阅读说明：本技术 一种氧化铝纤维增强的耐高温抗冲刷保温材料的制备方法 (Preparation method of alumina fiber reinforced high-temperature-resistant anti-scouring heat-insulating material ) 是由 阳海棠 于 2021-02-01 设计创作，主要内容包括：本发明属于陶瓷基复合材料技术领域,尤其涉及一种氧化铝纤维增强的耐高温抗冲刷保温材料的制备方法。所述制备方法包括下述步骤：S1.氧化铝预制体的制备、S2.制备耐高温涂料的浆料、S3.制备氧化铝预制体耐高温涂层、S4制备复合材料坯体、S5低温烧结制备氧化铝基体复合材料。本发明将氧化铝预制体浸泡在改性剂中,浸泡完成后,将S2所得浆料浸渍和/或涂覆和/或沉积到改性后的坯体上,这一设计能够快速、高效、均匀的获得优质耐高温涂层,配合后续的工艺制备出能同时满足耐高温抗冲刷保温绝热以及耐高温抗冲刷保温绝缘要求的材料。本发明步骤设计合理,过程简单可控,便于大规模的产业化应用。(The invention belongs to the technical field of ceramic matrix composite materials, and particularly relates to a preparation method of an alumina fiber reinforced high-temperature-resistant anti-scouring heat-insulating material. The preparation method comprises the following steps: s1, preparing an aluminum oxide preform, S2, preparing slurry of a high-temperature-resistant coating, S3, preparing a high-temperature-resistant coating of the aluminum oxide preform, S4, preparing a composite material blank, and S5, sintering at a low temperature, and preparing the aluminum oxide matrix composite material. According to the invention, the alumina preform is soaked in the modifier, and after the soaking is finished, the slurry obtained in S2 is soaked and/or coated and/or deposited on the modified blank, so that a high-quality high-temperature-resistant coating can be rapidly, efficiently and uniformly obtained, and the material capable of meeting the requirements of high-temperature-resistant scouring-resistant heat insulation and high-temperature-resistant scouring-resistant heat insulation can be prepared by matching with a subsequent process. The method has reasonable step design and simple and controllable process, and is convenient for large-scale industrial application.)

1. A preparation method of a high-temperature-resistant and anti-scouring alumina fiber reinforced heat-insulating composite material is characterized by comprising the following steps of; the method comprises the following steps:

s1, preparation of aluminum oxide preform

Preparing an alumina preform with pores according to requirements;

s2, preparing slurry of high-temperature-resistant coating

Putting ceramic powder, a solvent, a dispersant and an adhesive into a ball milling tank according to a certain proportion, ball milling and mixing uniformly, then adding ammonia water to adjust the pH value to 7-9, or adding an acidic solution to adjust the pH value to 3-5, and stirring uniformly to prepare alumina fiber high-temperature-resistant coating slurry;

s3, preparing the high-temperature-resistant coating of the aluminum oxide preform

Soaking the S1 alumina preform in a modifier, and after soaking, washing the alumina preform with an aqueous solution with the pH of 3-5 or 9-10 to obtain a modified blank; then impregnating and/or coating and/or depositing the slurry obtained in the step S2 on the modified green body; sintering at a high temperature of 400-1400 ℃; obtaining a uniform high-temperature coating of 50-500 nm on the surface of the prefabricated fiber; the modifier is selected from at least one of polyethyleneimine, polyvinyl acetate, polyethylene glycol, polymethyl methacrylate and acrylic resin;

s4 preparation of composite material blank

Placing the alumina preform with the high-temperature-resistant coating obtained in the step S3 into alumina matrix slurry for pressure impregnation to obtain a composite material blank;

s5 low-temperature sintering preparation of alumina matrix composite material

Sintering the composite material blank to obtain the high-temperature-resistant and anti-scouring alumina matrix composite material.

2. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 1, characterized by comprising the following steps:

s4, the preparation of the composite material blank specifically comprises the following steps:

putting alumina ceramic powder, graphene, a solvent, a dispersant, a binder and a pore-forming agent into a ball milling tank according to a certain proportion, ball milling and mixing uniformly, then adding ammonia water to adjust the pH value to 7-9, or adding an acidic solution to adjust the pH value to 3-5, and stirring uniformly to obtain alumina matrix slurry;

placing the alumina preform with the high-temperature-resistant coating obtained in the step S3 in alumina matrix slurry for pressure impregnation, vacuumizing and pressurizing the alumina preform in a mold, taking out the alumina preform, and placing the alumina preform on a hot press for hot pressing, wherein the hot pressing temperature is 100-350 ℃, and the hot pressing time is 2-10 hours, so as to obtain a composite material blank;

the specific operation of preparing the alumina matrix composite material by low-temperature sintering of S5 is as follows:

and sintering the composite material blank in a high-temperature furnace at the sintering temperature of 800-1400 ℃ for 0.5-50 h to obtain the high-temperature-resistant and anti-scouring alumina matrix composite material.

3. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 1, characterized by comprising the following steps: the alumina preform comprises at least one of alumina paper, alumina cotton, alumina needle felt, alumina fiber cloth, alumina felt, alumina woven belt, alumina sleeve and alumina woven rope.

4. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 3, characterized by comprising the following steps:

the density of the alumina paper is 0.1-1.5 g/cm³The thickness is 0.01-2 mm;

the density of the alumina cotton is 0.1-1.5 g/cm³The thickness is 0.5 to 100 mm, and the thermal conductivity coefficient at-250 to 1600 ℃ is 0.001 to 0.45W/(m.K);

the density of the alumina cloth is 0.2-2.8 g/cm³The areal density is 20 to 2000g/cm²The thickness of the fabric is 0.02-2 mm, the weaving mode is selected from at least one of plain weaving, twill weaving, double twill weaving, satin weaving and mesh plain weaving, and the warp or weft of the fabric per 1cm is 2-20 strands;

the aluminum oxide felt consists of aluminum oxide fiber cloth, aluminum oxide cotton and aluminum oxide textile yarns, wherein the upper layer and the lower layer of aluminum oxide fiber thick cloth are arranged, the middle layer of aluminum oxide cotton is arranged, each aluminum oxide textile yarn consists of 100-2000 continuous aluminum oxide fibers, and the heat conductivity coefficient of the felt at-250-1600 ℃ is 0.001-0.5W/(m.K);

the density of the aluminum oxide woven belt body is 0.5-2.8 g/cm³The linear density is 10-100 g/m, the thickness is 0.2-3 mm, the weaving mode is selected from at least one of plain weaving, twill weaving and satin weaving, the warp or weft of each 1cm of the fabric is 3-30 strands, and the width of the belt is 10-200 mm;

the density of the aluminum oxide braided sleeve body is 0.5-2.5 g/cm³The linear density is 2-800 g/m, the inner diameter is 0.5-200 mm, and the braided rope is made ofThe number of the braided ropes is 10-100.

5. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 1, characterized by comprising the following steps: the modifier is prepared from polyethyleneimine, polyvinyl acetate, polyethylene glycol and polymethyl methacrylate in a mass ratio of 1: 1: 1: 2.

6. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 1, characterized by comprising the following steps:

in S2, the ceramic powder is selected from LaPO₄、SnO₂、TiO₂、ZrO₂、Y₂O₃、Y₃Al₅O₁₂、SiO₂、Al₂O₃At least one of Mullite; the granularity of the ceramic powder is 0.02-5 microns;

in S2, the solvent is at least one selected from deionized water and ethanol;

in S2, the dispersing agent is at least one selected from acrylic resin, polyurethane resin emulsion and polycarboxylic acid-based copolymer;

s2, the adhesive is at least one selected from cellulose derivatives, acrylic resin, polyvinyl acetate and polyethylene glycol;

in S2, the mass ratio of the ceramic powder, the solvent, the dispersant and the adhesive is 20-70: 75-30: 0.2% -5%: 0.5% -10%.

7. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 1, characterized by comprising the following steps:

s3, soaking the S1 aluminum oxide preform in a modifier for at least 10min, washing the preform with an aqueous solution with the pH of 3-5 or 9-10 until the concentration of the modifier in a washing liquid is 0.1-1mol/L to obtain a modified blank, and drying the modified blank at the temperature of 80-250 ℃ for at least 20 min;

in S3, the impregnation process is: pressurizing in an inert atmosphere, wherein the pressure is 0.1-10 MPa, and the dipping time is 20-300 min;

in S3, the coating process is: coating the prefabricated part by using a coating tool, wherein the weight increment range of the coated and dried prefabricated part is controlled to be 0.05-10%;

in S3, the deposition process includes: the deposition temperature is 500-1200 ℃, the deposition time is 20-600 min, and the deposition pressure is 100-10000 Pa.

8. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 1, characterized by comprising the following steps: when the alumina preform is an alumina heat-preservation felt, the density of the finished product is 1.2g/cm³Porosity of 80% and fiber volume content of 15%; the tensile strength of the obtained product is 100-105 MPa, the high temperature resistance is more than or equal to 2200 ℃, and the heat conductivity coefficient is 0.08W/(m.K); when the gas scouring speed is 6.8km/s, the time is 60s and the temperature is 2200 ℃, the mass loss is less than 1 percent.

9. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 2, characterized by comprising the following steps:

in S4, the granularity of the alumina ceramic powder is 0.01-10 microns;

in S4, the average particle size of graphene is 0.02-5 microns;

in S4, the solvent is at least one selected from water, ethanol and acetone;

in S4, the dispersant is at least one selected from at least one of acrylic resin, polyurethane resin emulsion, and polycarboxylic acid-based copolymer;

at least one of a cellulose derivative, an acrylic resin, polyvinyl acetate, and polyethylene glycol in S4;

in S4, the pore-forming agent is at least one selected from carbon black and starch;

in S4, the mass ratio of the alumina ceramic powder, the graphene, the solvent, the dispersant, the adhesive and the pore-forming agent is 20-70%: 0.5-5%: 20-60%: 0.1-5%: 1-10%: 0 to 5 percent.

10. The preparation method of the high-temperature-resistant scouring-resistant alumina fiber reinforced heat-insulating composite material according to claim 2, characterized by comprising the following steps:

when the alumina preform is alumina cotton, the density of the alumina cotton is 0.8g/cm³When the thickness is 25mm, the density of the finished product of the composite material obtained by S5 is 2.9 g/cm³Porosity of 20% and fiber volume content of 40%; the tensile strength of the obtained product is 180-190 MPa, the bending strength is 250-255 MPa, the fracture toughness is 19.3MPa, the high temperature resistance is more than or equal to 2200 ℃, and the heat conductivity coefficient is 0.1W/(m.K); when the gas scouring speed is 7.8km/s, the time is 50s and the temperature is 2200 ℃, the mass loss is less than 1 percent.

