Oxide fiber composite material and preparation method and application thereof

Abstract

The invention discloses an oxide fiber composite material as well as a preparation method and application thereof. The preparation method of the oxide fiber composite material comprises the following steps: mixing quartz powder and boron oxide powder, grinding, and sieving to obtain mixed powder; uniformly mixing the mixed powder, transition metal boron / silicide and boron carbide to obtain a total mixture; adding a dispersing agent and water into a part of the mixture, and adjusting the water quantity to prepare slurry A with the solid content of 20-25%; preparing the rest part into slurry B with the solid content of 35-40% according to the same way; injecting the slurry A into the oxide fiber, performing slurry A supplementary dipping on the injection area, coating the dipping surface with the slurry B, and drying for later use; and sintering the surface, coated with the slurry B, of the dried sample for 20-30 minutes by using a heating spray gun. Muffle furnace sintering is replaced with spray gun sintering, local spray gun sintering treatment is carried out on the oxide fibers, the high-temperature embrittlement phenomenon of the oxide fibers is effectively inhibited, and the mechanical property of the composite material is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature ceramic materials, and in particular relates to an oxide fiber composite material and a preparation method and application thereof. Background Art

[0002] Oxide fiber composites (Oxide Fiber Composites) are high-performance materials made by combining oxide ceramic fibers (such as Al2O3, ZrO2, SiO2, and Y2O3) as reinforcements with a ceramic, metal, or polymer matrix through a specific process. These materials offer advantages such as long-term high-temperature resistance, excellent oxidation resistance, relatively low manufacturing costs, and low density. Consequently, they are widely used in a variety of fields: in aerospace, they are used in engine hot-end components and high-temperature thermal insulation layers; in the energy and environmental fields, they serve as neutron absorbers and thermal insulation materials in solid oxide fuel cells and nuclear reactors; and in the functional materials field, they are used as insulating layers in electronic devices.

[0003] Oxide fiber composites are typically prepared using processes such as chemical vapor deposition, precursor infiltration pyrolysis, hot pressing, and sol-gel methods. Slurry infiltration and hot pressing offer the advantages of relatively simple processing and suitability for complex structural molding. However, hot pressing at high temperatures (>1200°C) can easily cause fiber grain coarsening, resulting in a strength drop of up to 40–60%, significantly weakening the material's performance. Lee et al. investigated the effect of sintering temperature on the mechanical properties of alumina fiber composites during hot pressing. They found that when hot pressed below 1250°C and at a pressure of 40 MPa for 1 h, all composites with coated fibers exhibited non-catastrophic failure behavior. However, when the temperature rose above this threshold, the failure mode shifted to complete brittle fracture. Although chemical vapor infiltration (CVI) can achieve material preparation at lower temperatures and produce composites with pure interfaces, its deposition efficiency is low (typically requiring cycles exceeding 100 h) and its manufacturing cost is high. Although the sol-gel method can be prepared at a lower temperature and has a lower cost than CVI, its process is relatively complicated and requires multiple impregnation steps. At the same time, due to the large shrinkage rate during the drying process of the gel, it is easy to cause problems such as interlayer cracking.

[0004] Furthermore, existing oxide fiber composite sintering technologies generally suffer from excessively high sintering temperatures, and the mechanical properties of most oxide fibers significantly degrade at such high temperatures. For example, quartz fibers exhibit excellent mechanical properties and a low thermal expansion coefficient below 800°C. However, when the temperature rises above 1000°C, the amorphous SiO2 undergoes a phase transition to cristobalite / phosphotarbeitite, and exhibits significant viscous flow behavior above 1200°C, resulting in a strength loss exceeding 90%. For alumina fibers, within the 1000–1200°C range, γ-Al2O3 undergoes a phase transition to α-Al2O3 (approximately 1100°C), accompanied by volume shrinkage and the induction of microcracks. Above 1200°C, α-Al2O3 grains rapidly grow (from an initial 0.5 μm to 2–5 μm), resulting in a 30–50% decrease in strength. When the temperature rises further to above 1200°C, α-Al2O3 fibers may experience grain boundary sliding under stress, and the creep rate increases significantly at 1400°C, resulting in a sharp drop in strength. Furthermore, other types of oxide fibers, such as ZrO2 fibers, mullite fibers, and Al2O3 fibers, also commonly face problems such as phase transformation cracking or crystallization embrittlement under ultra-high temperature conditions.

