Molybdenum round sheet, molybdenum plate for molybdenum round sheet, and method for manufacturing the same

Abstract

The application discloses a molybdenum round sheet, a molybdenum plate for the molybdenum round sheet and a preparation method of the molybdenum plate. The preparation method comprises the following steps: selecting a molybdenum plate blank with a mass of more than 30 kg and a thickness of more than 28 mm, and performing heat treatment on the molybdenum plate blank, then performing more than three passes of reversing deformation treatment, that is, the direction of deformation treatment in each pass is perpendicular to the direction of deformation treatment in the previous pass, and performing more than twice of heat flattening treatment and thickness processing on the obtained plate after deformation treatment until the plate reaches a target thickness, and the excess amount of the target thickness relative to the thickness of the molybdenum round sheet is less than 20%. The application can significantly reduce the machining allowance in the machining process of the molybdenum plate, improve the machining stability, reduce the hole defects in the obtained molybdenum plate and improve the isotropy of the molybdenum plate, and further improve the quality and performance of the molybdenum round sheet and reduce the production cost and resource consumption.

Description

Technical Field

[0001] This invention relates to the technical field of molybdenum wafers, and particularly to a method for preparing molybdenum plates as substrates for molybdenum wafers. Background Technology

[0002] In the fields of power semiconductors and vacuum electro-optics, high-power devices place stringent requirements on the thermal stability and thermal conductivity of heat dissipation materials to ensure efficient and stable operation. Currently, high-power thyristors commonly use molybdenum wafers as heat dissipation materials, and the performance of molybdenum wafers mainly depends on the processing technology and quality of their substrate, namely the molybdenum plate. Traditional methods for preparing molybdenum sheets typically involve using small, straight-edged molybdenum billets with a thickness of 10-12 mm and a weight of 1-1.5 kg. These billets are heated to 980℃-1200℃ and rolled to achieve a target thickness of 2.0-5.0 mm. However, in these methods, the cumulative deformation of the sheet is only 50%-83.3%, making it difficult to weld the holes and defects in the billets. This results in defects such as black spots and holes in the finished molybdenum wafers, reducing the material's thermal conductivity. Furthermore, the rolling deformation in each direction is not strictly controlled, leading to inconsistencies and anisotropy. This anisotropy can further cause warping of the molybdenum wafers during subsequent processing or use, affecting their quality stability, thermal conductivity, and heat dissipation stability. In addition, to meet the dimensional accuracy requirements of the molybdenum wafers, these methods require a large machining allowance (≥25%), which not only increases processing costs but also wastes molybdenum resources. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a novel method for preparing molybdenum plates for molybdenum wafers, as well as the resulting molybdenum plates and molybdenum wafers. This method can significantly reduce the processing allowance during the processing of molybdenum plates, improve processing stability, reduce pore defects in the resulting molybdenum plates, and improve their isotropy, thereby improving the quality and performance of molybdenum wafers and reducing production costs and resource consumption.

[0004] The technical solution of the present invention is as follows:

[0005] A method for preparing a molybdenum plate for molybdenum discs, comprising:

[0006] A rectangular molybdenum plate blank with a weight of over 30 kg and a thickness of over 28 mm, and four symmetrical arc surfaces, is used as the preparation material.

[0007] The prepared slab is heat-treated at 800-1400℃, and then subjected to more than 3 passes of reversing deformation treatment, that is, the direction of each deformation treatment is perpendicular to the direction of the previous deformation treatment, until the deformation amount in each direction of the obtained slab is more than 50%, and the deformed slab is obtained.

[0008] The deformed sheet is subjected to more than two heat straightening and thickness processing processes until it reaches the target thickness, wherein the target thickness has a margin of less than 20% relative to the thickness of the molybdenum disc.

[0009] In the above preparation method of the present invention, the four sides are the four sides of the molybdenum plate blank in the thickness direction. Using a cuboid molybdenum plate blank with four arc-shaped sides as the preparation material can significantly reduce the delamination defects caused by uneven extension of the edges and core in traditional deformation treatment, especially deformation treatment with top and bottom force application, and significantly improve the uniformity of the extension of the core and edges of the plate. The cumulative deformation is greater than 50%, which can ensure that the core and edges of the molybdenum plate produce sufficient uniform deformation, making the molybdenum plate structure more uniform along the thickness direction. Furthermore, by reducing stress concentration in various directions through reversing deformation treatment, stress is released uniformly, and the microstructure in various directions is consistent, resulting in a product with stable and uniform mechanical properties and excellent and stable flatness.

