Alumina porous cover and preparation method therefor, and probe containing same and used for measuring hydrogen in molten steel

Abstract

An alumina porous cover, comprising the following components by mass fraction (wt%): 20-90 of hollow alumina spheres, 5-40 of a high-alumina micropowder, 5-30 of a silica micropowder, and 2-10 of a binder. The present invention also provides a method for preparing an alumina porous cover, the method comprising the following operation steps: S1, mixing given proportions of hollow alumina spheres, a high-alumina micropowder and a silica micropowder, then adding an appropriate amount of a binder, mixing same until uniform, granulating the resulting mixture, and then performing compression molding to obtain a green body of an alumina porous cover; and S2, drying the green body of the alumina porous cover at 50-120°C for 2-4 hours, then slowly heating same to 500-800°C for debinding, then slowly heating same to 1500-1650°C and sintering same for 2-4 hours, and then allowing same to naturally cool to room temperature along with the furnace, so as to prepare a finished product of the alumina porous cover. The present invention further provides a probe containing the alumina porous cover and used for measuring hydrogen in molten steel. By means of the present invention, the air permeability of the alumina porous cover therein can be increased to 60% or higher, and the alumina porous cover can endure for a longer period of time in a measurement state.

Description

Alumina porous cover, preparation method thereof and molten steel hydrogen content probe containing the same

[0001] The present application claims priority to the Chinese patent application No. 202410997775.4, filed on July 24, 2024, and entitled "Alumina porous cover, preparation method thereof and molten steel hydrogen content probe containing the same", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of sensors for metal smelting, in particular to an alumina porous cover, a preparation method thereof and a molten steel hydrogen content probe containing the same. BACKGROUND

[0003] The hydrogen content in steel is an important performance indicator of steel, and online real-time measurement of the hydrogen content in molten steel has become an important means to improve process control accuracy. Currently, the online hydrogen analyzer and the matching hydrogen content probe are commonly used in the market. In the device, nitrogen gas enters the metal melt through the gas joint and the gas blowing pipe as a carrier gas to form gas bubbles. After the nitrogen bubbles absorb hydrogen in the metal melt, they pass through the alumina porous cover inside the probe and return to the pneumatic cabinet. The carrier gas is continuously circulated in the loop, gradually reaching a balanced state, and then the hydrogen content in the molten steel is calculated according to the Westcott law.

[0004] The alumina porous cover has the functions of fixing the gas pipeline and carrying and collecting the gas. Since the measurement environment of the hydrogen content probe is usually at 1600-1700℃, and the entire test time is as long as 30-70 seconds, the gas permeable holes of the alumina porous cover are easily blocked by the molten steel during the test, thereby affecting the gas balance. If the balance time is too long, the molten steel gradually erodes the alumina porous cover and other components in the hydrogen content probe, affecting the hydrogen content measurement accuracy. Therefore, how to make the alumina porous cover maintain a high gas permeability for a long time is a technical problem to be solved by those skilled in the art. SUMMARY

[0005] To solve the above technical problems, the present application provides an alumina porous cover, a preparation method thereof and a molten steel hydrogen content probe containing the same, which can increase the gas permeability of the alumina porous cover in it to more than 60% and maintain it for a longer time in the measurement state.

[0006] The technical solutions provided by the present application are as follows:

[0007] An alumina porous cover, comprising the following components by mass fraction (wt%):

[0008] Alumina hollow spheres 20-90,

[0009] High-aluminum micro powder 5-40,

[0010] Silicon micro powder 5-30,

[0011] Binder 2-10.

[0012] Preferably, the particle size of the alumina hollow sphere is 0.1-1mm.

[0013] Preferably, the content of alumina in the high-alumina powder is 70-90wt%.

[0014] Preferably, the particle size of the high-alumina powder is 3000-8000 mesh.

[0015] Preferably, the content of silicon dioxide in the silicon powder is 70-90wt%.

[0016] Preferably, the particle size of the silicon powder is 3000-8000 mesh.

