Method for recovering deformed molybdenum product

Abstract

The invention discloses a method for recovering a deformed molybdenum product, which comprises the following steps: adopting a medium-frequency control heating furnace as equipment, arranging a mold in a temperature field of the medium-frequency control heating furnace, and arranging a movable mold and a fixed mold in the temperature field of the medium-frequency control heating furnace; and the deformed molybdenum product is placed in a fixed mold, a movable mold abuts against the molybdenum product, under the protective gas atmosphere, the deformed molybdenum product is subjected to heat treatment till the molybdenum product is softened, then mold closing and cooling are conducted, and the molybdenum product with the recovered shape is obtained. According to the method, on one hand, the original shape of the deformed molybdenum product can be effectively recovered, the assembly precision of all parts is remarkably improved, and the uniformity of thermal field distribution is ensured; and on the other hand, the method also has the shape recovery effect on the special-shaped molybdenum product, the service life of the molybdenum product can be remarkably prolonged, the thermal field stability is maintained, and meanwhile the oxidation and pollution risks of the product in the using process are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of shape recovery of deformed molybdenum products, and in particular to a method for recovering deformed molybdenum products. Background Art

[0002] Molybdenum products have important applications in the thermal field preparation for doped YAG crystal growth in resistance furnaces. These products require excellent deformation resistance and high component fit precision. However, in actual use, molybdenum products are prone to deformation in high-temperature areas, resulting in a decrease in component fit precision, which in turn reduces temperature field uniformity and ultimately affects the internal quality of the crystal. In severe cases, the product may even be scrapped due to improper component fit.

[0003] Currently, the industry has not yet developed effective methods and processes for repairing deformation of molybdenum products. Therefore, once a molybdenum product is deformed and affects the uniformity of the temperature field, it has to be scrapped even if the material itself remains intact. This situation significantly increases the cost of the crystal growth process.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for restoring a deformed molybdenum product and to improve the fitting accuracy of the molybdenum product.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a method for recovering a deformed molybdenum product, comprising:

[0008] The equipment used is a medium frequency controlled heating furnace, and a mold is set in the temperature field of the medium frequency controlled heating furnace, and the mold includes a movable mold and a fixed mold;

[0009] The deformed molybdenum product is placed in a fixed mold and the movable mold and the molybdenum product are pressed against each other. In a protective gas atmosphere, the deformed molybdenum product is heat treated until the molybdenum product is softened, and then the mold is closed and cooled to obtain a molybdenum product with restored shape.

[0010] In an optional embodiment, the heat treatment power is 23-30KW, and the heat treatment time is 60 minutes to 120 minutes.

[0011] In an optional embodiment, the heat treatment further includes preheating the deformed molybdenum product before the heat treatment, with a preheating power of 5KW-10KW and a preheating time of 10 minutes to 30 minutes;

[0012] When the heat treatment is completed, the temperature of the molybdenum product is 1800°C-2200°C.

[0013] In an optional embodiment, the temperature of the molybdenum product at the end of preheating is 200°C-400°C.

[0014] In an optional embodiment, the deformed molybdenum product is made of at least one of elemental molybdenum and high-temperature molybdenum.

[0015] In an optional embodiment, the mold is made of graphite;

[0016] And / or, the mold includes a receiving cavity, and the shape and size of the receiving cavity are adapted to the shape and size of the molybdenum product.

[0017] In an optional embodiment, the deformed molybdenum product is free of defects, carburization, cracks and bulges.

[0018] In an optional embodiment, the molybdenum product is at least one of a cylinder, a column, and a heterogeneous component obtained by stacking a cylinder and a column.

[0019] In an optional embodiment, before heat treatment, the furnace is first evacuated and then a protective gas is injected into the furnace until the gauge pressure in the furnace is -0.005 MPa to 0 MPa.

[0020] In an optional embodiment, the protective gas is argon.