Technical Field

The invention belongs to the technical field of ceramic matrix composite materials, and particularly relates to a high-temperature-resistant anti-scouring thermal insulation material and a preparation method thereof.

Background

The alumina ceramic fiber has excellent performances of high temperature resistance, high strength, high rigidity, low density, corrosion resistance, high elasticity, suitability for weaving and the like, and is mainly compounded with a high-temperature resistant coating/alumina matrix to obtain the alumina fiber reinforced composite material with excellent toughness.

The alumina fiber reinforced ceramic matrix composite has the characteristics of low density, high specific strength, high specific modulus, high temperature resistance, oxidation resistance, good reliability and the like, and can be widely applied to the fields of high-performance aeroengines, high-temperature furnaces, heavy-duty automobile exhaust emission devices, space rockets and the like as structural load-bearing materials with high-temperature heat insulation, high-temperature scouring, ultralow temperature, low-temperature heat preservation and the like. Which has a natural advantage in the direction of ablation resistance. The traditional ablation material (including low-density ablation material and high-density ablation material) is compounded by taking phenolic resin, epoxy resin, organic silicon resin, polytetrafluoroethylene and the like as ablation matrixes and taking fibers, phenolic microspheres, glass fiber reinforced plastic honeycombs and the like as fillers or reinforcing materials. When high-heat-flow pneumatic flushing is carried out, the high-efficiency ablation effect can be exerted, and the stable state of the internal structure of the aircraft is ensured. However, this type of material has relatively high density and high thermal conductivity, is difficult to ablate/insulate for a long time, is prone to surface peeling and peeling after ablation, and cannot maintain the aerodynamic shape. Based on this, rigid ceramic tiles have been developed; rigid ceramic tiles are the primary solution employed for large area thermal protection of the american space shuttle. It is formed by sintering high-temperature resistant ceramic fibers at high temperature and has higher technical maturity. However, the material has the defects of high brittleness, poor deformability, complex assembly, long period, high maintenance cost and the like, has the highest temperature resistance of only 1600 ℃, and is difficult to meet the thermal protection requirement of future hypersonic aircrafts. Aiming at the defects of the rigid ceramic tile, several technologies for compounding the rigid heat insulation tile and the aerogel heat insulation material are developed successively; such as: the technology disclosed in application publication No. CN103449825A and application publication No. CN 108116002A; in CN103449825A, it discloses a micro-ablation thermal insulation composite material comprising an ablation resin and a rigid thermal insulation material, said rigid thermal insulation material comprising a ceramic matrix and an aerogel material, obtained by vacuum impregnation of a rigid matrix with a formulated aerogel precursor solution, followed by sol-gel, solvent displacement and supercritical drying. According to the technology, the aerogel material and the ceramic matrix are compounded, so that the high-efficiency heat insulation of the material is realized, and the added ablative resin realizes the high-efficiency ablative heat insulation of the material. However, the thermal insulation properties of the material still leave room for improvement, with the risk of flight reliability. Meanwhile, the material prepared by the technology is difficult to work effectively at the temperature of more than 2000 ℃. Chinese patent application publication No. CN108116002A discloses punching aerogel composite thermal insulation material sandwich layer, and laying braided fabric on the upper surface and the lower surface of the sandwich layer respectively, sewing up to obtain the sandwich structure prefabricated member, then using ceramic precursor solution to impregnate the sandwich structure prefabricated member for many times, and obtaining the sandwich structure thermal protection material with high panel strength after sintering. The material is endowed with higher strength by multiple times of impregnation, but the density of the material is greatly improved, and the method is not suitable for application scenes with light requirements on the material. And the production cost of the product is extremely high because the impregnation needs to be repeated (the impregnation times are excessive).

Aiming at the problems that the preparation period is long, the working procedures are excessive, the time consumption is overlong, the high-temperature resistance of the product is poor, the form of the product preform is single, and the product requirements of many application fields cannot be met in the preparation of the high-temperature-resistant anti-scouring aluminum oxide heat-insulating composite material in the prior art, the invention designs and prepares the material capable of meeting the requirements of high-temperature-resistant anti-scouring heat-insulating and high-temperature-resistant anti-scouring heat-insulating at the same time for the first time.

Disclosure of Invention

Aiming at the prior art, the invention provides a method for efficiently preparing a high-performance high-temperature-resistant anti-scouring heat-insulating material, and a reinforcement of the material is continuous alumina fiber.

The method provided by the invention can obtain the composite material with high temperature resistance, gas scouring resistance and heat preservation/insulation.

In order to realize the purpose of the invention, the invention provides a preparation method of a high-temperature-resistant and anti-scouring alumina fiber reinforced heat-insulation composite material, which specifically comprises the following steps:

s1, preparing an aluminum oxide preform:

preparing an alumina preform with pores according to requirements;

s2, preparing slurry of the high-temperature-resistant coating:

putting ceramic powder, a solvent, a dispersant and an adhesive into a ball milling tank according to a certain proportion, ball milling and mixing uniformly, then adding ammonia water to adjust the pH value to 7-9, or adding an acidic solution to adjust the pH value to 3-5, and stirring uniformly to prepare alumina fiber high-temperature-resistant coating slurry;

s3, preparing a high-temperature-resistant coating of the aluminum oxide preform:

soaking the S1 alumina preform in a modifier, and after soaking, washing the alumina preform with an aqueous solution with the pH of 3-5 or 9-10 to obtain a modified blank; then impregnating and/or coating and/or depositing the slurry obtained in the step S2 on the modified green body; sintering at a high temperature of 400-1200 ℃; obtaining a uniform high-temperature coating of 50-500 nm on the surface of the prefabricated fiber; the modifier is selected from at least one of Polyethyleneimine (PEI), polyvinyl acetate (PVA), polyethylene glycol (PEG), polymethyl methacrylate and acrylic resin;

s4, preparing a composite material blank; placing the alumina preform with the high-temperature-resistant coating obtained in the step S3 into alumina matrix slurry for pressure impregnation to obtain a composite material blank,

s5 low-temperature sintering to prepare the alumina matrix composite material: sintering the composite material blank to obtain the high-temperature-resistant and anti-scouring alumina matrix composite material.

