A novel lightweight heat-insulating material and its preparation method

Abstract

The present invention discloses a novel lightweight anti-insulation material and a preparation method thereof, which is a method for rapidly preparing zirconium oxide sol and preparing a novel lightweight anti-insulation material with this sol. First, zirconium oxychloride, sodium hydroxide, strong acid, etc. are used as raw materials, and alkali solution is added dropwise to a zirconium oxychloride aqueous solution until the whole mixture is in an alkaline state, so that zirconium is separated from the chlorine element in the form of a complex precipitation, and after cleaning by suction filtration, impurity elements are removed to obtain a wet filter cake, which is then dissolved with deionized water, and a strong acid is added to return it to an acidic state. The filter cake is placed in a sealed container, and is kept warm for more than 15 hours at 100 ° C to prepare zirconium oxide sol. After mixing this zirconium oxide sol with silica sol by volume, a gradient fiber cotton felt is impregnated. After 5-6 impregnations, the mixture is treated at 600 ° C-1000 ° C to obtain a novel lightweight, high-temperature resistant anti-insulation material.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic composite materials, and in particular relates to a novel lightweight heat-insulating material and a preparation method thereof. Background Art

[0002] The aerospace industry is currently experiencing rapid growth, with aircraft flying at ever-increasing speeds. High-speed aircraft experience intense friction with the air in the atmosphere. The faster the speed, the more intense the friction, the more heat generated, and the higher the surface temperature. To better protect the safety of the aircraft's internal components, the internal temperature must be kept within a certain range. To achieve this without increasing the weight of the aircraft itself, materials with improved thermal insulation and higher temperature resistance must be used. Traditionally, replacing conventional materials with more heat-resistant raw materials has been used, but this significantly increases overall material costs. Achieving higher temperature resistance requirements through minor adjustments without changing the original materials is undoubtedly a viable solution.

[0003] There are currently studies on zirconium sols, such as CN201780052950.0, in which zirconium sol is prepared by mixing a zirconium oxychloride solution with an alkaline solution, and after a long period of aging, the preparation cycle is relatively long. CN200810109057.X, in which organic matter is used as a raw material for the preparation of zirconium sol, zirconium sol can be prepared, and organic solvent-type zirconium sol can be prepared by replacing the solvent, but organic solvents have many problems that need to be solved in waste liquid treatment. CN202111060662.4, in which zirconium sol is prepared by a one-step method, all impurities in the raw materials are retained in the sol, and the use of dialysis membrane to remove impurities takes a long time.

[0004] There are also relevant studies on heat-insulating materials. CN202210736953.9 proposes a 1500°C resistant heat-insulating integrated composite structural ceramic and its preparation method. The composite material uses Al2O3 aerogel composite material as the core layer to prepare a porous ceramic structure heat-insulating material. However, the process requires a lot of manual participation, a long preparation cycle, low production efficiency, and many human factors. At the same time, in the preparation of this material, the mold sizes required for the aerogel stage and the later material forming stage are not the same, which invisibly increases the material cost.

[0005] Therefore, it is necessary to develop lightweight, high-temperature resistant and heat-insulating materials that are quick to prepare and low in cost. Summary of the Invention

[0006] To address the issues of insufficient temperature resistance and long production cycles associated with existing raw materials used to prepare thermal insulation materials, the present invention provides a novel lightweight thermal insulation material and its preparation method, specifically a zirconium sol for impregnation, a lightweight thermal insulation material, and its preparation method. Unlike traditional processes that simply modify a single raw material or impregnation liquid, the present invention utilizes a self-made zirconium sol for the entire impregnation of the preform. This approach not only accommodates changes in the impregnation liquid but also modifies the preform, shortening the process cycle, reducing production costs, and improving material performance.

[0007] The technical solutions of the present invention are as follows:

[0008] A method for preparing a new lightweight thermal insulation material involves rapidly preparing a zirconium oxide sol and using this sol to prepare the new lightweight thermal insulation material. First, using zirconium oxychloride, sodium hydroxide, and a strong acid as raw materials, an alkali solution is added dropwise to an aqueous zirconium oxychloride solution until the mixture becomes alkaline, separating the zirconium from the chlorine element as a complex precipitate. After filtration and cleaning, impurities are removed to obtain a wet filter cake. This cake is then dissolved in deionized water and restored to an acidic state by adding a strong acid. The cake is then placed in a sealed container and kept at a temperature above 100°C for at least 15 hours to prepare the zirconium oxide sol. This zirconium oxide sol is then mixed with a silica sol in a volume ratio and impregnated into a gradient fiber felt. After five to six impregnations, the mixture is treated at 600°C to 1000°C to obtain the new lightweight, high-temperature-resistant thermal insulation material.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A method for preparing a novel lightweight heat-insulating material comprises the following steps:

