AlSiC module preparation process and equipment based on gravity variable pressure infiltration

Abstract

The invention discloses an AlSiC module preparation process and equipment based on gravity variable pressure infiltration, which adopts a staged gradient pressurization and gradient cooling synergistic process: firstly, realizing gravity infiltration of molten metal aluminum in a vacuum environment, and then completing layer-by-layer densification of an AlSiC composite material through multi-stage pressure regulation and control; and finally, the interface thermal stress is effectively controlled by combining a gradient cooling strategy of forced cooling and natural cooling. The corollary equipment is of a vertical cavity high-pressure kettle structure and comprises a first cavity and a second cavity which are distributed up and down, and accurate linkage of the two cavities is achieved through a switch structure. The equipment integrates an intelligent pressure regulation and control system and a composite temperature control system, and realizes multi-parameter programmed control of a pressure and temperature time sequence through a central control system. Through the synergistic effect of the dynamic pressure field and the temperature field, the infiltration efficiency and the interface bonding strength of the AlSiC composite material are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of IGBT modules, and in particular to a process and equipment for preparing an AlSiC module based on gravity-induced voltage infiltration. Background Art

[0002] Silicon carbide (SiC)-based composites have attracted considerable attention in the aerospace, electronic packaging, and nuclear energy sectors due to their excellent high-temperature strength, wear resistance, and thermal stability. However, existing metal infiltration processes still face numerous challenges: conventional gravity infiltration relies on a single pressure environment, which can lead to uneven infiltration due to insufficient metal fluidity, particularly in complex porous SiC matrices where unfilled areas are likely to form. While constant high-pressure infiltration can increase the filling rate, sudden pressure increases can easily induce microcracks in the matrix. Furthermore, solidification shrinkage of high-melting-point metals (such as aluminum alloys) can easily generate internal residual stresses, reducing the interfacial bonding strength of the composite material.

[0003] Current equipment designs mostly use a single-chamber structure. The simultaneous heating of the molten metal and the substrate can easily cause metal oxidation or composition segregation, and the pressure control accuracy is insufficient, making it difficult to achieve staged optimization of the infiltration process. For example, patent publication number CN216826932U proposes a workpiece vacuum infiltration device, but its pressure control relies on a single gas source input, which cannot achieve step-by-step pressure increase and dynamic pressure balance, resulting in limited infiltration depth. In addition, the cooling stage mostly uses a single rate of cooling, lacking a gradient temperature control mechanism, resulting in the concentration of thermal stress inside the material, affecting the dimensional stability of the finished product.

[0004] To address these issues, there is an urgent need to develop an infiltration process and dedicated apparatus that can synergistically regulate the pressure gradient and temperature profile. This involves achieving layer-by-layer infiltration of the molten metal through staged pressurization, combined with gradient cooling to suppress interfacial defects, thereby improving the density and mechanical properties of SiC composites. The proposed variable-pressure gravity infiltration method and apparatus, through dual-chamber isolated heating, programmable pressure gradient loading, and a multimodal cooling strategy, effectively addresses the core issues of existing technologies, such as low infiltration efficiency, numerous structural defects, and poor process controllability. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides an AlSiC module preparation process based on gravity pressure infiltration.

[0006] The technical solution of the present invention is achieved as follows:

[0007] The present invention discloses a process for preparing an AlSiC module based on gravity pressure infiltration, comprising the following steps:

[0008] Si. The SiC substrate assembly is heated to 700-800°C and placed in the first chamber of the autoclave;

[0009] S2. The molten aluminum is injected into the second chamber of the autoclave, the second chamber being located above the first chamber and the two are connected via a switch mechanism;

[0010] S3. Evacuate the autoclave to an absolute pressure of less than 0.1 kPa;

[0011] S4. Open the switch mechanism so that the molten aluminum liquid is infiltrated into the SiC matrix module under gravity;

[0012] S5. Apply gradient pressure in stages: first apply pressure to 0.5-1.5 MPa for primary infiltration, then gradually increase pressure to 5-6 MPa for deep infiltration;

[0013] S6. Start the gradient cooling mode while maintaining the final pressure state, so that the temperature drops to the range of 400-600℃;

[0014] S7. After pressure release and natural cooling, the AlSiC composite matrix is ​​subjected to mechanical processing.

[0015] Preferably, the heating temperature of the molten aluminum liquid is controlled between 700-800°C.

