A method for preparing surface coating on thermal insulation tile

Abstract

The present invention provides a method for preparing a surface coating on a thermal insulation tile, belonging to the field of thermal insulation tiles. The method for preparing a surface coating on a thermal insulation tile is composed of the following steps: preparing a first spray coating, preparing a second spray coating, a primary surface treatment, and a secondary surface treatment. The method for preparing a surface coating on a thermal insulation tile of the present invention can improve the defects of existing thermal insulation tiles such as high brittleness, inability to withstand high-speed airflow scouring, and low damage tolerance, while improving the compatibility of the thermal insulation tile substrate and its surface coating, improving the bonding performance of the surface coating and the thermal insulation tile substrate, improving the durability of the thermal insulation tile surface coating, and extending the effective service life; at the same time, it improves the stability of the thermal insulation tile surface coating, improves the thermal matching performance of the surface coating and the thermal insulation tile substrate, and avoids the problems of warping, deformation, and shedding of the surface coating of the thermal insulation tile in a working environment with rapid temperature rise and fall.

Description

Technical Field

[0001] The invention relates to the field of thermal insulation tiles, in particular to a method for preparing a surface coating on a thermal insulation tile. Background Art

[0002] When a hypersonic aircraft flies at high speed for a long time in the atmosphere, its surface is subjected to severe aerodynamic forces and aerodynamic heat, which poses a great safety hazard. Adding lightweight, high-temperature resistant, heat-insulating and wave-transparent thermal insulation materials on the surface of the aircraft can effectively prevent external heat from being transferred to the inside and ensure the normal operation of internal equipment. Therefore, it is very important to insulate the aircraft. The thermal insulation materials on the outer surface of the aircraft play an extremely important role in its safety and flight stability. In recent years, ceramic thermal insulation tiles have gradually become a research hotspot for heat-insulating materials and thermal protection technologies for hypersonic aircraft. Rigid thermal insulation tiles are generally lightweight rigid thermal insulation materials with a three-dimensional mesh structure formed by overlapping one or more short-cut fibers. They have high porosity, certain load-bearing capacity, good wave-transmitting performance and thermal insulation, and are ideal aircraft thermal insulation materials.

[0003] However, the ceramic thermal insulation tile matrix has the defects of high brittleness, inability to withstand high-speed airflow erosion, and low damage tolerance. When the working environment temperature of the ceramic thermal insulation tile is greater than 800K, or when it is used as an anti-thermal insulation component on the surface of a hypersonic aircraft, the surface of the ceramic thermal insulation tile usually needs to be coated with a surface coating to improve the brittleness of the thermal insulation tile matrix, block the erosion of high-temperature and high-speed airflow, and protect the stability of the internal structure of the thermal insulation tile matrix.

[0004] However, the above method has the defect that the compatibility between the insulation tile substrate and its surface coating is poor, and the bonding performance between the surface coating and the insulation tile substrate needs to be further improved; at the same time, the durability of the insulation tile surface coating is poor, and it is prone to aging, cracking, and falling off, and the effective service life is short.

[0005] Furthermore, the surface coating of the thermal insulation tile has poor stability and has thermal matching problems with the thermal insulation tile substrate. In a working environment with rapid temperature rise and fall, the surface coating is prone to warping and deformation due to heat, which in turn leads to a significant reduction in the bonding performance between the surface coating and the thermal insulation tile substrate, and the loss of its due protective performance.

[0006] Therefore, while improving the defects of existing insulation tiles such as high brittleness, inability to withstand high-speed airflow erosion, and low damage tolerance, the compatibility of the insulation tile substrate and its surface coating is improved, the bonding performance between the surface coating and the insulation tile substrate is improved, the durability of the insulation tile surface coating is improved, and the effective service life is extended; at the same time, the stability of the insulation tile surface coating is improved, the thermal matching performance of the surface coating and the insulation tile substrate is improved, and the warping, deformation, and falling off of the surface coating of the insulation tile in a working environment with rapid temperature rise and fall is avoided, which has important technical significance. Summary of the invention

[0007] In order to solve the technical problems existing in the prior art, the present invention provides a method for preparing a surface coating on a thermal insulation tile, which can improve the defects of the existing thermal insulation tiles such as high brittleness, inability to withstand high-speed airflow erosion, and low damage tolerance, while improving the compatibility of the thermal insulation tile substrate and its surface coating, improving the bonding performance between the surface coating and the thermal insulation tile substrate, improving the durability of the thermal insulation tile surface coating, and extending the effective service life; at the same time, the stability of the thermal insulation tile surface coating is improved, and the thermal matching performance of the surface coating and the thermal insulation tile substrate is improved, thereby avoiding the warping, deformation, and falling off of the surface coating of the thermal insulation tile in a working environment with rapid temperature rise and fall.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a surface coating on a heat-insulating tile comprises the following steps: preparing a first spray coating, preparing a second spray coating, primary surface treatment, and secondary surface treatment.