When the application requirements require that the material has excellent formability, low density, low thermal conductivity, and high thermal insulation, the product only needs to be subjected to steps S1-S3. When the product requires more times of use, long service life and high mechanical property, the preparation steps of S4 and S5 are required.

Wherein the specific operation of S4 is:

putting alumina ceramic powder, graphene, a solvent, a dispersant, a binder and a pore-forming agent into a ball milling tank according to a certain proportion, ball milling and mixing uniformly, then adding ammonia water to adjust the pH value to 7-9, or adding an acidic solution to adjust the pH value to 3-5, and stirring uniformly to obtain alumina matrix slurry;

placing the alumina preform with the high-temperature-resistant coating obtained in the step S3 in alumina matrix slurry for pressure impregnation, vacuumizing and pressurizing the alumina preform in a mold, taking out the alumina preform, and placing the alumina preform on a hot press for hot pressing, wherein the hot pressing temperature is 100-350 ℃, the preferred hot pressing temperature is 150-250 ℃, the hot pressing time is 2-10 hours, and the preferred hot pressing time is 3-8 hours, so as to obtain a composite material blank;

wherein the specific operation of S5 is:

and sintering the composite material blank in a high-temperature furnace, wherein the sintering temperature is 800-1400 ℃, the preferred temperature is 1000-1300 ℃, the heat preservation time is 0.5-5 h, and the preferred scheme is 1-3 h, so as to obtain the high-temperature-resistant and anti-scouring alumina matrix composite material.

As a preferred scheme, when the alumina preform is prepared, alumina fibers are prepared into preforms with different shapes, different densities and different purposes according to actual requirements, and the method comprises the following steps of (1) preparing ultra-light and porous alumina fiber cotton by adopting alumina fiber pulp; (2) weaving orthogonal, twill and satin alumina fiber cloth by using continuous alumina fiber bundles; (3) weaving an alumina fiber bundle into a woven belt in a twill, plain or satin mode; (4) weaving the alumina fiber bundles or the alumina braided ropes into a sleeve; (5) preparing a prefabricated body by adopting alumina fiber paper pulp; (6) and weaving the alumina fiber cloth, the alumina cotton and the alumina textile yarns into an alumina fiber felt. Further, the alumina preform comprises alumina paper, alumina cotton, alumina fiber cloth, alumina felt, an alumina braid, an alumina sleeve and an alumina braid rope.

In a further preferred embodiment, the density of the alumina paper is 0.1 to 1.5g/cm³Preferably 0.2 to 1.2g/cm³The thickness is 0.01 to 2mm, preferably 0.1 to 1 mm.

In a further preferable embodiment, the density of the alumina wool is 0.1 to 1.5g/cm³Preferably 0.2 to 1.0 g/cm³The thickness is 0.5 to 100 mm and the thermal conductivity at-250 to 1600 ℃ is 0.001 to 0.45W/(m.K). The alumina cellucotton designed in the invention can be directly used as a high-temperature resistant material and can also be used as an ultralow-temperature or low-temperature heat-insulating material and a safety protection material, such as a heat-insulating material and a safety protection material of a high-pressure liquid nitrogen tank/a liquid oxygen tank/a liquid hydrogen tank. Of course, the material can be used as a high-temperature resistant material after being treated by the S3, S3, S4 and S5 of the inventionAnd ultra-low temperature or low temperature heat preservation materials and safety protection materials, the performance is more excellent.

In a further preferred embodiment, the density of the alumina cloth is 0.2 to 2.8g/cm³Preferably 0.5 to 2.5g/cm³The areal density is 20 to 2000g/cm²The thickness is 0.02-2 mm, weaving modes comprise plain weave, twill weave, double twill weave, satin weave, mesh plain weave and the like, and the warp or weft of the fabric per 1cm is 2-20 strands.

As a further preferable scheme, the alumina felt is composed of alumina fiber cloth, alumina cotton and alumina textile yarns, wherein the upper layer and the lower layer are two layers of alumina fiber thick cloth, the middle layer is alumina cotton, each strand of alumina textile yarn is composed of 100-2000 continuous alumina fibers, and the thermal conductivity coefficient of the felt at-250-1600 ℃ is 0.001-0.45W/(m.k).

As a further preferable scheme, the density of the aluminum oxide woven belt body is 0.5-2.8 g/cm³Preferably 0.8 to 2.6 g/cm³The linear density is 10-100 g/m, the thickness is 0.2-3 mm, weaving modes include plain weave, twill weave, satin weave and the like, the warp or weft of the fabric per 1cm is 3-30 strands, and the width of the belt is 10-200 mm.

