Method for rapidly preparing aluminum-based composite material sample by using thermal simulation testing machine

Abstract

The invention discloses a method for rapidly preparing an aluminum-based composite material sample by using a thermal simulation testing machine, which specifically comprises the following steps: uniformly mixing aluminum powder and a reinforcing phase, and carrying out cold-pressing densification to form a mixed powder cold-pressed blank; and the powder cold-pressed blank is placed in a test cabin of a thermal simulation testing machine to be subjected to hot-pressed sintering, cooling and pressure reduction are conducted after hot-pressed sintering is finished, and finally the aluminum-based composite material sample is obtained. According to the method, a thermal simulation testing machine is adopted for preparing aluminum alloy and aluminum-based composite material samples, the range of hot pressing sintering equipment is expanded, the sample preparation efficiency is improved, and meanwhile the problems of time consumption and low efficiency of auxiliary procedures such as long preparation time, long temperature rising time and long follow-up cooling time of common hot pressing sintering can be solved; and the process method is simple and effective, is high in operability and has a relatively wide popularization and application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material forming, and in particular relates to a method for rapidly preparing aluminum-based composite material samples by using a thermal simulation testing machine. Background Art

[0002] Among the commonly used preparation methods of aluminum-based composites, the powder metallurgy process for preparing composites can not only avoid material component segregation and solve the problem of reinforcement dispersion, thereby increasing the content of the added reinforcement phase, but also refine the organization, improve the organization morphology and distribution characteristics, and obtain advantages that other composite material preparation methods do not have. Therefore, powder metallurgy has become one of the main methods for preparing high-performance aluminum-based composites.

[0003] The hot pressing sintering process commonly used in powder metallurgy is used to prepare samples in a vacuum hot pressing sintering furnace. Depending on the equipment, the vacuum time before hot pressing sintering is generally 15 to 60 minutes. After the aluminum-based composite material is sintered at 460℃ to 560℃, the furnace chamber is continuously cooled indirectly by circulating water. The cooling time is long and may even take 6 to 8 hours. The aluminum-based composite material sample takes a long time and has low preparation efficiency, which greatly affects the progress of material testing and development. In addition, the temperature measuring thermocouples of the hot pressing sintering furnace are mostly set at the furnace wall. The larger the furnace chamber, the more difficult it is to control the temperature uniformity. In addition, the structures and properties of different hot pressing sintering molds are different (such as graphite molds and steel molds), resulting in large differences in the actual sintering temperature of the samples and the difficulty in accurately controlling the hot pressing sintering process. In order to solve the problems of long overall hot pressing and sintering process time, high requirements for hot pressing and sintering equipment, low hot pressing and sintering efficiency, and difficulty in accurately controlling the sintering process temperature of samples when using a vacuum hot pressing and sintering furnace for the preparation of aluminum-based composites by powder metallurgy, it is of great significance to use test equipment with rapid vacuuming, heating, and pressurization to quickly prepare powder metallurgy hot pressing and sintering samples. Summary of the invention

[0004] The purpose of the present invention is to propose a method for quickly preparing aluminum-based composite material samples using a thermal simulation testing machine, which solves the problems of long test cycle, low preparation efficiency and difficult precise control of process temperature in the prior art of using a hot pressing sintering furnace to prepare samples.

[0005] The technical solution adopted by the present invention is a method for quickly preparing aluminum-based composite material samples using a thermal simulation testing machine, specifically: after the aluminum powder and the reinforcement phase are evenly mixed, cold pressing and densification are performed to form a mixed powder cold-pressed billet; the powder cold-pressed billet is placed in a thermal simulation testing machine for hot pressing and sintering, and after the hot pressing and sintering are completed, the temperature and pressure are reduced to finally obtain an aluminum-based composite material sample.

[0006] The present invention is also characterized in that: The test chamber of the thermal simulation test machine includes a test chamber body, a pad inside the test chamber body, and an arc groove is arranged at the center of the upper surface of the pad; it also includes a hot pressing and sintering mold, the hot pressing and sintering mold is located in the arc groove, and two ejector rods are arranged inside the hot pressing and sintering mold, one end of the two ejector rods is placed in the hot pressing and sintering mold, and the ends are respectively connected to one end of two thermocouples, and the other ends of the two ejector rods are placed outside the hot pressing and sintering mold, the ejector rods can slide in the hot pressing and sintering mold, and the two thermocouples are electrically connected to the thermal simulation test machine terminals; thermal simulation test machine pressure heads are also arranged on the inner walls on both sides of the test chamber body of the thermal simulation test machine, and the ends of the two thermal simulation test machine pressure heads are close to the ejector rods, and an inflation port and a vacuum channel are also arranged on the inner wall of the test chamber body of the thermal simulation test machine.