[0010] This invention, through the design of molybdenum plate shape and the coordinated control of quality, thickness and deformation, can directly process molybdenum plate blanks weighing more than 30 kg and with a thickness of more than 28 mm into high-quality molybdenum discs with a thickness allowance of less than 20%.

[0011] According to some preferred embodiments of the present invention, after each reversing deformation process before the last reversing deformation process, the obtained plate is subjected to reheating treatment in a furnace, and after the last reversing deformation process, it is subjected to heat straightening treatment.

[0012] According to some preferred embodiments of the present invention, the temperature of the reheat treatment gradually decreases as the thickness of the obtained sheet decreases.

[0013] According to some preferred embodiments of the present invention, the thermal straightening and thickness processing includes:

[0014] After the final deformation process, the sheet material is heat-straightened to achieve a flatness of less than 2mm, thus obtaining the first heat-straightened sheet material.

[0015] The first heat-leveled board is reheated in the furnace at a temperature of 700-850℃, and then the thickness is processed to reach the target thickness. Then, it is heat-leveled again to make the flatness of the board less than 1.5mm.

[0016] According to some preferred embodiments of the present invention, the deformation process is rolling.

[0017] According to some preferred embodiments of the present invention, the mass of the molybdenum plate blank is 30-40 kg.

[0018] According to some preferred embodiments of the present invention, the thickness of the molybdenum plate blank is 30-40 mm.

[0019] According to some preferred embodiments of the present invention, the width of the molybdenum plate blank is 330-430 mm.

[0020] According to some preferred embodiments of the present invention, the length of the molybdenum plate blank is 310-410 mm.

[0021] According to some preferred embodiments of the present invention, the reduction rate of each deformation process is 10-20%.

[0022] According to some preferred embodiments of the present invention, the radius of curvature of the four sides of the molybdenum plate blank is 10-20 mm.

[0023] According to some preferred embodiments of the present invention, the preparation method includes:

[0024] (1) The prepared slab is heat-treated at 1150-1400℃ for 8-30 minutes, followed by a first deformation treatment with a reduction rate of 10-20% to obtain the first deformation treatment slab.

[0025] (2) The first-deformed plate is reheated in the furnace, and then a second deformation process is carried out, which is perpendicular to the direction of the first deformation process, so that the length of the plate is 1.01-2.6 times the initial length of the blank, and a second-deformed plate is obtained.

[0026] (3) The plate that has undergone secondary deformation treatment is reheated in the furnace and subjected to a third deformation treatment that is perpendicular to the direction of the second deformation treatment, so that the length of the plate is more than 1.01 times the length of the plate that has undergone secondary deformation treatment, thus obtaining a plate that has undergone tertiary deformation treatment.

[0027] (4) The plate that has undergone three deformation treatments is reheated in the furnace and subjected to a fourth deformation treatment that is perpendicular to the direction of the third deformation treatment. Then, a heat straightening treatment is performed to make the flatness of the plate less than 2mm, thus obtaining the first heat straightened plate.

[0028] (5) The first heat-leveled plate is reheated in the furnace at a temperature of 700-850℃, then processed to the target thickness, and then heat-leveled again to make the flatness of the plate less than 1.5mm, thus obtaining a molybdenum plate for molybdenum discs.

[0029] The present invention further provides a molybdenum plate for molybdenum discs prepared according to the above preparation method.

[0030] The density of this molybdenum plate is greater than 10.14 g / cm³. 3It has no defects such as microscopic pores, black spots, or delamination. Its mechanical properties are consistent in all directions, exhibiting isotropy. The tensile strength in both the transverse and longitudinal directions is greater than 700 MPa. The thickness allowance relative to the thickness of the molybdenum disc that needs further processing is less than 20%.

