An experimental device and method for representing a powder particle packing gradation

Abstract

The application discloses a kind of experimental device of powder particle packing gradation characterization, device is equipped with the loading material container of upper opening, the air-permeable sheet is equipped in the loading material container, the air-permeable sheet is densely covered with air-permeable round hole, the bottom of the loading material container is communicated with the top of connecting pipe, the bottom end of the connecting pipe is connected with the one end of U-shaped tube, the U-shaped tube is equipped with mark line on the pipe wall of one side of connecting pipe, the connecting pipe is equipped with valve three-way pipe, the valve three-way pipe is connected with vacuum pump in main machine by bypass connection.The application obtains the gradation index of powder particle packing by detecting the time of a certain amount of gas crossing the compacted powder particle packing pore layer by layer, calculating the ratio of the increasing time of gas permeating powder particle packing structure and the increasing thickness layer by layer, taking the arithmetic average of each layer ratio, reflecting the gradation state of real accumulation of powder particle.

Description

Technical Field

[0001] This invention relates to the field of experimental equipment technology, and in particular to an experimental apparatus for characterizing the packing gradation of powder particles. Background Technology

[0002] The chemical, building materials and metallurgical industries often use powders and granules as raw materials. The final properties of the products made from powders and granules are closely related to the particle packing. Powder packing gradation is an important indicator for materials engineering to obtain durability, density and other excellent properties. It is necessary to obtain the powder packing gradation to control particle packing and optimize product performance. However, conventional equipment cannot directly test the packing gradation of powders and granules.

[0003] In industrial practice and applications, laser particle size analysis is typically used to obtain the particle size distribution of powders. Then, based on Fuller curves, the particle size distribution is adjusted to achieve a continuous distribution of powder particles, obtaining theoretically graded particles. However, graded particles are not necessarily densely packed in order of size. The particle size obtained by laser particle size analysis is an imaginary size, differing significantly from the actual shape and size of the powder. Furthermore, the graded powder prepared according to Fuller curves is only a rough approximation of the theory. Additionally, the Fuller curve-based particle gradation method is not applicable to powders and granules with a wide particle size range.

[0004] In the compacted particle packing structure, the finer the pore size and the greater the number of pores, the longer it takes for a certain amount of gas to pass through. The time it takes for a fixed amount of gas to pass through the pores of compacted particle packing is closely related to the particle packing gradation. When the particles are packed in order of particle size, the resulting packing pores are small and elongated, resulting in high resistance to gas passage and a long time. When the particles are packed in increasingly thick layers in order of particle size, the resulting packing pores are even smaller and elongated, resulting in even greater resistance to gas passage and an even longer time. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to realize a characterization method based on the actual packing gradation of powder particles by utilizing the law of gas permeation of the powder particle packing structure, and the device for realizing the method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an experimental device for characterizing the packing gradation of powder and granules, the device having a filling container with an open top, a breathable thin plate inside the filling container, the breathable thin plate being densely covered with breathable round holes, the bottom of the filling container being connected to the top of a connecting pipe, the bottom end of the connecting pipe being connected to one end of a U-shaped pipe, the U-shaped pipe and the connecting pipe having marking lines on one side of the pipe wall, the connecting pipe having a valved tee pipe, the valved tee pipe being connected to a vacuum pump in the main unit via a bypass.

[0007] The filling container has a cylindrical or cuboid structure. The inner wall of the filling container has a protruding support for the permeable sheet. The permeable sheet is placed on the support, and the distance between the permeable sheet and the top of the connecting pipe is 1-2 cm. The wall thickness of the filling container and the thickness of the metal sheet are 0.5-1.5 cm. The thickness of the support is 0.1-1.0 times the wall thickness of the filling container. A depth gauge is provided on the inner wall of the filling container above the permeable sheet, and the smallest division of the depth gauge is 1 mm. The filling container is used to hold powder particles with a particle size range of 0.01μm-2cm. The inner diameter of the filling container is 2-20 times the largest particle size of the powder particles it holds. The minimum inner diameter of the filling container is 2cm. The ratio of the height of the filling container above the permeable thin plate to the thickness of the filling layer is 1.0-1.5. The filling container and the connecting pipe are integrally cast. The area between the base of the filling container and the connecting pipe has a bucket-shaped structure that is larger at the top and smaller at the bottom.

[0008] The number of breathable holes on the breathable thin plate is 20-70 per cm. 2 The diameter of the permeable round hole is 0.1-0.5mm, and 1-3 layers of qualitative filter paper are placed on the permeable thin plate. The device is equipped with a support for the filling container.