[0021] The present invention has the following beneficial effects:

[0022] In the method for restoring deformed molybdenum products of the present application, the deformed molybdenum product is first placed in a mold and then heat treated, so that the molybdenum product is softened to the point where it can recover its deformation under the action of the mold, thereby obtaining a molybdenum product that meets the use requirements. On the one hand, the method of the present application can effectively restore the original shape of the deformed molybdenum product, significantly improve the assembly accuracy between the various components, and ensure the uniformity of the thermal field distribution; on the other hand, the method also has a shape recovery effect on special-shaped molybdenum products, which can significantly extend the service life of the molybdenum product, maintain the thermal field stability, and reduce the risk of oxidation and contamination of the product during use. The present application can not only reduce the material procurement cost during the crystal growth process, but also significantly improve the quality of the prepared crystals, with obvious economic benefits and technical advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1A schematic diagram of a structure of a medium frequency controlled heating furnace involved in this application;

[0025] Figure 2 Schematic diagram of the structure of the molybdenum cylinder before recovery (left) and after recovery (right) in Example 1;

[0026] Figure 3 Schematic diagram of the structure of the molybdenum cylinder before recovery (left) and after recovery (right) in Example 2;

[0027] Figure 4 Schematic diagram of the structure of the molybdenum cylinder before recovery (left) and after recovery (right) in Example 3.

[0028] Diagram: 100-furnace frame; 101-furnace body; 102-induction coil; 103-heater and temperature field; 104-mold; 105-molybdenum product; 106-rising mechanism; 107-medium frequency power supply; 108-gas supply system; 109-vacuum and water cooling system. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0030] An embodiment of the present invention provides a method for restoring a deformed molybdenum product, comprising:

[0031] The equipment used is a medium frequency controlled heating furnace, and a mold is set in the temperature field of the medium frequency controlled heating furnace, and the mold includes a movable mold and a fixed mold;

[0032] The deformed molybdenum product is placed in a fixed mold and the movable mold and the molybdenum product are pressed against each other. In a protective gas atmosphere, the deformed molybdenum product is heat treated until the molybdenum product is softened, and then the mold is closed and cooled to obtain a molybdenum product with restored shape.

[0033] In the method for restoring deformed molybdenum products of the present application, the deformed molybdenum product is first placed in a mold and then heat treated, so that the molybdenum product is softened to the point where it can recover its deformation under the action of the mold, thereby obtaining a molybdenum product that meets the use requirements. On the one hand, the method of the present application can effectively restore the original shape of the deformed molybdenum product, significantly improve the assembly accuracy between the various components, and ensure the uniformity of the thermal field distribution; on the other hand, the method also has a shape recovery effect on special-shaped molybdenum products, which can significantly extend the service life of the molybdenum product, maintain the thermal field stability, and reduce the risk of oxidation and contamination of the product during use. The present application can not only reduce the material procurement cost during the crystal growth process, but also significantly improve the quality of the prepared crystals, with obvious economic benefits and technical advantages.

[0034] It should be noted that the mold in this application is compatible with the shape and size of the deformed molybdenum product and needs to be customized and selected according to the deformed molybdenum product.

[0035] It should also be noted that the equipment used in the method for recovering deformed molybdenum products of the present application can be as follows: Figure 1 As shown, the apparatus comprises a furnace frame 100, a furnace body 101, an induction coil 102, a heater and a heat field 103, and a mold 104 and a molybdenum product 105 workpiece placed within the heat field. Mold 104 comprises a movable mold and a fixed mold, the movable mold being connected to and driven up and down by a lifting mechanism 106. An intermediate frequency power supply 107, an air supply system 108, and a vacuum and water cooling system 109 respectively regulate the power, pressure, and temperature of the intermediate frequency-controlled heating furnace. During heat treatment, the molybdenum product 105 cannot come into direct contact with the heater to prevent it from melting due to excessive temperatures.

[0036] In some embodiments, the deformed molybdenum product 105 is polished and cleaned before correction to remove attachments on the surface of the molybdenum product 105 and reduce the introduction of pollutants.