[0007] The sliding surface of the top rod is provided with a groove having a diameter equal to that of the temperature measuring thermocouple.

[0008] The formation process of the mixed powder cold pressed billet is as follows: the aluminum powder and the reinforcing phase are mixed evenly and loaded into a hot pressing and sintering mold, one end of the temperature measuring thermocouple is placed on the contact surface between the push rod and the mixed powder through the grooves on the two push rods, and cold pressing and densification are performed to form a mixed powder cold pressed billet.

[0009] The process of placing the powder cold compact in a thermal simulation test machine for hot pressing and sintering is specifically as follows: the powder cold compact is loaded together with the hot pressing and sintering mold onto the pad in the test chamber of the thermal simulation test machine, the thermal simulation test machine pressure head and the push rod are driven to contact, and the thermal simulation test machine pressure head and the hot pressing and sintering mold are ensured to be coaxial, the test chamber of the thermal simulation test machine is repeatedly vacuumed by filling inert gas through the vacuum channel or the inflation port, and the thermal simulation test machine is started for hot pressing and sintering.

[0010] After repeated vacuuming, the vacuum degree of the test chamber of the thermal simulation test machine is finally ensured to be 2-20Pa and the filling gas pressure of the inert gas is 0.01-0.05MPa.

[0011] After hot pressing and sintering, the cooling and pressure reduction process is as follows: Under the action of the cooling medium, the pressure head of the thermal simulation test machine begins to cool down to below 100°C together with the ejector rod and the sample; the pressure head of the thermal simulation test machine is retreated 1-3mm, the vacuum channel or the inflation port on the test chamber of the thermal simulation test machine is opened, the air is deflated / inflated to normal pressure, the hot pressing sintering mold is taken out after opening the test chamber door, and cooled to room temperature.

[0012] The beneficial effects of the present invention are: (1) The test chamber of the thermal simulation test machine of the present invention is used to conduct hot pressing and sintering tests on composite material samples without adding other accessories. The volume of the test chamber is relatively small, and the vacuuming or filling time is shorter than that of the hot pressing and sintering furnace, so the test cost is low; (2) The specimen on the thermal simulation test machine is directly heated by resistance, with a maximum value not exceeding The sample can be heated at a rate of 800℃ / s or maintained at a stable equilibrium temperature within ±1℃. Compared with the thermal radiation heating method of the hot pressing sintering furnace, the overall heat flux of the material is increased, the sample temperature control accuracy and temperature stability are higher, and the sample heating efficiency is increased by more than 50 times.

[0013] (3) Compared with the existing hot pressing sintering technology, the method of the present invention is simple to operate, and the direct resistance heating efficiency of the sample is high. At the same time, the maximum axial controllable cooling rate can reach 400℃ / s, eliminating the cooling link of the circulating water cooling test chamber, and the hot pressing sintering sample preparation efficiency is increased by more than 2 times.

[0014] (4) Compared with the existing hot pressing and sintering technology, in the method of the present invention, the temperature measuring thermocouple does not need to be welded to the sample, and can be directly loaded into the mold during the cold pressing stage, thereby solving the problem that aluminum-based composite material samples with medium and high volume fractions of reinforced phases are not easy to be welded to the temperature measuring thermocouple.

[0015] (5) Compared with the existing hot pressing and sintering technology, the use of thermal simulation testing machines for the preparation of aluminum alloy and aluminum-based composite materials has expanded the scope of equipment that can be used for hot pressing and sintering. While improving the efficiency of sample preparation, it can also solve the problems of time-consuming and inefficient auxiliary processes such as long pre-preparation time and long subsequent cooling time in ordinary hot pressing and sintering. The process method is simple and effective, with strong operability and has a broad prospect for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the layout of a test chamber of a thermal simulation test machine in the method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine of the present invention; Figure 2 It is a microstructure diagram of the sintered 20% SiC / 2024 aluminum-based composite material of the present invention; Figure 3 It is a microstructure diagram of the sintered 7075 aluminum alloy material of the present invention.