[0011] S1. Preparation of zirconia sol: zirconia sol is prepared from zirconium-containing raw materials. The main component of the prepared zirconia sol is zirconium dioxide. The sol is light blue or milky white liquid with a concentration of 2%-8% and a density of 1.01g / cm 3 , viscosity ≤15mPa·s;

[0012] The zirconium-containing raw material is selected from zirconium oxychloride (ZrOCl2), zirconium oxynitrate (ZrO(NO3)2), zirconium tetrachloride (ZrCl4), zirconium nitrate (Zr(NO3)4), zirconium sulfate (Zr(SO4)2), zirconium oxycarbonate (ZrOCO3), etc., or a mixture of any proportions thereof;

[0013] S2. The zirconium oxide sol prepared in S1 is mixed with the silicon oxide sol in a volume ratio of ≤5:1. After mixing, the fiber preform is impregnated. The fiber preform has a gradient structure. The gradient fiber preform is a silicon oxide fiber felt, which is divided into upper and lower surface layers and a middle core layer. The fiber felt is an integral structure. The upper and lower surface layers are mixed with fiber cloth and fiber cotton. The middle core layer is composed entirely of fiber cotton. The thickness of the upper surface layer is 0.5 mm to 10.0 mm, the thickness of the lower surface layer is 0.3 mm to 2.0 mm, and the thickness of the middle core layer is 10 mm to 30 mm.

[0014] S3. After the impregnation is completed, the obtained gradient fiber preform is subjected to high temperature treatment to obtain a new lightweight heat-insulating material with a thickness of 10mm-35mm and a density of 0.5g / cm 3 -0.8g / cm 3 , thermal conductivity is 0.047W / m·K; it has strong oxidation resistance, can withstand the burning of oxygen-liquefied petroleum gas flame at 1600℃, can withstand quartz lamp temperature ≥1500℃, and the heat resistance temperature of typical ballistic heating environment ≥1500℃.

[0015] Furthermore, in step S1, alkali solution is used for adjustment during the preparation of zirconium oxide sol, and the amount of alkali solution is higher than the amount of zirconium used, so that the zirconium can be completely precipitated and separated; the alkali solution used is one or more of LiOH, NaOH, KOH or ammonia water, the concentration of hydroxide is 5%-20%, and the concentration of ammonia water is 15%-27%.

[0016] Furthermore, in step S1, the acid used in the process of preparing the zirconium oxide sol is an inorganic strong acid, selected from one or more of hydrochloric acid, nitric acid, and sulfuric acid, with a concentration of 30%-60%; or an organic acid such as acetic acid, oxalic acid, lactic acid, tartaric acid, etc.

[0017] Furthermore, in step S1, during the preparation of the zirconium oxide sol, the dissolution temperature of the zirconium-containing raw material is room temperature.

[0018] Furthermore, in step S1, during the preparation of the zirconium oxide sol, some stabilizers need to be added, which may be yttrium compounds.

[0019] Furthermore, in step S1, during the preparation of the zirconium oxide sol, after the dissolution is completed, a closed container is used for subsequent reactions.

[0020] Furthermore, in step S2, the impregnation is carried out in which the impregnation liquid is a mixture of homemade zirconium oxide sol and silicon oxide sol, the sols are both acidic, the sols are uniform after mixing, the viscosity does not change, the mixing ratio is ≤5:1 by volume, and the impregnation method is vacuum impregnation; the impregnation also includes a curing step, the curing atmosphere is air, the curing temperature is 100°C-300°C, the curing time is 30min-120min, and a mold is used to fix the shape of the material during curing. Different molds are used according to the different shapes of the materials. After the shape of the material is fixed, the mold can no longer be used.

[0021] Furthermore, in step S2, the fiber cotton felt is a fiber cotton felt body developed in previous experiments; in step S2, except for curing and high-temperature treatment, all other processes are carried out at room temperature.

[0022] Furthermore, in step S2, the gradient fiber preform is a silica fiber felt, the thickness of the upper surface layer is 0.5mm-10.0mm, the thickness of the lower surface layer is 0.3mm-2.0mm, and the thickness of the middle core layer is 10m-30mm. The proportion of each part can also be adjusted according to the use requirements, and the subsequent molding method is generally the same.

[0023] Furthermore, in step S3, the high temperature treatment is performed at a temperature of 600° C. to 1000° C. for a time of 30 min to 120 min in an air atmosphere.

