A method for producing a quartz fiber-reinforced quartz composite material containing a lanthanum phosphate interface phase

Abstract

The application discloses a preparation method of quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase, and the method comprises the following steps: vacuum impregnating a quartz fiber fabric from which an impregnant is removed in a lanthanum phosphate precursor solution, and obtaining the quartz fiber fabric containing the lanthanum phosphate interface phase after high-temperature sintering; vacuum impregnating the quartz fiber fabric in a silica sol, and repeating impregnation-drying until densification after drying; and high-temperature sintering the quartz fiber reinforced quartz composite material blank, and continuing to repeat the impregnation-drying-sintering process for multiple cycles after sintering, so as to finally obtain the dense and uniform quartz fiber reinforced quartz composite material containing the lanthanum phosphate interface phase. Since the lanthanum phosphate interface phase exists, the quartz fiber reinforced quartz composite material prepared has good denseness, improved material toughness and enhanced mechanical properties.

Description

Technical Field

[0001] This application relates to the field of fiber-reinforced ceramic matrix composites, and in particular to a method for preparing a quartz fiber-reinforced quartz composite material containing a lanthanum phosphate interfacial phase. Background Technology

[0002] Missiles, being precision components, require the protection of radomes during high-speed flight. Quartz fiber reinforced quartz composites are an important category of radomes. The quartz matrix has good dielectric properties and a low coefficient of thermal expansion, while the reinforcing quartz fiber also performs well in terms of chemical stability, ablation resistance, and mechanical properties, achieving the effect of strengthening and toughening. As one of the excellent choices for high-performance radome materials, it has been the subject of extensive research both domestically and internationally.

[0003] The sol-gel method is suitable for oxide-based composites and is the main process for preparing quartz fiber reinforced quartz composites. The process involves immersing a pre-woven quartz fiber in silica sol, removing it, drying it, and then performing sol-gelation. Finally, it is sintered at high temperature. Due to the significant shrinkage of silica sol during sintering, this impregnation-curing-sintering densification cycle needs to be repeated multiple times to achieve the ideal density of the quartz fiber reinforced quartz composite. This multi-cycle composite preparation affects the overall performance of the composite material. The prolonged heat treatment during preparation causes thermal damage to both the fibers and the matrix, resulting in a decrease in strength. Furthermore, the excessively tight bonding between the fibers and the matrix in the quartz fiber reinforced quartz composite leads to a decrease in toughness due to excessively high interfacial bonding strength, thus affecting the overall performance of the composite. Summary of the Invention

[0004] This invention provides a method for preparing a quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase, which is used to overcome the mechanical property defects or deficiencies of existing quartz fiber reinforced quartz composite materials, such as poor toughness.

[0005] To achieve the above objectives, this invention proposes a method for preparing a quartz fiber-reinforced quartz composite material containing a lanthanum phosphate interfacial phase, comprising the following steps:

[0006] S1. Pre-treat the quartz fiber fabric to remove the sizing agent from the fabric surface;

[0007] S2. Lanthanum phosphate precursor solution was prepared using lanthanum phosphate hydrate, deionized water and dilute nitric acid;

[0008] S3. The quartz fiber fabric obtained in step S1 is vacuum impregnated in a lanthanum phosphate precursor solution for reaction. Then the quartz fiber fabric is taken out, dried, and the impregnation-drying process is repeated several times before high-temperature heat treatment to obtain a quartz fiber fabric containing a lanthanum phosphate interface phase.

[0009] S4, vacuum impregnating the quartz fiber fabric containing the lanthanum phosphate interface phase with a silica sol, drying at a constant temperature to gel, repeating the impregnation-drying step until the weight gain rate is <1%, to obtain a quartz fiber reinforced quartz composite material blank;

[0010] S5, high-temperature sintering the quartz fiber reinforced quartz composite material blank, and naturally cooling to room temperature;

[0011] S6, repeating steps S4 and S5, to obtain a quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase.

[0012] Compared with the prior art, the beneficial effects of the present application are:

[0013] 1. The preparation method of the quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase provided by the present application first prepares a lanthanum phosphate interface phase on the surface of the quartz fiber, realizes weak interface bonding, effectively avoids brittle fracture of the material caused by too strong fiber and matrix interface bonding when the composite material breaks down, and improves the toughness of the composite material.