[0010] The method for preparing the first spray coating material comprises the following steps: putting borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder into a ball mill, controlling the ball-to-water ratio to be 4-5:1:0.45-0.5, the ball milling speed to be 200-220 rpm, and drying after ball milling for 50-60 min to obtain a first ball milled powder; then putting the first ball milled powder into 3-3.5 times the weight of a modified coating liquid, stirring at room temperature for 1-2 h, and filtering out solid matter; after the solid matter is allowed to stand at room temperature for 20-24 h, it is transferred into a drying oven, heat-cured at 75-85° C. for 1.5-2 h, heat-cured at 105-115° C. for 1.5-2 h, and ground evenly to obtain a first modified powder; then the first modified powder, ethyl orthosilicate, boron carbide and deionized water are evenly mixed to obtain a first spray coating material.

[0011] In the preparation of the first spray coating, the weight ratio of borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder is 25-27:20-22:2-2.3:10-12:8-9.

[0012] The preparation method of the modified coating liquid is as follows: acetic acid, silane coupling agent KH-550 and silane coupling agent KH-570 are added into anhydrous ethanol, stirred for 10-20 minutes, then formic acid is added, stirred for 5-10 minutes, heated to 32-36° C. in a water bath, kept warm and allowed to stand for 120-130 hours to obtain a composite sol liquid; then the composite sol liquid is added into tetrahydrofuran, stirred for 10-20 minutes, then phenolic resin is added, stirred for 2-3 hours to obtain a modified coating liquid.

[0013] In the preparation of the modified coating solution, the weight ratio of acetic acid, silane coupling agent KH-550, silane coupling agent KH-570, anhydrous ethanol and formic acid is 7-7.3:12-12.5:10.5-11:20-22:2.2-2.5;

[0014] The weight ratio of the composite sol liquid, tetrahydrofuran and phenolic resin is 3.2-3.5:9-9.2:30-32.

[0015] In the preparation of the first spray coating material, the weight ratio of the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 95-100:2-3:0.6-0.7:170-180.

[0016] The method for preparing the second spray coating material comprises: putting borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder into a ball mill, controlling the ball-to-water ratio to be 6-6.5:1:0.45-0.5, the ball milling speed to be 160-180 rpm, ball milling for 50-60 minutes, drying to obtain a second ball milled powder; then putting the second ball milled powder into 7-8 times the weight of a modified treatment liquid, stirring and heating to 40-45° C., keeping the temperature and stirring for 5-6 hours, filtering out solids, drying to obtain a second modified powder; then evenly mixing the second modified powder, ethyl orthosilicate, boron carbide and deionized water to obtain a second spray coating material.

[0017] In the preparation of the second spray coating, the weight ratio of borosilicate glass powder, fused quartz powder, aluminum oxide powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder is 28-30:25-27:2.3-2.5:10-11:10-11:4.5-5:4.5-5.

[0018] The modified treatment liquid is an anhydrous ethanol solution in which bis(dioctyloxypyrophosphate)ethylene titanate is dissolved; the content of bis(dioctyloxypyrophosphate)ethylene titanate in the modified treatment liquid is 5.5-6wt%.

[0019] In the preparation of the second spray coating, the weight ratio of the second modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 95-100:5-6:1.2-1.5:170-180.

[0020] The method for the one-time surface treatment is to mix vinyl trimethoxysilane and ethanol solution (volume concentration is 80-85%) evenly to prepare a pretreatment solution; then completely immerse the thermal insulation tile substrate into 1.5-2 times the volume of the pretreatment solution, control the vacuum degree to 0.08-0.09MPa, and after vacuum immersion for 10-12h, take out the thermal insulation tile substrate; transfer the thermal insulation tile substrate into a drying oven, dry it at 100-105°C to constant weight, and obtain the pretreated thermal insulation tile substrate. Substrate; then evenly spray the first spray coating onto the outer surface of the pretreated thermal insulation tile substrate, control the spraying air pressure to 0.2-0.25MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate to be 10-12cm; after spraying, transfer it to a drying oven, dry it at 85-90℃ for 20-24h, transfer it to a baking furnace, heat it to 800-850℃, keep it warm and bake it for 30-40min, and then cool it to room temperature with the furnace to obtain a single surface treated thermal insulation tile.

[0021] In the primary surface treatment, the weight ratio of vinyltrimethoxysilane to ethanol solution in the pretreatment solution is 12-12.5:100;

[0022] In the thermal insulation tile with a single surface treatment, the coating thickness formed by the first spray coating on the outer surface of the pre-treated thermal insulation tile substrate is 1.2-1.3 mm.

[0023] The secondary surface treatment method is as follows: placing the thermal insulation tile with the primary surface treatment in a plasma treatment device, controlling the distance between the discharge center in the plasma treatment device and the outer surface of the thermal insulation tile with the primary surface treatment to be 10-12 cm; then in an argon environment, controlling the plasma treatment frequency to be 4-4.2 MHz, the discharge power to be 400-500 W, performing plasma treatment for 8-12 minutes, and obtaining a surface-activated thermal insulation tile; then uniformly spraying the second spray coating onto the outer surface of the surface-activated thermal insulation tile, controlling the spraying air pressure to be 0.25-0.3 MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate to be 10-12 cm; after the spraying is completed, transferring to a drying oven, drying at 85-90° C. for 20-24 hours, transferring to a baking furnace, heating to 1000-1050° C., keeping warm and baking for 50-60 minutes, cooling to room temperature with the furnace, and obtaining a thermal insulation tile with a surface coating.