[0017] In the figure, 1. hot pressing sintering mold; 2. temperature measuring thermocouple; 3. mold ejector; 4. test chamber of thermal simulation test machine; 5. pad; 6. terminal of thermal simulation test machine; 7. vacuum channel; 8. inflation port; 9. pressure head of thermal simulation test machine. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] The method for rapidly preparing aluminum-based composite material samples by using a thermal simulation test machine is implemented by using a thermal simulation test machine. The test chamber of the thermal simulation test machine is as follows: Figure 1As shown, it includes a test chamber 4 of a thermal simulation test machine, a pad 5 inside the test chamber 4 of the thermal simulation test machine, and an arc groove is arranged at the center of the upper surface of the pad 5; it also includes a hot pressing and sintering mold 1, the hot pressing and sintering mold 1 is located in the arc groove, and two ejector rods 3 are arranged inside the hot pressing and sintering mold 1, one end of the two ejector rods 3 is placed in the hot pressing and sintering mold 1, and the ends are respectively connected to one end of two thermocouples 2, and the other ends of the two ejector rods 3 are placed outside the hot pressing and sintering mold 1, the ejector rods 3 can slide in the hot pressing and sintering mold 1, and the sliding surface of the ejector rod 3 is provided with a groove with a diameter equal to that of the temperature measuring thermocouple 2, so as to facilitate the simultaneous movement of the thermocouple 2 and the ejector rod 3. The two thermocouples 2 are electrically connected to the terminal 6 of the thermal simulation test machine; the inner walls of the test chamber 4 of the thermal simulation test machine are also provided with pressure heads 9 of the thermal simulation test machine, the ends of the two pressure heads 9 of the thermal simulation test machine are close to the ejector rod 3, and the two pressure heads 9 of the thermal simulation test machine are coaxially arranged with the hot pressing sintering mold 1; the inner wall of the test chamber 4 of the thermal simulation test machine is also provided with an air filling port 8 and a vacuum channel 7; The method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine of the present invention is specifically implemented according to the following steps: Step 1: Preparation of cold powder compacts; After the aluminum powder and the reinforcing phase are mixed evenly, they are loaded into a hot pressing sintering mold 1, and one end of a temperature measuring thermocouple 2 is placed on the contact surface between the push rod 3 and the mixed powder through the grooves on the two push rods 3, and cold pressing and densification are performed to form a mixed powder cold pressed blank; The reinforcement phase can be a fiber reinforcement phase such as SiC f , carbon fiber, and can also be particle reinforcement such as Al2O3, TiB2, B4C, SiC, etc.; Step 2: Load the cold pressed powder billet together with the hot pressing sintering mold onto the pad 5 in the test chamber 4 of the thermal simulation test machine, drive the thermal simulation test machine pressure head 9 to contact the push rod 3, connect the temperature measuring thermocouple 2 to the thermal simulation test machine terminal 6, and ensure that the thermal simulation test machine pressure head 9 is coaxial with the hot pressing sintering mold 1, and fill the test chamber 4 of the thermal simulation test machine with inert gas through the vacuum channel 7 or the filling port 8 to repeatedly evacuate the test chamber 4 of the thermal simulation test machine. The test under vacuum environment ensures that the final vacuum degree of the test chamber 4 of the thermal simulation test machine is 2 to 20Pa, and the filling inert gas under atmosphere protection ensures that the final filling gas pressure is 0.01 to 0.05MPa; The inert gas can be filled with nitrogen, argon and mixed gases; repeated vacuuming and filling is mainly to ensure that the sample is not oxidized, and at the same time the pressure difference between the inside and outside of the test chamber is balanced, which is also conducive to improving the accuracy of the test data. When testing under atmosphere protection conditions, the final filling gas pressure is set to 0.01-0.05MPa, because if the pressure is set too high, it will prolong the deflation time, and if the pressure is set too low, it will easily lead to insufficient pressure in the test chamber door, resulting in leakage.

[0020] Step 3: According to the hot pressing sintering process, set the heating time, heating rate, holding temperature, holding time, sintering pressure, continuous pressurization time during cooling process, axial cooling time rate, and cooling time parameters on the thermal simulation test machine, and start the thermal simulation test machine to perform hot pressing sintering; Step 4: After the hot pressing sintering is completed, the pressure head of the thermal simulation test machine begins to cool down to below 100°C together with the ejector rod 3 and the sample under the action of the cooling medium, and the cooling rate can be maintained at 50-100°C / min.

