A hollow silicon carbide structure, its preparation method and application

Abstract

This invention relates to a silicon carbide hollow structure, its preparation method, and its application. The preparation method of the silicon carbide hollow structure includes the following steps: (1) uniformly mixing silicon powder and silicon carbide powder, and then molding the resulting mixed powder to obtain a silicon-silicon carbide blank; (2) processing two silicon-silicon carbide blanks obtained in step (1), then molding them, and then performing hot-press diffusion welding. The resulting assembly is then post-processed to obtain the silicon-silicon carbide hollow structure. This invention achieves the integral molding of complex irregular hollow structures, while reducing the deformation after hot-press diffusion welding and increasing the strength of the weld joint, thus meeting the requirements for structural components used in integrated circuit equipment or materials used in photovoltaic chips.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit structural materials technology, specifically to a silicon carbide hollow structure, its preparation method, and its application. Background Technology

[0002] Silicon carbide is a covalent compound with strong Si-C bonds, exhibiting extremely high hardness and significant brittleness, making it difficult to perform precision machining. Furthermore, silicon carbide has a high melting point, making it difficult to achieve densification and near-net-shape sintering. Therefore, the fabrication of large-size, complex, irregularly shaped hollow precision silicon carbide structural components is challenging, limiting the widespread application of silicon carbide in high-end equipment manufacturing fields such as integrated circuits.

[0003] Currently, silicon carbide welding technologies mainly include direct bonding, solid-state diffusion bonding with a metal interlayer, transient eutectic bonding, oxide-glass bonding, Si-C reactive bonding, MAX phase bonding, and brazing. Among these, direct bonding and interlayer bonding significantly impact the performance of the welded joints due to the inherent inertness of Si-C and the mismatch in thermophysical properties between the interlayer and the metal. Other welding methods are limited in application mainly due to their complex processes and high production costs.

[0004] CN 113042879A discloses a silicon carbide diffusion welding method and a silicon carbide heat exchanger. The silicon carbide diffusion welding method includes: cleaning silicon carbide parts, stacking at least two silicon carbide parts according to the structure of the product to be formed, and placing them in a diffusion welding furnace; evacuating the diffusion welding furnace to a pressure not exceeding 10 kJ / m³. -2 Alternatively, a protective gas can be introduced into the diffusion welding furnace to a pressure of 0.2-0.5 MPa; the furnace temperature can be raised to 2000-2400℃, and a pressure of 20-25 MPa can be applied to the silicon carbide parts, maintaining a constant temperature and pressure for at least 50 minutes; the furnace can then be cooled to no higher than 300℃ before being opened to obtain the silicon carbide diffusion-welded product. However, this invention has a relatively high sintering temperature, resulting in significant deformation after welding, and the joint strength needs to be improved.

[0005] CN 113828880A discloses a method for bonding silicon carbide ceramics using a refractory high-entropy alloy interlayer via spark plasma diffusion. This method uses a refractory high-entropy alloy TaxHfZrTi (where x = 0.5-1, Ta (at.%) = 14.2-25%, and Hf, Zr, and Ti are in equimolar amounts) as the interlayer material. Two SiC ceramic substrates are then bonded using SPS technology via solid-state diffusion welding to obtain a SiC ceramic welded joint. However, the thermal properties of the interlayer in this invention need improvement in their compatibility with Si-C, which may affect the subsequent welding effect of the joint.

[0006] Therefore, in view of the shortcomings of the existing technology, there is a need to provide a method that results in small deformation and high joint strength in silicon carbide welding. Summary of the Invention

[0007] The purpose of this invention is to provide a silicon carbide hollow structure, its preparation method and application. Using silicon and silicon carbide as raw materials, non-metallic silicon is used to form a liquid phase at high temperature, thereby forming a new diffusion layer at the interface, realizing the integral molding of complex irregular hollow structures, which has the characteristics of small welding deformation and high joint strength.

[0008] To achieve this objective, the present invention employs the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a hollow silicon carbide structure, the method comprising the following steps:

[0010] (1) Silicon powder and silicon carbide powder are uniformly mixed, and the resulting mixed powder is shaped to obtain silicon-silicon carbide billet;

[0011] (2) After processing the two silicon-silicon carbide blanks obtained in step (1), they are molded and then hot-pressed diffusion welding is performed. The resulting assembly is post-processed to obtain the silicon-silicon carbide hollow structure.