[0009] The connection between the connecting tube and the U-shaped tube is provided with a small rubber plug. The small rubber plug has a through hole in the center. The bottom end of the connecting tube is inserted into the through hole, and the outer periphery of the small rubber plug is inserted into the U-shaped tube. The small rubber plug makes the connection between the connecting tube and the U-shaped tube airtight.

[0010] The diameter of the U-shaped tube is 3-50 times the maximum particle size in the powder, and the height of the U-shaped tube is 20-600 times the maximum particle size in the powder. There are three marking lines, from top to bottom: the first marking line, the second marking line, and the third marking line. The first marking line is located at 0.8-0.9 times the total height of the U-shaped tube, the second marking line is located at 0.7-0.8 times the total height of the U-shaped tube, and the third marking line is located at 0.5-0.7 times the total height of the U-shaped tube.

[0011] The U-shaped tube is filled with liquid at a height of 0.3-0.5 times the total height of the U-shaped tube, and the liquid is deionized water or purified water.

[0012] The main unit has a vacuum pump and a power supply fixed inside its housing. The surface of the housing is provided with a screen for displaying the timing time. The power supply provides power to the vacuum pump and the screen. The surface of the housing is provided with a button area, which contains buttons for controlling the timing and operation of the vacuum pump.

[0013] A method for characterizing the packing gradation of powder particles, the method using a powder particle packing gradation characterization experimental apparatus, includes the following steps:

[0014] Step 1: Fill the container with one layer of packing material;

[0015] Step 2: Connect the vacuum pump to the U-tube using the valved tee, and start the vacuum pump until the liquid level crosses the second marking line;

[0016] Step 3: Control the valved tee to connect the packing container to the U-tube, and start timing when the liquid level drops to the second mark line;

[0017] Step 4: The timer ends when the liquid level drops to the third mark.

[0018] Step 5: Repeat steps 2-4 until the preset number of repeated measurements is reached, and take the arithmetic mean as the final test result;

[0019] Step 6: Repeat steps 1-5 until the required number of packing layers is reached.

[0020] In step 1, the thickness of each filler layer is 1.1-2.0 times the maximum particle size in the powder, and the minimum thickness is 0.5 cm. Each filler layer uses 1-20 MPa pressure compacted filler, and the total thickness of the stacked filler layers is 8-20 times the thickness of a single layer.

[0021] In step 5, the measurement is repeated 3-5 times. An error of 1-2 seconds in each repeated measurement is considered acceptable; otherwise, it is considered unacceptable.

[0022] Before the experiment, an airtightness test of the apparatus is required. During the test, liquid is injected into the U-shaped tube, and a small rubber stopper connects the U-shaped tube and the connecting pipe. The vacuum pump is connected to the U-shaped tube by controlling the valved tee. The vacuum pump is turned on, and when the water level on one side of the U-shaped tube exceeds the first mark line, the vacuum pump is stopped. If the liquid level does not change for a set time, the airtightness test is qualified, and the powder packing gradation characterization experiment can be carried out. The corresponding values ​​of packing thickness and air permeability time are obtained through the powder packing gradation characterization experiment method, and then the matching correlation between the specific values ​​and the packing gradation index is obtained.

[0023] This invention obtains the gradation index of the powder pack by detecting the time it takes for a certain amount of gas to pass through the pores of a compacted powder pack layer by layer, calculating the ratio of the increase in time to the increase in thickness of the gas passing through the powder pack structure layer by layer, and taking the arithmetic mean of the ratios of each layer, thus reflecting the gradation state of the actual powder pack. Attached Figure Description

[0024] The following is a brief explanation of the content and markings in each of the accompanying drawings in this specification:

[0025] Figure 1 A schematic diagram of the experimental setup for characterizing the packing gradation of powder particles;

[0026] The markings in the above figures are as follows: 1. Filler container; 2. Breathable sheet; 3. Connecting pipe; 4. Tee with valve; 5. Small rubber stopper; 6. First marking line; 7. Second marking line; 8. Third marking line; 9. Liquid; 10. U-tube; 11. Main unit; 12. Screen; 13. Button area. Detailed Implementation