[0014] 2. The lanthanum phosphate precursor solution prepared by the present application does not need to be stored at low temperature, and can exist stably at room temperature for a long time without particle agglomeration. The precursor solution used in the present application is the final product after the lanthanum phosphate hydrate in the raw material is configured in a solution, and does not need to be generated in situ on the fiber surface. By adding HNO3 solution to control the pH value, the hydrate is uniformly dispersed in the precursor by precipitation through the surface charge, and a precursor similar to sol can be prepared. At the same time, nitrate can be decomposed in the subsequent high-temperature preparation process, and no impurity residue is generated. The precursor of the present application is more suitable for long-term storage, and can fully impregnate the preform. The preparation process has lower requirements on time, and the process is more convenient.

[0015] 3. The quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase provided by the present application has good mechanical properties and compactness, and can be applied to the field of aerospace as a radome material. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0017] Figure 1 is the preparation flowchart of the quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase of the present application;

[0018] Figure 2 A photograph of the interface phase of the quartz fiber 2.5D fabric containing the lanthanum phosphate interface phase provided in Example 1 of the present application;

[0019] Figure 3 A photograph of the quartz fiber reinforced quartz composite material containing the lanthanum phosphate interface phase provided in Example 1 of the present application;

[0020] Figure 4 A photograph of the bending test fracture morphology of the quartz fiber reinforced quartz composite material containing the lanthanum phosphate interface phase provided in Example 1 of the present application;

[0021] Figure 5 A load-displacement curve diagram of the bending test of Example 1 and Comparative Example 1 of the present application.

[0022] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0024] In addition, the technical solutions in the embodiments of the present application can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize the combination. When the combination of the technical solutions appears to be contradictory or unachievable, it should be considered that the combination of the technical solutions does not exist and is not within the protection scope of the present application.

[0025] Unless otherwise specified, the medicines / reagents used are commercially available.

[0026] The present application provides a preparation method of a quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase, comprising the following steps:

[0027] S1, pretreating a quartz fiber fabric to remove the infiltrant on the surface of the fabric;

[0028] S2, preparing a lanthanum phosphate precursor solution by using a lanthanum phosphate hydrate, deionized water and dilute nitric acid;

[0029] S3, vacuum impregnating the quartz fiber fabric obtained in step S1 in the lanthanum phosphate precursor solution for reaction, then taking out the quartz fiber fabric, drying, repeating the impregnation-drying for several times and then performing high-temperature heat treatment to obtain a quartz fiber fabric containing a lanthanum phosphate interface phase.

[0030] S4, vacuum impregnating the quartz fiber fabric containing the lanthanum phosphate interface phase with a silica sol, drying at a constant temperature to gelate, repeating the impregnation-drying step until the weight gain rate is <1%, to obtain a quartz fiber reinforced quartz composite material blank;

[0031] S5, high-temperature sintering the quartz fiber reinforced quartz composite material blank, and naturally cooling to room temperature;

[0032] S6, repeating steps S4 and S5, to obtain a quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase.

[0033] Preferably, in step S1, the pretreatment conditions are specifically:

[0034] Temperature: 500-600℃; atmosphere: air atmosphere; pressure: normal pressure; time: 1.5-2h.

[0035] Preferably, in step S2, the preparation of the lanthanum phosphate precursor solution is specifically:

[0036] Stirring the lanthanum phosphate hydrate in deionized water for a period of time to obtain a lanthanum phosphate solution, while preparing a dilute nitric acid solution, then dropping the dilute nitric acid solution into the lanthanum phosphate solution drop by drop until the pH value of the lanthanum phosphate solution is 1.8-2.2, stirring at room temperature for a period of time, and finally ultrasonic oscillation, to complete the preparation of the lanthanum phosphate precursor. The concentration of the lanthanum phosphate precursor is 20-30g / L, and the concentration of the dilute nitric acid solution is 25-30g / L. Too low or too high pH value will cause the precursor to settle prematurely, affecting the performance of the precursor. The lanthanum phosphate precursor prepared by the present application has stable performance, simple process, and good effect, and can be applied to the vacuum impregnation of large-size woven parts, and has application prospects for large-scale production and preparation in the industrial field.