[0024] In the secondary surface treatment, in the secondary surface treated thermal insulation tile, the coating thickness formed by the second spray coating on the outer surface of the surface activated thermal insulation tile is 0.5-0.6mm.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The method for preparing a surface coating on a heat-insulating tile of the present invention comprises the following steps: in the step of preparing a first spray coating material, borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder, and tantalum boride powder are selected to prepare a first ball-milled powder, and then a modified coating liquid is used to modify and coat the first ball-milled powder to obtain a first modified powder, and then a first spray coating material is prepared using the first modified powder; in the preparation of the modified coating liquid, silane coupling agent KH-550 and silane coupling agent KH-570 are used to hydrolyze under the promotion of formic acid and acetic acid to form a sol, which is combined with a phenolic resin to form a mutually cross-linked body structure to prepare a modified coating liquid; and the first ball-milled powder is coated and modified by the modified coating liquid. The invention discloses a method for preparing a second spray coating material, wherein the first spray coating material is used to improve the compatibility and bonding performance between the first spray coating material and the heat insulating tile substrate, and the thermal matching performance between the first spray coating material and the heat insulating tile substrate is improved, and the stability of the first spray coating material is improved; and the first spray coating material serves as a transition layer to connect the heat insulating tile substrate and the second spray coating material, and further improves the stability of the surface coating of the heat insulating tile in a working environment where the temperature rises and falls rapidly; in the step of preparing the second spray coating material, after the second ball milled powder is prepared from borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder, and tantalum boride powder, the second ball milled powder is modified by a chelated titanate coupling agent to prepare a second spray coating material; by chelating The modification effect of the type titanate coupling agent on the second ball-milled powder promotes the bonding effect between the second spray coating and the surface activated thermal insulation tile after plasma treatment, further improves the bonding performance of the second spray coating and the surface activated thermal insulation tile, and improves the durability of the coating; then in the first surface treatment step, vinyl trimethoxy silane is used to perform surface hydrophobic modification on the thermal insulation tile substrate, which promotes the spreading and adhesion of the subsequently sprayed first spray coating on the outer surface of the thermal insulation tile substrate, thereby forming a uniform surface coating and improving the bonding performance of the first spray coating and the thermal insulation tile substrate; then in the secondary surface treatment step, the first surface treated thermal insulation tile is firstly subjected to plasma treatment, and the plasma high The energy particles can activate the outer surface of the thermal insulation tile with a single surface treatment, further promoting its bonding performance with the second spray coating; the aforementioned technical means cooperate with each other and work synergistically to improve the defects of existing thermal insulation tiles, such as high brittleness, inability to withstand high-speed airflow erosion, and low damage tolerance, while improving the compatibility of the thermal insulation tile substrate and its surface coating, improving the bonding performance between the surface coating and the thermal insulation tile substrate, improving the durability of the thermal insulation tile surface coating, and extending the effective service life; at the same time, improving the stability of the thermal insulation tile surface coating, improving the thermal matching performance between the surface coating and the thermal insulation tile substrate, and avoiding the warping, deformation, and shedding of the surface coating of the thermal insulation tile in a working environment with rapid temperature rise and fall.

[0027] (2) The method for preparing a surface coating on a thermal insulation tile of the present invention, wherein the thermal insulation tile having a surface coating has no deformation, warping, or delamination of the surface coating, and the thermal insulation tile having a surface coating has a tensile strength of 1.8-1.9 MPa, a compressive strength of 4.6-4.7 MPa, and a fracture toughness of 0.90-0.93 MPa·m 1 / 2 The bonding strength between the surface coating and the thermal insulation tile is 4.2-4.5MPa.

[0028] (3) The method for preparing a surface coating on a thermal insulation tile of the present invention, wherein the thermal insulation tile having a surface coating is subjected to an indenter load of 40N and a hemispherical indenter (indenter diameter 6mm) is used to maintain the load for 30 minutes. The surface coating of the thermal insulation tile has no through cracks. After the load is removed, the bonding strength between the surface coating and the thermal insulation tile can still reach 4.1-4.4MPa, and the thermal insulation tile has good resistance to contact damage.

[0029] (4) The method for preparing a surface coating on a thermal insulation tile of the present invention, after the thermal insulation tile with a surface coating has been subjected to 20 rapid temperature changes (from room temperature to 1300°C), the surface coating has no deformation, warping, or delamination, and the fracture toughness can still reach 0.87-0.88MPa·m 1 / 2 The bonding strength between the surface coating and the thermal insulation tile is 4.1-4.3MPa. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0031] Example 1

[0032] This embodiment provides a method for preparing a surface coating on a thermal insulation tile, specifically:

[0033] 1. Prepare the first spray coating

[0034] Borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder are put into a ball mill, the ball-to-water ratio is controlled to be 4:1:0.45, the ball mill speed is 200 rpm, and after ball milling for 50 minutes, it is dried to obtain a first ball-milled powder; then the first ball-milled powder is put into 3 times the weight of the modified coating liquid, stirred at room temperature for 1 hour, and the solid is filtered out; after the solid is allowed to stand at room temperature for 20 hours, it is transferred to a drying oven, heat-cured at 75°C for 1.5 hours, and then heat-cured at 105°C for 1.5 hours, and ground evenly to obtain a first modified powder; then the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water are evenly mixed to obtain a first spray coating.