[0021] Step 5: After the thermal simulation test machine program is finished, the thermal simulation test machine pressure head 9 is retreated 1-3 mm, the vacuum channel 7 or the inflation port 8 on the thermal simulation test machine test chamber 4 is opened, and the air is deflated / inflated to normal pressure. After opening the test chamber door, the hot pressing sintering mold 1 is taken out and cooled to room temperature to obtain an aluminum-based composite material sample.

[0022] The present invention aims to quickly prepare aluminum-based composite material samples by hot pressing and sintering by powder metallurgy. The invention uses a thermal simulation test machine with a test chamber rapid vacuum function and a gas filling function, a sample rapid heating and pressurization function, and a rapid cooling function, and cooperates with a hot pressing and sintering mold to realize the hot pressing and sintering of composite material samples that generally need to be completed in a vacuum hot pressing and sintering furnace. In addition, compared with the hot pressing and sintering furnace, the thermal simulation test machine also has the advantages of rapid vacuuming (vacuum degree to within 20Pa) or filling with inert gas (less than 0.1MPa), direct rapid heating of the sample by resistance (maximum rate exceeding 800℃ / s), rapid cooling of the pressure head by circulating water (maximum axial controllable cooling rate can reach 400℃ / s), high temperature control accuracy of the mold connected to the temperature measuring thermocouple (maintaining a stable equilibrium temperature within ±1℃), etc., and the sample preparation efficiency can be increased by more than 2 times compared with the hot sintering furnace.

[0023] Aluminum powder or aluminum and reinforcement phase mixed powder is first pre-cold pressed and densified to form a mixed powder cold pressed billet (relative density is generally greater than 50%), and then loaded into the test chamber of the thermal simulation test machine together with the hot pressing and sintering mold. The thermal simulation test machine's resistance heating function, pressurization function, medium or non-medium cooling function, test chamber vacuum or inert gas protection function, etc. are used to provide heating, pressurization, cooling functions, and atmosphere protection conditions similar to those of a hot pressing and sintering furnace. In conjunction with the hot pressing and sintering mold and precise temperature measurement design, powder metallurgy hot pressing and sintering samples can be quickly prepared.

[0024] Example 1 The method of the present invention for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine is specifically as follows: Step 1: After the 2024 aluminum powder and SiC reinforcement phase are evenly mixed by ball milling, they are loaded into the hot pressing sintering mold for pre-pressing to form a 20% SiC / 2024Al mixed powder cold pressed billet. During the cold pressing process, a thermocouple is placed at one end of the cold pressed billet and led out of the mold from one end of the mold ejector pin.

[0025] Step 2: Load the 20%SiC / 2024Al mixed powder cold pressed billet together with the hot pressing sintering mold horizontally into the test chamber of the MMS-100 thermal simulation test machine, and connect the exposed ends of the two thermocouples to the terminal of the thermal simulation test machine.

[0026] Step 3: Close the test chamber and evacuate the chamber to 20 Pa for 2 minutes. Step 4: Heating time is 5 minutes, hot pressing sintering is carried out at 500℃ for 60 minutes, sintering pressure is 50MPa, and pressure is continuously applied during cooling process, and cooling time is 5 minutes. After the program is completed, the pressure head of the thermal simulation test machine retreats 3mm.

[0027] Step 5: Start the thermal simulation test machine until the program runs to the end, cool down to 100°C, open the vent valve on the test chamber, and inhale air to normal pressure in 30 seconds.

[0028] Step 6: Open the test chamber door, take out the hot pressing sintering mold and cool it to room temperature, then take out the hot pressing sintering sample 1#. Take part of sample 1 for microstructure analysis. Figure 2 The microstructure of the sintered 20%SiC / 2024 aluminum-based composite material is dense, and the reinforcement phase is well combined with the matrix.

[0029] Example 2 The method of the present invention for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine is specifically as follows: Step 1: After the 7075 aluminum powder is loaded into the hot pressing sintering mold, it is first cold pressed and densified to form a 7075 aluminum powder cold pressed billet. During the cold pressing process, a thermocouple is placed at one end of the cold pressed billet and led out of the mold from one end of the mold ejector rod.