[0024] The present invention also relates to a novel lightweight heat-insulating material, which is obtained according to the preparation method of the novel lightweight heat-insulating material. The novel lightweight heat-insulating material prepared has a zirconium oxide sol preparation cycle of 20h-80h, a material molding cycle of 4d-8d, a thickness of 10mm-35mm, and a density of 0.5g / cm 3 -0.8g / cm 3 , thermal conductivity is 0.047W / m·K; it has strong oxidation resistance, can withstand the burning of oxygen-liquefied petroleum gas flame at 1600℃, can withstand quartz lamp temperature ≥1500℃, and the heat resistance temperature of typical ballistic heating environment ≥1500℃.

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

[0026] 1. The novel lightweight heat-insulating material prepared by the present invention is a nano-scale zirconium oxide sol. The sol particles are relatively uniform in size and have a light green or milky white appearance. It can be stored for a long time. The sol can be prepared continuously to meet its own needs, greatly saving the material preparation cost.

[0027] 2. The method for preparing a novel lightweight heat-insulating material described in the present invention utilizes the sol prepared in step S1 to prepare a novel lightweight heat-insulating material, providing a ceramic composite material preform with controllable thickness and adjustable system. By controlling the impregnation efficiency, the density of the material is effectively controlled. This method effectively shortens the material preparation cycle, greatly reducing production costs and delivery cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 A flow chart of the preparation method of the novel lightweight heat-insulating material provided by the present invention;

[0030] Figure 2 This is the appearance of the zirconium oxide sol prepared in Example 1 of the present invention;

[0031] Figure 3 This is an appearance diagram of the new lightweight heat-insulating material prepared in Example 1 of the present invention;

[0032] Figure 4 This is a diagram showing the treatment of the novel lightweight heat-insulating material prepared in Example 1 of the present invention at 1600° C. using an oxygen-liquefied petroleum gas flame;

[0033] Figure 5 This is a diagram showing the test results of the novel lightweight heat-insulating material prepared in Example 1 of the present invention under a quartz lamp at 1500°C;

[0034] Figure 6 This is a comparison chart of the new lightweight heat-insulating material prepared in Example 1 of the present invention before and after the 1500°C quartz lamp test; wherein, Figure 6 (a) is the comparison picture before ablation. Figure 6 (b) is the comparison picture after ablation. DETAILED DESCRIPTION

[0035] The preparation of the novel lightweight heat-insulating material of the present invention is described in detail below, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0036] like Figure 1 The figure shows a flow chart of a method for preparing a novel lightweight heat-insulating material provided by the present invention. The present invention provides a method for preparing a novel lightweight heat-insulating material, which mainly includes two major parts: one part is the preparation of zirconium oxide sol, and the other part is the preparation of the lightweight heat-insulating material using the prepared zirconium oxide sol, which specifically includes the following steps:

[0037] S1: Preparation of zirconium oxide sol, the prepared sol has a certain concentration and low viscosity;

[0038] S2: A self-made zirconium oxide sol is mixed with a silicon oxide sol and then impregnated into a fiber preform having a gradient structure.

[0039] S3: After the impregnation is completed, the gradient fiber preform is subjected to high-temperature treatment, and a lightweight heat-insulating material can be obtained after the high-temperature treatment;

[0040] Furthermore, in step S1, the raw materials may be one or more of zirconium oxychloride (ZrOCl2), zirconium oxynitrate (ZrO(NO3)2), zirconium tetrachloride (ZrCl4), zirconium nitrate (Zr(NO3)4), zirconium sulfate (Zr(SO4)2), zirconium oxycarbonate (ZrOCO3), etc.;

[0041] Furthermore, in step S1, alkali solution is used for adjustment in the preparation of zirconium oxide sol. The alkali solution used is one or more of LiOH, NaOH, KOH or ammonia water. The amount of alkali solution is higher than the amount of zirconium. The concentration of hydroxide is 5%-20%, and the concentration of ammonia water is 15%-27%.

[0042] Furthermore, in step S1, the acid used in the preparation of the sol is an inorganic strong acid, which can be one or more of hydrochloric acid, nitric acid, and sulfuric acid, with a concentration of 30%-60%; organic acids such as acetic acid, oxalic acid, lactic acid, and tartaric acid can also be used;

[0043] Furthermore, in step S1, during the preparation of the sol, the required temperature for dissolving the raw materials is room temperature;

[0044] Furthermore, in step S1, some stabilizers need to be added during the preparation of the sol, which may be yttrium compounds;

[0045] Furthermore, in step S1, during the preparation of the sol, after the dissolution is completed, a closed container is used for subsequent reactions;

[0046] Furthermore, in step S2, the gradient fiber preform is a silica fiber felt, which is divided into upper and lower surface layers and a middle core layer. The fiber felt is an integral structure, the upper and lower surface layers are a mixture of fiber cloth and fiber cotton, and the middle core layer is composed entirely of fiber cotton.

