Silica / alumina / titania composite matrix thermal bridge break material and method for producing same

Abstract

The present application relates to a kind of silica / alumina / titanium oxide composite matrix thermal bridge blocking material and its preparation method.The composite matrix thermal bridge blocking material includes reinforcing fiber and composite matrix, the reinforcing fiber is quartz fiber, and the composite matrix includes silica, alumina and titanium oxide.The preparation method includes: preparing low fiber volume content three-dimensional quartz fiber fabric;Preparation of alumina, titanium oxide modified silica sol;The low fiber volume content three-dimensional quartz fiber fabric is dipped in the alumina, titanium oxide modified silica sol, and is gelled, dried and heat treated, to obtain silica / alumina / titanium oxide composite matrix thermal bridge blocking material.The present application solves the problem that current quartz-based thermal bridge blocking material is difficult to have low thermal conductivity and high strength simultaneously.

Description

Technical Field

[0001] This invention relates to the field of fiber-reinforced oxide ceramic matrix composites, and more particularly to a silicon oxide / alumina / titanium oxide composite matrix thermal bridging material and its preparation method. Background Technology

[0002] As aircraft speeds and operating times continue to increase, the force and thermal challenges faced by aircraft structural components become increasingly severe. High-temperature and ultra-high-temperature structures in aircraft generally utilize ceramic matrix composites, while the majority of the fuselage structure connected to them still uses metallic materials. When ceramic matrix composite structures and metallic structures are connected by fasteners, thermal bridges are formed at the fasteners. To prevent the cold-load-bearing structure of the fuselage from overheating and to ensure that internal equipment can operate at suitable temperatures, thermal bridge-breaking materials are usually placed between the two. These materials need to have both low thermal conductivity and high mechanical strength, and are typically oxide ceramic matrix composites. Currently, the most widely used ceramic matrix thermal bridge-breaking materials are quartz fiber reinforced silica matrix composites.

[0003] The mechanical and thermal properties of existing oxide ceramic matrix composites, exemplified by quartz fiber-reinforced silica composites, are closely related to their material density. High material density results in high mechanical properties but also high thermal conductivity; conversely, low material density leads to low thermal conductivity but also low mechanical properties. Therefore, resolving the contradiction between low thermal conductivity and high strength is crucial for developing ceramic-based thermal bridging materials. Further improving the high-temperature mechanical strength and reducing the thermal conductivity of these materials presents new challenges to the design and modification of the matrix composition, the design and optimization of the reinforcing fabric structure, and the molding process of the composite materials. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material, and correspondingly provides a method for preparing the silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material comprises reinforcing fibers and a composite matrix, wherein the reinforcing fibers are quartz fibers, and the main components of the composite matrix are silicon oxide, alumina, and titanium oxide; the silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material is prepared by a sol-gel process.

[0007] Preferably, the density of the silicon oxide / alumina / titanium oxide composite matrix thermal bridging material is 1.5-1.7 g / cm³. 3The thermal conductivity is less than 0.6 W / m·K at room temperature - 300℃, the tensile strength is above 30 MPa at room temperature - 1000℃, and the compressive strength is above 100 MPa at room temperature - 1000℃.

[0008] This invention also provides a method for preparing a silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material, comprising the following steps:

[0009] Preparation of three-dimensional quartz fiber fabrics with low fiber volume content;

[0010] Preparation of alumina and titanium dioxide modified silica sol;

[0011] The low-fiber-volume-content three-dimensional quartz fiber fabric is impregnated with the alumina and titanium dioxide modified silica sol, and then gelled, dried and heat-treated to obtain a silica / alumina / titanium dioxide composite matrix thermal bridging material.

[0012] Furthermore, the structure of the low fiber volume content three-dimensional quartz fiber fabric can be a 2.5D structure or a triaxial orthogonal structure, with a fiber volume content of 25-35%.