[0030] Step 2: The 7075 aluminum powder cold pressed billet and the hot pressing sintering mold are loaded into a thermal simulation test machine, and the exposed end of the thermocouple is connected to the terminal of the thermal simulation test machine.

[0031] Step 3: Close the test chamber door and conduct the test under atmosphere protection. First, evacuate the chamber for 4 minutes to 2Pa, then fill it with nitrogen to 0.05MPa. Fill the chamber with inert gas pressure to ensure the sealing of the test chamber door.

[0032] Step 4: Set the heating time to 4 minutes, hot pressing and sintering at 480°C for 90 minutes, sintering pressure to 50 MPa, continuous pressurization during cooling, cooling time to 5 minutes, and the pressure head of the thermal simulation test machine to retreat 1 mm after the program is completed.

[0033] Step 5: Start the thermal simulation test machine until the program runs to the end, cool down to 60℃, open the vent valve on the test chamber and exhaust to normal pressure.

[0034] Step 6: Take out the hot pressing sintering mold and cool it to room temperature, then take out the hot pressing sintering sample 2#. Take part of sample 2# for microstructure analysis. Figure 3 It is a sintered 7075 aluminum alloy material with a dense microstructure and no visible defects.

[0035] Example 3 Preparation of cold pressed powder: Select appropriate amount of aluminum powder and SiCf fiber reinforcement phase, load the mixed powder into hot pressing sintering mold 1, use two ejector pins 3, place one end of temperature measuring thermocouple 2 on the contact surface between ejector pin 3 and mixed powder, and use the groove on ejector pin 3 to fix the position of thermocouple 2. Then, use cold pressing equipment to perform cold pressing and densification operation on the mixed powder in the mold to form a cold pressed powder.

[0036] Place the hot pressing sintering mold 1 with the powder cold compact on the pad 5 in the test chamber 4 of the thermal simulation test machine. Start the thermal simulation test machine and drive the pressure head 9 to move forward until the pressure head 9 and the ejector rod 3 are in good contact. At the same time, accurately connect the temperature measuring thermocouple 2 to the terminal 6 of the thermal simulation test machine, and carefully adjust the position of the pressure head 9 of the thermal simulation test machine to ensure that it remains coaxial with the hot pressing sintering mold 1.

[0037] The test is carried out in a vacuum environment. The test chamber 4 of the thermal simulation test machine is repeatedly evacuated through the vacuum channel 7. The vacuum degree is checked after each evacuation. The evacuation is continued until the vacuum degree of the test chamber 4 reaches 2Pa. This ensures that the sample is not oxidized during the preparation process. At the same time, the pressure difference inside and outside the test chamber is balanced to improve the accuracy of the test data.

[0038] According to the predetermined hot pressing sintering process, the control system of the thermal simulation test machine is set to set the heating time to 30 minutes, the heating rate to 20℃ / min, the holding temperature to 600℃, the holding time to 20 minutes, the sintering pressure to 50MPa, the continuous pressurization time during the cooling process to 15 minutes, the axial cooling time rate to 30℃ / min, and the cooling time to 25 minutes. After completing the parameter setting, start the thermal simulation test machine and start the hot pressing sintering process.

[0039] After the hot pressing sintering process is completed, the thermal simulation test machine head 9 begins to cool down under the action of the cooling medium, and the ejector rod 3 and the sample also cool down. In this process, the cooling rate is maintained at 50°C / min until the temperature drops below 100°C.

[0040] When the program of the thermal simulation test machine is finished, the pressure head 9 of the thermal simulation test machine is controlled to retreat 1 mm. Then, the vacuum channel 7 on the test chamber 4 of the thermal simulation test machine is opened, and the air is slowly released until the pressure in the test chamber reaches normal pressure. Then, the test chamber door is opened, and the hot pressing sintering mold 1 is carefully taken out and placed in a room temperature environment for natural cooling, and finally an aluminum-based composite material sample is obtained.

[0041] Example 4 Weigh a certain amount of aluminum powder and Al2O3 particle reinforcement phase, stir and mix them thoroughly in a stirring device to ensure that the two are evenly mixed. Put the mixed powder into the hot pressing sintering mold 1, place the temperature measuring thermocouple 2 through the groove on the ejector 3, and then perform cold pressing and densification to form a mixed powder cold pressed blank.

