A test device and a measuring method for the contact angle between liquid steel and liquid slag

Abstract

The present invention relates to a test device for the contact angle between liquid steel and liquid slag, comprising a flange; a corundum furnace tube, the internal cavity of which is a test cavity; a sample table, which is used to fix the test sample; a corundum gasket, which is used to receive the droplets of the test sample dripping during the high-temperature melting process; a steel base plate, the upper end surface of which is provided with a groove, the groove is used to hold the powdered steelmaking slag, and the powdered steelmaking slag in the steel base plate constitutes the test sample after being filled with a thick layer; a heating element, which is used to heat the corundum furnace tube; a high-definition camera, which is used to shoot the entire melting process of the test sample. The test device and measurement method for the contact angle between liquid steel and liquid slag described in the present invention can realize the online measurement of the contact angle between liquid steel and liquid slag in the high-temperature melting process, stably and effectively capture the contact angle of liquid steel and liquid slag, and accurately analyze the liquid / liquid interface properties, which provides important guidance for improving the cleanliness of steel grades and the surface quality of ingots.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a test device and a measurement method for the contact angle between liquid steel and liquid slag. Background Art

[0002] In the whole process of iron and steel metallurgical production, there are multiple interfaces between gas, liquid and solid phases, including the contact angle and interfacial tension of the interaction system of molten iron, molten steel, slag, refractory materials and inclusions. The interface plays a vital role in the transfer of matter and energy between the two phases and the interfacial chemical action.

[0003] At present, the test of the contact angle between steel and slag is mainly limited to that between liquid slag and solid steel. This is mainly because the melted liquid steel and liquid slag have strong fluidity and cannot stably and effectively capture the situation where the liquid slag adheres to the surface of liquid steel. The existing measurement of the contact angle of the liquid / liquid interface (refer to CN102749269B) is mostly concentrated between the oil and water phases, which is not suitable for the measurement of the liquid / liquid contact angle in the steel smelting process, which greatly restricts the analysis of the liquid / liquid interface properties in the field of steel metallurgy.

[0004] Therefore, there is an urgent need for an online measurement method and test device for the contact angle between liquid steel and liquid slag, so as to deeply explore the liquid / liquid interface properties between liquid steel, slag, refractory materials and inclusions in the field of iron and steel metallurgy, and provide solutions to the problems of low cleanliness of liquid steel and frequent surface quality defects of ingots (slag inclusions, refractory damage and inclusion aggregation and growth) faced by high-end steel manufacturing. Stable and effective capture of the contact angle between liquid steel and liquid slag is a problem that needs to be solved urgently. Summary of the invention

[0005] Based on the lack of a method for measuring the contact angle between liquid steel and liquid slag, the present invention provides an online measurement method and test device for the contact angle between liquid steel and liquid slag, which can stably and effectively capture the contact angle of liquid steel and liquid slag, and accurately analyze the liquid / liquid interface properties, which provides important guidance for improving the cleanliness of steel grades and the surface quality of ingots.

[0006] In order to solve the above technical problems, the present invention provides a test device and a measurement method for the contact angle between liquid steel and liquid slag, comprising: a flange plate, which serves as a support member; a corundum furnace tube, which is arranged on the flange plate, and the inner cavity of the corundum furnace tube is a test cavity; a sample table, which is arranged on the inner wall of the corundum furnace tube, and the sample table is used to fix the test sample; a corundum gasket, which is installed on the sample table, and the corundum gasket is used to receive droplets of the test sample dripping during the high-temperature melting process; a steel substrate, which is arranged on the corundum gasket, and the upper end surface of the steel substrate away from the corundum gasket is provided with a groove, and the groove is used to hold powdered steelmaking slag, and the powdered steelmaking slag held in the steel substrate constitutes the test sample after thickness; a heating element, which is arranged on the flange plate, and the heating element is used to heat the corundum furnace tube; a high-definition camera, which is arranged outside the corundum furnace tube, and the lens of the high-definition camera is facing the steel substrate, and the high-definition camera is used to shoot the entire melting process of the test sample.

[0007] In one embodiment of the present invention, the flange is provided with an opening, and the opening of the flange is sealed with quartz glass.