[0016] Preferably, the gradient pressure application includes at least three pressure stages: an initial pressure holding stage of 0.8-1.2 MPa, a main infiltration stage of 5.0-5.8 MPa, and a final pressure setting stage of 5.5-6.0 MPa.

[0017] Preferably, the gradient cooling program includes two stages: forced cooling and natural cooling, and the forced cooling rate is controlled at 10-30°C / min.

[0018] The present invention also discloses a variable pressure gravity infiltration device, comprising:

[0019] An integrated high-pressure reactor body has a first chamber and a second chamber disposed vertically and connected via a switch mechanism;

[0020] Pressure control system, including vacuum pump group, high-pressure gas source input module and pressure regulating valve module;

[0021] Intelligent temperature control system, integrating induction heating unit and circulating cooling module;

[0022] The central control system is equipped with a pressure gradient program control unit, a temperature curve program control unit and a timing logic control unit.

[0023] Preferably, the pressure regulating valve module comprises: a first pressure regulating valve located at the upper portion of one side of the kettle body, a second pressure regulating valve located at the lower portion of the other opposite side of the kettle body, and a third pressure regulating valve located at the bottom of the kettle body.

[0024] Preferably, the first chamber is located directly below the second chamber, and the capacity of the first chamber is greater than that of the second chamber.

[0025] Preferably, the second chamber includes a cylindrical chamber and a conical chamber, and a through hole communicating with the first chamber is provided at the bottom of the conical chamber.

[0026] Preferably, the conical head of the switching mechanism is adapted to the bottom of the conical chamber, and its actuating mechanism extends outside the second chamber and is signal-connected to the central control system.

[0027] Preferably, the first chamber and the second chamber are detachably connected to the kettle body.

[0028] Implementing a preparation process and device for an AlSiC module based on gravity variable-pressure infiltration of the present invention has the following beneficial technical effects:

[0029] 1. Improvement in infiltration efficiency and densification: Through the dynamic cooperation of vacuum gravity infiltration and multi-stage gradient pressurization (0.5 → 6.0 MPa), the hierarchical directional penetration of the molten metal in the pores of the SiC matrix is achieved, effectively eliminating pore defects, the densification of the composite material is increased by more than 98%, and the infiltration efficiency is increased by 30 - 50% compared with the traditional pressure infiltration process.

[0030] 2. Enhancement of interfacial bonding strength: The gradient cooling strategy (forced cooling at 30 °C / min + natural cooling) precisely controls the difference in thermal expansion coefficients of the metal / SiC interface, and the interfacial bonding strength reaches more than 400 MPa, which is 2 - 3 times higher than that of the conventional quenching process, significantly reducing the microcrack generation rate (<0.5%).

[0031] 3. Breakthrough in process stability: The special device realizes a pressure fluctuation accuracy of ±0.05 MPa level through the coordinated control of the multi-chamber pressure decoupling design (upper chamber for liquid storage / lower chamber for infiltration) and the multi-way pressure regulating valve group, ensuring the infiltration uniformity of complex components (size deviation <0.1 mm), and is particularly suitable for the preparation of thin-walled (<1 mm) special-shaped structures.

[0032] 4. Optimization of energy consumption and cost: The integrated design of the induction heating and circulating cooling system reduces the overall energy consumption by more than 40%, and through the programmed pressure-temperature time sequence control, the process cycle is shortened to 1 / 2 of the traditional process, and the yield of batch production is increased to more than 95%.

[0033] This technology effectively solves industry problems such as weak interfacial bonding, insufficient infiltration, and large residual stress in metal / SiC composite materials, providing a reliable technical path for the industrial production of high-strength and lightweight composite components. Description of the Drawings

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 1 is a schematic diagram of the process structure of Example 1 of the AlSiC module preparation process based on gravity pressure infiltration of the present invention;

[0036] Figure 2 is a cross-sectional view of Example 2 of the variable pressure gravity infiltration equipment of the present invention;

[0037] Figure 3 2 is a schematic structural diagram of a second embodiment of a variable pressure gravity infiltration apparatus according to the present invention;

[0038] Figure 4 Schematic diagram of the chamber and switch mechanism structure of embodiment 2 of the variable pressure gravity infiltration equipment of the present invention;

[0039] Figure 5 Schematic diagram of the exploded view of the second chamber and switch mechanism of Example 2 of the variable pressure gravity infiltration equipment of the present invention.