[0012] The method for preparing silicon carbide hollow structures provided by this invention uses silicon and silicon carbide as raw materials. It utilizes the non-metallic silicon to form a liquid phase at high temperature, and mutual diffusion occurs between atoms, thereby forming a new diffusion layer at the interface. This achieves the integral molding of complex irregular hollow structures. At the same time, the process parameters of molding and hot-press diffusion welding are controlled to ensure that the deformation after hot-press diffusion welding is small and the weld joint strength is high, which can meet the requirements of structural components used in integrated circuit equipment.

[0013] Preferably, the purity of the silicon powder in step (1) is 3-5N, for example, it can be 3N, 4N or 5N, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the average particle size of the silicon powder in step (1) is 1-10 μm, for example, it can be 1 μm, 3 μm, 5 μm, 8 μm or 10 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, the purity of the silicon carbide powder in step (1) is 3-4N, for example, it can be 3N or 4N, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] Preferably, the average particle size of the silicon carbide powder in step (1) is 1-20 μm, for example, it can be 1 μm, 5 μm, 10 μm, 15 μm or 20 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the mass percentage of silicon powder in the mixed powder in step (1) is 10-40 wt%, for example, it can be 10 wt%, 15 wt%, 20 wt%, 30 wt% or 40 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the forming process in step (1) includes cold isostatic pressing or pre-sintering.

[0019] The forming process can be either cold isostatic pressing, combined with subsequent hot pressing diffusion welding to complete the preparation of the silicon carbide hollow structure; or a two-step sintering method can be used, that is, the forming process adopts pre-sintering treatment, omitting the cold isostatic pressing step, and the mixed powder is loaded into a graphite mold for pre-firing.

[0020] Preferably, the pressure of the cold isostatic pressing is 90-120 MPa, for example, it can be 90 MPa, 95 MPa, 100 MPa, 110 MPa or 120 MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the cold isostatic pressing time is 5-10 minutes, for example, 5 minutes, 6 minutes, 8 minutes, 9 minutes or 10 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, the cold isostatic pressing process is performed in a rubber sleeve.

[0023] In the cold isostatic pressing process, the mixed powder is loaded into a specific rubber sleeve, which can then be used to prepare different complex hollow structures, such as square hollow blanks, according to production target requirements.

[0024] Preferably, the temperature of the pre-sintering treatment is 1420-1600℃, for example, it can be 1420℃, 1450℃, 1500℃, 1550℃ or 1600℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the pre-sintering treatment time is 30-90 min, for example, it can be 30 min, 45 min, 60 min, 75 min or 90 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the processing method described in step (2) includes milling.

[0027] The milling process can smooth the surfaces of the two silicon-silicon carbide blanks, which is beneficial for subsequent hot-press diffusion welding.

[0028] Preferably, the flatness of the processed silicon-silicon carbide blank in step (2) is <0.25mm, for example, it can be 0.22mm, 0.2mm, 0.18mm, 0.15mm or 0.1mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the mold used in step (2) includes a graphite mold.

[0030] Preferably, the hot-press diffusion welding in step (2) is performed under nitrogen or vacuum conditions.

[0031] Preferably, the temperature of the hot-press diffusion welding in step (2) is 1420-1450℃, for example, it can be 1420℃, 1425℃, 1430℃, 1440℃ or 1450℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the pressure of the hot-press diffusion welding in step (2) is 20-40 MPa, for example, it can be 20 MPa, 25 MPa, 30 MPa, 35 MPa or 40 MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the hot-press diffusion welding time in step (2) is 1-2 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.8 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the post-processing in step (2) includes demolding and fine grinding.

[0035] As a preferred embodiment of the preparation method described in this invention, the preparation method includes the following steps:

[0036] (1) A silicon powder with a purity of 3-5N and an average particle size of 1-10μm is uniformly mixed with a silicon carbide powder with a purity of 3-4N and an average particle size of 1-20μm to obtain a mixed powder with a silicon powder mass percentage of 10-40wt%; the obtained mixed powder is then shaped to obtain a silicon-silicon carbide billet.