[0005] Therefore, there is currently no single preparation technology that can simultaneously meet the comprehensive requirements of low cost, short cycle time, and effective avoidance of fiber embrittlement. Therefore, it is urgent to develop a new low-temperature, short-cycle preparation technology suitable for oxide fiber composites to promote their widespread application in the field of high-performance structural materials. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide an oxide fiber composite material and its preparation method and application, aiming to solve the key technical problems such as high cost, long cycle and fiber embrittlement in the existing preparation process.

[0007] The purpose of the present invention is achieved through the following technical solutions: A method for preparing an oxide fiber composite material comprises the following steps: (1) quartz powder and boron oxide powder are mixed, ground, and sieved to obtain a mixed powder; (2) The obtained mixed powder, transition metal boron / silicide and boron carbide are uniformly mixed to obtain a total mixture; a portion is added with a dispersant and water, and the amount of water is adjusted to obtain a slurry A with a solid content of 10% to 25%; the remaining portion is prepared in the same manner to obtain a slurry B with a solid content of 35% to 40%; (3) Inject slurry A into the oxide fiber, then re-impregnate the injected area with slurry A, and finally apply slurry B on the impregnated surface, dry it, and set it aside; (4) The side of the dried sample coated with slurry B is sintered with a heating spray gun for 20 to 30 minutes to obtain the oxide fiber composite material.

[0008] In this invention, to prepare a composite material with a gradient structure, a low-solids, easily pore-filling slurry (A) is vacuum-impregnated into oxide fibers. A higher-solids, less fluid slurry (B) is then applied to the surface of the material by brushing or spraying, forming a denser surface layer. Because processes such as CVI, sol-gel, hot pressing, and chemical cracking often suffer from high costs, long cycles, complex processes, or fiber embrittlement, this invention utilizes a low-cost, readily available spray gun (using butane as fuel) to achieve low-temperature sintering of the coating in a relatively short time, while effectively preserving the original strength of the substrate.

[0009] Preferably, the mass ratio of the quartz powder to the boron oxide powder in step (1) is 4-6:0.5-1, and more preferably, the mass ratio of the quartz powder to the boron oxide powder is 5:1.

[0010] Preferably, the specific method of grinding in step (1) is: using ethanol as the liquid medium, using ZrO2 as the grinding medium, the material-ball ratio is 2:1, the grinding speed is 200~300rpm, and the grinding time is 8~10h.

[0011] In the wet grinding step of the present invention, ethanol is used as the liquid medium; after the grinding is completed, the ethanol is removed from the obtained material by rotary evaporation, and then the material is sieved.

[0012] Preferably, the mesh size of the sieving in step (1) is 200-300 mesh.

[0013] Preferably, the mass ratio of the mixed powder, transition metal boron / silicide and boron carbide in step (2) is 36:18~24:0.5~1.

[0014] In this invention, borosilicate glass (introduced from quartz powder and boron oxide) serves as a binder, transition metal boron / silicide serves as an emissive, and boron carbide serves as a sintering aid. Too little borosilicate glass powder can impair the coating's bonding, while too much can lead to poor thermal insulation. Similarly, too little boron carbide can't effectively densify the coating, while too much can significantly impact coating performance.

[0015] Preferably, in the slurry A and slurry B prepared in step (2), the amount of dispersant added is 0.4% to 0.8% of the total mass of the slurry.

[0016] Preferably, the dispersant is at least one of polyacrylamide, polyethylene glycol, sodium hexametaphosphate and sodium dodecylbenzene sulfonate.

