Preparation method and application of potassium hexatitanate-coated aluminum oxide refractory brick

Abstract

The present invention discloses a preparation method of potassium hexatitanate-coated alumina refractory bricks, which comprises the following steps: the surface of the alumina refractory bricks is coated with a potassium hexatitanate slurry, and the alumina refractory bricks coated with the potassium hexatitanate slurry are dried. The solid content of the potassium hexatitanate is 5-25%, and the peak intensities of the diffraction peaks of the potassium hexatitanate at 2θ angles of 11.4±0.3° and 13.78±0.3° in the XRD pattern are both less than the peak intensities of the diffraction peaks at 2θ angles of 29.46±0.3° and 30.06±0.3°. In this application, graphene is added during the electrospinning process, and the added graphene wraps the active planes (200) and (-201), so that the peak intensities of the diffraction peaks of the generated potassium hexatitanate at 2θ angles of 11.4±0.3° and 13.78±0.3° are both less than the peak intensities of the diffraction peaks at 2θ angles of 29.46±0.3° and 30.06±0.3°. The alumina refractory bricks after surface coating with the above potassium hexatitanate slurry have excellent mechanical properties and thermal conductivity, and can meet the application of alumina refractory bricks in a higher temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, and particularly relates to a preparation method and application of a potassium hexa-titanate-coated aluminum oxide refractory brick. Background Art

[0002] Refractory bricks are suitable for use as linings of molten metal containers such as converters, ladles, and smelting reduction furnaces, or as fillers for the tapping openings of blast furnaces, installed in continuous casting equipment, etc., and crucibles of melting furnaces for non-ferrous metals. When manufacturing refractory bricks formed from existing refractory brick compositions, it is difficult to strongly bond refractory aggregates through adhesives. As a result, there are problems related to thermal shock such as bursting or cracking when the refractory bricks are heated to high temperatures, or problems with insufficient strength of the refractory bricks such as compressive strength. Summary of the Invention

[0003] In view of this, an object of the present invention is to provide a preparation method and application of a potassium hexa-titanate-coated aluminum oxide refractory brick to solve one or more of the above-mentioned problems in the prior art.

[0004] To achieve the above object, on the one hand, a preparation method of a potassium hexa-titanate-coated aluminum oxide refractory brick provided by the present invention is characterized by including the following steps:

[0005] Surface coating of an aluminum oxide refractory brick with a potassium hexa-titanate slurry, and drying the aluminum oxide refractory brick coated with the potassium hexa-titanate slurry. The solid content of the potassium hexa-titanate is 5 - 25%, and the potassium hexa-titanate has characteristic diffraction peaks at 2θ angular positions of 11.4 ± 0.3°, 13.78 ± 0.3°, 29.46 ± 0.3°, and 30.06 ± 0.3° in the XRD pattern. The peak intensities of the diffraction peaks at 2θ angles of 11.4 ± 0.3° and 13.78 ± 0.3° are both less than the peak intensities of the diffraction peaks at 2θ angles of 29.46 ± 0.3° and 30.06 ± 0.3°.

[0006] In some embodiments, the aluminum oxide refractory brick is coated with the potassium hexa-titanate slurry by impregnation treatment, and the impregnation time is 3 - 4 h to obtain a potassium hexa-titanate-coated aluminum oxide refractory brick.

[0007] In some embodiments, after the impregnation, the drying treatment temperature is 70 - 80°C, and the drying treatment time is 20 - 24 h.

[0008] In some embodiments, the potassium hexa-titanate is prepared through the following steps:

[0009] Stirring a titanium-containing raw material, a potassium-containing raw material, graphene, PVP, and an aqueous polyethylene glycol solution at room temperature for 12 h to form a uniform mixed solution with a certain viscosity;

[0010] Transfer the mixed solution into an electrospinning container box, and perform electrospinning at a scanning speed of 30 - 50 mm / min, with the voltage set at 20 - 30 kV, the air humidity maintained at 30% RH, and the electrospinning distance adjusted to 15 cm to obtain potassium hexa-titanate fibers;

[0011] Pre-oxidize the potassium hexa-titanate fibers in an air atmosphere and calcine them at a high temperature of 600 - 800 °C for 20 - 120 min to obtain the potassium hexa-titanate.