[0008] In one embodiment of the present invention, the test device also includes an air compressor and high-purity argon gas, the air compressor is used to evacuate the inner cavity of the corundum furnace tube into a vacuum state, the flange is provided with an air inlet and an air outlet, the air inlet is connected to the high-purity argon gas, and the high-purity argon gas is used to transport argon gas into the corundum furnace tube through the air inlet and the air outlet to maintain an inert atmosphere in the corundum furnace tube.

[0009] In one embodiment of the present invention, the test device also includes a temperature control and imaging system, which is used to real-time control the temperature, heating rate, and insulation time in the corundum furnace tube, and to display and record real-time online images of the entire melting process of the test sample.

[0010] In one embodiment of the present invention, the test device further comprises a halogen lamp, which is arranged opposite to the quartz glass and is used to adjust the light in the corundum furnace tube.

[0011] The present invention also provides a method for measuring the contact angle between liquid steel and liquid slag, comprising the following steps:

[0012] S1. Cut a small square steel block, drill a square groove in the center of the small steel block, put powdered steelmaking slag into the groove until the surface is flush with the steel substrate to make a test sample, place the prepared test sample on the corundum gasket, then place the corundum gasket on the sample table and fix it, and put the entire sample device stably into the corundum furnace tube for testing;

[0013] S2. Use an air compressor to extract the air in the corundum furnace tube. After stopping the extraction, inject argon gas into the corundum furnace tube through the air inlet, and exhaust the argon gas in the corundum furnace tube through the air outlet to ensure that the air in the corundum furnace tube is completely exhausted and maintain an inert atmosphere;

[0014] S3, start the temperature control and imaging system to set the heating program, the first step, from 0 to 800 ° C, manual heating, the second step, from 800 to 1600 ° C, automatic heating, the third step, keep the temperature at 1600 ° C for 60 minutes, so that the temperature in the corundum furnace tube remains stable;

[0015] S4. Use a high-definition camera to continuously shoot and record clear images of the melting process of the test sample, and display them clearly online in the temperature control and imaging system, focusing on the process of the bulge formed after the groove in the steel substrate melts to squeeze out the liquid protective slag. Use image processing software to fit the contours of liquid slag and liquid steel. At the steel-slag-gas three-phase contact, the contact angle between the liquid slag and liquid steel is obtained by making tangents to the contours of the liquid slag and liquid steel;

[0016] S5. Based on Young's equation, combined with the mold slag surface tension model and the low alloy steel surface tension model, the contact angle between liquid steel and liquid slag obtained by measurement can be used to further solve the change of the interfacial tension between liquid steel and liquid slag at different temperatures;

[0017] S6. After the experiment, turn off the power supply program and gas equipment.

[0018] In one embodiment of the present invention, in the above step S2: using an air compressor to extract the air in the corundum furnace tube, when the air pressure reaches 10 -3 MPa, stop pumping, and flush high-purity argon with a purity of 99.999% into the corundum furnace tube through the air inlet to restore the air pressure in the corundum furnace tube to 1 standard atmospheric pressure. Then, the argon in the corundum furnace tube is exhausted through the air outlet, and the air compressor is used to evacuate the air again. The whole flushing and exhausting process is repeated 3 times to ensure that the air in the corundum furnace tube is exhausted and an inert atmosphere is maintained.

[0019] In one embodiment of the present invention, in the above step S3: turn on the temperature control and imaging system to set the heating program, the first step, from 0 to 800 ° C, manually heat up, the heating rate does not exceed 7 ° C / min, the voltage display number is controlled at 100 to 150V, the current display number is controlled at 0 to 40A, the second step, from 800 to 1600 ° C, automatically heat up, the heating rate is 10 ° C / min, the heating time is 80min, the third step, keep warm at 1600 ° C for 60min, so that the temperature in the corundum furnace tube remains stable, the maximum voltage does not exceed 300V, and the maximum current does not exceed 100A.