[0017] In the present invention, slurry A and slurry B are mixed by ball milling during their preparation to achieve highly uniform dispersion of the components.

[0018] Preferably, the transition metal boron / silicide in step (2) is at least one of HfB2, ZrB2, TaB2, WB2, MoSi2, ZrSi2, NbSi2, TaSi2 and WSi2.

[0019] Preferably, the oxide fiber in step (3) is at least one of quartz fiber, mullite fiber and alumina fiber.

[0020] Preferably, in step (3), the injection depth of slurry A is controlled not to exceed the fiber thickness.

[0021] In this invention, a gradient composite material was prepared using a partial impregnation method. By reducing the difference in elastic modulus between the coating and substrate, stress concentration at the interface was reduced, resulting in an optimized coating structure. Alternatively, a full impregnation method could be used to achieve gradient sintering by exploiting the temperature difference between the coating surface and interior during spray gun sintering.

[0022] In the present invention, slurry A is injected into the oxide fiber through a syringe, and its injection depth is controlled not to exceed the total thickness of the fiber. In some embodiments, the oxide fiber used has a thickness of 20 mm and a bulk density of 0.4 g / cm 3 , the injection depth of slurry A is 3mm.

[0023] In order to further improve the filling effect of the internal voids of the fiber, the injected area was impregnated with a depth of 4 to 5 mm to ensure that the injected area was fully densified.

[0024] Preferably, in step (3), the coating thickness of slurry B on the impregnated surface is 3-4 mm.

[0025] Preferably, the flame temperature of the heating spray gun in step (4) is 1080~1120℃.

[0026] The oxide fiber composite material is prepared by the above-mentioned method for preparing the oxide fiber composite material.

[0027] Application of the above oxide fiber composite material as a high-temperature thermal insulation material.

[0028] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a novel method for preparing oxide fiber composites, using spray gun sintering instead of the traditional muffle furnace sintering process. Furthermore, localized spray gun sintering of the oxide fibers effectively suppresses the embrittlement of fibers in other areas of the sample at high temperatures, significantly improving the mechanical properties of the sintered composite. Furthermore, this method eliminates the need for energy-intensive muffle furnace equipment, resulting in low manufacturing costs and significantly shortened production cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the microstructure of the oxide fiber composite material prepared in Example 1 of the present invention, wherein (a) is the cross-sectional morphology in the thickness direction of the material, (b) is the cross-sectional morphology of the coating-impregnated area, (c) is the cross-sectional morphology of the non-impregnated area, and (d) is the surface morphology after sintering.

[0030] Figure 2 This is the XRD diffraction spectrum of the oxide fiber composite material prepared in Example 1. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] Example 1 A method for preparing an oxide fiber composite material, comprising the following specific steps: (1) 20.0 g of fused quartz powder and 4.0 g of B2O3 powder were mixed and added to a grinding machine. Ethanol was used as the liquid medium and 10 mm ZrO2 balls were used as the grinding medium. The material-to-ball ratio was 2:1. After wet grinding at 200 rpm for 10 h, the ethanol was removed from the resulting slurry by rotary evaporation and then filtered through a 200-300 mesh sieve to obtain a uniform mixed powder. (2) The obtained mixed powder, 15.7 g of MoSi2 and 0.6 g of boron carbide were mixed uniformly to obtain a total mixture; 0.5 g of polyacrylamide, 0.5 g of n-octanol (as a defoaming agent, not an essential component) and water were added to a portion of the mixture, the amount of water was adjusted and the mixture was ball-milled for 3 h to obtain slurry A with a solid content of 10%; the remaining portion was prepared in the same manner to obtain slurry B with a solid content of 35%; (3) Inject slurry A into the quartz fiber (thickness 20mm, bulk density 0.4g / cm 3 ), the injection depth was controlled to be 3 mm, and then the injection area was supplementally impregnated with slurry A to a depth of 4-5 mm for 30 min. Finally, a layer of slurry B was applied on the impregnated surface to a thickness of 145-155 μm, and dried at 80°C for 2 days before use; (4) Install the X-axis moving platform on the lifting platform, and fix the fixture above it. Connect the spray gun to the butane gas tank and fix it horizontally in the fixture. Subsequently, place the sample obtained in step (3) on the heat insulation board, adjust the moving platform to align the spray gun with the sample, and then adjust the lifting platform so that the distance between the spray gun outlet and the sample surface is controlled to be 8 cm. Adjust the spray gun so that the flame direction is 90° to the sample surface. At this position, the side of the sample coated with slurry B is heated by the spray gun. The flame temperature is 1080~1100℃, and the sintering is continued for 20 minutes to obtain the oxide fiber composite material.