[0012] In some embodiments, the viscosity of the mixed solution is 2000 - 4000 mPa·S.

[0013] In some embodiments, the mass percentage concentration of polyethylene glycol in the polyethylene glycol aqueous solution is 1% - 10%.

[0014] In some embodiments, the titanium-containing raw material and the potassium-containing raw material are uniformly mixed according to a molar ratio of TiO 2 ︰K 2 O = 4 - 7.

[0015] In some embodiments, the titanium-containing raw material is metatitanic acid and the potassium-containing raw material is potassium sulfate.

[0016] In some embodiments, in the mixed solution, the mass concentration of the titanium-containing raw material and the potassium-containing raw material is 8 - 15%, the mass concentration of graphene is 1 - 3%, the mass concentration of PVP is 3 - 7%, and the mass concentration of the polyethylene glycol aqueous solution is 75 - 88%.

[0017] On the other hand, the present invention provides the application of the potassium hexa-titanate-coated alumina refractory brick obtained by the above method as a refractory material.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] In this application, by adding graphene during the electrospinning process, the added graphene wraps the active planes (2 00) plane and (-2 0 1), such that the peak intensities of the diffraction peaks of the generated potassium hexa-titanate at 2θ angles of 11.4 ± 0.3° and 13.78 ± 0.3° are both less than the peak intensities of the diffraction peaks at 2θ angles of 29.46 ± 0.3° and 30.06 ± 0.3°.

[0020] The above-mentioned potassium hexatitanate slurry-coated alumina refractory brick can change the structure of the alumina refractory brick and reduce the internal pore diameter of the alumina refractory brick. When the solid content of the surface-coated potassium hexatitanate slurry is 10%, the transverse and longitudinal tensile strengths of the alumina refractory brick are increased to 51.3 MPa and 94.4 MPa. In addition, the thermal conductivity of the alumina refractory brick coated with the potassium hexatitanate slurry with a solid content of 10% is reduced to 0.32 W / m·K. The alumina refractory brick with the surface-coated potassium hexatitanate slurry has excellent mechanical properties and thermal conductivity, can meet the application of the alumina refractory brick in a higher temperature environment, and further broadens the application field of the alumina refractory brick. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 XRD pattern of a potassium hexatitanate-coated alumina refractory brick obtained in an embodiment of the present invention;

[0022] Figure 2 SEM image of the surface of a potassium hexatitanate-coated alumina refractory brick obtained in an embodiment of the present invention;

[0023] Figure 3 SEM image of the surface of a potassium hexatitanate-coated alumina refractory brick obtained in an embodiment of the present invention;

[0024] Figure 4 XRD pattern of a potassium hexatitanate-coated alumina refractory brick obtained in a comparative example of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1:

[0027] 6.9 g of metatitanic acid, 3.1 g of potassium sulfate, 2 g of graphene, 4 g of PVP, and 84 g of polyethylene glycol aqueous solution were stirred at room temperature for 12 h to form a uniform and viscous mixed solution;

[0028] The mixed solution was transferred to an electrospinning container box and electrospun at a scanning speed of 30 - 50 mm / min, with the voltage set at 20 - 30 kV, the air humidity maintained at 30% RH, and the electrospinning distance adjusted to 15 cm to obtain potassium hexatitanate fibers;

[0029] The potassium hexatitanate fibers were pre-oxidized in an air atmosphere and calcined at 600 - 800 °C for 20 - 120 min to obtain the potassium hexatitanate;

[0030] The XRD pattern of the potassium hexatitanate is as shown in Figure 1As shown, the potassium hexatitanate has characteristic diffraction peaks at 2θ angular positions of 11.4±0.3°, 13.78±0.3°, 29.46±0.3°, and 30.06±0.3° in the XRD pattern. The peak intensities of the diffraction peaks at 2θ angles of 11.4±0.3° and 13.78±0.3° are both less than those of the diffraction peaks at 2θ angles of 29.46±0.3° and 30.06±0.3°.