[0020] In one embodiment of the present invention, in the above step S4: as the temperature rises, the halogen lamp is adjusted to improve the light in the corundum furnace tube, a high-definition camera is used to continuously capture and record clear images of the melting process of the test sample, which are clearly displayed online in the temperature control and imaging system, focusing on the process of the bulge formed after the groove in the steel substrate melts to squeeze out the liquid protective slag, and the image processing software is used to fit the contours of the liquid slag and liquid steel. At the steel-slag-gas three-phase contact, the contact angle between the liquid slag and liquid steel is obtained by making tangents to the contours of the two.

[0021] In one embodiment of the present invention, in the above step S5: the formula for calculating the interfacial tension between liquid steel and liquid slag is:

[0022]

[0023] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0024] The test device and measurement method of the contact angle between liquid steel and liquid slag described in the present invention can realize online measurement of the contact angle between liquid steel and liquid slag in a high-temperature melting process, stably and effectively capture the contact angle of liquid steel and liquid slag, and accurately analyze the liquid / liquid interface properties, which provides important guidance for improving the cleanliness of steel grades and the surface quality of castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

[0026] Figure 1 A schematic diagram of the structure of a test device for the contact angle between liquid steel and liquid slag provided in an embodiment of the present invention;

[0027] Figure 2 The embodiment of the present invention provides Figure 1 A partial enlarged view of

[0028] Figure 3 A schematic diagram of the structure of a test sample provided by an embodiment of the present invention;

[0029] Figure 4 The embodiment of the present invention provides Figure 2 A partial enlarged view of .

[0030] Explanation of the reference numerals in the specification: flange 1; steel base plate 2; corundum gasket 3; sample table 4; air compressor 5; high-purity argon gas 6; air inlet 7; air outlet 8; temperature control and imaging system 9; U-shaped heating element 10; halogen lamp 11; quartz glass 12; high-definition camera 13; corundum furnace tube 14. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0032] Reference Figure 1-4 As shown, a test device for the contact angle between liquid steel and liquid slag of the present invention comprises: a flange 1, which serves as a support; a corundum furnace tube 14, which is arranged on the flange 1, and the inner cavity of the corundum furnace tube 14 is a test cavity; a sample table 4, which is arranged on the inner wall of the corundum furnace tube 14, and the sample table 4 is used to fix the test sample; a corundum gasket 3, which is installed on the sample table 4, and the corundum gasket 3 is used to receive the droplets of the test sample dripping during the high-temperature melting process; a steel substrate 2, which is arranged on the corundum gasket 3, and the upper end surface of the steel substrate 2 away from the corundum gasket 3 is provided There is a groove, which is used to hold powdered steelmaking slag. The steel substrate 2 is filled with powdered steelmaking slag to form a test sample; a heating element 10, which is arranged on the flange 1, and the heating element 10 is arranged in a U shape. The heating element 10 is arranged in a plurality on the flange 1, and the plurality of heating elements 10 are arranged around the corundum furnace tube 14, and the heating element 10 is used to heat the corundum furnace tube 14; a high-definition camera 13, which is arranged outside the corundum furnace tube 14, and the lens of the high-definition camera 13 is facing the steel substrate 2, and the high-definition camera 13 is used to shoot the entire melting process of the test sample.

[0033] The flange 1 is provided with an opening, and the opening of the flange 1 is sealed with quartz glass 12 .

[0034] The test device of the above structure also includes an air compressor 5 and high-purity argon gas 6. The air compressor 5 is used to evacuate the inner cavity of the corundum furnace tube 14 into a vacuum state. The flange 1 is provided with an air inlet 7 and an air outlet 8. The air inlet 7 is connected to the high-purity argon gas 6. The high-purity argon gas 6 is used to transport argon gas into the corundum furnace tube 14 through the air inlet 7 and the air outlet 8 to maintain an inert atmosphere in the corundum furnace tube 14.

[0035] The test device of the above structure also includes a temperature control and imaging system 9, which is used to real-time control the temperature, heating rate, and insulation time in the corundum furnace tube 14, and to display and record the real-time online picture of the entire melting process of the test sample.

[0036] The test device of the above structure also includes a halogen lamp 11, which is arranged opposite to the quartz glass 12, and is used to adjust the light in the corundum furnace tube 14. The inner diameter of the corundum furnace tube 14 is 100 mm and the length is 500 mm. The quartz glass 12 has the characteristics of good heat insulation performance and high light transmittance.