[0040] In the figure: kettle body 1; first chamber 11; second chamber 12; cylindrical cavity 121; conical cavity 122; through hole 123; switch mechanism north; cone head north 1; actuator north 2; first pressure regulating valve 14; second pressure regulating valve 15; third pressure regulating valve 16 DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] Example 1

[0043] See also Figure 1 The AlSiC module preparation process based on gravity pressure infiltration includes the following steps:

[0044] Step Si: Pretreatment and molding of SiC substrate:

[0045] 1. Process the porous SiC ceramic substrate into the target shape (such as a rectangular module with dimensions of 200 mm × 150 mm × 50 mm) and embed metal connectors;

[0046] 2. Place the SiC substrate assembly on the high-temperature resistant support in the first chamber of the autoclave;

[0047] 3. Start the induction heating unit of the intelligent temperature control system and heat the first chamber to 750±10℃ at a rate of 15℃ / min. Keep it at this temperature for 30 minutes to eliminate the internal stress of the SiC substrate.

[0048] Step S2: Aluminum molten melting and injection:

[0049] 1. Use pure aluminum ingot (purity ≥99.9%) and heat to 750±10℃ for melting;

[0050] 2. Open the liquid injection port of the second chamber of the autoclave;

[0051] 3. 750℃ molten aluminum is injected into the second chamber through a quantitative pouring system, and the liquid level is controlled 20mm below the junction of the conical cavity and the cylindrical cavity.

[0052] Step S3: Vacuum environment construction:

[0053] 1. Close the airtight valve (i.e., the switch mechanism) between the first chamber and the second chamber;

[0054] 2. Start the vacuum pump group and evacuate the vacuum to an absolute pressure of 0.092 kPa (vacuum degree> 99.9%) through the third pressure regulating valve at the bottom of the kettle body, and maintain it for 10 minutes to ensure that the gas in the matrix pores is discharged.

[0055] Step S4: Gravity infiltration start:

[0056] 1. The central control system sends a command to drive the switch actuator (pneumatic gate valve, opening 100%) at the bottom hole of the tapered cavity;

[0057] 2. The aluminum liquid flows into the first chamber through the through hole of the tapered cavity under the action of gravity;

[0058] 3. The initial soaking phase lasts 10-20 seconds.

[0059] Step S5: Gradient pressure infiltration:

[0060] 1. Initial pressure holding stage: nitrogen is input through the high-pressure gas source and pressurized to 1.0±0.1MPa through the first pressure regulating valve (located on the upper left side of the kettle body). The pressure is maintained for 300 seconds to complete surface wetting and shallow penetration;

[0061] 2. Main impregnation stage: The pressure is increased step by step through the second pressure regulating valve (located at the lower right side of the kettle body), with each stage increasing by 1.0 MPa and maintaining the pressure for 180 seconds, finally reaching 5.5 MPa;

[0062] 3. Final pressure setting stage: Activate the third pressure regulating valve (bottom) and fine-tune it to 5.8±0.1MPa. Maintain the pressure for 600 seconds to ensure that the micron-sized pores are completely filled.

[0063] Step S6: Gradient cooling control:

[0064] 1. Forced cooling stage: Start the circulating cooling module (water cooling system) and reduce the temperature from 750°C to 550°C at a rate of 20°C / min. Maintain a pressure of 5.8 MPa during the cooling process.

[0065] 2. Natural cooling stage: Turn off the cooling system and cool with the furnace to 450℃ (cooling rate <5℃ / min). During this period, the positive pressure is maintained by the pressure regulating valve to prevent shrinkage defects.

[0066] Step S7: Post-processing and processing:

[0067] 1. Open the pressure relief valve and release the pressure to normal pressure at a rate of 0.5 MPa / min;

[0068] 2. Take out the AlSiC composite matrix and use diamond tools for precision milling. The surface roughness is controlled to Ra≤1.6μm;

[0069] The test results of the AlSiC module prepared in this example are as follows:

[0070] Relative density: 98.7%

[0071] Three-point bending strength: 360Mpa

[0072] Thermal conductivity (25°C): 210W / (m·K)

[0073] Thermal expansion coefficient (20-200℃): 7.2×10 -6 / ℃.