[0013] Furthermore, the low-fiber-volume-content three-dimensional quartz fiber fabric is produced using a loop-forming ply yarn process. Before weaving, when plying the quartz fibers, 1-2 strands of longer quartz fibers are plyed and twisted with other shorter quartz fibers. With the ply yarns aligned end-to-end, the longer yarns will emerge from the ply yarns in a loop-forming manner after twisting, resulting in a ply yarn surface covered with looped yarns, forming a swollen ply yarn. Using such a loop-forming ply yarn, 2.5D structure fabrics and three-dimensional orthogonal structure fabrics with fiber volume contents far lower than normal can be obtained.

[0014] Further, the preparation of alumina and titanium dioxide modified silica sol includes: preparing titanium compound modified silica sol and aluminum sol, and adjusting the pH value of the titanium compound modified silica sol and aluminum sol to 2-4 using an acidic solution. The prepared titanium compound modified silica sol is slowly added dropwise to the rapidly stirred aluminum sol to obtain alumina and titanium dioxide modified silica sol.

[0015] The preparation method of the titanium compound modified silica sol is disclosed in Chinese Patent CN115947346A.

[0016] The aluminum sol has a pH of 3.5–5, a particle size range of 5–100 nm, and an aluminum oxide content of 5–40%.

[0017] In the alumina and titanium dioxide modified silica sol, the mass ratio of alumina to silicon dioxide is 0.1 to 1.0.

[0018] The acidic solution is one or more of dilute nitric acid, dilute hydrochloric acid, acetic acid, and citric acid.

[0019] Further, the impregnation process includes: firstly, pretreating the low-fiber-volume-content fabric to remove its surface sizing agent; then, placing the fabric in a mold, evacuating it under vacuum, and impregnating it with the modified silica sol; subsequently, applying pressure to allow the modified silica sol to further penetrate the pores of the fabric. Given the instability of the modified sol, the preferred vacuum impregnation time is 1–2 hours, and the pressure holding time is 2–8 hours.

[0020] Further, the gelation process involves placing the mold containing the sol and fabric in an oven and heating it to gel the modified silica sol. After natural cooling, the mold is removed to obtain a wet blank of a quartz fiber-reinforced silica / alumina / titanium oxide composite matrix thermal bridge-blocking material. The heating rate is 1–3 min / ℃, the temperature is 60–90℃, and the holding time is 12–24 h.

[0021] Further, the drying process includes: first, placing the wet blank of the quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material in a forced-air drying oven for drying, then naturally cooling it to room temperature before removing it to obtain a dry blank of the thermal bridge blocking material. The drying process employs a gradient temperature increase method, with a selectable heating rate of 3–5 °C / min and a temperature control sequence of 50 °C for 1–2 h, 100 °C for 1–2 h, and 200 °C for 1–2 h. Other drying procedures can also be selected to achieve thorough drying.

[0022] Further, the heat treatment includes: placing the thermal bridge blocking blank in a muffle furnace and holding it at 900–1000°C for 0.5–2 hours. After cooling to room temperature, a quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material is obtained.

[0023] Further, repeat the above steps of impregnation, gelation, drying, and heat treatment until the composite density reaches 1.5–1.7 g / cm³. 3 .

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] (1) The quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material designed and prepared in this invention solves the problem that current quartz-based thermal bridge blocking materials cannot achieve both low thermal conductivity and high strength.

[0026] (2) The present invention uses the loop-forming and ply-forming process to solve the problem that the fiber volume content of the current 2.5d and three-dimensional orthogonal structure three-dimensional fabric is difficult to reduce, and realizes the reduction of fiber volume content of high strength reinforced fabric. The strength of this fabric is much higher than that of needle-punched fabric with the same fiber volume content.

[0027] (3) The composite material of the present invention is a low fiber volume content three-dimensional fabric reinforced composite matrix ceramic matrix composite material, which has better strength than the needle-punched structure quartz fiber reinforced silica matrix composite material commonly used in thermal bridge blocking materials, and has better heat insulation performance than the high fiber volume content three-dimensional fabric reinforced silica matrix composite material.