[0033] Comparative Example 1 Comparative Example 1 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1000°C, and the sintering time is 20 minutes.

[0034] Comparative Example 2 Comparative Example 2 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1100°C, and the sintering time is 20 minutes.

[0035] Comparative Example 3 Comparative Example 3 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1200°C, and the sintering time is 20 minutes.

[0036] Example 2 A method for preparing an oxide fiber composite material, comprising the following specific steps: (1) 20.0 g of fused quartz powder and 4.0 g of B2O3 powder were mixed and added to a grinding machine. Ethanol was used as the liquid medium and 10 mm ZrO2 balls were used as the grinding medium. The material-to-ball ratio was 2:1. After wet grinding at 200 rpm for 10 h, the ethanol was removed from the resulting slurry by rotary evaporation and then filtered through a 200-300 mesh sieve to obtain a uniform mixed powder. (2) The obtained mixed powder, 15.7 g ZrB2 and 0.6 g boron carbide were mixed uniformly to obtain a total mixture; 0.5 g polyacrylamide, 0.5 g n-octanol (as a defoaming agent, not an essential component) and water were added to a portion of the mixture, the amount of water was adjusted and the mixture was ball-milled for 3 h to obtain slurry A with a solid content of 10%; the remaining portion was prepared in the same manner to obtain slurry B with a solid content of 35%; (3) Inject slurry A into the quartz fiber (thickness 20mm, bulk density 0.4g / cm3 ), the injection depth was controlled to be 3 mm, and then the injection area was supplementally impregnated with slurry A to a depth of 4-5 mm for 30 min. Finally, a layer of slurry B was applied on the impregnated surface to a thickness of 145-155 μm, and dried at 80°C for 2 days before use; (4) Install the X-axis moving platform on the lifting platform, and fix the fixture above it. Connect the spray gun to the butane gas tank and fix it horizontally in the fixture. Subsequently, place the sample obtained in step (3) on the heat insulation board, adjust the moving platform to align the spray gun with the sample, and then adjust the lifting platform so that the distance between the spray gun outlet and the sample surface is controlled to be 8 cm. Adjust the spray gun so that the flame direction is 90° to the sample surface. At this position, heat the sample with the slurry B on the side of the sample with the spray gun. The flame temperature is 1080~1120℃, and the sintering is continued for 20 minutes to obtain the oxide fiber composite material.

[0037] Comparative Example 4 Comparative Example 4 provides a method for preparing an oxide fiber composite material. Compared with Example 2, the only difference is that the spray gun sintering in step (4) of Example 2 is replaced by muffle furnace sintering, the sintering temperature is 1000°C, and the sintering time is 20 minutes.

[0038] Comparative Example 5 Comparative Example 5 provides a method for preparing an oxide fiber composite material. Compared with Example 2, the only difference is that the spray gun sintering in step (4) of Example 2 is replaced by muffle furnace sintering, the sintering temperature is 1100°C, and the sintering time is 20 minutes.

[0039] Comparative Example 6 Comparative Example 6 provides a method for preparing an oxide fiber composite material. Compared with Example 2, the only difference is that the spray gun sintering in step (4) of Example 2 is replaced by muffle furnace sintering, the sintering temperature is 1200°C, and the sintering time is 20 minutes.