[0027] The following description, with reference to the accompanying drawings, details the specific implementation of the present invention, including the shape and structure of each component, the relative positions and connections between the parts, the function and working principle of each part, the manufacturing process, and the operation and use methods, to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0028] like Figure 1 As shown, the experimental apparatus for characterizing the packing gradation of powder particles includes a packing container 1 with an open top. The upper part of the packing container 1 is a metal cylinder or cuboid, and a protruding support is provided on the inner wall near the bottom. The support is used to place a breathable thin plate 2. The support can be multiple protruding points or a ring structure. The breathable thin plate 2 is also made of metal, and its overall shape is such that its edges fit snugly against the packing container 1. The breathable thin plate 2 is placed horizontally on the support and can be removed from the support, making it a detachable structure for easy cleaning. The breathable thin plate 2 is densely covered with breathable round holes, generally... The application requires 1-3 layers of qualitative filter paper to be placed on the breathable thin plate 2. The bottom of the filling container 1 is connected to the top of the connecting pipe 3. That is, the filling container 1 is an open structure at both the top and bottom. The powder is placed in the middle through the breathable thin plate 2. The bottom end of the connecting pipe 3 is connected to one end of the U-shaped pipe 10. The U-shaped pipe 10 and the pipe wall on one side of the connecting pipe 3 are marked with a line. The connecting pipe 3 is equipped with a valved tee pipe 4. That is, the connecting pipe 3 is cut in the middle, and the cut part is connected to the two ports of the valved tee pipe 4. The other port of the valved tee pipe 4 is connected to the vacuum pump in the main unit 11 through a hose.

[0029] The main unit 11 has a vacuum pump and a power supply fixed inside its housing. The surface of the housing is provided with a screen 12 for displaying the timing time. The power supply provides power to the vacuum pump and the screen 12. The surface of the housing is provided with a button area 13, which contains buttons for controlling the timing and operation of the vacuum pump. This allows the timing to be controlled and the vacuum pump to be controlled at the same time, facilitating experimental operations. The valve control rod of the valve-equipped three-way pipe 4 is on the valve body. The valve-equipped three-way pipe 4 can control two passage states: one is to connect the vacuum pump to the U-tube 10, and the other is to connect the packing container 1 to the U-tube 10.

[0030] The experimental apparatus for characterizing the packing gradation of powder particles has parameter requirements. Therefore, for different experimental powder particles, it is necessary to select an experimental apparatus of different sizes for characterizing the packing gradation of powder particles. Specifically, the inner diameter of the filling container 1 is 2-20 times the particle size of the largest particle in the powder particles. If the minimum inner diameter of the filling container 1 is less than 2cm, 2cm is taken as the minimum diameter of the container. The height of the filling container 1 above the permeable thin plate 2 is 1.0-1.5 times the thickness of the filling layer. The distance between the bottom of the permeable thin plate 2 and the top of the connecting pipe 3 is 1-2 cm. The wall thickness of the filling container 1 and the wall thickness of the permeable thin plate 2 are 0.5-1.5 cm. The size of the support platform is 0.1-1.0 times the wall thickness. The diameter of the opening at the connection point between the filling container 1 and the connecting pipe 3 is 0.5-1.0 cm. A depth scale with a minimum graduation of 1 mm is engraved on the filling container 1 above the permeable thin plate 2. The permeable thin plate 2 is uniformly designed with permeable circular holes with a diameter of 0.1-0.5 mm, and the number of holes is 20-70 per cm. 2 .

[0031] The diameter of the U-tube 10 is 3-50 times the largest particle size in the powder, and the height of the U-tube 10 is 20-600 times the largest particle size in the powder. The first marking line 6 is 0.8-0.9 times the total height of the U-tube 10, the second marking line 7 is 0.7-0.8 times the total height of the U-tube 10, and the third marking line 8 is 0.5-0.7 times the total height of the U-tube 10. The U-tube 10 contains 0.3-0.5 times the total height of the U-tube 10, usually deionized water or purified water. The power of the vacuum pump is determined by the size of the U-tube 10, and is generally selected within the range of 5-500W.

[0032] To ensure airtightness, a small rubber plug 5 is provided at the connection between the connecting pipe 3 and the U-shaped pipe 10. The small rubber plug 5 has a through hole in the center. The bottom end of the connecting pipe 3 is inserted into the through hole, and the outer wall of the connecting pipe 3 is interference-fitted with the through hole. The outer periphery of the small rubber plug 5 is inserted into the U-shaped pipe 10. The small rubber plug 5 ensures airtightness at the connection between the connecting pipe 3 and the U-shaped pipe 10. An airtightness test is required before each use of the device. First, control the valve-equipped three-way pipe 4 to connect the vacuum pump to the U-shaped pipe 10. Then, turn on the vacuum pump. When the water level on one side of the U-shaped pipe 10 exceeds the first marking line 6, stop the vacuum pump. Use the three-way pipe to quickly connect the U-shaped pipe to the sealed packing container at the top. If there is no change in the liquid level within 60-120 seconds, the device is considered to be airtight.