In a further preferable scheme, the density of the aluminum oxide braided sleeve body is 0.5-2.5 g/cm³Preferably 0.6 to 2.2g/cm³The linear density is 2-800 g/m, the inner diameter is 0.5-200 mm, and the braided rope is braided, and the number of braided ropes is 10-100.

Preferably, the modifier contains at least one of Polyethyleneimine (PEI), polyvinyl acetate (PVA), polyethylene glycol (PEG), and polymethyl methacrylate. More preferably, the modifier contains Polyethyleneimine (PEI), polyvinyl acetate (PVA), polyethylene glycol (PEG), and polymethyl methacrylate. As a further preferable scheme, the modifier is prepared from Polyethyleneimine (PEI), polyvinyl acetate (PVA), polyethylene glycol (PEG), polymethyl methacrylate (pmma) and a mixture of polyethylene glycol (PEI) and polyvinyl acetate (PVA) in a mass ratio of 1: 1: 1: 2. The solvent used for the modifier is preferably at least one of acetone, xylene and ethanol.

As a preferred embodiment; the mass percentage concentration of Polyethyleneimine (PEI) in the modifier is 1-15%, and more preferably 2-10%; the mass percentage concentration of polyvinyl acetate (PVA) is 1-18%, and the preferable mass percentage concentration is 2-12%; the mass percentage concentration of the polyethylene glycol (PEG) is 1-20%, and the preferable concentration is 2-15%.

Preferably, in S2, the ceramic powder is selected from LaPO₄、SnO₂、TiO₂、ZrO₂、Y₂O₃、Y₃Al₅O₁₂、SiO₂、Al₂O₃And Mullite. The granularity of the ceramic powder is 0.02-5 microns. Preferably alpha-Al₂O₃Alumina ceramic powder and Y₂O₃The yttrium oxide ceramic powder.

Preferably, in S2, the solvent is at least one selected from deionized water and ethanol.

Preferably, in S2, the dispersant is at least one selected from the group consisting of an acrylic resin, a polyurethane resin emulsion, and a polycarboxylic acid-based copolymer.

Preferably, in S2, the binder is at least one selected from the group consisting of a cellulose derivative, an acrylic resin, polyvinyl acetate, and polyethylene glycol.

Preferably, in S2, the mass ratio of the ceramic powder, the solvent, the dispersant and the adhesive is 20-70: 75-30: 0.2% -5%: 0.5% -10%.

Preferably, in S3, the S1 aluminum oxide preform is soaked in a modifier for at least 20min, preferably 20-60 min, and then washed by a water solution with pH of 3-5 or 9-10 until the concentration of the modifier in a washing solution is 0.1-1mol/L to obtain a modified blank, and the modified blank is dried at 80-250 ℃ for at least 20min, preferably 30-120 min.

Preferably, in S3, the impregnation process is: pressurizing in an inert atmosphere, wherein the pressure is 0.1-10 MPa, the preferable scheme is 0.1-5 MPa, and the dipping time is 20-300 min.

Preferably, in S3, the coating process is: and (3) brushing the prefabricated part by adopting a coating tool, wherein the weight gain range of the painted and dried prefabricated part is controlled to be 0.05-10%, and preferably 0.1-5%.

Preferably, in S3, the deposition process is: the deposition temperature is 500-1200 ℃, the deposition time is 20-600 min, and the deposition pressure is 100-10000 Pa, preferably 500-5000 Pa.

Compared with the prior art, the method has the advantage that the time for preparing the high-temperature-resistant coating is greatly shortened. Meanwhile, the same process parameters are adopted, and the thickness of the coating obtained by 1 time of treatment in unit time is more than 1.5 times of that of the coating obtained by the method in the prior art. The efficiency and product quality of the present invention is particularly evident when dip coating is employed.

When the alumina preform is an alumina heat-preservation felt, the density of the finished product is 1.2g/cm³Porosity of 80% and fiber volume content of 15%; the tensile strength of the product obtained by S3 is 100-105 MPa, the high temperature resistance is more than or equal to 2200 ℃, and the heat conductivity coefficient is 0.08W/(m.K); when the gas scouring speed is 6.8km/s, the time is 60s and the temperature is 2200 ℃, the mass loss is less than 1 percent.

Preferably, in S4, the alumina ceramic powder has a particle size of 0.01 to 10 μm.

Preferably, in S4, the graphene has an average particle size of 0.02 to 5 μm.

Preferably, in S4, the solvent is at least one selected from water, ethanol, and acetone.

Preferably, in S4, the dispersant is at least one selected from at least one of an acrylic resin, a polyurethane resin emulsion, and a polycarboxylic acid-based copolymer.

Preferably, in S4, at least one of a cellulose derivative, an acrylic resin, polyvinyl acetate, and polyethylene glycol is used.

Preferably, in S4, the pore former is at least one selected from carbon black and starch.

Preferably, in S4, the mass ratio of the alumina ceramic powder, the graphene, the solvent, the dispersant, the binder and the pore-forming agent is 20-70%: 0.5-5%: 20-60%: 0.1-5%: 1-10%: 0 to 5 percent.

When the alumina preform is alumina cotton, the density of the alumina cotton is 0.8g/cm³When the thickness is 25mm, the density of the finished product of the composite material obtained by S5 is 2.9 g/cm³Porosity of 20% and fiber volume content of 40%; the tensile strength of the obtained product is 180-190 MPa, the bending strength is 250-255 MPa, the fracture toughness is 19.3MPa, the high temperature resistance is more than or equal to 2200 ℃, and the heat conductivity coefficient is 0.1W/(m.K); when the gas scouring speed is 7.8km/s, the time is 50s and the temperature is 2200 ℃, the mass loss is less than 1 percent.