[0042] Place the hot pressing sintering mold 1 with the cold pressed blank on the pad 5 of the test chamber 4 of the thermal simulation test machine, drive the thermal simulation test machine pressure head 9 to contact the ejector 3, connect the temperature measuring thermocouple 2 and the terminal 6, and ensure the coaxiality. Select atmosphere protection, fill argon into the test chamber 4 through the filling port 8, repeat the vacuum-filling operation, and finally make the filling gas pressure reach 0.01MPa to prevent the sample from oxidizing.

[0043] On the thermal simulation test machine, set the heating time to 40 minutes, the heating rate to 15℃ / min, the holding temperature to 550℃, the holding time to 30 minutes, the sintering pressure to 40MPa, the continuous pressurization time during the cooling process to 20 minutes, the axial cooling time rate to 25℃ / min, and the cooling time to 30 minutes. After the settings are completed, start the thermal simulation test machine for hot pressing sintering.

[0044] After the hot pressing sintering is completed, the thermal simulation test machine pressure head 9 drives the ejector rod 3 and the sample to cool down together under the action of the cooling medium, and the cooling speed is controlled at 80°C / min until the temperature drops below 100°C.

[0045] After the thermal simulation test machine program is completed, the thermal simulation test machine pressure head 9 is retreated 2 mm, the inflation port 8 is opened, the air is inflated to normal pressure, the test cabin door is opened, the hot pressing sintering mold 1 is taken out, and the aluminum-based composite material sample is obtained after cooling to room temperature.

[0046] Example 5 Aluminum powder and TiB2 particle reinforcement phase are mixed evenly in proportion and loaded into hot pressing sintering mold 1. One end of temperature measuring thermocouple 2 is placed on the contact surface between ejector rod 3 and mixed powder (fixed by the groove of ejector rod 3), and cold pressing and densification operation is performed to obtain mixed powder cold pressed blank.

[0047] Place the cold pressed powder green sheet together with the hot pressing sintering mold 1 on the pad 5 in the test chamber 4 of the thermal simulation test machine, drive the thermal simulation test machine pressure head 9 to contact the ejector 3, connect the temperature measuring thermocouple 2 and the terminal 6 to ensure that the two are coaxial. Perform multiple vacuum operations on the test chamber 4 through the vacuum channel 7, and finally make the vacuum degree reach 15Pa, creating a good preparation environment for the sample.

[0048] According to the hot pressing sintering process, the heating time is set to 35 minutes, the heating rate is 18℃ / min, the holding temperature is 580℃, the holding time is 25 minutes, the sintering pressure is 45MPa, the continuous pressurization time during the cooling process is 18 minutes, the axial cooling time rate is 35℃ / min, and the cooling time is 28 minutes. The hot pressing sintering is started on the thermal simulation test machine.

[0049] After the hot pressing sintering is completed, the thermal simulation test machine head 9 cools the ejector rod 3 and the sample under the action of the cooling medium, and the cooling rate is 70°C / min until the temperature is lower than 100°C; After the thermal simulation test machine program is finished, the thermal simulation test machine pressure head 9 is retreated 3 mm, the vacuum channel 7 is opened to release air to normal pressure, the test cabin door is opened, the hot pressing sintering mold 1 is taken out and cooled to room temperature, and the aluminum-based composite material sample is obtained.

[0050] Example 6 The hot pressing sintering process commonly used in powder metallurgy is used to prepare samples in a vacuum hot pressing sintering furnace. For the vacuum hot pressing sintering sample preparation of general aluminum alloys and aluminum-based composite materials, taking the sintering temperature of 500℃ as an example, according to the equipment differences, the vacuum is usually evacuated to less than 10Pa before hot pressing sintering for 15 to 60 minutes. After sintering at 500℃, the circulating water continues to indirectly cool the furnace chamber. The cooling time to below 100℃ is as long as 4 hours, and the furnace chamber with a large volume may even take 6 hours. The sample preparation time is long and the preparation efficiency is low, which greatly affects the progress of material testing and development. In addition, the temperature measuring thermocouples of the hot pressing sintering furnace are mostly set at the furnace wall. The larger the furnace chamber, the more difficult it is to control the temperature uniformity. In addition, the structures and properties of different hot pressing sintering molds are different (such as graphite molds and steel molds), resulting in large differences in the actual sintering temperature of the samples. Even if the conventional setting of the heating rate is ≤10℃ / min, the difference between the actual temperature of the sample and the measured temperature at the temperature measuring thermocouple at 500℃ is 20 to 50℃, and the hot pressing sintering process is difficult to accurately control. The present invention adopts resistance heating to heat the sample, and the maximum heating rate can reach more than 800℃ / s. The temperature measuring thermocouple is directly connected to the sample, and the sample maintains a stable equilibrium temperature within ±1℃, which improves the accuracy of the measured temperature compared with the thermal radiation heating method. The overall time for sample preparation is greatly reduced, and the sample preparation efficiency is increased by more than 2 times.