[0031] The present invention further provides a molybdenum wafer obtained by processing the molybdenum wafer using a molybdenum plate.

[0032] The present invention has the following beneficial effects:

[0033] The molybdenum plate prepared by this invention has significantly improved density, reduced defects such as micropores and delamination, and exhibits mechanical property differences of less than 15% in the vertical direction, demonstrating good isotropy. At the same time, it increases the material utilization rate of molybdenum wafers by more than 5% and better ensures the thermal stability of molybdenum wafers, making the flatness of key characteristics of molybdenum wafers easy to obtain and control. Attached Figure Description

[0034] Figure 1 This is a three-dimensional schematic diagram of the molybdenum plate blank used in the embodiment.

[0035] Figure 2 This is a schematic diagram of the cross-sectional shape of the molybdenum plate blank used in the example.

[0036] Figure 3 This is a photograph of the molybdenum plate blank used in the example.

[0037] Figure 4 Metallographic illustrations of molybdenum plates for molybdenum discs obtained in Examples 1-3.

[0038] Figure 5 SEM images of molybdenum plates for molybdenum wafers obtained in Examples 1-3 are shown.

[0039] Figure 6 Metallographic illustrations of molybdenum plates used for molybdenum discs obtained in Comparative Examples 1-3.

[0040] Figure 7 SEM images of molybdenum plates used for molybdenum wafers obtained in Comparative Examples 1-3. Detailed Implementation

[0041] The technical solutions of the present invention will be further described below with reference to embodiments thereof. The embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0042] The following are schematic diagrams illustrating the morphology of the molybdenum plate blanks used in the embodiments. Figure 1-2 As shown in the attached image, the actual object is also shown. Figure 3As shown.

[0043] Example 1

[0044] Molybdenum plates for molybdenum wafers are prepared using the following steps:

[0045] (1) Select a molybdenum plate blank with a thickness of 30±2mm, a width of 330±10mm, a length of 310±10mm, a mass of 30kg, and four sides with rounded arc surfaces as the preparation blank. The radius of the arc of the molybdenum plate blank is 10-20mm, and the four sides are smoothly transitioned with the upper and lower surfaces.

[0046] (2) The prepared slab is heat-treated at 1250℃ for 12 min, and then the first pass rolling is carried out with a first pass reduction rate of 13% and rolling is performed along the width direction to obtain the first hot-rolled plate.

[0047] (3) The first hot-rolled plate is reheated in the furnace at a temperature of 950℃ for 2 minutes. It is then rolled in a direction perpendicular to the first rolling direction, along the length direction, so that the length of the plate is extended to 500±10mm to obtain the second hot-rolled plate.

[0048] (4) The second hot-rolled slab is reheated in the furnace at a temperature of 950°C for 2 minutes. It is then rolled in a direction perpendicular to the second rolling direction and rolled again in the width direction to extend the length of the plate to 650±10mm, thus obtaining the third hot-rolled plate.

[0049] (5) The 3-time hot-rolled slab is reheated in the furnace at a temperature of 950°C for 2 minutes. It is then rolled in a direction perpendicular to the second rolling direction. It is rolled again along the length direction until the cumulative deformation rate in the width, length and thickness directions reaches 50%. After the reversal rolling, it is hot-leveled at a temperature of 750°C for 3 minutes to make the flatness of the plate less than 2 mm, thus obtaining the first hot-leveled plate.

[0050] (6) The first hot-leveled plate is reheated in the furnace at a temperature of 750°C for 2 minutes. Then, it is processed in the forward direction (rolled in the length direction) to 2.0±0.1mm according to the thickness. Then, it is hot-leveled again at a temperature of 750°C for 1 minute to make the flatness of the plate less than 1.5mm, so as to obtain a molybdenum plate that can produce molybdenum discs with a thickness of 1.8mm.

[0051] Example 2

[0052] Molybdenum plates for molybdenum wafers are prepared using the following steps:

[0053] (1) Select a molybdenum plate blank with a thickness of 30±2mm, a width of 330±10mm, a length of 350±10mm, a mass of 35kg, and four sides with rounded arc surfaces as the preparation blank. The radius of the arc of the molybdenum plate blank is 10-20mm, and the four sides are smoothly transitioned with the upper and lower surfaces.