[0037] The forming process includes cold isostatic pressing or pre-sintering; the pressure of the cold isostatic pressing is 90-120 MPa, and the time is 5-10 min; the temperature of the pre-sintering is 1420-1600℃, and the time is 30-90 min.

[0038] (2) After milling the two silicon-silicon carbide blanks obtained in step (1) to a flatness of <0.25mm, they are placed into a graphite mold and then hot-pressed diffusion welding is performed under nitrogen or vacuum conditions at a temperature of 1420-1450℃, a pressure of 20-40MPa, and a time of 1-2h. The resulting assembly is demolded and finely ground to obtain the silicon-silicon carbide hollow structure.

[0039] In a second aspect, the present invention provides a silicon carbide hollow structure, which is prepared by the preparation method described in the first aspect.

[0040] The silicon carbide hollow structure provided by this invention realizes the integral molding of complex irregular hollow structures, with a deformation of 0.02-0.03 mm after welding and high weld joint strength.

[0041] Thirdly, the present invention provides an application of the silicon carbide hollow structure as described in the second aspect, wherein the silicon carbide hollow structure is used as a structural component for key equipment of integrated circuits or as a material for photovoltaic chips.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The method for preparing silicon carbide hollow structures provided by this invention uses silicon and silicon carbide as raw materials. It utilizes the liquid phase formed by non-metallic silicon at high temperature, where interatomic diffusion occurs, thereby forming a new diffusion layer at the interface. This achieves the integral molding of complex irregular hollow structures. At the same time, the process parameters of molding and hot-press diffusion welding are controlled, resulting in a small deformation after hot-press diffusion welding, which is 0.02-0.03 mm. The weld joint strength can reach 271 MPa, which can meet the requirements for structural components used in integrated circuit equipment or materials used in photovoltaic chips. Detailed Implementation

[0044] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0045] Example 1

[0046] This embodiment provides a hollow silicon carbide structure, the preparation method of which includes the following steps:

[0047] (1) Silicon powder with a purity of 4N and an average particle size of 5μm and silicon carbide powder with a purity of 4N and an average particle size of 10μm are uniformly mixed to obtain a mixed powder with a silicon powder mass percentage of 20wt%; the obtained mixed powder is subjected to cold isostatic pressing at 100MPa for 8min to obtain silicon-silicon carbide billet.

[0048] (2) After milling the two silicon-silicon carbide blanks obtained in step (1) to a flatness of 0.1 mm, they are placed into a graphite mold and then hot-pressed diffusion welding is performed under vacuum conditions at a temperature of 1430℃, a pressure of 30 MPa, and a time of 1.5 h. The resulting composite is demolded and finely ground to obtain the silicon-silicon carbide hollow structure.

[0049] Example 2

[0050] This embodiment provides a hollow silicon carbide structure, the preparation method of which includes the following steps:

[0051] (1) Silicon powder with a purity of 3N and an average particle size of 1μm and silicon carbide powder with a purity of 3N and an average particle size of 1μm are uniformly mixed to obtain a mixed powder with a silicon powder mass percentage of 10wt%; the obtained mixed powder is subjected to cold isostatic pressing at 90MPa for 10min to obtain silicon-silicon carbide billet.

[0052] (2) After milling the two silicon-silicon carbide blanks obtained in step (1) to a flatness of 0.15 mm, they are placed into a graphite mold and then hot-pressed diffusion welding is performed under vacuum conditions at a temperature of 1420℃, a pressure of 20 MPa, and a time of 2 h. The resulting assembly is demolded and finely ground to obtain the silicon-silicon carbide hollow structure.

[0053] Example 3

[0054] This embodiment provides a hollow silicon carbide structure, the preparation method of which includes the following steps:

[0055] (1) Silicon powder with a purity of 5N and an average particle size of 10μm was uniformly mixed with silicon carbide powder with a purity of 4N and an average particle size of 20μm to obtain a mixed powder with a silicon powder mass percentage of 40wt%; the obtained mixed powder was subjected to cold isostatic pressing at 120MPa for 5min to obtain silicon-silicon carbide billet.