[0047] Furthermore, in step S2, the thickness of the upper surface layer is 0.5 mm to 10.0 mm, the thickness of the lower surface layer is 0.3 mm to 2.0 mm, and the thickness of the intermediate core layer is 10 mm to 30 mm. The proportions of each part can also be adjusted according to the use requirements, and the subsequent molding method is generally the same;

[0048] Furthermore, in step S2, the impregnation liquid is a mixture of self-made zirconium oxide sol and silicon oxide sol, the sols are both acidic, the sol is uniform after mixing, the viscosity does not change, the mixing ratio is ≤5:1 (volume ratio), and the impregnation method is vacuum impregnation;

[0049] Furthermore, step S2 includes a curing step, wherein the curing atmosphere is air, the curing temperature is 100°C-300°C, and the curing time is 30 minutes-120 minutes. During the curing, a mold is used to fix the shape of the material. Different molds are used according to the different shapes of the materials. After the shape of the material is fixed, the mold can be no longer used.

[0050] Furthermore, in step S3, the high temperature treatment atmosphere is air, the high temperature treatment temperature is 600°C-1000°C, and the time is 30min-120min; before the high temperature treatment, the excess part of the material is neatly cut off;

[0051] Furthermore, the thickness of the novel lightweight heat-insulating material is 10mm-35mm and the density is 0.5-0.8g / cm 3 ;

[0052] This thermal insulation material has a gradient distribution. The upper and lower surface layers have good density and high strength. The middle core layer has a porous structure and has good thermal insulation performance, which can effectively block heat.

[0053] Furthermore, the novel lightweight heat-insulating material has strong oxidation resistance and can withstand the burning of an oxygen-liquefied petroleum gas flame at 1600°C and can withstand the temperature of a quartz lamp ≥1500°C.

[0054] The present invention is explained below with reference to specific embodiments.

[0055] Example 1:

[0056] A method for preparing a novel lightweight heat-insulating material comprises the following steps:

[0057] First, zirconia sol is prepared, and a solution is prepared with zirconium oxychloride. The amount of zirconium oxychloride used is 20g, and the amount of deionized water used is 180g. After the solution is prepared, 0.8g of yttrium nitrate is added thereto, and after stirring evenly and completely dissolved, 10% NaOH solution is added thereto dropwise and stirred continuously until the pH reaches 10. After stirring evenly, it is allowed to stand for 3 hours and then filtered. It is washed several times with deionized water to obtain 80g of wet filter cake. After dissolving it with deionized water, 50% nitric acid is added to adjust the pH to 1 and stop. Then, it is placed in a sealed container and kept warm at 150°C for 15 hours, or kept warm at 100°C for 45 hours. After taking it out, zirconia sol is obtained, and the color is light blue or milky white.

[0058] like Figure 2, which is the appearance of the zirconium oxide sol prepared in Example 1;

[0059] A gradient fiber preform is also prepared. The preform is a silica fiber felt having upper and lower surface layers and a middle core layer, all made of silica fiber; the upper surface layer is 2-5 mm thick; the lower surface layer is 1 mm thick; and the middle core layer is 20 mm thick.

[0060] The preform is fixed with a matching mold and vacuum impregnated with a mixed sol. The mixed sol is a mixture of zirconium oxide sol and silicon oxide sol. The zirconium oxide sol is a homemade sol in the previous step, and the silicon oxide sol is purchased. The mixing ratio is 2:1 by volume. After impregnation, the material is solidified at a temperature of 180°C and a time of 4 hours. This process is repeated 5 times. The material after impregnation and solidification is treated at 800°C for 80 minutes to obtain a new lightweight heat-insulating material.

[0061] like Figure 3 The figure shows the appearance of the new lightweight heat-insulating material prepared in Example 1.

[0062] The basic properties of various materials obtained in the preparation of the new lightweight heat-insulating material in Example 1 are as follows:

[0063] (1) The density of zirconia sol is 1.01g / cm 3 , concentration is 5%, viscosity ≤15mPa·s, and is light blue or milky white. The sol particles prepared by this method are 50nm and can transmit red light;

[0064] (2) The density of the prepared new lightweight thermal insulation material is 0.71 g / cm 3 , panel tensile strength 60MPa, panel bending strength 40MPa;

[0065] (3) If Figure 5 As shown in FIG. 1 , the new lightweight heat-insulating material prepared in Example 1 was subjected to a quartz lamp single-sided radiation heating test at 1500°C for 1 hour. After the test, the surface structure of the material was intact with no obvious damage, indicating that the material system can be used normally at 1500°C for a long time.