The invention achieves the following beneficial effects:

1. according to the method, an alumina preform is pretreated by flushing Polyethyleneimine (PEI) or polyvinyl acetate (PVA) or polyethylene glycol (PEG) or polymethyl methacrylate and distilled water with the pH of 3-5 or 9-10, so that the alumina preform is uniformly and stably charged; adjusting the pH value of the high-temperature coating slurry; a layer of uniform Zeta potential is formed between the alumina preform and the ceramic slurry, the Zeta potential enables ceramic particles in the slurry to be uniformly and rapidly distributed on the surface of each fiber, the bonding force is strong, according to an experimental result, a coating prepared by the method is 200nm thick (shown in figure 1) after being impregnated for 3-4 times without adopting the method, and the coating is 50nm and is not uniform;

2. the invention can prepare all kinds of nano coatings on the alumina preform, and mainly prepares the coating which resists high-temperature gas scouring;

3. the high-temperature coating can be directly coated on alumina fiber cloth, alumina fiber felt, an alumina braid and an alumina sleeve to serve as a high-temperature resistant matrix of an alumina preform without further impregnating alumina slurry and sintering, so that the production period is greatly shortened and simplified, the production cost of a product is reduced, the good formability of the alumina preform is reserved, and the alumina preform can be processed into a protective jacket with any customized size;

4. the alumina preform treated by the high-temperature resistant coating improves the strength and the high-temperature resistance of the alumina fiber, thereby further improving the sintering temperature of the composite material and finally improving the strength, the toughness and the high-temperature resistance of the composite material.

5. The slurry of the invention is added with 0.1-0.3 mu m active alpha-Al₂O₃Alumina ceramic powder and 0.1 to 0.3 mu m of active Y₂O₃The yttrium oxide ceramic powder has uniform particle size distribution, micropores with uniform size distribution are easily formed in sintering, secondary recrystallization is prevented, and the high strength and high hardness of an alumina matrix are ensured.

6. According to the invention, the Zeta potential is adopted to prepare the high-temperature coating on the alumina preform, the high-temperature coating is uniform and has excellent strength and toughness, and the coating volatilizes to form a micropore or weak interface in the sintering process, when the composite material matrix is subjected to an external load, the functions of reinforcing and toughening of alumina fibers are fully exerted through the expansion of cracks of the composite material matrix along the interface and the pulling-out and bridging mechanisms of the alumina fibers, so that the toughness of the alumina matrix composite material is greatly improved.

7. The high temperature resistance of the alumina fiber prepared by the high temperature coating is enhanced, so that the high temperature resistance is further improved, and the highest temperature of scouring resistance can reach 2200 ℃ and above.

8. According to the invention, through pretreatment of the alumina fiber, preparation of the high-temperature coating and the slurry, a high-performance alumina product with high-temperature gas scouring resistance, heat insulation and heat preservation can be obtained, and meanwhile, a high-performance alumina matrix composite material with uniform size distribution, multiple micropores, high density, weak interface, high strength, high toughness and high temperature resistance can be obtained.

Drawings

FIG. 1 is a pictorial view of an alumina bushing used in the present invention;

FIG. 2 is a schematic representation of an aluminum oxide braid used in the present invention;

FIG. 3 is a schematic representation of an alumina fiber cloth used in the present invention;

FIG. 4 is a pictorial view of an aluminum oxide braided rope used in the present invention;

FIG. 5 is a pictorial view of an alumina sewing thread used in the present invention;

FIG. 6 is a schematic representation of an alumina felt used in the present invention.

FIG. 7 is a schematic representation of an alumina felt made in accordance with the present invention.

FIG. 8 is a microstructure of the alumina with high temperature coating prepared by the present invention.

FIG. 9 is a micro-topography of the product obtained in example 1 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

S1, preparing an aluminum oxide preform:

preparing an alumina preform with pores according to requirements; the alumina preform is alumina cotton, and the density of the alumina cotton is 0.8g/cm³The thickness is 25mm, and the thermal conductivity coefficient at 25-1600 ℃ is 0.05-0.45W/(mK).

S2, preparing slurry of the high-temperature-resistant coating:

putting ceramic powder, a solvent, a dispersant and an adhesive into a ball milling tank according to a certain proportion, ball milling and mixing uniformly, then adding ammonia water to adjust the pH value to 7-9, and stirring uniformly to prepare alumina fiber high-temperature-resistant coating slurry;

the ceramic powder is alpha-Al₂O₃Alumina ceramic powder and yttrium oxide. The granularity of the ceramic powder is 0.1-0.3 micron (the mass ratio of the two is 1: 1).

The solvent is deionized water.

The dispersant is an acrylic resin.

The adhesive is acrylic resin.

In S2, the mass ratio of the ceramic powder, the solvent, the dispersant and the adhesive is 60: 33: 2: 5.

s3, preparing a high-temperature-resistant coating of the aluminum oxide preform:

soaking the S1 alumina preform in a modifier for 30min, and after soaking, washing the alumina preform with an aqueous solution with the pH of 9-10 to obtain a modified blank; then soaking the modified blank body into the slurry obtained in S2 for vacuum impregnation for 30min, wherein the impregnation pressure is 0.1Pa (the soaking times are 1 time); sintering at 800 deg.C; obtaining a uniform high-temperature coating of 200-205 nm on the surface of the prefabricated fiber; the modifier is prepared from Polyethyleneimine (PEI), polyvinyl acetate (PVA), polyethylene glycol (PEG), polymethyl methacrylate and polyethylene glycol (PEG) in a mass ratio of 1: 1: 1: 2. The mass percentage concentration of Polyethyleneimine (PEI) in the modifier is 5%.