[0037] The test device for the contact angle between liquid steel and liquid slag of the present invention comprises a flange 1 for fixing a corundum furnace tube 14 and a quartz glass 12 to ensure the stability of the entire device; a groove in the middle of the steel substrate 2 is used to hold an appropriate amount of powdered steelmaking slag, which is placed on a corundum gasket 3 to prevent droplets from falling into the furnace during the high-temperature melting process, and then the whole device is placed on a sample table 4 to fix the test sample; an air compressor 5 is used to evacuate the inside of the corundum furnace tube 14 into a vacuum state, and a high-purity argon gas 6 is used to introduce argon gas into the corundum furnace tube 14 to maintain an inert atmosphere in the corundum furnace tube 14, and an air inlet 7 and an air outlet 8 is used for conveying gas in the corundum furnace tube 14; the temperature control and imaging system 9 is used for real-time control of the heating furnace temperature, heating rate, insulation time, and displaying and recording real-time online images of the entire sample melting process; the U-shaped heating element 10 is used for heating the furnace body; the halogen lamp 11 is used for controlling the light in the corundum furnace tube 14; the high-definition camera 13 is used for clearly photographing the entire process of steel and slag melting; the heating element 10 is used for heating the corundum furnace tube 14, and the maximum temperature can reach 1650°C; the halogen lamp 11 is used for controlling the light in the furnace, so as to maintain the clarity and stability of the imaging picture, and can be moved forward and backward to adjust the angle.

[0038] The specific steps of the test are as follows:

[0039] S1: Use a wire cutting machine to cut a small square steel block (low alloy content), i.e., a steel substrate 2, with a size of 30×30×5mm, from the steel ingot. Use a drill bit with a diameter of 20mm to drill a square groove with a size of 20×20×2mm in the center of the small steel block. Fill the pre-melted protective slag powder with a particle size less than 200 mesh into the groove until the surface is flush with the upper end surface of the steel substrate 2. Place the prepared sample horizontally at the center of the corundum gasket 3 with a size of 50×50×10mm to prevent the liquid steel and slag from moving and dripping onto the furnace tube during the high-temperature melting process. Then place the steel substrate 2 and the corundum gasket 3 on the sample table and fix them. Place the entire sample device stably above the corundum furnace tube 14 for testing.

[0040] S2: Use the air compressor 5 to extract the air in the corundum furnace tube 14. When the air pressure reaches 10-3MPa, stop exhausting, and inject high-purity argon gas with a purity of 99.999% into the corundum furnace tube 14 through the air inlet 7 to restore the air pressure in the corundum furnace tube 14 to 1 standard atmospheric pressure. Then, the argon gas in the corundum furnace tube 14 is exhausted through the air outlet 8, and the air compressor 5 is used to evacuate the air again. The entire exhaust and flushing process is repeated 3 times to ensure that the air in the corundum furnace tube 14 is exhausted and an inert atmosphere is maintained.

[0041] S3: Turn on the temperature control and imaging system 9 to set the heating program. The first step is to manually heat from 0 to 800°C, with a heating rate not exceeding 7°C / min, the voltage display number is controlled at 100 to 150V, and the current display number is controlled at 0 to 40A. The second step is to automatically heat from 800 to 1600°C, with a heating rate of 10°C / min and a heating time of 80min. The third step is to keep the temperature at 1600°C for 60min to keep the temperature in the corundum furnace tube 14 stable, with a maximum voltage not exceeding 300V and a maximum current not exceeding 100A.

[0042] S4: As the temperature rises, the halogen lamp is adjusted to improve the light inside the corundum furnace tube 14. The high-definition camera 13 is used to continuously capture and record clear images of the steel and slag melting process, which are clearly displayed online in the temperature control and imaging system 9. Focus is placed on the process of the bulge formed after the groove in the steel substrate 2 melts to squeeze out the liquid protective slag. The image processing software is used to fit the contours of the liquid slag and liquid steel. At the steel-slag-gas three-phase contact, the contact angle between the liquid slag and liquid steel is obtained by making tangents to the contours of the two.