[0056] (2) After milling the two silicon-silicon carbide blanks obtained in step (1) to a flatness of 0.22 mm, they are placed into a graphite mold and then hot-pressed diffusion welding is performed under nitrogen conditions at a temperature of 1450℃, a pressure of 40 MPa, and a time of 1 h. The resulting assembly is demolded and finely ground to obtain the silicon-silicon carbide hollow structure.

[0057] Example 4

[0058] This embodiment provides a silicon carbide hollow structure. The preparation method of the silicon carbide hollow structure is different from that of Embodiment 1. Except for adjusting the cold isostatic pressing step (1) to a pre-sintering treatment at 1600°C for 30 minutes, the rest is the same as that of Embodiment 1.

[0059] Example 5

[0060] This embodiment provides a silicon carbide hollow structure. The preparation method of the silicon carbide hollow structure is different from that of Embodiment 1. Except for adjusting the cold isostatic pressing step (1) to a pre-sintering treatment at 1420°C for 90 minutes, the rest is the same as that of Embodiment 1.

[0061] Example 6

[0062] This embodiment provides a silicon carbide hollow structure. The difference between the preparation method of the silicon carbide hollow structure and that of Embodiment 1 is that, except for adjusting the pressure of the cold isostatic pressing in step (1) to 80 MPa, the rest is the same as that of Embodiment 1.

[0063] Example 7

[0064] This embodiment provides a silicon carbide hollow structure. The difference between the preparation method of the silicon carbide hollow structure and that of Embodiment 1 is that, except for adjusting the pressure of the cold isostatic pressing in step (1) to 130 MPa, the rest is the same as that of Embodiment 1.

[0065] Example 8

[0066] This embodiment provides a silicon carbide hollow structure. The difference between the preparation method of the silicon carbide hollow structure and that of Embodiment 1 is that, except for milling to a flatness of 0.25 mm as described in step (2), the rest is the same as that of Embodiment 1.

[0067] Example 9

[0068] This embodiment provides a silicon carbide hollow structure. The difference between the preparation method of the silicon carbide hollow structure and that of Embodiment 1 is that, except for adjusting the temperature of the hot-press diffusion welding in step (2) to 1410°C, the rest is the same as that of Embodiment 1.

[0069] Example 10

[0070] This embodiment provides a silicon carbide hollow structure. The difference between the preparation method of the silicon carbide hollow structure and that of Embodiment 1 is that, except for adjusting the temperature of the hot-press diffusion welding in step (2) to 1460°C, the rest is the same as that of Embodiment 1.

[0071] Comparative Example 1

[0072] This comparative example provides a silicon carbide hollow structure. The difference between the preparation method of the silicon carbide hollow structure and that of Example 1 is that the silicon powder in step (1) is replaced with carbon powder in equal mass, and the rest is the same as that of Example 1.

[0073] Comparative Example 2

[0074] This comparative example provides a silicon carbide hollow structure. The difference between the preparation method of the silicon carbide hollow structure and that of Example 1 is that there is no processing step in step (2), while the rest are the same as in Example 1.

[0075] The silicon carbide hollow structures provided in Examples 1-10 and Comparative Example 2, as well as the silicon carbide hollow structure provided in Comparative Example 1, were subjected to welding deformation tests using a dial indicator. The weld joint strength was tested using the four-point bending strength method. The results are shown in Table 1.

[0076] Table 1

[0077] Welding deformation (mm) Welded joint strength (MPa) Example 1 0.020 271 Example 2 0.021 249 Example 3 0.021 197 Example 4 0.023 258 Example 5 0.022 223 Example 6 0.028 243 Example 7 0.023 247 Example 8 0.03 237 Example 9 0.025 255 Example 10 0.028 261 Comparative Example 1 0.034 158 Comparative Example 2 0.042 174

[0078] As can be seen from Table 1, the silicon carbide hollow structure provided by the present invention has a small welding deformation and high welding joint strength, which can meet the requirements for structural components used in key equipment of integrated circuits or materials used in photovoltaic chips.