S4, preparing a composite material blank:

putting alumina ceramic powder, graphene, a solvent, a dispersant, a binder and a pore-forming agent into a ball milling tank according to a certain proportion, ball milling and mixing uniformly, then adding ammonia water to adjust the pH value to 7-9, and stirring uniformly to obtain alumina matrix slurry;

in S4, the alumina ceramic powder has a particle size of 1 μm.

In S4, the graphene had an average particle size of 0.5 μm.

In S4, the solvent is deionized water.

In S4, the dispersant is a polyurethane resin emulsion.

In S4, the binder is a cellulose derivative.

In S4, the pore former is starch.

In S4, the mass ratio of the alumina ceramic powder, the graphene, the solvent, the dispersant, the adhesive and the pore-forming agent is 55: 3: 31: 2: 4: 5.

placing the alumina preform with the high-temperature-resistant coating obtained in the step S3 into alumina matrix slurry for pressure impregnation (the pressure is 0.4MPa, the impregnation time is 60 min), then vacuumizing and pressurizing the alumina preform in a mould, taking out the alumina preform, placing the alumina preform on a hot press for hot pressing, wherein the hot pressing temperature is 250 ℃, and the hot pressing time is 3h, so as to obtain a composite material blank;

s5, preparing the alumina matrix composite material by low-temperature sintering:

and (3) sintering the composite material blank in a high-temperature furnace, wherein the sintering temperature is 1100 ℃, and the heat preservation time is 2 hours, so as to prepare the high-temperature-resistant reinforced and toughened alumina matrix composite material. The performance measurements are shown in Table 1.

TABLE 1 Performance test Table for alumina reinforced matrix composites

	Test results	Remarks for note
			Length x width x thickness	180mm×80mm×3mm	--
Tensile Strength (MPa)	184.1	--
			Flexural Strength (MPa)	252.5	--
Fracture toughness (MPa)	19.3	--
			Density (g/cm)3）	2.9	--
Porosity (%)	20	--
			Fiber volume content (%)	40	--
High temperature resistance (. degree. C.)	2200	50s high temperature gas scouring
			Gas scouring performance	Loss of mass<1%	When the gas scouring speed is 7.8km/s and the time is 50s
Thermal conductivity (W/(m.K))	0.1	The test temperature is normal temperature
			Coefficient of thermal expansion (1/. degree.C.)	3.2×10-6	The test temperature is normal temperature

Application example 1.1

Wrapping the liquid nitrogen tank with the product obtained in example 1; when the liquid nitrogen tank is used for transfusion, the phenomena of water and frost formation on the outer surface of the liquid nitrogen tank are obviously relieved.

Example 2

S1, preparing an aluminum oxide preform:

preparing an alumina preform with pores according to requirements; the aluminum oxide prefabricated body is an aluminum oxide felt, the aluminum oxide felt is composed of aluminum oxide fiber cloth, aluminum oxide cotton and aluminum oxide textile threads, and the upper layer and the lower layer are two layersThe aluminum oxide fiber thick cloth and the aluminum oxide cotton in the middle are arranged, each aluminum oxide spinning thread is composed of 1000 continuous aluminum oxide fibers, and the thermal conductivity coefficient of the felt at 25-1600 ℃ is 0.05-0.5W/(m.K). The average density of the alumina felt is 1.2g/cm³And the thickness is 12 mm.

S2, preparing slurry of the high-temperature-resistant coating:

putting ceramic powder, a solvent, a dispersant and an adhesive into a ball milling tank according to a certain proportion, ball milling and mixing uniformly, then adding ammonia water to adjust the pH value to 7-9, and stirring uniformly to prepare alumina fiber high-temperature-resistant coating slurry;

the ceramic powder is zirconia and yttria. The granularity of the ceramic powder is 0.01-5 microns.

The solvent is deionized water.

The dispersant is an acrylic resin.

The adhesive is acrylic resin.

In S2, the mass ratio of the ceramic powder, the solvent, the dispersant and the adhesive is 60: 33: 2: 5.

s3, preparing a high-temperature-resistant coating of the aluminum oxide preform:

soaking the S1 alumina preform in a modifier for 30min, and after soaking, washing the alumina preform with an aqueous solution with the pH of 9-10 to obtain a modified blank; then soaking the modified blank body into the slurry obtained in S2 for vacuum impregnation for 30min, wherein the pressure is 0.1 Pa; sintering at 800 deg.C; obtaining a uniform high-temperature coating of 50-500 nm on the surface of the prefabricated fiber; the modifier is prepared from Polyethyleneimine (PEI), polyvinyl acetate (PVA), polyethylene glycol (PEG) and polymethyl methacrylate according to a mass ratio of 1: 1: 1: 2. The properties of the product obtained in S3 are shown in Table 2.