[0054] (2) The prepared slab is heat-treated at 1300℃ for 15 minutes, and then the first pass rolling is carried out. The first pass rolling is along the width direction, and the first pass reduction rate is 13%, to obtain the first hot-rolled plate.

[0055] (3) The first hot-rolled plate is reheated in the furnace at a temperature of 1050℃ for 3 minutes. It is then rolled in a direction perpendicular to the first rolling direction, along the length direction, so that the length of the plate is extended to 530±10mm to obtain the second hot-rolled plate.

[0056] (4) The second hot-rolled slab is reheated in the furnace at a temperature of 1050℃ for 3 minutes. It is then rolled in a direction perpendicular to the second rolling direction, along the width direction, so that the length of the plate is further extended to more than 660mm to obtain the third hot-rolled plate.

[0057] (5) The 3rd hot-rolled slab is reheated in the furnace at a temperature of 1050℃ for 3 minutes. It is then rolled in a direction perpendicular to the second rolling direction along the length. After the reversal rolling, it is hot-straightened at a temperature of 800℃ for 3 minutes to make the flatness of the plate less than 2mm, thus obtaining the first hot-straightened plate.

[0058] (6) The first heat-leveled plate is reheated in the furnace. The heating temperature is controlled at 800℃ and the time is 3min. Then, it is processed in the forward direction according to the thickness to 2.0±0.1mm. Then, it is heat-leveled again. The heating temperature is 800℃ and the time is 1min, so that the flatness of the plate reaches less than 1.5mm, and a molybdenum plate that can produce molybdenum discs with a thickness of 1.8mm is obtained.

[0059] Example 3

[0060] Molybdenum plates for molybdenum wafers are prepared using the following steps:

[0061] (1) Select a molybdenum plate blank with a thickness of 30±2mm, a width of 330±10mm, a length of 390±10mm, a mass of 39kg, and four sides with rounded arc surfaces as the preparation blank. The radius of the arc of the molybdenum plate blank is 10-20mm, and the four sides are smoothly transitioned with the upper and lower surfaces.

[0062] (2) The prepared slab is heat-treated at 1350℃ for 18 minutes, and then the first rolling is carried out. The first rolling is along the width direction, and the first reduction rate is 13%, to obtain the first hot-rolled plate.

[0063] (3) The first hot-rolled plate is reheated in the furnace at a temperature of 1080℃ for 3 minutes. It is then rolled in a direction perpendicular to the first rolling direction, along the length direction, so that the length of the plate is extended to 560±10mm to obtain the second hot-rolled plate.

[0064] (4) The second hot-rolled slab is reheated in the furnace at a temperature of 1080℃ for 3 minutes. It is then rolled in a direction perpendicular to the second rolling direction, along the width direction, so that the length of the plate is further extended to more than 660mm to obtain the third hot-rolled plate.

[0065] (5) The 3rd hot-rolled slab is reheated in the furnace and rolled in a direction perpendicular to the second rolling direction. It is rolled along the length direction. After the reversal rolling, it is hot-leveled at a temperature of 800℃ for 3 minutes to make the flatness of the plate less than 2mm and obtain the first hot-leveled plate.

[0066] (6) The first heat-leveled plate is reheated in the furnace. The heating temperature is controlled at 850℃ and the time is 3min. Then, it is processed in the forward direction according to the thickness to 2.0±0.1mm. Then, it is heat-leveled again. The heating temperature is 850℃ and the time is 1min, so that the flatness of the plate reaches less than 1.5mm, and a molybdenum plate that can produce molybdenum discs with a thickness of 1.8mm is obtained.

[0067] Comparative Example 1

[0068] Molybdenum plates for molybdenum wafers are prepared using the following steps:

[0069] (1) Select a molybdenum plate blank with a thickness of 12±1.5mm, a width of 60±5mm, a length of 140±10mm, a weight of 1kg, and straight edges as the preparation blank;

[0070] (2) The prepared slab is heat-treated at 1250℃ for 12 minutes, and then rolled for the first time to obtain the first hot-rolled plate. The first rolling is along the width direction with a reduction rate of 20%, so that the width of the plate is extended from 60mm to 140mm.