[0066] like Figure 6 As shown, the new lightweight heat-insulating material prepared in Example 1 is compared before and after the 1500°C quartz lamp test, and the new lightweight heat-insulating material prepared in Example 1 is compared before and after the 1500°C quartz lamp test (a is the comparison diagram before ablation, b is the comparison diagram after ablation);

[0067] like Figure 4As shown, the new lightweight heat-insulating material prepared in Example 1 was treated with an oxygen-liquefied petroleum gas flame at 1600°C. There was no obvious change after ablation for 5 minutes under the conditions of an oxygen-liquefied petroleum gas flame at 1600°C, indicating that the material has strong oxidation resistance.

[0068] Example 2:

[0069] A method for preparing a novel lightweight heat-insulating material comprises the following steps:

[0070] First, zirconia sol is prepared, and a solution is prepared with zirconium oxychloride. The amount of zirconium oxychloride used is 30g, and the amount of deionized water used is 170g. After the solution is prepared, 1.5g of yttrium nitrate is added thereto. After stirring evenly and completely dissolving, 26% ammonia solution is added thereto dropwise and stirred continuously until the pH reaches 10. After stirring evenly, the solution is allowed to stand for 3 hours and then filtered. The solution is washed several times with deionized water to obtain 130g of a wet filter cake. The solution is dissolved with deionized water and 50% nitric acid is added to adjust the pH to 1. The solution is then placed in a sealed container and kept warm at 150°C for 15 hours, or kept warm at 100°C for 45 hours. After taking out, zirconia sol is obtained, and the color is light blue or milky white.

[0071] A gradient fiber preform is also prepared. The preform is a silica fiber felt having upper and lower surface layers and a middle core layer, all made of silica fiber; the thickness of the upper surface layer of the preform is 5 mm; the thickness of the lower surface layer of the preform is 1 mm; and the thickness of the middle core layer of the preform is 30 mm.

[0072] The preform is fixed with a matching mold and vacuum impregnated with a mixed sol. The mixed sol is a mixture of zirconium oxide solution and silicon oxide sol. The zirconium oxide sol is a homemade sol in the previous step, and the silicon oxide sol is purchased. The mixing ratio is 4:1 by volume. After impregnation, the material is solidified at a temperature of 180°C and a time of 4 hours. This process is repeated 4 times. The material after impregnation and solidification is treated at 800°C for 80 minutes to obtain a new lightweight heat-insulating material.

[0073] The basic properties of various materials obtained in the preparation of the new lightweight heat-insulating material in Example 2 are as follows:

[0074] (1) The density of zirconia sol is 1.01g / cm 3 , concentration is 6.5%, viscosity ≤15mPa·s, and is light blue or milky white. The sol particles prepared by this method are 40nm and can transmit red light;

[0075] (2) The density of the prepared new lightweight thermal insulation material is 0.69 g / cm 3 , panel tensile strength 56MPa, panel bending strength 41MPa;

[0076] (3) The new lightweight heat-insulating material prepared in this embodiment was subjected to a quartz lamp single-sided radiation heating test at 1500°C for 1 hour. After the test, the surface structure of the material was intact without obvious damage, indicating that the material system can be used normally for a long time at 1500°C. There was no obvious change after ablation at 1600°C under oxygen-liquefied petroleum gas flame conditions for 5 minutes, indicating that the material has strong antioxidant properties.

[0077] Example 3:

[0078] A method for preparing a novel lightweight heat-insulating material comprises the following steps:

[0079] First, prepare zirconium oxide sol and prepare a solution with zirconium oxychloride. The amount of zirconium oxychloride used is 20g, and the amount of deionized water used is 180g. After the solution is prepared, add 0.8g of yttrium nitrate, stir evenly, and dissolve it completely before use. Prepare 200g of 5% NaOH solution, stir evenly, and set aside.

[0080] The zirconium oxychloride solution was added to the NaOH solution several times with continuous stirring. After complete addition, stirring was continued for 2 hours before stopping, and then suction filtration was performed. After suction filtration, 130 g of wet cake was obtained. After rinsing several times, it was dissolved with deionized water, 50% nitric acid was added thereto to adjust the pH to 1, and stirring was continued for 2 hours. After that, the solution was placed in a sealed container, kept at 150°C for 15 hours, and then taken out to completely form a sol. The sol was acidic and light blue or milky white in color.

[0081] A gradient fiber preform is also prepared. The preform is a silica fiber felt having upper and lower surface layers and a middle core layer, all made of silica fiber. The thickness of the upper surface layer of the preform is 2-5 mm; the thickness of the lower surface layer of the preform is 1 mm; and the thickness of the middle core layer of the preform is 20 mm.