[0040] Example 3 A method for preparing an oxide fiber composite material, comprising the following specific steps: (1) 20.0 g of fused quartz powder and 4.0 g of B2O3 powder were mixed and added to a grinding machine. Ethanol was used as the liquid medium and 10 mm ZrO2 balls were used as the grinding medium. The material-to-ball ratio was 2:1. After wet grinding at 200 rpm for 10 h, the ethanol was removed from the resulting slurry by rotary evaporation and then filtered through a 200-300 mesh sieve to obtain a uniform mixed powder. (2) The obtained mixed powder, 4.91 g of MoSi2, 10.79 g of ZrB2 and 0.6 g of boron carbide were mixed uniformly to obtain a total mixture; 0.5 g of polyacrylamide, 0.5 g of n-octanol (as a defoaming agent, not an essential component) and water were added to a portion of the mixture, the amount of water was adjusted and the mixture was ball-milled for 3 h to obtain slurry A with a solid content of 10%; the remaining portion was prepared in the same manner to obtain slurry B with a solid content of 35%; (3) and (4) are the same as in Example 1.

[0041] Comparative Example 7 Comparative Example 7 provides a method for preparing an oxide fiber composite material. Compared with Example 3, the only difference is that the spray gun sintering in step (4) of Example 3 is replaced by muffle furnace sintering, the sintering temperature is 1000°C, and the sintering time is 20 minutes.

[0042] Comparative Example 8 Comparative Example 8 provides a method for preparing an oxide fiber composite material. Compared with Example 3, the only difference is that the spray gun sintering in step (4) of Example 3 is replaced by muffle furnace sintering, the sintering temperature is 1100°C, and the sintering time is 20 minutes.

[0043] Comparative Example 9 Comparative Example 9 provides a method for preparing an oxide fiber composite material. Compared with Example 3, the only difference is that the spray gun sintering in step (4) of Example 3 is replaced by muffle furnace sintering, the sintering temperature is 1200°C, and the sintering time is 20 minutes.

[0044] Example 4 A method for preparing an oxide fiber composite material, comprising the following specific steps: (1) 20.0 g of fused quartz powder and 4.0 g of B2O3 powder were mixed and added to a grinding machine. Ethanol was used as the liquid medium and 10 mm ZrO2 balls were used as the grinding medium. The material-to-ball ratio was 2:1. After wet grinding at 200 rpm for 10 h, the ethanol was removed from the resulting slurry by rotary evaporation and then filtered through a 200-300 mesh sieve to obtain a uniform mixed powder. (2) The obtained mixed powder, 4.356 g HfB2, 2.466 g ZrB2, 4.419 g TaB2, 4.472 g WB2 and 0.6 g boron carbide were mixed uniformly to obtain a total mixture; 0.5 g polyacrylamide, 0.5 g n-octanol (as a defoaming agent, not an essential component) and water were added to a portion, the water amount was adjusted and the mixture was ball-milled for 3 h to obtain slurry A with a solid content of 10%; the remaining portion was prepared in the same manner to obtain slurry B with a solid content of 35%; (3) and (4) are the same as in Example 1.

[0045] Comparative Example 10 Comparative Example 10 provides a method for preparing an oxide fiber composite material. Compared with Example 4, the only difference is that the spray gun sintering in step (4) of Example 4 is replaced by muffle furnace sintering, the sintering temperature is 1000°C, and the sintering time is 20 minutes.

[0046] Comparative Example 11 Comparative Example 11 provides a method for preparing an oxide fiber composite material. Compared with Example 4, the only difference is that the spray gun sintering in step (4) of Example 4 is replaced by muffle furnace sintering, the sintering temperature is 1100°C, and the sintering time is 20 minutes.

[0047] Comparative Example 12 Comparative Example 12 provides a method for preparing an oxide fiber composite material. Compared with Example 4, the only difference is that the spray gun sintering in step (4) of Example 4 is replaced by muffle furnace sintering, the sintering temperature is 1200°C, and the sintering time is 20 minutes.