[0071] (3) The first hot-rolled plate is reheated in the furnace at a temperature of 950℃ for 2 minutes. It is rolled in the direction of reversal perpendicular to the first rolling direction, and rolled in the length direction to extend the length of the plate to 350±10mm, thus obtaining the second hot-rolled plate.

[0072] (4) The first heat-leveled plate is reheated in the furnace. The heating temperature is controlled at 750℃ and the time is 2min. Then, it is processed in the forward direction according to the thickness to 2.3±0.1mm. Then, it is heat-leveled again. The processing temperature is 750℃ and the time is 1min, so that the flatness of the plate reaches less than 1.5mm, and a molybdenum plate that can produce molybdenum discs with a thickness of 1.8mm is obtained.

[0073] Comparative Example 2

[0074] Molybdenum plates for molybdenum wafers are prepared using the following steps:

[0075] (1) Select a molybdenum plate blank with a thickness of 12±1.5mm, a width of 60±5mm, a length of 140±10mm, a weight of 1kg, and straight edges as the preparation blank;

[0076] (2) The prepared slab is heat-treated at 1300℃ for 15 minutes, and then rolled for the first time to obtain the first hot-rolled plate. The first rolling is along the width direction with a reduction rate of 20%, so that the width of the plate is extended from 60mm to 140mm.

[0077] (3) The first hot-rolled plate is reheated in the furnace at a temperature of 1050℃ for 3 minutes. It is rolled in the direction of reversal perpendicular to the first rolling direction, and rolled in the direction of elongation so that the length of the plate is extended to 350±10mm to obtain the second hot-rolled plate.

[0078] (4) The first heat-leveled plate is reheated in the furnace. The heating temperature is controlled at 800℃ and the time is 3min. Then, it is processed in the forward direction according to the thickness to 2.3±0.1mm. Then, it is heat-leveled again. The heating temperature is controlled at 800℃ and the time is 1min so that the flatness of the plate reaches below 1.5mm, and a molybdenum plate that can produce molybdenum discs with a thickness of 1.8mm is obtained.

[0079] Comparative Example 3

[0080] Molybdenum plates for molybdenum wafers are prepared using the following steps:

[0081] (1) Select a molybdenum plate blank with a thickness of 12±1.5mm, a width of 60±5mm, a length of 140±10mm, a weight of 1kg, and straight edges as the preparation blank;

[0082] (2) The prepared slab is heat-treated at 1350℃ for 18 minutes, and then rolled for the first time to obtain the first hot-rolled plate. The first rolling is along the width direction with a reduction rate of 20%, so that the width of the plate is extended from 60mm to 140mm.

[0083] (3) The first hot-rolled plate is reheated in the furnace at a temperature of 1080℃ for 3 minutes. It is rolled in the direction of reversal perpendicular to the first rolling direction, and rolled in the length direction to extend the length of the plate to 350±10mm to obtain the second hot-rolled plate.

[0084] (4) The first heat-leveled plate is reheated in the furnace. The heating temperature is controlled at 850℃ and the time is 3min. Then, it is processed in the forward direction according to the thickness to 2.3±0.1mm. Then, it is heat-leveled again. The heating temperature is controlled at 850℃ and the time is 1min to make the flatness of the plate reach less than 1.5mm, so as to obtain a molybdenum plate that can produce molybdenum discs with a thickness of 1.8mm.

[0085] The molybdenum plates obtained in Examples 1-3 and Comparative Examples 1-3 were subjected to tests for density, mechanical properties, microstructure, and direct metal yield, respectively. The test methods were as follows:

[0086] Density: The density of the molybdenum plate was determined by the water displacement method;

[0087] Mechanical properties: The tensile strength of the molybdenum plate was obtained by using a tensile testing machine according to the national standard GB / T228-2002.

[0088] Microstructure: Observed using a scanning electron microscope;

[0089] Metal yield: Calculated as the ratio of the weight of the finished molybdenum rounds to the weight of the molybdenum plate blanks.