[0017] Preferably, the binder comprises a silica sol, and the content of silicon dioxide in the silica sol is 20-50wt%.

[0018] Preferably, the pH of the silica sol is 1-5.

[0019] A preparation method of an alumina porous cover, comprising the following operation steps:

[0020] S1, mixing alumina hollow spheres, high-alumina powder and silicon powder in a certain proportion, adding an appropriate amount of binder, mixing uniformly, granulating and then pressing to form an alumina porous cover green body;

[0021] S2, drying the alumina porous cover green body at 50-120℃ for 2-4 hours, slowly heating to 500-800℃ to remove glue, then slowly heating to 1500-1650℃ and sintering for 2-4 hours, and then naturally cooling to room temperature in the furnace to obtain an alumina porous cover finished product.

[0022] Preferably, the pressure of the pressing in step S1 is controlled to be 100MPa-200MPa.

[0023] A molten steel hydrogen determination probe, comprising a coated sand protection pipe and a metal fixing cover, the bottom end of the metal fixing cover is provided with a metal cap, the inner cavity of the coated sand protection pipe is provided with a fire-retardant paper tube, the inner cavity bottom of the fire-retardant paper tube is provided with a gas connector, the gas connector is communicated with a gas guide assembly, the gas guide assembly comprises a first gas guide pipe and a second gas guide pipe, the inner cavity of the first gas guide pipe is filled with alumina hollow spheres, the bottom of the first gas guide pipe is provided with the alumina porous cover, the second gas guide pipe passes through and extends out of the alumina porous cover, and the first gas guide pipe, the second gas guide pipe and the alumina porous cover are filled with high-temperature resistant cement.

[0024] The present application has the following advantages over the prior art:

[0025] The alumina porous cover prepared by the preparation method of the present application is dry-pressed from alumina hollow spheres, and a large number of open pores are formed after high-temperature sintering, so that the air permeability can reach more than 60%, the average pore size is about 400 μm, and the apparent density is 1.8 g / cm 3 The alumina porous cover of the present application can be permeable to air and impermeable to metal melt; the alumina porous cover of the present application can be kept for more than 60 seconds in a normal measuring state while maintaining good air permeability; the molten steel hydrogen determination probe of the present application does not react with the metal melt and does not contain foreign gas substances, thereby ensuring the accuracy of gas measurement in the melt. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0027] Fig. 1 is a structural schematic view of the alumina porous cover in the embodiment of the present application;

[0028] Fig. 2 is an A-A sectional view of Fig. 1;

[0029] Fig. 3 is a structural schematic view of the molten steel hydrogen determination probe in the embodiment of the present application.

[0030] Reference signs: 1, alumina porous cover; 2, coated sand protection tube; 3, metal fixing cover; 4, fire-retardant paper tube; 5, gas joint; 6, first gas guide tube; 7, second gas guide tube. DETAILED DESCRIPTION

[0031] In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the scope of protection of the present application.

[0032] The alumina porous cover provided in the embodiment of the present application comprises the following components in terms of mass fraction (wt%):

[0033] Alumina hollow spheres 20-90,

[0034] High-alumina micropowder 5-40,

[0035] Silicon micropowder 5-30,

[0036] Binder 2-10.

[0037] In this embodiment, the particle size of the alumina hollow sphere is 0.1-1 mm.

[0038] In this embodiment, the content of alumina in the high-aluminum powder is 70-90 wt%. The particle size of the high-aluminum powder is 3000-8000 mesh.

[0039] In this embodiment, the content of silicon dioxide in the silicon powder is 70-90 wt%. The particle size of the silicon powder is 3000-8000 mesh.

[0040] In this embodiment, the binder includes silica sol, and the content of silicon dioxide in the silica sol is 20-50 wt%. The pH of the silica sol is 1-5.