[0035] Among them, the weight ratio of borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder is 25:20:2:10:8.

[0036] The preparation method of the modified coating liquid is as follows: acetic acid, silane coupling agent KH-550 and silane coupling agent KH-570 are added to anhydrous ethanol, stirred for 10 minutes, then formic acid is added, stirred for 5 minutes, heated to 32° C. in a water bath, kept warm and allowed to stand for 120 hours to obtain a composite sol liquid; then the composite sol liquid is added to tetrahydrofuran, stirred for 10 minutes, then phenolic resin is added, stirred for 2 hours to obtain a modified coating liquid.

[0037] The weight ratio of acetic acid, silane coupling agent KH-550, silane coupling agent KH-570, anhydrous ethanol and formic acid is 7:12:10.5:20:2.2.

[0038] The weight ratio of the composite sol liquid, tetrahydrofuran and phenolic resin is 3.2:9:30.

[0039] The weight ratio of the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 95:2:0.6:170.

[0040] 2. Prepare the second spray coating

[0041] Borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder are put into a ball mill, the ball-to-water ratio is controlled to be 6:1:0.45, the ball mill speed is 160 rpm, and after ball milling for 50 minutes, the second ball milled powder is dried to obtain a second ball milled powder; the second ball milled powder is then put into 7 times the weight of the modified treatment liquid, stirred and heated to 40°C, kept warm and stirred for 5 hours, the solid matter is filtered out, and dried to obtain a second modified powder; the second modified powder, tetraethyl orthosilicate, boron carbide and deionized water are then evenly mixed to obtain a second spray coating.

[0042] Among them, the weight ratio of borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder is 28:25:2.3:10:10:4.5:4.5.

[0043] The modified treatment liquid is an anhydrous ethanol solution in which bis(dioctyloxypyrophosphate)ethylene titanate is dissolved; the content of bis(dioctyloxypyrophosphate)ethylene titanate in the modified treatment liquid is 5.5wt%.

[0044] The weight ratio of the second modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 95:5:1.2:170.

[0045] 3. Primary surface treatment

[0046] Vinyltrimethoxysilane and ethanol solution (volume concentration of 80%) were mixed evenly to prepare a pretreatment liquid; then the thermal insulation tile substrate was completely immersed in 1.5 times the volume of the pretreatment liquid, the vacuum degree was controlled to be 0.08MPa, and after vacuum immersion for 10 hours, the thermal insulation tile substrate was taken out; the thermal insulation tile substrate was transferred to a drying oven, dried at 100°C to constant weight, and a pretreated thermal insulation tile substrate was obtained; then the first spray coating was evenly sprayed onto the outer surface of the pretreated thermal insulation tile substrate, the spraying air pressure was controlled to be 0.2MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate was 10cm; after spraying was completed, it was transferred to a drying oven, dried at 85°C for 20 hours, and then transferred to a baking furnace, heated to 800°C, and baked at this temperature for 30 minutes, and then cooled to room temperature with the furnace to obtain a single surface treated thermal insulation tile.

[0047] Wherein, the weight ratio of vinyltrimethoxysilane to ethanol solution in the pretreatment solution is 12:100.

[0048] In the thermal insulation tile with a single surface treatment, the coating thickness formed by the first spray coating on the outer surface of the pre-treated thermal insulation tile substrate is 1.2 mm.

[0049] 4. Secondary surface treatment

[0050] Place the thermal insulation tile with a single surface treatment in a plasma treatment device, and control the distance between the discharge center in the plasma treatment device and the outer surface of the thermal insulation tile with a single surface treatment to be 10 cm; then, in an argon environment, control the plasma treatment frequency to be 4 MHz, the discharge power to be 400 W, and perform plasma treatment for 8 minutes to obtain a surface-activated thermal insulation tile; then, spray the second spray coating evenly onto the outer surface of the surface-activated thermal insulation tile, control the spraying air pressure to be 0.25 MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate to be 10 cm; after spraying, transfer it to a drying oven, dry it at 85°C for 20 hours, transfer it to a baking furnace, heat it to 1000°C, keep it warm and bake it for 50 minutes, and then cool it to room temperature with the furnace to obtain a thermal insulation tile with a surface coating.

[0051] Among them, in the secondary surface treated thermal insulation tile, the coating thickness formed by the second spray coating on the outer surface of the surface activated thermal insulation tile is 0.5mm.

[0052] Example 2

[0053] This embodiment provides a method for preparing a surface coating on a thermal insulation tile, specifically:

[0054] 1. Prepare the first spray coating

[0055] Borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder are put into a ball mill, the ball-to-water ratio is controlled to be 4.3:1:0.47, the ball mill speed is 210 rpm, and after ball milling for 55 minutes, it is dried to obtain a first ball-milled powder; then the first ball-milled powder is put into 3.2 times the weight of the modified coating liquid, stirred at room temperature for 1.5 hours, and the solid is filtered out; after the solid is allowed to stand at room temperature for 22 hours, it is transferred to a drying oven, and heat-cured at 80°C for 1.75 hours, and then heat-cured at 110°C for 1.75 hours, and ground evenly to obtain a first modified powder; then the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water are evenly mixed to obtain a first spray coating.