[0031] The potassium hexatitanate slurry was coated on the alumina refractory brick by impregnation treatment. The solid content of the potassium hexatitanate was 10%, and the impregnation time was 4 h to obtain a potassium hexatitanate-coated alumina refractory brick. After impregnation, the drying treatment temperature was 80°C, and the drying treatment time was 20 h.

[0032] The SEM images of the surface of the potassium hexatitanate-coated alumina refractory brick are as Figure 2 and 3 shown, with a dense and thermally stable structure formed by the stacking of potassium hexatitanate on the surface of the refractory brick.

[0033] Example 2:

[0034] The difference from Example 1 is that the solid content of the potassium hexatitanate slurry is 5%.

[0035] Example 3:

[0036] The difference from Example 1 is that the solid content of the potassium hexatitanate slurry is 25%.

[0037] Comparative Example 1:

[0038] Commercially available alumina refractory bricks.

[0039] Comparative Example 2:

[0040] The potassium hexatitanate prepared by the method disclosed in Chinese Patent CN106048727B was used to coat the potassium hexatitanate slurry on the alumina refractory brick by impregnation treatment. The solid content of the potassium hexatitanate was 10%, and the impregnation time was 4 h to obtain a potassium hexatitanate-coated alumina refractory brick. After impregnation, the drying treatment temperature was 80°C, and the drying treatment time was 20 h.

[0041] The alumina refractory bricks of Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests. The test methods for measuring the tensile strength and thermal conductivity of the alumina refractory bricks are as follows:

[0042] 1. Tensile strength: Tensile strength is usually measured using an experimental method called a tensile test. The following are the basic steps:

[0043] - Preparation of samples: The samples should be standard rectangles or cylinders and should be ensured to be dry and clean before measurement.

[0044] - Use a tensile testing machine: Mount the sample on the tensile testing machine. This machine gradually increases the force applied to the sample until the sample breaks.

[0045] - Record data: Record the force at which the sample breaks and calculate the tensile strength based on the cross-sectional area of the sample.

[0046] 2. Thermal conductivity: The thermal conductivity is usually measured using a method called the steady-state method. The following are the basic steps:

[0047] - Preparation of samples: The samples should be uniform plates, and the size and thickness should be suitable for the testing device used.

[0048] - Use steady-state method testing equipment: This equipment applies a constant heat flux on one side of the sample and then measures the temperature gradient on the other side of the sample.

[0049] - Record data: Based on the measured heat flux and temperature gradient, the thermal conductivity can be calculated.

[0050] The test results are shown in the following table:

[0051]

[0052] Compared with Comparative Example 1, in Example 1, the alumina refractory brick was coated with potassium hexatitanate slurry, which changed the structure of the alumina refractory brick and reduced the internal pore diameter of the alumina refractory brick, and a dense and thermally stable fiber structure as shown in Figure 2 and 3 was formed on the surface, resulting in a significant improvement in both the mechanical properties and thermal conductivity of the alumina refractory brick.

[0053] Compared with Comparative Example 2, in this application, graphene was added during the electrospinning process. The added graphene wrapped the active planes (2 0 0) and (-2 0 1), making the peak intensities of the diffraction peaks of potassium hexatitanate at 2θ angles of 11.4±0.3° and 13.78±0.3° less than the peak intensities of the diffraction peaks at 2θ angles of 29.46±0.3° and 30.06±0.3°. While for Comparative Example 2, the peak intensities of the diffraction peaks of potassium hexatitanate at 2θ angles of 11.4±0.3° and 13.78±0.3° were greater than the peak intensities of the diffraction peaks at 2θ angles of 29.46±0.3° and 30.06±0.3°.