TABLE 2 Performance test Table for alumina insulation felt material

	Test results	Remarks for note
			Length x width x thickness	240mm×180mm×25mm	--
Tensile Strength (MPa)	100.3	--
			Density (g/cm)3）	1.2	--
Porosity (%)	80	--
			Fiber volume content (%)	15	--
High temperature resistance (. degree. C.)	2200	60s high-temperature gas scouring
			Thermal insulation performance	The front temperature of the gas washing is 1700 DEG C	Back temperature 102 deg.C
Gas scouring performance	Loss of mass<1%	When the gas scouring speed is 6.8km/s and the time is 60s
			Thermal conductivity (W/(m.K))	0.08	The test temperature is normal temperature
Coefficient of thermal expansion (1/. degree.C.)	3.5×10-6	The test temperature is normal temperature

Example 3

Other conditions were the same as in example 1; the difference lies in that

The alumina preform is alumina fiber cloth, and the density of the alumina cloth is 1.8g/cm³The thickness of the fabric is 0.3mm, the weaving mode is double twill, and every 1cm of the fabric has 9 strands of warp yarns or weft yarns.

The density of the finished product of the composite material obtained from S5 is 2.2g/cm³Porosity of 30% and fiber volume content of 28%; the tensile strength of the obtained product is 202MPa, the bending strength is 380MPa, and the fracture toughness is 8MPa^1/2The high temperature resistance is more than or equal to 2200 ℃, and the heat conductivity coefficient is 0.5W/(m.K); when the gas scouring speed is 6.8km/s, the time is 50s and the temperature is 2200 ℃, the mass loss is less than 1 percent.

Example 4

Other conditions were the same as in example 1; the difference lies in that

The aluminum oxide prefabricated body is an aluminum oxide woven belt, and the density of the aluminum oxide woven belt body is 1.85 g/cm³The linear density is 80g/m, the thickness is 1.5 mm, the weaving mode is double twill, and each 1cm of the fabric has 10 strands of warp yarns or weft yarns.

The final density of the composite material obtained in S5 was 1.9 g/cm³Porosity of 65% and fiber volume content of 35%; the tensile strength of the obtained product is 250MPa. Bending strength of 390MPa, fracture toughness of 9MPa^1/2The high temperature resistance is more than or equal to 2200 ℃, and the heat conductivity coefficient is 0.6W/(m.K); when the gas scouring speed is 6.8km/s, the time is 50s and the temperature is 2200 ℃, the mass loss is less than 1 percent.

Example 5

Other conditions were the same as in example 1; the difference lies in that

The alumina prefabricated body is an alumina sleeve, and the bulk density of the alumina sleeve is 1.4g/cm³The yarn has a linear density of 70g/m and a thickness of 0.8 mm, and is formed by weaving braided ropes with 10-100 braided rope numbers. The weaving mode is double twill.

The density of the finished product of the composite material obtained from S5 is 1.6 g/cm³Porosity of 70% and fiber volume content of 30%; the tensile strength of the obtained product is 190MPa, the bending strength is 240MPa, and the fracture toughness is 5MPa^1/2The high temperature resistance is more than or equal to 2200 ℃, and the heat conductivity coefficient is 0.3W/(m.K); when the gas scouring speed is 7.5km/s, the time is 50s and the temperature is 2200 ℃, the mass loss is less than 1 percent.

Comparative example 1

The other conditions were the same as in example 1 except that: and (3) directly dipping without modification in S3, wherein the mechanical property and the high-temperature and anti-scouring property of the obtained product are as follows: the density of the finished product of the composite material obtained from S5 is 2.58g/cm³Porosity of 23% and fiber volume content of 40%; the tensile strength of the obtained product is 155MPa, the bending strength is 203MPa, the fracture toughness is 10.3MPa, the high temperature resistance is about 2000 ℃, and the heat conductivity coefficient is 0.3W/(m.K); when the gas scouring speed is 6.8km/s, the time is 30s and the temperature is 1600 ℃, the mass loss is about 1 percent.

Comparative example 2

The other conditions were the same as in example 2 except that: the product is directly impregnated without modification in S3, and the density of the finished product is 1.1g/cm³Porosity of 83% and fiber volume content of 15%; s3, the tensile strength of the product is 81MPa, the high temperature resistance is about 2000 ℃, and the heat conductivity coefficient is 0.35W/(m.K); when the gas scouring speed is 6.8km/s and the time is 6At a temperature of 2000 ℃ for 0s, the mass loss already reaches 1%.

Comparative example 3

The other conditions were the same as in example 1 except that: the granularity of the ceramic powder in the S2 is 6-10 mu m;

the density of the finished product of the composite material obtained from S5 is 2.63g/cm³Porosity of 22.7% and fiber volume content of 40%; the tensile strength of the obtained product is 168MPa, the bending strength is 229MPa, the fracture toughness is 17.6MPa, the high temperature resistance is about 2200 ℃, and the heat conductivity coefficient is 0.8W/(m.K); when the gas scouring speed is 7.8km/s, the time is 30s and the temperature is 2200 ℃, the mass loss is about 1 percent.

Comparative example 4

The other conditions were the same as in example 1 except that: the ceramic powder in S2 is only alpha-Al₂O₃Alumina ceramic powder of (2);

the final density of the composite material obtained in S5 was 2.88g/cm³Porosity of 20.1% and fiber volume content of 40%; the tensile strength of the obtained product is 179MPa, the bending strength is 245MPa, the fracture toughness is 19MPa, the high temperature resistance is about 2200 ℃, and the heat conductivity coefficient is 0.9W/(m.K); when the gas scouring speed is 7.8km/s, the time is 50s and the temperature is 2200 ℃, the mass loss is about 1 percent.