Claims

1. A method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine, characterized in that: Specifically, the aluminum powder and the reinforcing phase are mixed evenly, and then cold pressed and densified to form a mixed powder cold pressed billet; the powder cold pressed billet is placed in a thermal simulation test machine for hot pressing and sintering, and after the hot pressing and sintering, the temperature and pressure are reduced to finally obtain an aluminum-based composite material sample.

2. The method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine according to claim 1, characterized in that: The test chamber of the thermal simulation test machine comprises a test chamber body (4) of the thermal simulation test machine, a cushion block (5) inside the test chamber body (4), an arc-shaped groove being arranged at the center of the upper surface of the cushion block (5); and a hot pressing and sintering mold (1), the hot pressing and sintering mold (1) being located in the arc-shaped groove, two ejector pins (3) being arranged inside the hot pressing and sintering mold (1), one end of the two ejector pins (3) being placed inside the hot pressing and sintering mold (1), and the two ejector pins (3) being connected to one end of two thermocouples (2) respectively. The other end of the push rod (3) is placed outside the hot pressing sintering mold (1), and the push rod (3) can slide inside the hot pressing sintering mold (1). The two thermocouples (2) are electrically connected to the thermal simulation test machine terminal (6). The inner walls of both sides of the thermal simulation test machine test chamber (4) are also provided with thermal simulation test machine pressure heads (9), and the ends of the two thermal simulation test machine pressure heads (9) are close to the push rod (3). The inner wall of the thermal simulation test machine test chamber (4) is also provided with an inflation port (8) and a vacuum channel (7).

3. The method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine according to claim 2, characterized in that: The sliding surface of the push rod (3) is provided with a groove having a diameter equal to that of the temperature measuring thermocouple (2).

4. The method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine according to claim 2, characterized in that: The mixed powder cold pressed blank is formed by mixing aluminum powder and a reinforcement phase uniformly and loading the mixture into a hot pressing sintering mold (1); placing one end of a temperature measuring thermocouple (2) on the contact surface between the push rod (3) and the mixed powder through grooves on two push rods (3); and performing cold pressing and densification to form a mixed powder cold pressed blank.

5. The method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine according to claim 4, characterized in that: The process of placing the powder cold pressed blank in a thermal simulation test machine for hot pressing and sintering specifically comprises: placing the powder cold pressed blank together with the hot pressing and sintering mold (1) on a cushion block (5) in a test chamber (4) of the thermal simulation test machine, driving the thermal simulation test machine pressure head (9) and the ejector rod (3) to contact, and ensuring that the thermal simulation test machine pressure head (9) and the hot pressing and sintering mold (1) are coaxial, repeatedly vacuuming the test chamber (4) of the thermal simulation test machine by filling inert gas through a vacuum channel (7) or a gas filling port (8), and starting the thermal simulation test machine to perform hot pressing and sintering.

6. The method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine according to claim 5, characterized in that: After repeated vacuuming, the vacuum degree of the test chamber (4) of the thermal simulation test machine is finally ensured to be 2-20 Pa and the filling gas pressure of the inert gas is 0.01-0.05 MPa.

7. The method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine according to claim 5, characterized in that: After hot pressing and sintering, the cooling and pressure reduction process is as follows: The pressure head (9) of the thermal simulation test machine begins to cool down to below 100° C. together with the ejector rod (3) and the sample under the action of the cooling medium; the pressure head (9) of the thermal simulation test machine is moved back 1-3 mm, the vacuum channel (7) or the air filling port (8) on the test chamber (4) of the thermal simulation test machine is opened, and the air is deflated / filled to normal pressure. After the test chamber door is opened, the hot pressing sintering mold (1) is taken out and cooled to room temperature.

8. The method for rapidly preparing aluminum-based composite material samples using a thermal simulation test machine according to claim 7, characterized in that: The cooling rate is 50-100℃ / min.

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