[0082] The preform is fixed with a matching mold and vacuum impregnated with a mixed sol. The mixed sol is a mixture of zirconium oxide solution and silicon oxide sol. The zirconium oxide sol is a homemade sol in the previous step, and the silicon oxide sol is purchased. The mixing ratio is 3:1 by volume. After impregnation, the material is solidified at a temperature of 180°C and a time of 4 hours. This process is repeated 5 times. The material after impregnation and solidification is treated at 800°C for 80 minutes to obtain a new lightweight heat-insulating material.

[0083] The basic properties of various materials obtained in the preparation of the new lightweight heat-insulating material in Example 3 are as follows:

[0084] (1) The density of zirconia sol is 1.01g / cm 3, concentration is 4.5%, viscosity ≤15mPa·s, and is light blue or milky white. The sol particles prepared by this method are 30nm in size and can transmit yellow light;

[0085] (2) The density of the prepared new lightweight thermal insulation material is 0.68 g / cm 3 , panel tensile strength 53MPa, panel bending strength 40MPa;

[0086] (3) The new lightweight heat-insulating material prepared in this embodiment was subjected to a quartz lamp single-sided radiation heating test at 1500°C for 1 hour. After the test, the surface structure of the material was intact without obvious damage, indicating that the material system can be used normally for a long time at 1500°C. There was no obvious change after ablation at 1600°C under oxygen-liquefied petroleum gas flame conditions for 5 minutes, indicating that the material has strong antioxidant properties.

[0087] Comparative Example 1:

[0088] Zirconia sol was prepared using the method of Example 1. The color of the sol was light blue or milky white. The sol was mixed with silica sol at a volume ratio of 2:1.

[0089] A split preform is also prepared. The split preform is a composite structure of silica material, divided into upper and lower panels and a middle thermal insulation core layer. The upper panel is a 2.5D woven silica fiber with a thickness of 1mm-3mm; the lower panel is a twill silica fiber cloth with a thickness of 0.2mm-1mm; the middle thermal insulation core layer is a silica aerogel material with a thickness of 10mm-30mm.

[0090] Comparative Example 1 is the same as Example 1 except that the preform is different from that of Example 1;

[0091] The prepared lightweight heat-insulating material has the following properties:

[0092] (1) The zirconium oxide sol is substantially the same as that in Example 1;

[0093] (2) The density of the prepared new lightweight thermal insulation material is 0.65 g / cm 3 , panel tensile strength 70MPa, panel bending strength 45MPa;

[0094] (3) The new lightweight heat-insulating material prepared in Comparative Example 1 was subjected to a quartz lamp single-sided radiation heating test at 1500°C for 1 hour. After the test, the surface structure of the material was intact without obvious damage, indicating that the material system can be used normally for a long time at 1500°C. There was no obvious change after ablation at 1600°C under oxygen-liquefied petroleum gas flame conditions for 5 minutes, indicating that the material has strong antioxidant properties.

[0095] The results show that the materials prepared by Comparative Example 1 and Example 1 have similar temperature resistance and slightly better mechanical properties than Example 1. However, the split preform needs to prepare the middle thermal insulation core layer first, and then manually combine the upper and lower panels and the middle thermal insulation core layer after the preparation of the middle thermal insulation core layer is completed. This combination process requires manual multi-step operation and a long preparation cycle. The gradient fiber preform uses a machine instead of manual labor, and the steps are simple, which greatly shortens the preparation cycle and avoids interference from manual differences. In addition, in the split preform, the raw material cost of the upper and lower panels and the middle thermal insulation core layer is much higher than the fiber cloth and fiber cotton in the gradient fiber preform. In summary, comparing the two thermal insulation materials, the gradient fiber preform solution has higher advantages in preparation cycle and raw material price, and the difference in mechanical properties is not large. The overall cost is much lower than the split type. The solution of Example 1 is better than Comparative Example 1.

[0096] Comparative Example 2:

[0097] A gradient fiber preform is impregnated with silica sol alone. The preform is a silica fiber felt having upper and lower surface layers and a middle core layer, all made of silica fiber. The thickness of the upper surface layer is 2 mm to 5 mm; the thickness of the lower surface layer is 1 mm; and the thickness of the middle core layer is 20 mm.

[0098] The sol used in Comparative Example 2 is different from that in Example 1. Example 1 uses a mixed sol of zirconium oxide and silicon oxide with a volume ratio of 2:1, while Comparative Example 2 uses only silicon oxide sol, and the rest is the same as in Example 1.

[0099] The prepared lightweight heat-insulating material has the following properties:

[0100] (1) The density of the prepared thermal insulation material is 0.68g / cm 3 , panel tensile strength 58MPa, panel bending strength 41MPa;

[0101] (2) The new lightweight heat-insulating material prepared in Comparative Example 2 was subjected to a quartz lamp single-sided radiation heating test at 1500°C for 1 hour. After the test, the material structure was deformed and the surface partially collapsed, indicating that the material system was damaged at 1500°C. When ablated under oxygen-liquefied petroleum gas flame conditions at 1600°C for 5 minutes, the periphery of the material collapsed, indicating that the material could not withstand the high temperature of 1600°C.