[0033] When using the powder packing gradation characterization experimental apparatus, the thickness of each layer of filler should be 1.1-2.0 times the maximum particle size in the powder. If the thickness of a single layer is less than 0.5 cm, 0.5 cm should be the minimum thickness. The total thickness of the stacked filler layers should be 8-20 times the thickness of a single layer. The compaction pressure for each layer of filler is 1-20 MPa. Because each layer of filler needs to be compacted, the apparatus is equipped with a support for the filler container 1 to provide support for compaction.

[0034] First, control the valved three-way pipe 4 to connect the vacuum pump to the U-tube 10, then start the vacuum pump. When the liquid level crosses the second mark line 7, stop the vacuum pump. Then, control the valved three-way pipe 4 to connect the packing container 1 to the U-tube 10. The liquid level will continue to rise for a certain distance under inertia and then begin to fall. When the liquid level falls to the second mark line, start the stopwatch to start timing until the liquid level falls to the third mark line 8, at which point the timing will end.

[0035] Repeat the test 3-5 times. An error of 1-2 seconds per test is considered acceptable. Take the arithmetic mean as the final test result. If the test error is large, it is necessary to check the airtightness of the device and the rationality of the matching of various technical parameters of the analytical device. Measure the thickness of the first layer of powder particles using vernier calipers. Repeat the measurement 3-5 times. An error of 0.01-0.10 mm per measurement is considered acceptable. Take the arithmetic mean as the final test result. List the test results of the powder particle thickness and air permeability time in Table 1. Fill and compact the second layer of powder particles to be tested, and repeat the above operation. List the test data in Table 1. Finally, clean the powder particles from the metal container.

[0036] Using the thickness listed in Table 1 as the X-axis and the air permeability time as the Y-axis, (x1, y1) represents the coordinates of the first layer of powder particles, (x2, y2) represents the coordinates of the second layer of powder particles, and so on. The slopes of the line segments passing through points (x1, y1) and (x2, y2), and (x2, y2) and (x3, y3) are calculated for each point. The arithmetic mean of the slopes of each layer is then used as the index characterizing the actual packing gradation of the powder particles. The particle size range is 0.01 μm–2 cm, preferably 1 μm–1 cm.

[0037] Table 1 shows the data from the air permeability test.

[0038]

[0039] By filling in Table 1, experimental data can be easily recorded, and the required data results can be calculated.

[0040] The following describes different embodiments:

[0041] Example 1

[0042] Chemically pure nickel powder and iron powder were used. The nickel powder had a particle size range of 1-30 μm, and the iron powder had a particle size range of 150-500 μm. The nickel and iron powders were uniformly mixed at a weight ratio of 3:7. The inner diameter of the material-holding part of the filling device was 2 cm, the constriction diameter was 0.5 cm, and the venting hole diameter of the permeable plate 2 was 0.6 mm, with 30 permeable holes per cm. 2 Two layers of qualitative filter paper are covered on the breathable thin plate 2.

[0043] The bottom of the filling container 1, connecting pipe 3, valved tee pipe 4, U-shaped pipe 10, and main unit 11 are connected to each other. The U-shaped pipe 10 is placed vertically and parallel to the main unit 11. The diameter of the U-shaped pipe 10 is 1cm and the height of the U-shaped pipe 10 is 15cm. Three marking lines are designed on the side of the U-shaped pipe 10 near the main unit 11. From top to bottom, the first marking line 6 is at a height of 13cm, the second marking line 7 is at a height of 11cm, and the third marking line 8 is at a height of 9cm. The U-shaped pipe 10 is filled with 6cm of deionized water. The main unit 11 is connected to a vacuum pump and electrical control device. The power of the vacuum pump is 50W.

[0044] Use a large sealing rubber stopper to plug the top of the filling device container, turn on the vacuum pump of the main unit 11, and when the water level on one side of the U-tube 10 crosses the first marking line 6, stop the vacuum pump, and use a three-way pipe to quickly connect the U-tube to the filling container sealed at the top. If the liquid level does not change within 100 seconds, the device is considered to be in good condition.

[0045] Remove the large sealing rubber stopper, fill with 4.7g of the first layer of nickel-iron mixed powder, and compact the powder particle stack with a pressure of 3MPa.