[0037] Preferably, in step S3, the impregnation temperature is 20-30℃, and the impregnation time is not less than 2h. The impregnation temperature is limited by the requirements for precursor storage. The precursor storage of the present scheme has lower requirements for temperature, so the impregnation can be carried out at room temperature, and the long-time impregnation does not cause particle agglomeration and precipitation.

[0038] Preferably, in step S3, the drying temperature is 100-120℃, and the drying time is 1-2h; while drying, the quartz fiber fabric is placed in two parallel metal molds under pressure holding to control the thickness of the quartz fiber fabric.

[0039] The repeating cycle of impregnation-drying is not less than 6 times. The present scheme uses a precursor solution with a relatively low concentration, so it needs not less than 6 times of repeated impregnation-drying.

[0040] The vacuum impregnation method is adopted to ensure that the precursor can be fully coated on the surface of the coating, and the precursor is solidified after drying. The sol-like precursor completes the gel transition, and no excess particles are attached to the surface of the coating, so that cleaning is not required.

[0041] Preferably, in step S3, the temperature of the heat treatment is 700-800°C, and the time of the heat treatment is 1-1.5h.

[0042] Preferably, in step S4, the impregnation temperature is 20-30°C, and the impregnation time is not less than 2h.

[0043] Preferably, in step S4, the drying temperature is 120-150°C, and the drying time is 4-6h; while drying, the quartz fiber fabric is placed in two parallel metal molds under pressure holding to control the thickness of the quartz fiber fabric containing the lanthanum phosphate interface phase.

[0044] Preferably, in step S5, the high-temperature sintering conditions are as follows:

[0045] Temperature: 700-800°C; atmosphere: air atmosphere; pressure: normal pressure; time: 1-1.5h.

[0046] Preferably, in step S6, the number of times of repeating steps S4 and S5 is 2-3.

[0047] Example 1:

[0048] As shown in the Figure 1 The embodiment provides a preparation method of the quartz fiber reinforced quartz composite material containing a lanthanum phosphate interface phase, and the preparation method comprises the following steps:

[0049] (1) The quartz fiber 2.5D fabric is pretreated, and the size is 30mm*30mm*3.5mm, the single-fiber diameter is 7.5±1.0μm, and SiO2≥99.95%. The pretreatment conditions are 500°C, air atmosphere, and normal pressure, and the pretreatment time is 2h, so that the sizing agent on the surface of the fiber is removed;

[0050] (2) A 25g / L lanthanum phosphate precursor solution is prepared, the lanthanum phosphate hydrate is stirred in deionized water for 30min, a 20% HNO3 solution of 50mL is prepared, then the HNO3 solution is added drop by drop into the solution until the pH value of the solution is 2, the solution is stirred at room temperature for 4h, and finally ultrasonic oscillation is performed for 30min to complete the preparation of the precursor;

[0051] (3) The quartz fiber 2.5D fabric is placed in a vacuum container with a feeding port, the container is vacuumized, and then the prepared 25g / L lanthanum phosphate precursor is injected into the vacuum container by using the pressure difference, so that the precursor solution fully infiltrates the quartz fiber 2.5D fabric, the impregnation temperature is controlled to be 25°C, and the impregnation time is 2h.

[0052] (4) Take out the impregnated quartz fiber 2.5D fabric, place it in two parallel metal molds, dry it at 120℃ for 2h, and control its thickness to be 3.5mm under pressure holding;

[0053] (5) Repeat steps (3)-(4) for the quartz fiber 2.5D fabric containing lanthanum phosphate precursor after step (4) for 6 cycles.

[0054] (6) Sinter the quartz fiber 2.5D fabric containing lanthanum phosphate interfacial phase after step (5) at 700℃ in air atmosphere under normal pressure for 1h, cool it to room temperature, and obtain the quartz fiber 2.5D fabric containing lanthanum phosphate interfacial phase.