[0102] (3) The thermal conductivity of the test material is 0.056W / m·k.

[0103] The results show that the materials prepared in Comparative Example 2 and Example 1 have similar mechanical properties, but their temperature resistance and thermal insulation properties are much lower than those of Example 1. The solution in Example 1 is better than that in Comparative Example 2.

[0104] Comparative Example 3:

[0105] Zirconia sol was prepared using the method of Example 1. The color of the sol was light blue or milky white. The sol was mixed with silica sol at a volume ratio of 8:1.

[0106] A gradient fiber preform is also prepared. The preform is a silica fiber felt having upper and lower surface layers and a middle core layer, all made of silica fiber; the thickness of the upper surface layer is 2mm-5mm; the thickness of the lower surface layer is 1mm; and the thickness of the middle core layer is 20mm.

[0107] The difference between Comparative Example 3 and Example 1 is that the mixing ratio of zirconium oxide sol and silicon oxide sol is different, and the other aspects are the same as Example 1;

[0108] The prepared lightweight heat-insulating material has the following properties:

[0109] (1) The zirconium oxide sol is substantially the same as that in Example 1;

[0110] (2) The density of the prepared new lightweight thermal insulation material is 0.62 g / cm 3 , panel tensile strength 50MPa, panel bending strength 35MPa;

[0111] (3) The new lightweight heat-insulating material prepared in Comparative Example 3 was subjected to a quartz lamp single-sided radiation heating test at 1500°C for 1 hour. After the test, the surface structure of the material was intact without obvious damage, indicating that the material system can be used normally for a long time at 1500°C. There was no obvious change after ablation at 1600°C under oxygen-liquefied petroleum gas flame conditions for 5 minutes, indicating that the material has strong antioxidant properties.

[0112] The results show that although the density of the materials prepared in Comparative Example 3 and Example 1 is reduced, the mechanical properties are also reduced, and the temperature resistance and thermal insulation properties are similar to those of Example 1. Since the preparation cost of zirconia sol is higher than that of silica sol, using a larger proportion of zirconia sol not only increases the material preparation cost, but also reduces the material performance. Overall, Example 1 is superior.

[0113] Results and Discussion

[0114] 1. Through the comprehensive comparison of the embodiments and comparative examples, it can be seen that adjusting the ratio of zirconium oxide and silicon oxide sol within an appropriate range, or appropriately changing the thickness of the upper and lower surface layers and the middle core layer of the gradient fiber preform, will not have a substantial impact on the final performance of the lightweight thermal insulation material. The prepared thermal insulation materials have higher mechanical properties and better ability to withstand high temperatures.

[0115] 2. Comparing the comparative examples with the examples reveals that replacing the mixed sol with a pure silica sol or significantly increasing the proportion of zirconium oxide sol can lead to a certain degree of degradation in the mechanical and temperature resistance of the resulting thermal insulation material, or even an additional cost increase. Changing the gradient fiber preform to a split preform significantly increases the material preparation cycle and cost. Therefore, based on a comprehensive comparison of material properties, the examples are the preferred lightweight thermal insulation material, with Example 1 being the most optimal.

[0116] 3. The present invention provides a method for preparing a novel lightweight heat-insulating material, which can be used normally for a long time at 1500°C, can be prepared quickly, and has the characteristics of high temperature resistance and strong oxidation resistance.

[0117] In summary, the novel lightweight thermal insulation material produced by the present invention adopts a gradient structure, utilizing a porous silica fiber felt as the intermediate core layer to achieve enhanced thermal insulation performance. The upper and lower panels are made of silica composite materials. The upper surface layer is thick enough to provide thermal insulation and withstand sustained high temperatures, while the lower surface layer, designed to be bonded to the cabin during product application, is designed to be thicker than the lower surface layer. The combination of the intermediate core layer and the hot surface layer provides excellent heat resistance and insulation, enhancing overall thermal insulation performance.

[0118] Furthermore, the invention produces a novel lightweight, heat-resistant, and heat-insulating material, providing a ceramic composite preform with controllable thickness and adjustable structure. Its gradient distribution effectively enhances the bonding strength between layers, minimizes human factors, and improves production efficiency and material stability. This shortens the overall development cycle and indirectly reduces production costs.