[0043] S5: Based on Young's equation, combined with the protective slag surface tension model and the low alloy steel surface tension model, the change of the interfacial tension between liquid steel and liquid slag at different temperatures can be further solved by using the measured contact angle between liquid steel and liquid slag.

[0044] Calculated value of interfacial tension between liquid steel and liquid slag:

[0045]

[0046] S6: After the experiment, turn off the power program and gas equipment.

[0047] The test device for the contact angle between liquid steel and liquid slag of the present invention comprises: a flange 1, a steel substrate 2, a corundum gasket 3, a sample table 4, an air compressor 5, high-purity argon 6, an air inlet 7, an air outlet 8, a temperature control and imaging system 9, a U-shaped heating element 10, a halogen lamp 11, a quartz glass 12, a high-definition camera 13 and a corundum furnace tube 14 and other components, and a measuring method matching the device is adopted. On the one hand, steelmaking slag powder is contained in the groove of the steel plate, and the droplets formed by the melting of the slag during the heating process can be fixed in the groove. On the other hand, when the temperature is higher than the liquidus temperature of the steel substrate, the bottom of the steel plate groove melts to form a bulge, which can squeeze out the liquid slag. In this process, a high-definition camera is used to continuously shoot and completely record the entire melting process. The image processing software is used to fit the contours of liquid slag and liquid steel. At the steel-slag-gas three-phase contact, the contact angle between liquid slag and liquid steel is obtained by making tangents to the contours of liquid slag and liquid steel. Combined with Young's equation, the interfacial tension between liquid steel and liquid slag is solved. The present invention develops an online measurement method for the contact angle between liquid steel and liquid slag. The test results are accurate and the test device is simple. It overcomes the technical difficulty that the existing contact angle test between steel slag is limited to liquid slag and solid steel, and realizes the online measurement of the liquid / liquid contact angle between steel slag in the high-temperature melting process, which provides useful guidance for the analysis of high-temperature melt interface properties and the improvement of high-end steel grade cleanliness and ingot surface quality.

[0048] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for measuring the contact angle between liquid steel and liquid slag, characterized in that: The steps include: S1. Cut a small square steel block, drill a square groove in the center of the small steel block, put powdered steelmaking slag into the groove until the surface is flush with the steel substrate to make a test sample, place the prepared test sample on the corundum gasket, then place the corundum gasket on the sample table and fix it, and put the entire sample device stably into the corundum furnace tube for testing; S2. Use an air compressor to extract the air in the corundum furnace tube. After stopping the extraction, inject argon gas into the corundum furnace tube through the air inlet, and exhaust the argon gas in the corundum furnace tube through the air outlet to ensure that the air in the corundum furnace tube is completely exhausted and maintain an inert atmosphere; S3, turn on the temperature control and imaging system to set the heating program. The first step is to manually heat from 0 to 800°C. The second step is to automatically heat from 800 to 1600°C. The third step is to keep the temperature at 1600°C for 60 minutes. The U-shaped heating element is used to heat the furnace body to keep the temperature in the corundum furnace tube stable. S4. Use a high-definition camera to continuously shoot and record clear images of the melting process of the test sample, and display them clearly online in the temperature control and imaging system, focusing on the process of the bulge formed after the groove in the steel substrate melts to squeeze out the liquid protective slag. Use image processing software to fit the contours of liquid slag and liquid steel. At the steel-slag-gas three-phase contact, the contact angle between the liquid slag and liquid steel is obtained by making tangents to the contours of the liquid slag and liquid steel; S5. Based on Young's equation, combined with the mold slag surface tension model and the low alloy steel surface tension model, the contact angle between liquid steel and liquid slag measured can be used to further solve the change of the interfacial tension between liquid steel and liquid slag at different temperatures. The formula for calculating the interfacial tension between liquid steel and liquid slag is: γ 钢-渣 —Interface tension between liquid steel and liquid slag, mN / m; X i — mole fraction of component i in the slag, mol%; F i —Surface tension factor of component i in slag, mN / (mmol); θ—Contact angle between liquid slag and liquid steel, °; T—temperature, K; S6. After the experiment, turn off the power supply program and gas equipment.