[0074] This embodiment significantly improves the densification degree and interface bonding strength of the composite material by precisely controlling the synergistic effect of gravity infiltration and gradient pressurization, combined with a directional cooling strategy.

[0075] Example 2

[0076] See also Figure 2 、 Figure 3 、 Figure 4 and Figure 5 , variable pressure gravity infiltration equipment includes:

[0077] The integrated high-pressure reactor body 1 has a first chamber 11 and a second chamber 12 distributed vertically and connected to each other via a switch mechanism. The first chamber 11 and the second chamber 12 are detachably connected to the reactor body 1.

[0078] Pressure control system, including vacuum pump group, high-pressure gas source input module and pressure regulating valve module;

[0079] Intelligent temperature control system, integrating induction heating unit and circulating cooling module;

[0080] The central control system is equipped with a pressure gradient program control unit, a temperature curve program control unit and a timing logic control unit.

[0081] The pressure regulating valve module includes a first pressure regulating valve 14 located at the upper part of one side of the kettle body 1 , a second pressure regulating valve 15 located at the lower part of the other side of the kettle body 1 , and a third pressure regulating valve 16 located at the bottom of the kettle body 1 .

[0082] Specific implementation of the variable pressure gravity infiltration device:

[0083] 1. The structure of the integrated high-pressure reactor body. The reactor body 1 is made of a high-temperature resistant alloy material and is provided with upper and lower split chambers inside: the first chamber 11 (lower chamber) is used to load the SiC substrate module; the second chamber 12 (upper chamber) is located above the first chamber 11, and the capacity of the first chamber 11 is greater than that of the second chamber 12. The second chamber 12 consists of a cylindrical cavity 121 and a conical cavity 122. The bottom of the conical cavity 122 is provided with a through hole 123 connected to the first chamber 11.

[0084] The switch mechanism is located between the first chamber 11 and the second chamber 12. The switch mechanism adopts a programmable switch mechanism. The cone head 1 of the switch mechanism is adapted to the bottom of the conical cavity 122 of the second chamber 12. The actuator 2 of the switch mechanism extends to the outside of the upper end of the second chamber 12 and is connected to the central control system signal to control the opening and closing degree of the cone head 1 and the through hole 123 at the bottom of the conical cavity 122. The opening and closing degree can be adjusted in the range of 0-100%.

[0085] 2. Pressure control system configuration:

[0086] Vacuum pump unit, equipped with dry screw vacuum pump and Roots pump in series, with a pumping speed of 200m 3 / h, and rapid vacuuming is achieved through the third pressure regulating valve at the bottom of the kettle body 1.

[0087] The high-pressure gas source module uses a nitrogen storage tank (pressure 15MPa) and a gas booster. The output pressure range is 0.1-10MPa and is connected in three ways:

[0088] The first pressure regulating valve 14 (top left): proportional valve control, accuracy ±0.05MPa, used for precise pressure stabilization in the low pressure stage;

[0089] Second pressure regulating valve 15 (bottom right): fast response solenoid valve, pressure rise rate 0.5 MPa / s, used for pressurization in the main infiltration stage;

[0090] The third pressure regulating valve 16 (bottom center): has a pressure relief function and is equipped with a pressure sensor (range 0-10 MPa, accuracy 0.1% FS).

[0091] 3. Intelligent temperature control system:

[0092] Induction heating unit: The first chamber 11 is circumferentially arranged with a medium-frequency induction coil (frequency 10kHz, power 50kW), supporting temperature control within the range of ±5°C between 700-800°C. The outer wall of the second chamber 12 is embedded with a resistance heating belt (power 30kW) to ensure that the temperature fluctuation of the molten aluminum is less than ±3°C.

[0093] Recirculation cooling module:

[0094] Forced cooling stage: water cooling pipeline (flow rate 50L / min) is embedded in the interlayer of the kettle, and the cooling rate is adjustable from 10-30℃ / min;

[0095] Natural cooling stage: The heat dissipation air duct is opened (wind speed 3m / s), and the cooling rate automatically matches the pressure change.

[0096] 4. Central control system integration:

[0097] Hardware architecture: The main control PLC is equipped with a multi-channel data acquisition card to monitor parameters such as pressure, temperature, and valve opening in real time; the HMI human-machine interface has preset process templates such as "gradient infiltration" and "rapid cooling".