[0046] Start the vacuum pump. When the liquid level crosses the second mark 7, stop the vacuum pump. Quickly connect the U-shaped pipe to the filling container using the three-way pipe. The liquid level will continue to rise for a distance due to inertia before starting to fall. When the liquid level drops to the second mark, start the stopwatch. At 21 seconds, the liquid level drops to the third mark 8, and the timing ends. Repeat the test three times, for 20 seconds, 21 seconds, and 21 seconds respectively. Take the average value of 21 seconds as the final test result. Measure the thickness of the first layer of powder particles three times randomly using vernier calipers. The thicknesses are 0.52, 0.50, and 0.51 cm, respectively. Take 0.51 cm as the final test result. Fill and compact the second layer of iron-nickel mixed powder using the same method. List the test results in Table 2. Finally, clean the powder particles from the metal container.

[0047] The slopes of ten line segments passing through points (0.51, 21) and (1.00, 62), (1.00, 62) and (1.52, 91) were calculated point by point. The arithmetic mean of the slopes of the ten line segments was obtained, and the results are also listed in Table 2, thus obtaining the true particle packing gradation index.

[0048] Table 2: Data from the test in Example 1:

[0049]

[0050] Example 2

[0051] Industrial-grade pure chemical reagents ZrO2 powder, SiC powder, TiO2 powder, redispersible latex powder, and mullite powder are used. The particle size range of each powder is 60-120 mesh. The redispersible latex powder is mainly composed of acrylic acid copolymer. The powders are uniformly mixed in a weight ratio of 1:1:1:0.1:2. The inner diameter of the filling part of the filling device is 2 cm, and the total height is 5 cm. The distance between the permeable thin plate 2 and the constricted surface is 1 cm. The filling container 1 and the permeable thin plate 2 are 1.5 cm thick, and the support size is 10 mm. A depth scale with a minimum graduation of 1 mm is engraved on the inner side of the powder filling part of the metal container. The constricted diameter of the lower part of the metal container is 0.6 cm, and the diameter of the vent holes in the permeable thin plate 2 is 0.2 mm, with 40 vent holes per cm. 2 Three layers of qualitative filter paper are covered on the breathable thin plate 2.

[0052] The bottom of the filling container 1, connecting pipe 3, valved tee pipe 4, U-shaped pipe 10, and main unit 11 are interconnected. U-shaped pipe 10 is placed vertically, parallel to the main unit 11. The diameter of U-shaped pipe 10 is 0.5cm, and its height is 14cm. Three marking lines are designed on the side of U-shaped pipe 10 closest to the main unit 11: from top to bottom, the first marking line 6 is at a height of 12cm, the second marking line 7 is at 10cm, and the third marking line 8 is at 8cm. U-shaped pipe 10 contains 5cm of deionized water. The main unit 11 is connected to a vacuum pump and electrical control device; the vacuum pump has a power of 40W.

[0053] Use a large sealing rubber stopper to plug the top of the filling device container, turn on the vacuum pump of the main unit 11, and when the water level on one side of the U-tube 10 crosses the first marking line 6, stop the vacuum pump, and use a three-way pipe to quickly connect the U-tube to the filling container sealed at the top. If the liquid level does not change within 110 seconds, the device is considered to be in good condition.

[0054] Remove the large sealing rubber stopper and fill with 3.3g of a first layer of ZrO2, SiC, TiO2, redispersible latex powder, and mullite mixture. Compact the powder particles using a pressure of 15MPa. Fill a total of 10 layers, approximately 5cm thick.

[0055] Start the vacuum pump. When the liquid level crosses the second mark 7, stop the vacuum pump. Quickly connect the U-shaped pipe to the filling container using the three-way pipe. The liquid level will continue to rise for a distance due to inertia before starting to fall. When the liquid level drops to the second mark, start the stopwatch. After 23 seconds, the liquid level drops to the third mark 8, and the timing ends. Repeat the test three times, for 25 seconds, 22 seconds, and 24 seconds respectively. Take the average value of 24 seconds as the final test result. Measure the thickness of the first layer of powder particles three times randomly using vernier calipers. The thicknesses are 0.50, 0.49, and 0.48 cm respectively. Take 0.49 cm as the final test result. Fill and compact the second layer of ZrO2, SiC, TiO2, redispersible latex powder, and mullite mixture using the same method. List the test results in Table 3. Finally, clean the powder particles from the metal container.

[0056] The slopes of ten line segments passing through points (0.49, 24), (0.97, 55), (0.97, 55), and (1.49, 85) were calculated point by point. The arithmetic mean of the slopes of the ten line segments was obtained, and the results are also listed in Table 3, thus obtaining the true particle packing gradation index.