[0090] The measurement results are shown in Table 1 below:

[0091] Table 2 Results of Molybdenum Plate Performance Tests

[0092]

[0093] Test results show that, compared with the conventional preparation method of 1kg slab, the molybdenum plate obtained by the present invention has significantly improved performance and uniformity, and greatly saves molybdenum material consumption.

[0094] Metallographic images and SEM images of the molybdenum plates used for molybdenum wafers obtained in Examples 1-3 are attached. Figure 4 , 5 As shown, example images of metallographic and SEM images of molybdenum plates with micropores obtained in Comparative Examples 1-3 are attached. Figure 6 , 7 As shown.

[0095] It should be noted that the above descriptions are merely preferred embodiments of the present invention and should not limit the scope of protection of the technical solutions of the present invention. Any modifications made to the technical solutions described in the foregoing embodiments, or equivalent substitutions of technical features, by those skilled in the art within the spirit and principles of the present invention, should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a molybdenum plate for molybdenum discs, characterized in that, It includes: A cuboid molybdenum plate blank with a weight of 30-40 kg and a thickness of 30-40 mm, and four symmetrical arc surfaces on its four sides, is used as the preparation material to reduce delamination defects caused by uneven extension of the edges and core during deformation processing under top and bottom force application, and to improve the uniformity of extension of the core and edges of the plate. The molybdenum plate blank has a width of 330-430 mm, a length of 310-410 mm, and an arc radius of 10-20 mm on each of its four sides. The prepared blank is heat-treated at 800-1400℃, and then subjected to more than 3 passes of directional deformation treatment, that is, the direction of each deformation treatment is perpendicular to the direction of the previous deformation treatment, until the deformation amount in each direction of the obtained plate is more than 50%, and the deformed plate is obtained. The deformed sheet is then subjected to heat straightening treatment to achieve a flatness of less than 2mm, resulting in a first heat-straightened sheet. The first heat-leveled sheet is reheated in a furnace at a temperature of 700-850℃, and then the thickness is processed to achieve the target thickness. It is then heat-leveled again to make the flatness of the sheet less than 1.5mm. The target thickness has a margin of less than 20% relative to the thickness of the molybdenum disc. The deformation process is performed by rolling.

2. The preparation method according to claim 1, characterized in that, After each reversing deformation process before the final reversing deformation process, the resulting sheet material is subjected to reheating treatment in a furnace.

3. The preparation method according to claim 2, characterized in that, The temperature of the reheat treatment gradually decreases as the thickness of the resulting sheet decreases.

4. The preparation method according to claim 1, characterized in that, in, The reduction rate for each deformation treatment is 10-20%.

5. The preparation method according to any one of claims 1-4, characterized in that, It includes: (1) The prepared billet is heat-treated at 1150-1400℃ for 8-30 min, and then subjected to the first deformation treatment. The reduction rate of the deformation treatment is 10-20%, and the first deformation treatment plate is obtained. (2) The first-deformed plate is reheated in the furnace, and then a second deformation process is carried out, which is perpendicular to the direction of the first deformation process, so that the length of the plate is 1.01-2.6 times the initial length of the blank, and a second-deformed plate is obtained. (3) The plate that has undergone secondary deformation treatment is reheated in the furnace and subjected to a third deformation treatment that is perpendicular to the direction of the second deformation treatment, so that the length of the plate is more than 1.01 times the length of the plate that has undergone secondary deformation treatment, and thus a plate that has undergone tertiary deformation treatment is obtained. (4) The plate that has undergone three deformation treatments is reheated in the furnace and subjected to a fourth deformation treatment that is perpendicular to the direction of the third deformation treatment. The cumulative deformation rate of the plate relative to the width, length and thickness of the prepared blank reaches more than 50%. Then, a heat straightening treatment is performed to make the flatness of the plate less than 2mm, thus obtaining the first heat straightened plate. (5) The first heat-leveled plate is reheated in the furnace at a temperature of 700-850℃, then processed to the target thickness, and then heat-leveled again to make the flatness of the plate less than 1.5mm, thus obtaining a molybdenum plate for molybdenum discs.

6. A molybdenum plate for use with molybdenum discs prepared by the preparation method according to any one of claims 1-5.

7. The molybdenum wafer obtained by processing a molybdenum plate according to claim 6.

Images