[0037] In an optional embodiment, the heat treatment power is 23-30KW, and the heat treatment time is 60 minutes to 120 minutes.

[0038] At the end of the heat treatment, the temperature of the molybdenum product 105 is approximately 1800°C-2200°C. At this time, the molybdenum product 105 has been completely softened and the pollutants and oxides during use have been removed. In order to avoid damage to the molybdenum product 105 at high temperatures, the intermediate frequency power supply 107 must be turned off after heating for 60-120 minutes.

[0039] It should be noted that the heat treatment time can be adjusted according to the specifications of the wood product. If the thickness of the molybdenum product 105 is large, the heat treatment time can be extended to a certain extent; if the thickness of the molybdenum product 105 is small, the heat treatment time can be shortened to a certain extent.

[0040] In an optional embodiment, the heat treatment further includes preheating the deformed molybdenum product 105, with a preheating power of 5KW-10KW and a preheating time of 10 minutes-30 minutes.

[0041] At the end of preheating, the temperature of the molybdenum product 105 is 200° C.-400° C. Preheating can remove the contamination and oxides generated during the use of the molybdenum product 105 , and can ensure the heat treatment effect of the subsequent heat treatment steps.

[0042] In an optional embodiment, the deformed molybdenum product 105 is made of at least one of elemental molybdenum and high-temperature molybdenum.

[0043] Among them, high-temperature molybdenum refers to molybdenum materials or molybdenum alloys with excellent high-temperature performance, such as materials with metallic molybdenum (Mo) as the matrix, which are prepared by adding alloying elements (such as titanium, zirconium, hafnium, rare earth elements, etc.) or using special processes to enable them to maintain good performance in high-temperature environments.

[0044] In an optional embodiment, the material of the mold 104 is graphite; the temperature of the heat treatment of the molybdenum product 105 is relatively high. In order to avoid damage or deformation of the mold 104 caused by the heat treatment, the material of the mold 104 is preferably a cold isostatically pressed three-high graphite column, and an accommodating cavity is processed in the center of the column according to the shape and size of the workpiece.

[0045] In an optional embodiment, the mold 104 includes a receiving cavity, and the shape and size of the receiving cavity are adapted to the shape and size of the molybdenum product 105 .

[0046] In an optional embodiment, the deformed molybdenum product 105 does not have defects, carburization, cracks, or bulges.

[0047] Materials in the high-temperature zone will deform after being used a certain number of times, affecting crystal growth. At this time, if the material does not have any defects, carbonization, cracks, or bulging, but only the shape has changed - the ovality or warping exceeds the use requirements, then the method of this application can be used for restoration.

[0048] In an optional embodiment, the molybdenum product 105 is at least one of a cylinder, a column, and a heterogeneous component obtained by stacking a cylinder and a column.

[0049] In an optional embodiment, before heat treatment, the furnace is first evacuated and then a protective gas is injected into the furnace until the gauge pressure in the furnace is -0.005 MPa to 0 MPa.

[0050] In some embodiments, before preheating, the heating furnace is first evacuated to a gauge pressure of -0.1 MPa, and then filled with protective gas to a gauge pressure of -0.005 to 0 MPa. Evacuating the furnace and then filling it with protective gas before heat treatment reduces the probability of the molybdenum product 105 coming into contact with oxygen, reducing the probability of oxidation of the molybdenum material, and thereby reducing the content of impurities in the molybdenum product 105. This helps improve the quality of the molybdenum material, thereby improving the performance of the molybdenum product 105 during subsequent use and extending its service life.

[0051] In an optional embodiment, the protective gas is argon.

[0052] Molybdenum material is oxidized into molybdenum trioxide at about 600°C, which causes the molybdenum product 105 to become more brittle and easily damaged. Therefore, heat treatment in an oxygen environment can easily cause the molybdenum product 105 to be quickly oxidized and damaged. Therefore, heat treatment and preheating are both carried out in a protective atmosphere such as an argon atmosphere.