[0057] Table 3 Data from the test in Example 2

[0058]

[0059] Example 3

[0060] The materials used are industrial raw materials: quartz sand, oven-dried refractory clay, bauxite clinker powder, and dried diatomaceous earth. The quartz sand has a particle size of 1-2 mm, the refractory clay has a particle size of 0.01-0.10 mm, the bauxite clinker powder has a particle size range of 0.5-0.1 mm, and the diatomaceous earth has a particle size range of 1-0.5 mm. These powders are uniformly mixed in a weight ratio of 6:2:1:1. The inner diameter of the filling part of the filling device is 3 cm, and the total height is 7 cm. The distance between the metal permeable plate 2 and the constricted surface is 2 cm. The filling container 1 and the permeable plate 2 are 1.0 cm thick, and the support size is 5 mm. A depth scale with a minimum graduation of 1 mm is engraved on the inner side of the powder filling part of the metal container. The constriction diameter of the lower part of the metal container is 0.7 cm, and the diameter of the vent holes in the permeable plate 2 is 0.4 mm, with 60 vent holes per cm. 2 A layer of qualitative filter paper is placed on the breathable thin plate 2.

[0061] The bottom of the filling container 1, connecting pipe 3, valved tee pipe 4, U-shaped pipe 10, and main unit 11 are interconnected. U-shaped pipe 10 is placed vertically, parallel to the main unit 11. The diameter of U-shaped pipe 10 is 2cm, and its height is 20cm. Three marking lines are designed on the side of U-shaped pipe 10 closest to the main unit 11: the first marking line 6 is at a height of 18cm, the second marking line 7 is at 16cm, and the third marking line 8 is at 10cm. U-shaped pipe 10 contains 7cm of deionized water. The main unit 11 is connected to a vacuum pump and electrical control device; the vacuum pump has a power of 80W.

[0062] Use a large sealing rubber stopper to plug the top of the steel container of the packing device, turn on the vacuum pump of the main unit 11, and when the water level on one side of the U-tube 10 exceeds the first marking line 6, stop the vacuum pump, and use a three-way pipe to quickly connect the U-tube to the top-sealed packing container. If the liquid level does not change within 100 seconds, the device is considered to be in good condition.

[0063] Remove the large sealing rubber stopper, and fill with 6.0g of a first layer of a mixture of quartz sand, oven-dried refractory clay, bauxite clinker powder, and dried diatomaceous earth. Compact the powder layer using a pressure of 7MPa. Fill a total of 10 layers, approximately 5.5cm thick.

[0064] Start the vacuum pump. When the liquid level crosses the second mark (7), stop the vacuum pump. Quickly connect the U-shaped pipe to the filling container using the three-way pipe. The liquid level will continue to rise for a distance due to inertia before starting to fall. When the liquid level drops to the second mark, start the stopwatch. After 15 seconds, when the liquid level drops to the third mark (8), stop the timing. Repeat the test three times, for 16 seconds, 15 seconds, and 15 seconds respectively. Take the average of the 15-second results as the final test result. Measure the thickness of the first layer of powder particles three times randomly using vernier calipers. The thicknesses are 0.54, 0.55, and 0.57 cm, respectively. Take 0.55 cm as the final test result. Fill and compact the second layer of a mixture of quartz sand, oven-dried refractory clay, bauxite clinker powder, and dried diatomaceous earth using the same method. List the test results in Table 4. Finally, clean the powder particles from the metal container.

[0065] The slopes of ten line segments passing through points (0.55, 15), (1.12, 60), (1.12, 60), and (1.67, 95) were calculated point by point. The arithmetic mean of the slopes of the ten line segments was obtained, and the results are also listed in Table 4, thus obtaining the true particle packing gradation index.

[0066] Table 4. Data from the test in Example 3

[0067]

[0068] Example 4

[0069] The materials used are industrial raw materials: cement, fly ash, river sand, and crushed stone. The cement is 525 ordinary Portland cement. The fly ash is grade III fly ash with a particle size range of 5-100 μm. The river sand is washed with silt and dried, with a fineness modulus of 2.6. The crushed stone has a particle size range of 5-10 mm. The above powder and granules are uniformly mixed in a weight ratio of 1:2:3:4. The inner diameter of the filling part of the filling device is 6 cm, and the total height is 50 cm. The distance between the metal permeable plate 2 and the constriction surface is 2 cm. The thickness of the metal cylindrical container wall and the metal permeable plate 2 is 1.2 cm, and the support size is 12 mm. A depth scale with a minimum graduation of 1 mm is engraved on the inner side of the powder filling part of the metal container. The constriction diameter of the lower part of the metal container is 1.0 cm. The diameter of the vent holes in the permeable plate 2 is 0.5 mm, and the number of vent holes is 70 per cm. 2 Two layers of qualitative filter paper are covered on the breathable thin plate 2.