[0048] Example 5 A method for preparing an oxide fiber composite material, comprising the following specific steps: (1) 20.0 g of fused quartz powder and 4.0 g of B2O3 powder were mixed and added to a grinding machine. Ethanol was used as the liquid medium and 10 mm ZrO2 balls were used as the grinding medium. The material-to-ball ratio was 2:1. After wet grinding at 200 rpm for 10 h, the ethanol was removed from the resulting slurry by rotary evaporation and then filtered through a 200-300 mesh sieve to obtain a uniform mixed powder. (2) The obtained mixed powder, 2.578 g of MoSi2, 2.498 g of ZrSi2, 2.527 g of NbSi2, 4.018 g of TaSi2, 4.068 g of WSi2 and 0.6 g of boron carbide were mixed uniformly to obtain a total mixture; 0.5 g of polyacrylamide, 0.5 g of n-octanol (as a defoaming agent, not an essential component) and water were added to a portion of the mixture, the amount of water was adjusted and the mixture was ball-milled for 3 h to obtain slurry A with a solid content of 10%; the remaining portion was prepared in the same manner to obtain slurry B with a solid content of 35%; (3) and (4) are the same as in Example 1.

[0049] Comparative Example 13 Comparative Example 13 provides a method for preparing an oxide fiber composite material. Compared with Example 5, the only difference is that the spray gun sintering in step (4) of Example 5 is replaced by muffle furnace sintering, the sintering temperature is 1000°C, and the sintering time is 20 minutes.

[0050] Comparative Example 14 Comparative Example 14 provides a method for preparing an oxide fiber composite material. Compared with Example 5, the only difference is that the spray gun sintering in step (4) of Example 5 is replaced by muffle furnace sintering, the sintering temperature is 1100°C, and the sintering time is 20 minutes.

[0051] Comparative Example 15 Comparative Example 15 provides a method for preparing an oxide fiber composite material. Compared with Example 5, the only difference is that the spray gun sintering in step (4) of Example 5 is replaced by muffle furnace sintering, the sintering temperature is 1200°C, and the sintering time is 20 minutes.

[0052] Example 6 A method for preparing an oxide fiber composite material, comprising the following specific steps: (1) 20.0 g of fused quartz powder and 4.0 g of B2O3 powder were mixed and added to a grinding machine. Ethanol was used as the liquid medium and 10 mm ZrO2 balls were used as the grinding medium. The material-to-ball ratio was 2:1. After wet grinding at 200 rpm for 10 h, the ethanol was removed from the resulting slurry by rotary evaporation and then filtered through a 200-300 mesh sieve to obtain a uniform mixed powder. (2) The obtained mixed powder, 15.7 g of MoSi2 and 0.6 g of boron carbide were mixed uniformly to obtain a total mixture; 0.5 g of polyacrylamide, 0.5 g of n-octanol (as a defoaming agent, not an essential component) and water were added to a portion of the mixture, the amount of water was adjusted and the mixture was ball-milled for 3 h to obtain slurry A with a solid content of 10%; the remaining portion was prepared in the same manner to obtain slurry B with a solid content of 35%; (3) Inject slurry A into mullite fiber (thickness 20 mm, bulk density 0.4 g / cm 3 ), the injection depth was controlled to be 3 mm, and then the injection area was supplementally impregnated with slurry A to a depth of 4-5 mm for 30 min. Finally, a layer of slurry B was applied on the impregnated surface to a thickness of 145-155 μm, and dried at 80°C for 2 days before use; (4) Install the X-axis moving platform on the lifting platform, and fix the fixture above it. Connect the spray gun to the butane gas tank and fix it horizontally in the fixture. Subsequently, place the sample obtained in step (3) on the heat insulation board, adjust the moving platform to align the spray gun with the sample, and then adjust the lifting platform so that the distance between the spray gun outlet and the sample surface is controlled to be 8 cm. Adjust the spray gun so that the flame direction is 90° to the sample surface. At this position, the side of the sample coated with slurry B is heated by the spray gun. The flame temperature is 1080~1100℃, and the sintering is continued for 20 minutes to obtain the oxide fiber composite material.