[0056] Among them, the weight ratio of borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder is 26:21:2.2:11:8.5.

[0057] The preparation method of the modified coating liquid is as follows: acetic acid, silane coupling agent KH-550 and silane coupling agent KH-570 are added to anhydrous ethanol, stirred for 15 minutes, then formic acid is added, stirred for 8 minutes, heated to 35° C. in a water bath, kept warm and allowed to stand for 125 hours to obtain a composite sol liquid; then the composite sol liquid is added to tetrahydrofuran, stirred for 15 minutes, then phenolic resin is added, stirred for 2.5 hours to obtain a modified coating liquid.

[0058] The weight ratio of acetic acid, silane coupling agent KH-550, silane coupling agent KH-570, anhydrous ethanol and formic acid is 7.2:12.3:10.8:21:2.4.

[0059] The weight ratio of the composite sol liquid, tetrahydrofuran and phenolic resin is 3.3:9.1:31.

[0060] The weight ratio of the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 97:2.5:0.65:175.

[0061] 2. Prepare the second spray coating

[0062] Borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder are put into a ball mill, the ball-to-water ratio is controlled to be 6.3:1:0.47, the ball mill speed is 170 rpm, and after ball milling for 55 minutes, the second ball milled powder is dried to obtain a second ball milled powder; the second ball milled powder is then put into 7.5 times the weight of the modified treatment liquid, stirred and heated to 42°C, kept warm and stirred for 5.5 hours, the solid matter is filtered out, and dried to obtain a second modified powder; the second modified powder, ethyl orthosilicate, boron carbide and deionized water are then evenly mixed to obtain a second spray coating.

[0063] Among them, the weight ratio of borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder is 29:26:2.4:10.5:10.5:4.7:4.7.

[0064] The modified treatment liquid is an anhydrous ethanol solution in which bis(dioctyloxypyrophosphate)ethylene titanate is dissolved; the content of bis(dioctyloxypyrophosphate)ethylene titanate in the modified treatment liquid is 5.8wt%.

[0065] The weight ratio of the second modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 98:5.5:1.3:175.

[0066] 3. Primary surface treatment

[0067] Vinyltrimethoxysilane and ethanol solution (volume concentration of 82%) were mixed evenly to prepare a pretreatment liquid; then the thermal insulation tile substrate was completely immersed in 1.8 times the volume of the pretreatment liquid, the vacuum degree was controlled to be 0.085MPa, and after vacuum immersion for 11 hours, the thermal insulation tile substrate was taken out; the thermal insulation tile substrate was transferred to a drying oven and dried at 102°C to constant weight to obtain a pretreated thermal insulation tile substrate; then the first spray coating was evenly sprayed onto the outer surface of the pretreated thermal insulation tile substrate, the spraying air pressure was controlled to be 0.23MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate was 11cm; after spraying, it was transferred to a drying oven, dried at 88°C for 22 hours, and then transferred to a baking furnace, heated to 830°C, and baked at this temperature for 35 minutes, and then cooled to room temperature with the furnace to obtain a single surface treated thermal insulation tile.

[0068] Wherein, the weight ratio of vinyltrimethoxysilane to ethanol solution in the pretreatment solution is 12.2:100.

[0069] In the thermal insulation tile with a single surface treatment, the coating thickness formed by the first spray coating on the outer surface of the pre-treated thermal insulation tile substrate is 1.25 mm.

[0070] 4. Secondary surface treatment

[0071] Place the thermal insulation tile with a single surface treatment in a plasma treatment device, and control the distance between the discharge center in the plasma treatment device and the outer surface of the thermal insulation tile with a single surface treatment to be 11 cm; then, in an argon environment, control the plasma treatment frequency to be 4.1 MHz, and the discharge power to be 450 W, and perform plasma treatment for 10 minutes to obtain a surface-activated thermal insulation tile; then, spray the second spray coating evenly onto the outer surface of the surface-activated thermal insulation tile, control the spraying air pressure to be 0.28 MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate to be 11 cm; after spraying, transfer to a drying oven, dry at 88°C for 22 hours, transfer to a baking furnace, heat to 1030°C, and bake at this temperature for 55 minutes, and then cool to room temperature with the furnace to obtain a thermal insulation tile with a surface coating.

[0072] Among them, in the secondary surface treated thermal insulation tile, the coating thickness formed by the second spray coating on the outer surface of the surface activated thermal insulation tile is 0.55mm.

[0073] Example 3

[0074] This embodiment provides a method for preparing a surface coating on a thermal insulation tile, specifically:

[0075] 1. Prepare the first spray coating

[0076] Borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder are put into a ball mill, the ball-to-water ratio is controlled to be 5:1:0.5, the ball mill speed is 220 rpm, and after ball milling for 60 minutes, it is dried to obtain a first ball-milled powder; then the first ball-milled powder is put into 3.5 times the weight of the modified coating liquid, stirred at room temperature for 2 hours, and the solid is filtered out; after the solid is allowed to stand at room temperature for 24 hours, it is transferred to a drying oven, heat-cured at 85°C for 2 hours, and then heat-cured at 115°C for 2 hours, and ground evenly to obtain a first modified powder; then the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water are evenly mixed to obtain a first spray coating.

[0077] Among them, the weight ratio of borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder is 27:22:2.3:12:9.