[0055] (7) Vacuum impregnate the quartz fiber 2.5D fabric containing lanthanum phosphate interfacial phase with silica sol at 25℃ for 2h; place the impregnated quartz fiber 2.5D fabric containing lanthanum phosphate interfacial phase in two parallel metal molds, dry it at 150℃ for 4h to gelatinize it, and control its thickness to be 3mm under pressure holding; repeat the impregnation-drying steps until the weight gain rate is <1%, and obtain a quartz fiber reinforced quartz composite material blank;

[0056] (8) Sinter the quartz fiber reinforced quartz composite material blank containing lanthanum phosphate interfacial phase after completing the impregnation-drying steps at 800℃ in air atmosphere under normal pressure for 1h, cool it to room temperature, complete this step, and call it as completing one impregnation-drying-sintering process; finally repeat the impregnation-drying-sintering process for 3 times, and finally complete the preparation of the quartz fiber reinforced quartz composite material containing lanthanum phosphate interfacial phase.

[0057] The basic properties of the quartz fiber reinforced quartz composite material containing lanthanum phosphate interfacial phase provided in the embodiment are shown in Table 1. The composite material can be used at 800℃ or below for a long time, and the room temperature bending strength reaches 97MPa. Figure 2 It is a real photo of the interfacial phase of the quartz fiber 2.5D fabric containing lanthanum phosphate interfacial phase provided in Example 1 of the present application, Figure 3 It is a real photo of the quartz fiber reinforced quartz composite material containing lanthanum phosphate interfacial phase provided in Example 1 of the present application. Figure 4 It is a real photo of the bending test fracture morphology of the quartz fiber reinforced quartz composite material containing lanthanum phosphate interfacial phase provided in Example 1 of the present application. During the three-point bending strength test, obvious fiber pulling-out phenomenon was observed at the fracture position, which indicates that the fiber and matrix interfacial bonding in the material is moderate, the fracture toughness is high, and the material has excellent high temperature resistance and mechanical properties.

[0058] Comparative Example 1:

[0059] Referring to the process parameter conditions of Example 1, a quartz fiber reinforced quartz composite material without a lanthanum phosphate interface phase is prepared by using a quartz fiber 2.5D fabric and a silica sol as Comparative Example 1.

[0060] (1) The quartz fiber 2.5D fabric is pretreated, and a size of 30 mm x 30 mm x 3.5 mm is selected, with a single fiber diameter of 7.5 ± 1.0 μm and SiO2≥ 99.95%. The pretreatment conditions are 500°C, air atmosphere, and normal pressure, and the pretreatment time is 2 h, during which the sizing agent on the surface of the fiber is removed;

[0061] (2) The quartz fiber 2.5D fabric is placed in a vacuum container with a feeding port, and the container is vacuumed, and then the silica sol is injected by using a pressure difference to completely infiltrate the quartz fiber 2.5D fabric, and the infiltration time is 2 h. The infiltrated quartz fiber 2.5D fabric is placed in two parallel metal molds, dried at 150°C for 4 h to gel, and the thickness is controlled under pressure to be 3 mm. The infiltration-drying step is repeated until the weight gain rate is < 1%, and a quartz fiber reinforced quartz composite material blank is obtained;

[0062] (3) After the quartz fiber reinforced quartz composite material blank completes the infiltration-drying step, sintering is performed at 800°C, air atmosphere, and normal pressure, and the sintering time is 1 h, and then the material is cooled to room temperature. This step is completed and is referred to as completing one infiltration-drying-sintering process. Finally, the infiltration-drying-sintering process is repeated 3 times, and the preparation of the quartz fiber reinforced quartz composite material without a lanthanum phosphate interface phase is finally completed.

[0063] The basic properties of the quartz fiber reinforced quartz composite material without a lanthanum phosphate interface phase provided by the comparative example are shown in Table 2.

[0064] Table 1 Basic properties of the quartz fiber reinforced quartz composite material with a lanthanum phosphate interface phase in Example 1

[0065] Density 1.57 g-cm -3 ]]> Thickness 3.50 mm Bending strength 97 MPa

[0066] Table 2 Basic properties of the quartz fiber reinforced quartz composite material without a lanthanum phosphate interface phase in Comparative Example 1