[0053] The restoration method of the present application is used to treat the deformed molybdenum product 105. In addition to eliminating contamination and oxidation during use and improving the shape consistency of the molybdenum product 105, more importantly, it can significantly improve the fit between the molybdenum components, ensure the consistency of the temperature field, and provide an excellent environment for subsequent crystal growth, thereby being able to produce crystals of extremely excellent quality.

[0054] It should be noted that cooling after the heat treatment also needs to be carried out under the protection of inert gas. In some embodiments, natural cooling can be carried out, and the cooling time is ≥5h; in other embodiments, in order to accelerate cooling, protective gas can also be introduced into the furnace to accelerate heat loss and improve cooling efficiency.

[0055] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0056] Example 1:

[0057] This embodiment provides a method for restoring a deformed molybdenum product 105, which specifically includes the following steps:

[0058] Deformed molybdenum cylinder dimensions: That is, the outer diameter is 150mm, the inner diameter is 147mm, the tolerance is ±6mm, and the height is 160mm.

[0059] Molybdenum cylinder standard size requirements:

[0060] Use Figure 1 The intermediate frequency controlled heating furnace equipment is shown, and the deformed molybdenum product 105 is placed in the mold 104 so that the movable mold and the molybdenum product 105 are offset against each other. Under an argon atmosphere, the deformed molybdenum product 105 is preheated and heat treated in sequence, and then the mold is closed and the power of the intermediate frequency controlled heating furnace is turned off. It is naturally cooled for 5 hours to room temperature, and the furnace door is opened to remove the molybdenum component to obtain a molybdenum cylinder with restored shape. Figure 2 As shown;

[0061] The heating temperature control program for preheating and heat treatment is: increase the heating power from 0 to 5KW in 5 minutes and keep it for 10 minutes for preheating; then increase the heating power from 5KW to 25KW in 10 minutes and keep it for 60 minutes for heat treatment.

[0062] The two ends of the restored molybdenum tube are intact and the surface is not oxidized. The size of the molybdenum tube is The ovality tolerance is ±1.5mm, which meets the standard tolerance requirement (within ±2mm).

[0063] Example 2:

[0064] This embodiment provides a method for restoring a deformed molybdenum product 105. The method differs from the first embodiment mainly in that the shape of the workpiece is different. The method specifically includes the following steps:

[0065] Dimensions of deformed cylindrical molybdenum components: The flatness tolerance is measured to be ±8.6mm; the flatness tolerance of standard cylindrical molybdenum components is required to be less than ±2mm.

[0066] Use Figure 1 The intermediate frequency controlled heating furnace equipment is shown, and the deformed molybdenum product 105 is placed in the mold 104 so that the movable mold and the molybdenum product 105 are offset. In an argon atmosphere, the deformed molybdenum product 105 is preheated and heat treated in sequence. Then, the lifting mechanism 106 is started to rise 8.6 mm to close the mold and then the power of the intermediate frequency controlled heating furnace is turned off. It is naturally cooled for 5 hours to room temperature, and the furnace door is opened to take out the molybdenum component to obtain a cylindrical molybdenum component with restored shape, as shown. Figure 3 As shown;

[0067] The heating temperature control program for preheating and heat treatment is: increase the heating power from 0 to 5KW in 5 minutes and keep it for 10 minutes for preheating; then increase the heating power from 5KW to 25KW in 10 minutes and keep it for 60 minutes for heat treatment.

[0068] The cylindrical molybdenum component with restored shape was obtained. The two end faces were basically flat when observed with the naked eye. The flatness tolerance was measured to be ±1.6mm, which met the use requirements (within ±2mm).

[0069] Example 3:

[0070] This embodiment provides a method for restoring a deformed molybdenum product 105. The method differs from the first embodiment mainly in that the shape of the workpiece is different. The method specifically includes the following steps:

[0071] The flatness tolerance of a wave-shaped molybdenum component is measured to be ±7.5mm; the flatness tolerance of a standard wave-shaped molybdenum component is required to be ±2mm.