[0041] A preparation method of an alumina porous cover, comprising the following operation steps:

[0042] S1, mixing alumina hollow spheres, high-aluminum powder and silicon powder in a certain proportion, adding an appropriate amount of binder, mixing, granulating and then pressing to form a green body of the alumina porous cover, and the pressing pressure is controlled to be 100-200 MPa;

[0043] S2, drying the green body of the alumina porous cover at 50-120°C for 2-4 hours, slowly heating to 500-800°C to remove glue, then slowly heating to 1500-1650°C and sintering for 2-4 hours, and then naturally cooling to room temperature in the furnace to obtain a finished product of the alumina porous cover.

[0044] As shown in FIGS. 1-3, a molten steel hydrogen determination probe includes a coated sand protection tube 2 and a metal fixing cover 3, the bottom end of the metal fixing cover 3 is provided with a metal cap, the inner cavity of the coated sand protection tube 2 is provided with a fire-retardant paper tube 4, the inner cavity of the fire-retardant paper tube 4 is provided with a gas connector 5, the gas connector 5 is communicated with a gas guide assembly, the gas guide assembly includes a first gas guide tube 6 and a second gas guide tube 7, the inner cavity of the first gas guide tube 6 is filled with alumina hollow spheres, the bottom of the first gas guide tube 6 is provided with the alumina porous cover 1, the second gas guide tube 7 passes through and extends out of the alumina porous cover 1, and the first gas guide tube 6, the second gas guide tube 7 and the alumina porous cover 1 are filled with high-temperature resistant cement.

[0045] Example 1:

[0046] The alumina hollow sphere, high-aluminum powder and silicon powder are mixed in a mass percentage ratio of 70%:20%:10% to obtain base powder; 5% of the total mass of the base powder is added to the base powder as a binder silica sol, and after mixing and granulation, the mixture is baked at 80°C for 2 hours and sieved through a 40-mesh sieve; the sieved powder is double-faced die-pressed at a pressure of 100 MPa to obtain an alumina porous cover green body; the alumina porous cover green body is dried at 85°C for 2 hours, slowly heated to 300°C for 4 hours, slowly heated to 600°C for 4 hours, then slowly heated to 1600°C for 2 hours of sintering, and naturally cooled to room temperature in the furnace to obtain an alumina porous cover product.

[0047] Example 2:

[0048] The alumina hollow sphere, high-aluminum powder and silicon powder are mixed in a mass percentage ratio of 75%:18%:7% to obtain base powder; 3% of the total mass of the base powder is added to the base powder as a binder silica sol, and after mixing and granulation, the mixture is baked at 60°C for 2 hours and sieved through a 40-mesh sieve; the sieved powder is double-faced die-pressed at a pressure of 130 MPa to obtain an alumina porous cover green body; the alumina porous cover green body is dried at 65°C for 2 hours, slowly heated to 300°C for 4 hours, slowly heated to 600°C for 4 hours, then slowly heated to 1550°C for 2 hours of sintering, and naturally cooled to room temperature in the furnace to obtain an alumina porous cover product.

[0049] Example 3:

[0050] The alumina hollow sphere, high-aluminum powder and silicon powder are mixed in a mass percentage ratio of 80%:15%:5% to obtain base powder; 8% of the total mass of the base powder is added to the base powder as a binder silica sol, and after mixing and granulation, the mixture is baked at 100°C for 1.5 hours and sieved through a 40-mesh sieve; the sieved powder is double-faced die-pressed at a pressure of 150 MPa to obtain an alumina porous cover green body; the alumina porous cover green body is dried at 110°C for 2 hours, slowly heated to 300°C for 4 hours, slowly heated to 600°C for 4 hours, then slowly heated to 1580°C for 1.5 hours of sintering, and naturally cooled to room temperature in the furnace to obtain an alumina porous cover product.