[0098] Software functions: Pressure gradient program: Set a three-stage pressurization curve (e.g., 0.8MPa→5.5MPa→6.0MPa) and support customized pressure holding time; Temperature coordinated control: When the pressure rises to 5MPa, the cooling system is automatically triggered to prevent overheating of the molten aluminum; Fault protection logic: If the infiltration flow rate is lower than the set value (e.g., <0.8L / min), the pressure of the second pressure regulating valve is immediately increased for compensation.

[0099] The present device is used to perform the process of Example 1 to obtain:

[0100] Completeness of impregnation: X-ray testing shows pore filling rate ≥99.2%;

[0101] Interface bonding strength: measured by shear test >85MPa;

[0102] Equipment repeatability: After 10 consecutive productions, the pressure control deviation is <±1.5%, and the temperature fluctuation is <±8℃.

[0103] The technical effects of this embodiment are as follows:

[0104] 1. Precise gradient pressure control: Through the coordinated action of three pressure regulating valves, step-by-step control from low-pressure wetting to medium-pressure filling to high-pressure densification is achieved;

[0105] 2. Dynamic temperature compensation: Closed-loop control of induction heating and circulating cooling to avoid aluminum liquid solidification or substrate overheating;

[0106] 3. Modular expansion: The detachable chamber design supports rapid mold replacement and is suitable for the production of various specifications of AlSiC products.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The AlSiC module preparation process based on gravity pressure infiltration includes the following steps: Si. The SiC substrate assembly is heated to 700-800°C and placed in the first chamber of the autoclave; S2. The molten aluminum is injected into the second chamber of the autoclave, the second chamber being located above the first chamber and the two are connected via a switch mechanism; S3. Evacuate the autoclave to an absolute pressure of less than 0.1 kPa; S4. Open the switch mechanism so that the molten aluminum liquid is infiltrated into the SiC matrix module under gravity; S5. Apply gradient pressure in stages: first apply pressure to 0.5-1.5 MPa for primary infiltration, then gradually increase pressure to 5-6 MPa for deep infiltration; S6. Start the gradient cooling mode while maintaining the final pressure state, so that the temperature drops to the range of 400-600℃; S7. After pressure release and natural cooling, the AlSiC composite matrix is ​​subjected to mechanical processing.

2. The AlSiC module preparation process according to claim 1, characterized in that: The heating temperature of the molten aluminum liquid is controlled between 700-800°C.

3. The AlSiC module preparation process according to claim 1, characterized in that: The gradient pressure application includes at least three pressure stages: an initial pressure holding stage of 0.8-1.2 MPa, a main infiltration stage of 5.0-5.8 MPa, and a final pressure setting stage of 5.5-6.0 MPa.

4. The AlSiC module preparation process according to claim 1, characterized in that: The gradient cooling program includes two stages: forced cooling and natural cooling, and the forced cooling rate is controlled at 10-30°C / min.

5. An AlSiC module preparation device, characterized in that: include: An integrated high-pressure reactor body has a first chamber and a second chamber disposed vertically and connected via a switch mechanism; Pressure control system, including vacuum pump group, high-pressure gas source input module and pressure regulating valve module; Intelligent temperature control system, integrating induction heating unit and circulating cooling module; The central control system is equipped with a pressure gradient program control unit, a temperature curve program control unit and a timing logic control unit.

6. The AlSiC module preparation equipment according to claim 5, characterized in that: The pressure regulating valve module includes: a first pressure regulating valve located at the upper part of one side of the kettle body, a second pressure regulating valve located at the lower part of the other opposite side of the kettle body, and a third pressure regulating valve located at the bottom of the kettle body.

7. The AlSiC module preparation equipment according to claim 5, characterized in that: The first chamber is located directly below the second chamber, and the capacity of the first chamber is greater than that of the second chamber.

8. The AlSiC module preparation equipment according to claim 7, characterized in that: The second chamber includes a cylindrical chamber and a conical chamber, and a through hole communicating with the first chamber is provided at the bottom of the conical chamber.

9. The AlSiC module preparation equipment according to claim 8, characterized in that: The cone head of the switch mechanism is adapted to the bottom of the conical cavity, and the actuator thereof extends to the outside of the second cavity and is connected to the central control system signal.

10. The AlSiC module preparation equipment according to claim 5, characterized in that: The first chamber and the second chamber are detachably connected to the kettle body.

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