[0072] Use Figure 1 The intermediate frequency controlled heating furnace equipment is shown, and the deformed molybdenum product 105 is placed in the mold 104 so that the movable mold and the molybdenum product 105 are offset. In an argon atmosphere, the deformed molybdenum product 105 is preheated and heat-treated in sequence. Then, the lifting mechanism 106 is started to rise 7.5 mm to close the mold and then the power of the intermediate frequency controlled heating furnace is turned off. It is naturally cooled for 5 hours to room temperature, and the furnace door is opened to take out the molybdenum component to obtain a wave-shaped molybdenum component with restored shape, as shown in FIG. Figure 4 As shown;

[0073] The heating temperature control program for preheating and heat treatment is: increase the heating power from 0 to 5KW in 5 minutes and keep it for 10 minutes for preheating; then increase the heating power from 5KW to 25KW in 10 minutes and keep it for 60 minutes for heat treatment.

[0074] The outer tube of the wavy special-shaped molybdenum component with restored shape is intact, the surface is not oxidized, and the flatness tolerance is ±1.8mm, which meets the standard tolerance requirement (±2mm).

[0075] Comparative Example 1

[0076] This comparative example provides a method for restoring a deformed molybdenum product 105, which specifically includes the following steps:

[0077] Deformed molybdenum cylinder dimensions: 1 molybdenum cylinder

[0078] Molybdenum cylinder standard size requirements:

[0079] When a deformed molybdenum cylinder is heated in air with a conventional flame gun, the surface of the molybdenum cylinder is rapidly oxidized, and the overall temperature does not reach the softening temperature of the molybdenum material, and the deformation cannot be restored.

[0080] Comparative Example 2:

[0081] This comparative example provides a method for restoring a deformed molybdenum product 105, which specifically includes the following steps:

[0082] Deformed molybdenum cylinder dimensions:

[0083] Molybdenum cylinder standard size requirements:

[0084] Use Figure 1 The medium frequency controlled heating furnace equipment shown is used to heat the deformed molybdenum cylinder in the heating furnace, and the deformed molybdenum product 105 is placed in the mold 104 so that the movable mold and the molybdenum product 105 are pressed against each other. Under an argon atmosphere, the deformed molybdenum product 105 is preheated and heat-treated in sequence, and then the mold is closed and the power of the medium frequency controlled heating furnace is turned off. After natural cooling for 4 hours, the furnace door is opened to remove the molybdenum component to obtain a molybdenum cylinder with restored shape.

[0085] The heating temperature control program for preheating and heat treatment is: increase the heating power from 0 to 5KW in 5 minutes and keep it for 10 minutes for preheating; then increase the heating power from 5KW to 15KW in 10 minutes and keep it for 50 minutes for heat treatment.

[0086] The molybdenum tube with restored shape had cracks at both ends and oxidation on the surface, and the molybdenum tube was scrapped.

[0087] Comparative Example 3:

[0088] This comparative example provides a method for restoring a deformed molybdenum product 105, which specifically includes the following steps:

[0089] Deformed molybdenum cylinder dimensions: 1 molybdenum cylinder.

[0090] Molybdenum cylinder standard size requirements:

[0091] Use Figure 1 The medium frequency controlled heating furnace equipment shown is used to heat the deformed molybdenum cylinder in the heating furnace, and the deformed molybdenum product 105 is placed in the mold 104 so that the movable mold and the molybdenum product 105 are pressed against each other. Under an argon atmosphere, the deformed molybdenum product 105 is preheated and heat treated in sequence, and then the mold is closed and the power of the medium frequency controlled heating furnace is turned off. The furnace is naturally cooled for 4.5 hours, and the furnace door is opened to remove the molybdenum component to obtain a molybdenum cylinder with restored shape.

