manufacturing a spliced ​​tungsten alloy crucible according to claim 1, characterized in that, The crucible bottom used in step seven is obtained by wire cutting the sintered billet obtained in step three.

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