[0070] The bottom of the filling container 1, connecting pipe 3, valved tee pipe 4, U-shaped pipe 10, and main unit 11 are interconnected. The U-shaped pipe 10 is placed vertically, parallel to the main unit 11. The diameter of the U-shaped pipe 10 is 3cm, and its height is 25cm. Three marking lines are designed on the side of the U-shaped pipe 10 closest to the main unit 11. From top to bottom, the first marking line 6 is at a height of 22cm, the second marking line 7 is at 20cm, and the third marking line 8 is at 13cm. The U-shaped pipe 10 contains 9cm of deionized water. The main unit 11 is connected to a vacuum pump and electrical control device; the vacuum pump has a power of 400W.

[0071] Use a large sealing rubber stopper to plug the top of the steel container of the packing device, turn on the vacuum pump of the main unit 11, and when the water level on one side of the U-tube 10 exceeds the first marking line 6, stop the vacuum pump, and use a three-way pipe to quickly connect the U-tube to the top-sealed packing container. If the liquid level does not change within 120 seconds, the device is considered to be in good condition.

[0072] Remove the large sealing rubber stopper and fill with 79g of a first layer of a mixture of cement, fly ash, river sand, and crushed stone. Compact the powder layer using a pressure of 1MPa. Fill a total of 15 layers, approximately 45cm thick.

[0073] Start the vacuum pump. When the liquid level crosses the second mark 7, stop the vacuum pump. Quickly connect the U-shaped pipe to the filling container using the three-way pipe. The liquid level will continue to rise for a distance due to inertia before starting to fall. When the liquid level drops to the second mark, start the stopwatch. After 19 seconds, the liquid level drops to the third mark 8, and the timing ends. Repeat the test three times, at 18 seconds, 19 seconds, and 20 seconds respectively. Take the average of 19 seconds as the final test result. Measure the thickness of the first layer of powder particles three times randomly using vernier calipers. The thicknesses are 3.01 cm, 2.99 cm, and 3.02 cm respectively. Take 3.01 cm as the final test result. Fill and compact the second layer of cement, fly ash, river sand, and crushed stone mixture using the same method. List the test results in Table 5. Finally, clean the powder particles from the metal container.

[0074] Table 5: Data from the test in Example 4:

[0075]

[0076] Continued from Table 5

[0077]

[0078] The slopes of fifteen line segments passing through points (3.01, 19), (6.08, 63), (6.08, 63), and (9.05, 103) were calculated point by point. The arithmetic mean of the slopes of the fifteen line segments was obtained, and the results are also listed in Table 5, thus obtaining the true particle packing gradation index.

[0079] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. An apparatus for representing an experimental device for a powder particle packing gradation, characterized by: The device is provided with a filling material container with an upper opening, a gas-permeable sheet is arranged in the filling material container, the gas-permeable sheet is densely provided with gas-permeable round holes, the bottom of the filling material container is in communication with the top of a connecting pipe, the bottom end of the connecting pipe is connected to one end of a U-shaped pipe, a mark line is arranged on the pipe wall of one side of the U-shaped pipe and the connecting pipe, a valve three-way pipe is arranged on the connecting pipe, and the valve three-way pipe is connected to a vacuum pump in the main machine through a bypass; The filling material container is used for placing the powder particles to be tested; The vacuum pump is used for generating a test pressure between the filling material container and the U-shaped pipe.

2. The experimental apparatus for characterizing the particle size distribution of a granular material according to claim 1, wherein: The filling material container is in a cylindrical or cuboid structure, the inner wall of the filling material container is provided with a raised support platform for supporting the gas-permeable sheet, the gas-permeable sheet is placed on the support platform, the distance between the gas-permeable sheet and the top of the connecting pipe is 1-2 cm, the wall thickness of the filling material container and the thickness of the metal sheet are 0.5-1.5 cm, the thickness of the support platform is 0.1-1.0 times the wall thickness of the filling material container, the inner wall of the filling material container above the gas-permeable sheet is provided with a depth scale, the minimum scale of the depth scale is 1 mm, the filling material container is used for containing powder particles, the particle size range of the powder particles is 0.01 μm-2 cm, the inner diameter of the filling material container is 2-20 times the maximum particle size of the contained powder particles, the minimum inner diameter of the filling material container is 2 cm, the ratio of the height of the filling material container above the gas-permeable sheet to the thickness of the filling material layer is 1.0-1.5, the filling material container and the connecting pipe are integrally cast, and the area between the support platform of the filling material container and the connecting pipe is a bucket-shaped structure with a large upper part and a small lower part.