[0051] Example 4:

[0052] The alumina hollow sphere, high-alumina powder and silicon powder are mixed in a mass percentage ratio of 65:25:10 to obtain base powder; 6% of the total mass of the base powder is added to the base powder as a binder silica sol, and after mixing and granulation, the mixture is baked at 85°C for 1 hour and then sieved through a 40-mesh sieve; the sieved powder is double-faced molded under a pressure of 120 MPa to obtain an alumina porous cover green body; the alumina porous cover green body is dried at 90°C for 2 hours, slowly heated to 300°C for 4 hours, slowly heated to 600°C for 4 hours, then slowly heated to 1565°C and sintered for 1.5 hours, and then naturally cooled to room temperature in the furnace to obtain an alumina porous cover product.

[0053] The alumina porous cover obtained in each of the above examples is measured for pore size distribution by a mercury porosimeter, for apparent volume by a drainage method, and used for a hydrogen probe, and the hydrogen probe is connected to a hydrogen measuring gun and a hydrogen meter, and after air permeability detection, the hydrogen probe is immersed in molten steel at 1650°C for 60 seconds and then taken out, and the penetration of the molten steel into the alumina porous cover is observed. The test results are shown in Table 1.

[0054] Table 1: Test results of Examples 1-4

[0055] As can be seen from the above table, the air permeability of the alumina porous cover of Examples 1-4 is more than 60%, and the alumina porous cover can not be penetrated by a metal melt on the basis of good air permeability, and can be maintained for more than 60 seconds under normal measurement conditions.

[0056] The above description of disclosed examples enables one of ordinary skill in the art to make or use the application. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other examples without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An aluminum oxide porous shell, characterized by, Comprise the following components by mass fraction (wt%): alumina hollow spheres 20-90, high-alumina fines 5-40, silicon fines 5-30, and a binder 2-10.

2. The alumina porous shroud of claim 1, wherein, The alumina hollow spheres have a particle size of 0.1-1 mm.

3. The alumina porous shroud of claim 1, wherein, The high-alumina fines have an alumina content of 70-90 wt%.

4. The alumina porous shroud of claim 1, wherein, The high-alumina fines have a particle size of 3000-8000 mesh.

5. The alumina porous shroud of claim 1, wherein, The silicon fines have a silicon dioxide content of 70-90 wt%.

6. The alumina porous shroud of claim 1, wherein, The silicon fines have a particle size of 3000-8000 mesh.

7. The alumina porous shroud of claim 1, wherein, The binder comprises a silica sol having a silicon dioxide content of 20-50 wt%, and the silica sol has a pH of 1-5.

8. A method of producing an alumina porous shell, characterized by, The method comprises the following steps: S1. Alumina hollow spheres, high-alumina fines, and silicon fines are mixed in a certain proportion, and then an appropriate amount of binder is added, followed by mixing, granulation, and compression molding to obtain an alumina porous cover green body; S2. The alumina porous cover green body is dried at 50-120℃ for 2-4 hours, then slowly heated to 500-800℃ to remove glue, then slowly heated to 1500-1650℃ and sintered for 2-4 hours, and then naturally cooled to room temperature in the furnace to obtain an alumina porous cover product.

9. The method for producing an alumina porous cover according to claim 8, characterized by, The compression molding in step S1 is controlled at a pressure of 100-200 MPa.

10. A hydrogen probe for molten steel, characterized by comprising: The metal fixing cover is provided with a metal cap at the bottom end, the coated sand protection pipe is provided with a fire-retardant paper tube in the inner cavity, the inner cavity bottom of the fire-retardant paper tube is provided with a gas joint, the gas joint is communicated with a gas guide assembly, the gas guide assembly comprises a first gas guide pipe and a second gas guide pipe, the first gas guide pipe is provided with alumina hollow spheres in the inner cavity, the bottom of the first gas guide pipe is provided with the alumina porous cover according to any one of claims 1-7 or the alumina porous cover prepared by the preparation method according to any one of claims 8-9, the second gas guide pipe passes through and extends out of the alumina porous cover, and the first gas guide pipe, the second gas guide pipe, and the alumina porous cover are filled with high-temperature-resistant cement.

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