[0079] A comparison of Examples 1 with Examples 4 and 5 shows that using pre-sintering treatment instead of cold isostatic pressing can also yield silicon carbide hollow structures with better overall performance. A comparison of Examples 1 with Examples 6 and 7 shows that both insufficient and excessive pressure during cold isostatic pressing will adversely affect the welding deformation and joint strength of the silicon carbide hollow structures. A comparison of Examples 1 with Example 8 shows that excessively large milled flatness is not conducive to subsequent hot-press diffusion welding. A comparison of Examples 1 with Examples 9 and 10 shows that exceeding the temperature limit during hot-press diffusion welding will also increase welding deformation and reduce joint strength.

[0080] As can be seen from the comparison between Example 1 and Comparative Example 1, the diffusion effect of using carbon instead of silicon to form a liquid phase at high temperature is reduced compared to silicon, which in turn affects the welding deformation and the strength of the weld joint. As can be seen from the comparison between Example 1 and Comparative Example 2, the welding effect is significantly reduced if the silicon-silicon carbide billet is not processed.

[0081] In summary, the method for preparing silicon carbide hollow structures provided by this invention uses silicon and silicon carbide as raw materials. It utilizes the liquid phase formed by non-metallic silicon at high temperature, where interatomic diffusion occurs, thereby forming a new diffusion layer at the interface. This achieves the integral molding of complex irregular hollow structures. At the same time, by controlling the process parameters of molding and hot-press diffusion welding, the deformation after hot-press diffusion welding is small, ranging from 0.02 to 0.03 mm, and the weld joint strength can reach 271 MPa, which can meet the requirements for structural components used in integrated circuit equipment or materials used in photovoltaic chips.

[0082] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a hollow silicon carbide structure, characterized in that, The preparation method includes the following steps: (1) Silicon powder with an average particle size of 1-10 μm and silicon carbide powder with an average particle size of 1-20 μm are uniformly mixed to obtain a mixed powder with a silicon powder mass percentage of 10-40 wt%; the obtained mixed powder is shaped to obtain a silicon-silicon carbide billet. The forming process includes cold isostatic pressing or pre-sintering; the pressure of the cold isostatic pressing is 90-120 MPa, and the time is 5-10 min; the temperature of the pre-sintering is 1420-1600℃, and the time is 30-90 min. (2) After milling the two silicon-silicon carbide blanks obtained in step (1) to a flatness of <0.25mm, they are molded and then hot-pressed diffusion welding is performed under nitrogen or vacuum conditions. The temperature of the hot-pressed diffusion welding is 1420-1450℃, the pressure is 20-40MPa, and the time is 1-2h. The resulting assembly is post-processed to obtain the silicon-silicon carbide hollow structure.

2. The preparation method according to claim 1, characterized in that, The purity of the silicon powder in step (1) is 3-5N.

3. The preparation method according to claim 1, characterized in that, The purity of the silicon carbide powder in step (1) is 3-4N.

4. The preparation method according to claim 1, characterized in that, The mold used for molding in step (2) includes a graphite mold.

5. The preparation method according to claim 1, characterized in that, The post-processing described in step (2) includes demolding and fine grinding.

6. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) A silicon powder with a purity of 3-5N and an average particle size of 1-10μm is uniformly mixed with silicon carbide powder with a purity of 3-4N and an average particle size of 1-20μm to obtain a mixed powder with a silicon powder mass percentage of 10-40wt%; the obtained mixed powder is then shaped to obtain a silicon-silicon carbide billet. The forming process includes cold isostatic pressing or pre-sintering; the pressure of the cold isostatic pressing is 90-120 MPa, and the time is 5-10 min; the temperature of the pre-sintering is 1420-1600℃, and the time is 30-90 min. (2) After milling the two silicon-silicon carbide blanks obtained in step (1) to a flatness of <0.25mm, they are molded and then hot-pressed diffusion welding is performed under nitrogen or vacuum conditions at a temperature of 1420-1450℃, a pressure of 20-40MPa, and a time of 1-2h. The resulting assembly is demolded and finely ground to obtain the silicon-silicon carbide hollow structure.

7. A hollow silicon carbide structure, characterized in that, The silicon carbide hollow structure is prepared by the preparation method according to any one of claims 1-6.

8. An application of the silicon carbide hollow structure as described in claim 7, characterized in that, The silicon carbide hollow structure is used as a structural component for key equipment in integrated circuits or as a material for photovoltaic chips.