[0078] The preparation method of the modified coating liquid is as follows: acetic acid, silane coupling agent KH-550 and silane coupling agent KH-570 are added to anhydrous ethanol, stirred for 20 minutes, then formic acid is added, stirred for 10 minutes, heated to 36° C. in a water bath, kept warm and allowed to stand for 130 hours to obtain a composite sol liquid; then the composite sol liquid is added to tetrahydrofuran, stirred for 20 minutes, then phenolic resin is added, stirred for 3 hours to obtain a modified coating liquid.

[0079] The weight ratio of acetic acid, silane coupling agent KH-550, silane coupling agent KH-570, anhydrous ethanol and formic acid is 7.3:12.5:11:22:2.5.

[0080] The weight ratio of the composite sol liquid, tetrahydrofuran and phenolic resin is 3.5:9.2:32.

[0081] The weight ratio of the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 100:3:0.7:180.

[0082] 2. Prepare the second spray coating

[0083] Borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder are put into a ball mill, the ball-to-water ratio is controlled to be 6.5:1:0.5, the ball mill speed is 180 rpm, and after ball milling for 60 minutes, the second ball milled powder is dried to obtain a second ball milled powder; the second ball milled powder is then put into 8 times the weight of the modified treatment liquid, stirred and heated to 45°C, kept warm and stirred for 6 hours, the solid matter is filtered out, and dried to obtain a second modified powder; the second modified powder, ethyl orthosilicate, boron carbide and deionized water are then evenly mixed to obtain a second spray coating.

[0084] Among them, the weight ratio of borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder is 30:27:2.5:11:11:5:5.

[0085] The modified treatment liquid is an anhydrous ethanol solution in which bis(dioctyloxypyrophosphate)ethylene titanate is dissolved; the content of bis(dioctyloxypyrophosphate)ethylene titanate in the modified treatment liquid is 6wt%.

[0086] The weight ratio of the second modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 100:6:1.5:180.

[0087] 3. Primary surface treatment

[0088] Vinyltrimethoxysilane and ethanol solution (volume concentration of 85%) were mixed evenly to prepare a pretreatment liquid; then the thermal insulation tile substrate was completely immersed in 2 times the volume of the pretreatment liquid, the vacuum degree was controlled to be 0.09MPa, and after vacuum immersion for 12 hours, the thermal insulation tile substrate was taken out; the thermal insulation tile substrate was transferred to a drying oven and dried at 105°C to constant weight to obtain a pretreated thermal insulation tile substrate; then the first spray coating was evenly sprayed onto the outer surface of the pretreated thermal insulation tile substrate, the spraying air pressure was controlled to be 0.25MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate was 12cm; after spraying, it was transferred to a drying oven, dried at 90°C for 24 hours, and then transferred to a baking furnace, heated to 850°C, and baked at this temperature for 40 minutes, and then cooled to room temperature with the furnace to obtain a single surface treated thermal insulation tile.

[0089] Wherein, the weight ratio of vinyltrimethoxysilane to ethanol solution in the pretreatment solution is 12.5:100.

[0090] In the thermal insulation tile with a single surface treatment, the coating thickness formed by the first spray coating on the outer surface of the pre-treated thermal insulation tile substrate is 1.3 mm.

[0091] 4. Secondary surface treatment

[0092] Place the thermal insulation tile with a single surface treatment in a plasma treatment device, and control the distance between the discharge center in the plasma treatment device and the outer surface of the thermal insulation tile with a single surface treatment to be 12 cm; then, in an argon environment, control the plasma treatment frequency to be 4.2 MHz, and the discharge power to be 500 W, and perform plasma treatment for 12 minutes to obtain a surface-activated thermal insulation tile; then, spray the second spray coating evenly onto the outer surface of the surface-activated thermal insulation tile, control the spraying air pressure to be 0.3 MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate to be 12 cm; after spraying, transfer it to a drying oven, dry it at 90°C for 24 hours, and then transfer it to a baking furnace, heat it to 1050°C, and bake it for 60 minutes, and then cool it to room temperature with the furnace to obtain a thermal insulation tile with a surface coating.

[0093] Among them, in the secondary surface treated thermal insulation tile, the coating thickness formed by the second spray coating on the outer surface of the surface activated thermal insulation tile is 0.6mm.

[0094] Comparative Example 1

[0095] The technical solution of Example 2 is adopted, but the differences are as follows: 1) in the step of preparing the first spray coating material, the use of the modified coating liquid is omitted, and the first ball-milled powder is evenly mixed with tetraethyl orthosilicate, boron carbide, and deionized water to obtain the first spray coating material; 2) in the secondary surface treatment step, the plasma treatment is omitted.

[0096] Comparative Example 2

[0097] The technical scheme of Example 2 is adopted, but it differs in that: 1) in the step of preparing the second spray coating material, the use of the modified treatment liquid is omitted, and the second ball-milled powder is evenly mixed with tetraethyl orthosilicate, boron carbide and deionized water to obtain the second spray coating material; 2) in the primary surface treatment step, the treatment of the thermal insulation tile substrate with the pretreatment liquid containing vinyltrimethoxysilane is omitted, and the first spray coating material is directly sprayed on the thermal insulation tile substrate.