2. The method for measuring the contact angle between liquid steel and liquid slag according to claim 1, characterized in that: In the above step S2: use an air compressor to extract the air in the corundum furnace tube, and when the air pressure reaches 10 -3 MPa, stop pumping, and flush high-purity argon with a purity of 99.999% into the corundum furnace tube through the air inlet to restore the air pressure in the corundum furnace tube to 1 standard atmospheric pressure. Then, the argon in the corundum furnace tube is exhausted through the air outlet, and the air compressor is used to evacuate the air again. The whole flushing and exhausting process is repeated 3 times to ensure that the air in the corundum furnace tube is exhausted and an inert atmosphere is maintained.

3. The method for measuring the contact angle between liquid steel and liquid slag according to claim 1, characterized in that: In the above step S3: turn on the temperature control and imaging system to set the heating program. The first step is to manually heat up from 0 to 800°C, with a heating rate not exceeding 7°C / min, the voltage display number is controlled at 100 to 150V, and the current display number is controlled at 0 to 40A. The second step is to automatically heat up from 800 to 1600°C, with a heating rate of 10°C / min and a heating time of 80min. The third step is to keep warm at 1600°C for 60min to keep the temperature in the corundum furnace tube stable. The maximum voltage does not exceed 300V, and the maximum current does not exceed 100A.

4. The method for measuring the contact angle between liquid steel and liquid slag according to claim 1, characterized in that: In the above step S4: as the temperature rises, the halogen lamp is adjusted to improve the light in the corundum furnace tube, and a high-definition camera is used to continuously capture and record clear images of the melting process of the test sample, which are clearly displayed online in the temperature control and imaging system, focusing on the process of the bulge formed after the groove in the steel substrate melts to squeeze out the liquid protective slag, and the image processing software is used to fit the contours of the liquid slag and liquid steel. At the steel-slag-gas three-phase contact, the contact angle between the liquid slag and liquid steel is obtained by making tangents to the contours of the two.

5. The method for measuring the contact angle between liquid steel and liquid slag according to claim 1, characterized in that: The test equipment includes: flange, which serves as a support; A corundum furnace tube is arranged on a flange, and the inner cavity of the corundum furnace tube is a test cavity; A sample stage, which is arranged on the inner wall of the corundum furnace tube and is used to fix the test sample; A corundum gasket is installed on the sample stage and is used to receive droplets of the test sample during high-temperature melting; A steel substrate is arranged on a corundum gasket, wherein an upper end surface of the steel substrate away from the corundum gasket is provided with a groove, wherein the groove is used to contain powdered steelmaking slag, and the powdered steelmaking slag contained in the steel substrate constitutes a test sample; A heating element, which is arranged on the flange and is used to heat the corundum furnace tube; A high-definition camera is arranged outside the corundum furnace tube, and the lens of the high-definition camera is facing the steel substrate. The high-definition camera is used to shoot the entire melting process of the test sample.

6. The method for measuring the contact angle between liquid steel and liquid slag according to claim 5, characterized in that: The flange is provided with an opening, and the opening of the flange is sealed with quartz glass.

7. The method for measuring the contact angle between liquid steel and liquid slag according to claim 6, characterized in that: The test device also includes an air compressor and high-purity argon gas. The air compressor is used to evacuate the inner cavity of the corundum furnace tube into a vacuum state. The flange is provided with an air inlet and an air outlet. The air inlet is connected to the high-purity argon gas. The high-purity argon gas is used to transport argon gas into the corundum furnace tube through the air inlet and the air outlet to maintain an inert atmosphere in the corundum furnace tube.

8. The method for measuring the contact angle between liquid steel and liquid slag according to claim 5, characterized in that: The test device also includes a temperature control and imaging system, which is used to control the temperature, heating rate, and insulation time in the corundum furnace tube in real time, and to display and record real-time online images of the entire melting process of the test sample.

9. The method for measuring the contact angle between liquid steel and liquid slag according to claim 7, characterized in that: The test device also includes a halogen lamp, which is arranged opposite to the quartz glass and is used to adjust the light in the corundum furnace tube.

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