[0053] Comparative Example 16 Comparative Example 16 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1000°C, and the sintering time is 20 minutes.

[0054] Comparative Example 17 Comparative Example 17 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1100°C, and the sintering time is 20 minutes.

[0055] Comparative Example 18 Comparative Example 18 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1200°C, and the sintering time is 20 minutes.

[0056] Example 7 A method for preparing an oxide fiber composite material, comprising the following specific steps: (1) 20.0 g of fused quartz powder and 4.0 g of B2O3 powder were mixed and added to a grinding machine. Ethanol was used as the liquid medium and 10 mm ZrO2 balls were used as the grinding medium. The material-to-ball ratio was 2:1. After wet grinding at 200 rpm for 10 h, the ethanol was removed from the resulting slurry by rotary evaporation and then filtered through a 200-300 mesh sieve to obtain a uniform mixed powder. (2) The obtained mixed powder, 15.7 g of MoSi2 and 0.6 g of boron carbide were mixed uniformly to obtain a total mixture; 0.5 g of polyacrylamide, 0.5 g of n-octanol (as a defoaming agent, not an essential component) and water were added to a portion of the mixture, the amount of water was adjusted and the mixture was ball-milled for 3 h to obtain slurry A with a solid content of 10%; the remaining portion was prepared in the same manner to obtain slurry B with a solid content of 35%; (3) Slurry A was injected into the alumina fiber (thickness 20 mm, bulk density 0.4 g / cm 3 ), the injection depth was controlled to be 3 mm, and then the injection area was supplementally impregnated with slurry A to a depth of 4-5 mm for 30 min. Finally, a layer of slurry B was applied on the impregnated surface to a thickness of 145-155 μm, and dried at 80°C for 2 days before use; (4) Install the X-axis moving platform on the lifting platform, and fix the fixture above it. Connect the spray gun to the butane gas tank and fix it horizontally in the fixture. Subsequently, place the sample obtained in step (3) on the heat insulation board, adjust the moving platform to align the spray gun with the sample, and then adjust the lifting platform so that the distance between the spray gun outlet and the sample surface is controlled to be 8 cm. Adjust the spray gun so that the flame direction is 90° to the sample surface. At this position, the side of the sample coated with slurry B is heated by the spray gun. The flame temperature is 1080~1100℃, and the sintering is continued for 20 minutes to obtain the oxide fiber composite material.

[0057] Comparative Example 19 Comparative Example 19 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1000°C, and the sintering time is 20 minutes.

[0058] Comparative Example 20 Comparative Example 20 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1100°C, and the sintering time is 20 minutes.

[0059] Comparative Example 21 Comparative Example 21 provides a method for preparing an oxide fiber composite material. Compared with Example 1, the only difference is that the spray gun sintering in step (4) of Example 1 is replaced by muffle furnace sintering, the sintering temperature is 1200°C, and the sintering time is 20 minutes.

[0060] The mechanical and ablation properties of the composite materials obtained in Examples 1-7 and Comparative Examples 1-21 were tested. Specifically, the elastic modulus of the sample surface layer was measured by compression testing according to ASTM D6641. The Vickers hardness was calculated by converting the diagonal length of the indentation after holding the coated surface under a load of 1 kgf for 15 seconds according to ASTM E384. The mass ablation rate was measured and calculated by ablation at 1500°C for 5 minutes according to GJB 323A-1996. The relevant performance parameters are summarized in Table 1.

[0061] Table 1 Mechanical properties and ablation performance results

[0062]

[0063] As shown in Table 1, in each embodiment and its comparative example, the coatings sintered by the spray gun have significantly improved both mechanical properties and ablation properties compared to the comparative examples. This is because the substrate layer is not severely damaged after sintering, and its properties are relatively intact.