[0067] Density 1.55 g-cm -3 ]]> Thickness 3.50 mm Bending strength 70 MPa

[0068] It can be found from Example 1 and Comparative Example 1 that the quartz fiber reinforced quartz composite material with a lanthanum phosphate interface phase has a lanthanum phosphate interface layer between the fiber and the matrix, and a weak interface bonding is achieved. Figure 5 The load-displacement curve diagram for the bending test of Example 1 and Comparative Example 1 of the present application is shown in FIG. 1. Referring to FIG. 1, the load-displacement curve of Example 1 is shown by the solid line, and the load-displacement curve of Comparative Example 1 is shown by the dashed line. Figure 5The load displacement curve can find that the stress drops slowly when the fiber layer breaks, and the number of drop is four times, and the last one shows a steep drop, the mechanical properties remain good, the interface of lanthanum phosphate plays a good interface slip effect, the load of the matrix can be well transmitted to the interface, the interface debonding and pull-out toughening mechanism can be played, the interface bonding strength is in the appropriate interval, the macro mechanical properties are greatly improved, the brittle fracture of the material caused by the over strong bonding force between the fiber and the matrix of the composite material at high temperature is effectively avoided, the strength of the composite material is improved, and the toughness is enhanced.

[0069] The above has described the embodiments of the present application, the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for producing a quartz fiber-reinforced quartz composite material containing a lanthanum phosphate interface phase, characterized by, The method comprises the following steps: S1, pretreating the quartz fiber fabric to remove the infiltrant on the surface of the fabric; S2, preparing a lanthanum phosphate precursor solution by using lanthanum phosphate hydrate, deionized water and dilute nitric acid, specifically: stirring the lanthanum phosphate hydrate in the deionized water for 30 min to obtain a lanthanum phosphate solution, meanwhile, preparing a dilute nitric acid solution, then dropping the dilute nitric acid solution into the lanthanum phosphate solution drop by drop until the pH value of the lanthanum phosphate solution is 1.8-2.2, stirring at room temperature for 4 h, and finally ultrasonic oscillation, and the preparation of the lanthanum phosphate precursor is completed; wherein the concentration of the lanthanum phosphate precursor is 20-30 g / L, and the concentration of the dilute nitric acid solution is 25-30 g / L; S3, vacuum impregnating the quartz fiber fabric obtained in step S1 in the lanthanum phosphate precursor solution for reaction, then taking out the quartz fiber fabric, drying, repeating the impregnation-drying for several times, and then high-temperature heat treatment to obtain a quartz fiber fabric containing a lanthanum phosphate interfacial phase; S4, vacuum impregnating the quartz fiber fabric containing the lanthanum phosphate interfacial phase in a silica sol, drying at a constant temperature to gel, repeating the impregnation-drying steps until the weight gain rate is less than 1%, and obtaining a quartz fiber reinforced quartz composite material blank; S5, high-temperature sintering the quartz fiber reinforced quartz composite material blank, and the high-temperature sintering conditions are: temperature: 700-800℃; atmosphere: air atmosphere; pressure: normal pressure; time: 1-1.5 h, and natural cooling to room temperature; S6, repeating steps S4 and S5 to obtain a quartz fiber reinforced quartz composite material containing a lanthanum phosphate interfacial phase.

2. The production method according to claim 1, characterized by, In step S1, the pretreatment conditions are specifically: temperature: 500-600℃; atmosphere: air atmosphere; pressure: normal pressure; time: 1.5-2 h.

3. The method of claim 1, wherein, In step S3, the impregnation temperature is 20-30℃, and the impregnation time is not less than 2 h.

4. The method of claim 1, wherein, In step S3, the drying temperature is 100-120℃, and the drying time is 1-2 h; while drying, the quartz fiber fabric is placed in two parallel metal molds to control the thickness of the quartz fiber fabric under pressure holding; The repeating period of impregnation-drying is not less than 6 times.

5. The preparation method according to claim 1, characterized in that, In step S3, the heat treatment temperature is 700-800℃, and the heat treatment time is 1-1.5 h.

6. The method of claim 1, wherein, In step S4, the impregnation temperature is 20-30℃, and the impregnation time is not less than 2 h.

7. The preparation method according to claim 1, characterized in that, In step S4, the drying temperature is 120-150℃, and the drying time is 4-6 h; while drying, the quartz fiber fabric containing the lanthanum phosphate interfacial phase is placed in two parallel metal molds to control the thickness of the quartz fiber fabric containing the lanthanum phosphate interfacial phase under pressure holding.

8. The method of claim 1, wherein, In step S6, the number of times of repeating steps S4 and S5 is 2-3 times.

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