[0119] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a lightweight heat-insulating material, characterized by: The following steps are involved: S1. Preparation of zirconia sol: zirconia sol is prepared from zirconium-containing raw materials. The main component of the prepared zirconia sol is zirconium dioxide. The sol is light blue or milky white liquid with a concentration of 2%-8% and a density of 1.01g / cm 3 , viscosity ≤15mPa·s; The zirconium-containing raw material is selected from one or a mixture of any proportion of zirconium oxychloride, zirconium oxynitrate, zirconium tetrachloride, zirconium nitrate, zirconium sulfate, and zirconium oxycarbonate; S2. The zirconium oxide sol prepared in S1 is mixed with the silicon oxide sol in a volume ratio of ≤5:

1. The sols are both acidic. After mixing, the sols are uniform and the viscosity does not change. After mixing, the fiber preform is impregnated. The fiber preform has a gradient structure. The gradient fiber preform is a silicon oxide fiber cotton felt, which is divided into an upper and lower surface layer and a middle core layer. The fiber cotton felt is an integral structure. The upper and lower surface layers are mixed with fiber cloth and fiber cotton. The middle core layer is composed entirely of fiber cotton. The thickness of the upper surface layer is 0.5mm-10.0mm, the thickness of the lower surface layer is 0.3mm-2.0mm, and the thickness of the middle core layer is 10m-30mm. S3. After the impregnation is completed, the obtained gradient fiber preform is subjected to high temperature treatment to obtain a lightweight heat-insulating material with a thickness of 10mm-35mm and a density of 0.5g / cm 3 -0.8g / cm 3 , thermal conductivity is 0.047W / m·K; it has strong oxidation resistance, can withstand the burning of oxygen-liquefied petroleum gas flame at 1600℃, can withstand quartz lamp temperature ≥1500℃, and the heat resistance temperature of typical ballistic heating environment ≥1500℃.

2. The method for preparing a lightweight heat-insulating material according to claim 1, characterized in that: In step S1, alkali solution is used for adjustment during the preparation of zirconium oxide sol, and the amount of alkali solution is higher than the amount of zirconium used, so that the zirconium can be completely precipitated and separated; the alkali solution used is one or more of LiOH, NaOH, KOH or ammonia water, and the concentration of hydroxide in the alkali solution is 5%-20%, and the concentration of ammonia water is 15%-27%.

3. The method for preparing a lightweight heat-insulating material according to claim 1, characterized in that: In step S1, the acid used in the process of preparing the zirconium oxide sol is an inorganic strong acid, selected from one or more of hydrochloric acid, nitric acid, and sulfuric acid, with a concentration of 30%-60%; or acetic acid, oxalic acid, lactic acid, and tartaric acid.

4. The method for preparing a lightweight heat-insulating material according to claim 1, characterized in that: In step S1, during the process of preparing the zirconium oxide sol, the dissolution temperature of the zirconium-containing raw material is room temperature.

5. The method for preparing a lightweight heat-insulating material according to claim 1, characterized in that: In step S1, during the preparation of the zirconium oxide sol, an yttrium compound needs to be added as a stabilizer.

6. The method for preparing a lightweight heat-insulating material according to claim 1, characterized in that: In step S2, the impregnation is performed by vacuum impregnation using a mixture of homemade zirconium oxide sol and silicon oxide sol in a volume ratio of ≤5:

1. The impregnation also includes a curing step in which the curing atmosphere is air, the curing temperature is 100°C-300°C, and the curing time is 30min-120min. During the curing process, a mold is used to fix the shape of the material. Different molds are used according to the different shapes of the materials. After the shape of the material is fixed, the mold is no longer used.

7. The method for preparing a lightweight heat-insulating material according to claim 1, characterized in that: In step S2, except for the curing and high-temperature treatment, all other steps are performed at room temperature.

8. The method for preparing a lightweight heat-insulating material according to claim 1, characterized in that: In step S2, the gradient fiber preform is a silica fiber felt, and the proportion of each part is adjusted according to the use requirements. The subsequent molding method is the same.

9. The method for preparing a lightweight heat-insulating material according to claim 1, characterized in that: In step S3, the high temperature treatment is carried out at a temperature of 600° C. to 1000° C. for a time of 30 min to 120 min in an air atmosphere.

10. A lightweight heat-insulating material, characterized by: The method for preparing a lightweight heat-insulating material according to any one of claims 1 to 9 is used to prepare the lightweight heat-insulating material, wherein the zirconium oxide sol preparation cycle is 20h-80h, the material molding cycle is 4d-8d, the thickness is 10mm-35mm, and the density is 0.5g / cm 3 -0.8g / cm 3 , thermal conductivity is 0.047 W / m·K; it has strong oxidation resistance, can withstand the burning of oxygen-liquefied petroleum gas flame at 1600℃, can withstand quartz lamp temperature ≥1500℃, and the heat resistance temperature of typical ballistic heating environment ≥1500℃.

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