[0098] The surface coating on the thermal insulation tile is prepared by the method of Examples 1-3 and Comparative Examples 1-2, and the thermal insulation tile with the surface coating is observed to see whether the surface coating is deformed, warped, or delaminated. The tensile strength, compressive strength, fracture toughness, bonding strength between the surface coating and the thermal insulation tile, and contact damage resistance of the surface coating are respectively tested.

[0099] Among them, the tensile strength of the insulation tile matrix used in Example 1-3 and Comparative Example 1-2 is 1.3 MPa, the compressive strength is 4.4 MPa, and the fracture toughness is 0.47 MPa.

[0100] The fracture toughness was tested using the single edge notched beam method (SENB method).

[0101] The detection method of the contact damage resistance of the surface coating is to take the four corners and the center (a total of five points) of the outer surface of the thermal insulation tile as the test points, and use a universal testing machine in the fixed load mode, using a hemispherical indenter (indenter diameter 6mm), under the condition of the indenter load of 40N, while maintaining the load on the five test points for 30 minutes, observe whether the surface coating has any through cracks; after removing the load, detect the bonding strength between the surface coating and the thermal insulation tile.

[0102] The specific results are shown in the following table:

[0103]

[0104] Furthermore, the thermal insulation tiles with surface coatings prepared in Examples 1-3 and Comparative Examples 1-2 were respectively transferred to a high-temperature box furnace, and the heating rate and cooling rate were controlled to be 30°C / min, and 20 temperature changes were performed between room temperature and 1300°C; wherein, after the temperature of the thermal insulation tile reached room temperature or 1300°C, it was kept warm for 20 minutes, and then continued to be heated or cooled; after the 20 temperature changes were completed, the surface coating of the thermal tile was observed to see if there was any deformation, warping, or delamination after the 20 temperature changes, and the fracture toughness of the thermal insulation tile and the bonding strength between the surface coating and the thermal insulation tile after 20 temperature changes were tested. The specific results are shown in the following table:

[0105]

[0106] It can be seen that the method for preparing a surface coating on a thermal insulation tile of the present invention, in the step of preparing a first spray coating, borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder, and tantalum boride powder are selected to prepare a first ball-milled powder, and then the first ball-milled powder is modified and coated with a modified coating liquid to obtain a first modified powder, and then the first modified powder is used to prepare a first spray coating; in the preparation of the modified coating liquid, silane coupling agent KH-550 and silane coupling agent KH-570 are used under the promotion of formic acid and acetic acid to hydrolyze to form a sol, which is combined with a phenolic resin to form a mutually cross-linked body structure to prepare a modified coating liquid; the first ball-milled powder is coated with the modified coating liquid to modify the coating. The first spray coating layer acts as a transition layer to connect the thermal insulation tile substrate and the second spray coating layer, thereby further improving the stability of the surface coating of the thermal insulation tile in a working environment where the temperature rises and falls rapidly. In the step of preparing the second spray coating layer, the second ball-milled powder is prepared from borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder, and tantalum boride powder, and then the second ball-milled powder is modified by a chelated titanate coupling agent to prepare a second spray coating layer. The modification effect of the combined titanate coupling agent on the second ball-milled powder promotes the bonding effect between the second spray coating and the surface activated thermal insulation tile after plasma treatment, further improves the bonding performance of the second spray coating and the surface activated thermal insulation tile, and improves the durability of the coating; then in the first surface treatment step, vinyl trimethoxy silane is used to perform surface hydrophobic modification on the thermal insulation tile substrate, which promotes the spreading and adhesion of the subsequently sprayed first spray coating on the outer surface of the thermal insulation tile substrate, thereby forming a uniform surface coating and improving the bonding performance of the first spray coating and the thermal insulation tile substrate; then in the secondary surface treatment step, the first surface treated thermal insulation tile is firstly subjected to plasma treatment, and the plasma high The energy particles can activate the outer surface of the thermal insulation tile with a single surface treatment, further promoting its bonding performance with the second spray coating; the aforementioned technical means cooperate with each other and work synergistically to improve the defects of existing thermal insulation tiles, such as high brittleness, inability to withstand high-speed airflow erosion, and low damage tolerance, while improving the compatibility of the thermal insulation tile substrate and its surface coating, improving the bonding performance between the surface coating and the thermal insulation tile substrate, improving the durability of the thermal insulation tile surface coating, and extending the effective service life; at the same time, improving the stability of the thermal insulation tile surface coating, improving the thermal matching performance between the surface coating and the thermal insulation tile substrate, and avoiding the warping, deformation, and shedding of the surface coating of the thermal insulation tile in a working environment with rapid temperature rise and fall.

[0107] Unless otherwise specified, all percentages used in the present invention are by mass.