3. The apparatus according to claim 2, wherein: the particle size distribution is a cumulative distribution. The number of the air-permeable circular holes on the air-permeable sheet is 20-70 per cm 2 The diameter of the air-permeable circular holes is 0.1-0.5 mm, and 1-3 layers of qualitative filter paper are placed on the air-permeable sheet.

4. The powder assembly grading characterization test device according to claim 1, 2 or 3, characterized by: A small rubber plug is arranged at the connecting position of the connecting pipe and the U-shaped pipe, a through hole is arranged at the center of the small rubber plug, the bottom end of the connecting pipe is inserted into the through hole, the outer periphery of the small rubber plug is inserted into the U-shaped pipe, and the connecting position is air-tight through the small rubber plug.

5. The experimental apparatus for characterizing the particle size distribution of a granular material according to claim 4, characterized in that: The diameter of the U-shaped pipe is 3-50 times the maximum particle size of the powder particles, the height of the U-shaped pipe is 20-600 times the maximum particle size of the powder particles, the mark line is provided with three lines from top to bottom, namely a first mark line, a second mark line and a third mark line, the position of the first mark line is 0.8-0.9 times the total height of the U-shaped pipe, the position of the second mark line is 0.7-0.8 times the total height of the U-shaped pipe, and the position of the third mark line is 0.5-0.7 times the total height of the U-shaped pipe.

6. The experimental apparatus for characterizing the particle size distribution of a granular material according to claim 5, wherein: The U-shaped pipe contains a liquid with a height of 0.3-0.5 times the total height of the U-shaped pipe, and the liquid is deionized water or pure water.

7. The experimental apparatus for characterizing the particle size distribution of a granular material according to claim 1 or 6, characterized in that: A vacuum pump and a power supply are fixed in the shell of the main machine, a screen for displaying timing time is arranged on the surface of the shell, the power supply supplies power to the vacuum pump and the screen, a key area is arranged on the surface of the shell, and keys for controlling timing and the working of the vacuum pump are arranged in the key area.

8. A method for characterizing the particle packing gradation of a powder or granular material using the device according to any one of claims 1 to 7, characterized in that, The experimental method uses a powder particle packing gradation characterization experimental device, and includes the following steps: Step 1, filling a layer of material into the filling material container; Step 2, control the valve three-way pipe to make the vacuum pump communicate with the U-shaped pipe, and start the vacuum pump until the liquid level exceeds the second mark line; Step 3, control the valve three-way pipe to make the filling container communicate with the U-shaped pipe, and count the time when the liquid level drops to the second mark line; Step 4, until the liquid level drops to the third mark line, the timing ends Step 5, repeat steps 2-4 until the preset number of repeated measurements is reached, and take the arithmetic mean as the final test result; Step 6, repeat steps 1-5 until the number of filler layers reaches the layer number.

9. The method according to claim 8, wherein: the particle size distribution is determined by a laser diffraction method. In step 1, the thickness of each filler layer is 1.1-2.0 times the maximum particle size of the powder particles, and the minimum thickness is 0.5 cm. Each layer of filler is compacted using a pressure of 1-20 MPa, and the total thickness of the stacked filler layers is 8-20 times the thickness of a single layer. In step 5, the number of repeated measurements is 3-5, and the error of each repeated measurement is 1-2 s, which is qualified, otherwise it is judged as unqualified.

10. The method according to claim 8 or 9, wherein: the particle size distribution is determined by a laser diffraction method. Before the experiment, the device needs to be tested for air tightness. During the test, inject liquid into the U-shaped pipe, plug the upper opening of the filling container with a large rubber plug, connect the U-shaped pipe and the connecting pipe with a small rubber plug, control the valve three-way pipe to make the vacuum pump communicate with the U-shaped pipe, open the vacuum pump, and when the water level on one side of the U-shaped pipe exceeds the first mark line, stop the vacuum pump. The three-way pipe quickly connects the U-shaped pipe and the upper sealed filling container. If there is no change in liquid level height for a certain period of time, the air tightness test is qualified, and the powder particle packing gradation characterization experiment can be performed. Through the powder particle packing gradation characterization experiment method, the corresponding values of packing thickness and air permeation time are obtained, and the specific values are matched with the packing gradation index.

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