[0064] See also Figure 1 , Figure 1 Schematic diagram of the microstructure of the oxide fiber composite material prepared in Example 1 of the present invention, wherein (a) is the cross-sectional morphology in the thickness direction of the material, and (b) is the cross-sectional morphology of the coating impregnated area, which is the cross-sectional morphology of the oxide fiber composite material in Figure (a). The position indicated by (c) is the cross-sectional morphology of the unimpregnated area, which is the The indicated positions, (d) is the surface morphology after sintering.

[0065] from Figure 1 It can be seen that the coating gradually changes from dense to porous from the surface layer to the inside, which is due to the gradual decrease of the coating's internal pressure from the surface to the inside during the sintering process.

[0066] Figure 2 The XRD diffraction spectrum of the surface layer of the oxide fiber composite material prepared in Example 1 is as follows: Figure 2 It can be seen that after the flame ignition, the surface layer produces very little MoO3 and Mo, while a large amount of MoSi2 is still present, proving that the material did not undergo significant oxidation during the sintering process and that the spraying process has little effect on the material composition. This is also an important reason why the performance of the embodiment is superior to that of the comparative example.

[0067] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing an oxide fiber composite material, characterized in that: The steps include: (1) quartz powder and boron oxide powder are mixed, ground, and sieved to obtain a mixed powder; (2) The obtained mixed powder, transition metal boron / silicide and boron carbide are uniformly mixed to obtain a total mixture; a portion is added with a dispersant and water, and the amount of water is adjusted to obtain a slurry A with a solid content of 20% to 25%; the remaining portion is prepared in the same manner to obtain a slurry B with a solid content of 35% to 40%; (3) Inject slurry A into the oxide fiber, then re-impregnate the injected area with slurry A, and finally apply slurry B on the impregnated surface, dry it, and set it aside; (4) The side of the dried sample coated with slurry B is sintered with a heating spray gun for 20 to 30 minutes to obtain the oxide fiber composite material.

2. The method for preparing the oxide fiber composite material according to claim 1, characterized in that: The mass ratio of the quartz powder to the boron oxide powder in step (1) is 4-6:0.5-1.

3. The method for preparing the oxide fiber composite material according to claim 1, characterized in that: The specific method of grinding in step (1) is: using ethanol as the liquid medium, using ZrO2 as the grinding medium, the material-ball ratio is 2:1, the grinding speed is 200~300rpm, and the grinding time is 8~10h.

4. The method for preparing the oxide fiber composite material according to claim 1, characterized in that: The mesh size of the sieving in step (1) is 200-300 meshes.

5. The method for preparing the oxide fiber composite material according to any one of claims 1 to 3, characterized in that: The mass ratio of the mixed powder, transition metal boron / silicide and boron carbide in step (2) is 36:18~24:0.5~1.

6. The method for preparing the oxide fiber composite material according to claim 1, characterized in that: In the slurry A and slurry B prepared in step (2), the amount of dispersant added is 0.4% to 0.8% of the total mass of the slurry.

7. The method for preparing the oxide fiber composite material according to claim 6, characterized in that: The transition metal boron / silicide in step (2) is at least one of HfB2, ZrB2, TaB2, WB2, MoSi2, ZrSi2, NbSi2, TaSi2 and WSi2; and / or The dispersant is at least one of polyacrylamide, polyethylene glycol, sodium hexametaphosphate and sodium dodecylbenzene sulfonate; and / or In step (3), the injection depth of slurry A is controlled not to exceed the fiber thickness; and / or The oxide fiber is at least one of quartz fiber, mullite fiber and alumina fiber.

8. The method for preparing the oxide fiber composite material according to claim 1, characterized in that: In step (3), the coating thickness of slurry B on the impregnated surface is 100-200 μm; The flame temperature of the heating spray gun in step (4) is 1080~1120℃.

9. An oxide fiber composite material, characterized in that: The oxide fiber composite material is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the oxide fiber composite material according to claim 9 as a high-temperature thermal insulation material.

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