[0108] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a surface coating on a thermal insulation tile, characterized in that: The method comprises the following steps: preparing a first spray coating material, preparing a second spray coating material, performing a primary surface treatment, and performing a secondary surface treatment; The method for preparing the first spray coating material comprises: evenly grinding borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder to obtain a first ball-milled powder; then adding the first ball-milled powder into a modified coating liquid, stirring at room temperature, and filtering out solids; after the solids are allowed to stand at room temperature and heated to solidify, a first modified powder is obtained; then the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water are evenly mixed to obtain a first spray coating material; The preparation method of the modified coating liquid comprises the following steps: uniformly mixing acetic acid, silane coupling agent KH-550, silane coupling agent KH-570, anhydrous ethanol and formic acid, heating the mixture to 32-36° C. in a water bath, and keeping the mixture still to obtain a composite sol liquid; then adding the composite sol liquid into tetrahydrofuran and mixing the mixture uniformly, and then adding phenolic resin and stirring the mixture for 2-3 hours to obtain a modified coating liquid; The method for preparing the second spray coating comprises: evenly grinding borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder and tantalum boride powder to obtain a second ball-milled powder; adding the second ball-milled powder into a modified treatment liquid, heating the liquid to 40-45° C., stirring the liquid at the temperature, filtering out solids, and drying the liquid to obtain a second modified powder; and evenly mixing the second modified powder, ethyl orthosilicate, boron carbide and deionized water to obtain a second spray coating; The modified treatment liquid is an anhydrous ethanol solution in which bis(dioctyloxypyrophosphate)ethylene titanate is dissolved; The method for the primary surface treatment comprises: uniformly mixing vinyl trimethoxysilane with an ethanol solution to obtain a pretreatment liquid; vacuum impregnating the heat insulation tile substrate with the pretreatment liquid, and drying to obtain a pretreatment heat insulation tile substrate; spraying a first spray coating onto the outer surface of the pretreatment heat insulation tile substrate, and drying and calcining to obtain a primary surface treated heat insulation tile; The secondary surface treatment method is as follows: the primary surface treated thermal insulation tile is subjected to plasma treatment to obtain a surface activated thermal insulation tile; a second spray coating is sprayed onto the outer surface of the surface activated thermal insulation tile, and after drying and baking, a thermal insulation tile with a surface coating is obtained.

2. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the preparation of the first spray coating material, the weight ratio of the first ball-milled powder to the modified coating liquid is 1:3-3.5; The standing time at room temperature is 20-24h; Heat curing is to keep the temperature at 75-85℃ for 1.5-2h, and then keep the temperature at 105-115℃ for 1.5-2h.

3. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the preparation of the first spray coating, the weight ratio of borosilicate glass powder, fused quartz powder, zirconium oxide powder, hafnium boride powder and tantalum boride powder is 25-27:20-22:2-2.3:10-12:8-9; The weight ratio of the first modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 95-100:2-3:0.6-0.7:170-180.

4. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the preparation of the modified coating solution, the temperature is kept at 32-36°C for 120-130 hours; The weight ratio of acetic acid, silane coupling agent KH-550, silane coupling agent KH-570, anhydrous ethanol and formic acid is 7-7.3:12-12.5:10.5-11:20-22:2.2-2.5; The weight ratio of the composite sol liquid, tetrahydrofuran and phenolic resin is 3.2-3.5:9-9.2:30-32.

5. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the preparation of the second spray coating, the weight ratio of the second ball-milled powder to the modified treatment liquid is 1:7-8; Keep stirring at 40-45℃ for 5-6h; The content of bis(dioctyloxypyrophosphate)ethylene titanate in the modified treatment liquid is 5.5-6wt%.

6. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the preparation of the second spray coating, the weight ratio of borosilicate glass powder, fused quartz powder, alumina powder, molybdenum dioxide powder, silicon tetraborate powder, hafnium boride powder, and tantalum boride powder is 28-30:25-27:2.3-2.5:10-11:10-11:4.5-5:4.5-5; The weight ratio of the second modified powder, tetraethyl orthosilicate, boron carbide and deionized water is 95-100:5-6:1.2-1.5:170-180.

7. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the primary surface treatment, the volume concentration of the ethanol solution in the pretreatment solution is 80-85%; The weight ratio of vinyltrimethoxysilane to ethanol solution in the pretreatment solution is 12-12.5:100; The vacuum degree of vacuum impregnation is 0.08-0.09MPa, and the vacuum impregnation time is 10-12h.

8. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the primary surface treatment, the air pressure of the first spray coating is controlled to be 0.2-0.25 MPa, and the distance from the nozzle to the outer surface of the thermal insulation tile substrate is 10-12 cm; After spraying, the drying temperature is 85-90℃, and the drying time is 20-24h; the roasting temperature is 800-850℃, and the roasting time is 30-40min; The coating thickness formed by the first spray coating on the outer surface of the pre-treated thermal insulation tile substrate is 1.2-1.3 mm.

9. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the secondary surface treatment, the distance between the discharge center in the plasma treatment device and the outer surface of the primary surface treatment thermal insulation tile is controlled to be 10-12 cm; the plasma treatment is carried out in an argon environment, the plasma treatment frequency is 4-4.2 MHz, the discharge power is 400-500 W, and the plasma treatment time is 8-12 min.

10. The method for preparing a surface coating on a thermal insulation tile according to claim 1, characterized in that: In the secondary surface treatment, the air pressure of the first spray coating is controlled to be 0.25-0.3MPa, and the distance from the nozzle to the outer surface of the insulation tile substrate is 10-12cm; The drying temperature after spraying is 85-90℃, and the drying time is 20-24h; the roasting temperature is 1000-1050℃, and the roasting time is 50-60min; The coating thickness formed by the second spray coating on the outer surface of the surface activated thermal insulation tile is 0.5-0.6mm.

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