[0092] The heating temperature control program for preheating and heat treatment is: increase the heating power from 0 to 5KW in 5 minutes and keep it for 10 minutes for preheating; then increase the heating power from 5KW to 20KW in 10 minutes and keep it for 50 minutes for heat treatment.

[0093] The molybdenum tube with restored shape had cracks at both ends and slight oxidation on the surface, so the molybdenum tube was scrapped.

[0094] Experimental results:

[0095] From October 2024 to March 2025, the shape of 30 deformed molybdenum tubes collected were restored according to the method of Example 1, and 28 qualified shape-restored molybdenum tubes were obtained, with a pass rate of 93.3%; the shape of 50 cylindrical molybdenum components collected were restored according to the method of Example 2, and 47 qualified shape-restored cylindrical molybdenum components were obtained, with a pass rate of 94%.

[0096] This shape recovery method can be repeated if the molybdenum base material is not consumed. Take 10 molybdenum cylinders and 10 cylindrical molybdenum components. As of April 2025, all 10 molybdenum cylinders have undergone 2 shape recovery and all cylindrical molybdenum components have undergone 6 shape recovery, and all can be reused.

[0097] The molybdenum product 105 can be reused after shape restoration, and the production cost of the molybdenum cylinder can be reduced by more than 50%, and the cost of cylindrical molybdenum components and wave-shaped molybdenum components can be reduced by more than 70%, which can effectively reduce the consumption of molybdenum material resources.

[0098] After the shape of the deformed molybdenum product 105 is restored, the fit between the accessories can be increased, which is conducive to maintaining the consistency of the temperature field. The environment for crystal growth is improved, the crystal yield can be increased from 85% to 90% or above, and the internal quality (AC) of the crystal can be increased from 38% to about 45%.

[0099] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for restoring a deformed molybdenum product, characterized in that: include: The equipment used is a medium frequency controlled heating furnace, and a mold is set in the temperature field of the medium frequency controlled heating furnace, and the mold includes a movable mold and a fixed mold; The deformed molybdenum product is placed in a fixed mold and the movable mold and the molybdenum product are pressed against each other. In a protective gas atmosphere, the deformed molybdenum product is heat treated until the molybdenum product is softened, and then the mold is closed and cooled to obtain a molybdenum product with restored shape.

2. The method for restoring a deformed molybdenum product according to claim 1, wherein: The power of the heat treatment is 23-30KW, and the heat treatment time is 60 minutes to 120 minutes.

3. The method for restoring a deformed molybdenum product according to claim 2, characterized in that: Before the heat treatment, the deformed molybdenum product is preheated, with a preheating power of 5KW-10KW and a preheating time of 10 minutes-30 minutes; When the heat treatment is completed, the temperature of the molybdenum product is 1800°C-2200°C.

4. The method for restoring a deformed molybdenum product according to claim 3, characterized in that: At the end of preheating, the temperature of the molybdenum product is 200℃-400℃.

5. The method for restoring a deformed molybdenum product according to claim 1, characterized in that: The deformed molybdenum product is made of at least one of elemental molybdenum and high-temperature molybdenum.

6. The method for restoring a deformed molybdenum product according to claim 1, characterized in that: The material of the mold is graphite; And / or, the mold includes a receiving cavity, and the shape and size of the receiving cavity are adapted to the shape and size of the molybdenum product.

7. The method for restoring a deformed molybdenum product according to claim 1, characterized in that: The deformed molybdenum product has no defects, carbonization, cracks or bulges.

8. The method for restoring a deformed molybdenum product according to claim 1, wherein: The molybdenum product is at least one of a cylinder, a column, and a heterogeneous component obtained by stacking a cylinder and a column.

9. The method for restoring a deformed molybdenum product according to claim 1, wherein: Before heat treatment, the furnace is first evacuated and then filled with protective gas until the gauge pressure in the furnace is -0.005 MPa to 0 MPa.

10. The method for restoring a deformed molybdenum product according to claim 1, characterized in that: The protective gas is argon.

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