[0054] The present invention unexpectedly discovers that when the potassium hexatitanate slurry of the above Example 1 is coated on the alumina refractory brick, and when the solid content of the surface-coated potassium hexatitanate slurry is 10%, compared with Comparative Example 2, the transverse and longitudinal tensile strengths of the alumina refractory brick are increased to 51.3 MPa and 94.4 MPa. In addition, the thermal conductivity of the alumina refractory brick coated with the potassium hexatitanate slurry with a solid content of 10% is reduced to 0.32 W / m·K.

[0055] Therefore, the alumina refractory brick after being surface-coated with the potassium hexatitanate slurry prepared in the examples of the present invention has excellent mechanical properties and thermal conductivity, can meet the application of the alumina refractory brick in a higher temperature environment, and further broadens the application field of the alumina refractory brick.

[0056] Finally, it should be noted that those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. The above embodiments and the description in the specification only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements will fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A preparation method of potassium hexa-titanate-coated alumina refractory bricks, characterized in that, it includes the following steps: Surface coating of the alumina refractory bricks with a potassium hexa-titanate slurry, and drying the alumina refractory bricks coated with the potassium hexa-titanate slurry. The solid content of the potassium hexa-titanate slurry is 5-25%, and the potassium hexa-titanate has characteristic diffraction peaks at 2θ angular positions of 11.4±0.3°, 13.78±0.3°, 29.46±0.3° and 30.06±0.3° in the XRD pattern. The peak intensities of the diffraction peaks at 2θ angles of 11.4±0.3° and 13.78±0.3° are both less than the peak intensities of the diffraction peaks at 2θ angles of 29.46±0.3° and 30.06±0.3°; The potassium hexa-titanate is prepared by the following steps: Stirring a titanium-containing raw material, a potassium-containing raw material, graphene, PVP and an aqueous polyethylene glycol solution at room temperature for 12 h to form a uniform mixed solution with a certain viscosity; Transferring the mixed solution to an electrospinning container box, performing electrospinning at a scanning speed of 30-50 mm / min, setting the voltage to 20-30 kV, keeping the air humidity at 30%RH, and adjusting the electrospinning distance to 15 cm to obtain potassium hexa-titanate fibers; Performing pre-oxidation treatment on the potassium hexa-titanate fibers in an air atmosphere and calcining them at 600-800° for 20-120 min to obtain the potassium hexa-titanate.

2. The method according to claim 1, characterized in that, The potassium hexa-titanate slurry is coated on the alumina refractory bricks by impregnation treatment, and the impregnation time is 3-4 h to obtain potassium hexa-titanate-coated alumina refractory bricks.

3. The method according to claim 2, characterized in that, After the impregnation, the drying treatment temperature is 70-80°C and the drying treatment time is 20-24 h.

4. The method according to claim 1, characterized in that, The viscosity of the mixed solution is 2000-4000 mPa·S.

5. The method according to claim 1, characterized in that, The mass percentage concentration of polyethylene glycol in the aqueous polyethylene glycol solution is 1%-10%.

6. The method according to claim 1, characterized in that, Titanium-containing raw materials and potassium-containing raw materials are classified according to TiO 2 :K 2 The molar ratio of O=4 to 7 is mixed uniformly.

7. The method according to claim 6, characterized in that, The titanium-containing raw material is metatitanic acid, and the potassium-containing raw material is potassium sulfate.

8. The method according to claim 1, characterized in that, In the mixed solution, the mass concentration of the titanium-containing raw material and the potassium-containing raw material is 8-15%, the mass concentration of graphene is 1-3%, the mass concentration of PVP is 3-7%, and the mass concentration of the aqueous polyethylene glycol solution is 75-88%.

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