[0028] (4) The matrix material used in this invention is based on acidic silica sol, with titanium dioxide and aluminum oxide as modified functional components. By adjusting the solid content, particle size, pH and other indicators of the titanium-modified silica sol and aluminum sol, a relatively stable and low-solid-content gel modified composite sol is achieved. The addition of titanium dioxide and aluminum oxide improves the thermal insulation performance and strength of the silica matrix.

[0029] Instruction manual illustrations

[0030] Figure 1 This is a flowchart illustrating the steps of the preparation method of the silicon oxide / alumina / titanium oxide composite matrix thermal bridging material of the present invention.

[0031] Figure 2 This is a schematic diagram of a common three-ply yarn obtained by twisting and plying three yarns of the same length.

[0032] Figure 3 The intention is to create a three-ply yarn by twisting two short yarns and one long yarn together. Detailed Implementation

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below through specific embodiments.

[0034] This invention provides a method for preparing a silicon oxide / alumina / titanium oxide composite matrix thermal bridging material, such as... Figure 1 As shown, the steps include: preparing a three-dimensional quartz fiber fabric with low fiber volume content; preparing alumina and titanium dioxide modified silica sol; impregnating the three-dimensional quartz fiber fabric with low fiber volume content with the alumina and titanium dioxide modified silica sol, and performing gelation, drying and heat treatment to obtain a silica / alumina / titanium dioxide composite matrix thermal bridging material.

[0035] Among them, the low-fiber-volume-content three-dimensional quartz fiber fabric is produced using a loop-forming and ply-twisting process. This is different from the common method of twisting and plying three strands of yarn of the same length to obtain a three-ply yarn (such as...). Figure 2Unlike the previous method, the new method of plying quartz fibers involves using 1-2 strands of longer quartz fibers to ply and twist with other shorter quartz fibers before weaving. With the plyed yarn ends aligned, the longer yarns will emerge from the plyed yarn in a looped manner after twisting, resulting in a puffed plyed yarn surface covered with looped yarns. Figure 3 As shown. Using such loop-forming and ply-forming yarns, 2.5D structured fabrics and triaxial orthogonal structured fabrics with fiber volume content far lower than normal can be obtained.

[0036] Example 1: A quartz fiber-reinforced silica / alumina / titanium oxide composite thermal bridge blocking material. The reinforcing structure of the material is a 2.5D structured quartz fabric, and the main components of the composite matrix are silica, alumina, and titanium oxide. The silica / alumina / titanium oxide composite thermal bridge blocking material is prepared by a sol-gel process.

[0037] Table 1. Main performance parameters of the composite matrix thermal bridge blocking material prepared in Example 1

[0038]

[0039] A method for preparing a quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material includes the following steps:

[0040] (1) Prepare a low-density three-dimensional alumina fabric. The fabric structure is a 2.5d normal-reinforced shallow cross-bending structure, the fiber volume content is 35%, and the weaving process is a loop-forming ply yarn weaving process.

[0041] (2) Prepare a 2.5D structured quartz fiber fabric with low fiber volume content. The warp yarns have 3 plies, with one ply being longer than the other two, and a twist of 80 twists / m. The weft yarns have 6 plies, with two plies being longer than the other four, and a twist of 80 twists / m. The fiber volume content is 35%.

[0042] (3) Preparation of alumina and titanium dioxide modified silica sol: Prepare titanium compound modified silica sol and aluminum sol, and adjust the pH value of the titanium compound modified silica sol and aluminum sol to 2-3 using acidic solutions. Slowly drop the prepared titanium compound modified silica sol into the rapidly stirred aluminum sol to obtain alumina and titanium dioxide modified silica sol.

[0043] The preparation method of the titanium compound modified silica sol is disclosed in Chinese Patent CN115947346A, with a solid content of 20%.

[0044] The aluminum sol has a pH of 4.0, a particle size range of 70–80 nm, and an aluminum oxide content of 10%.

[0045] The mass ratio of alumina to silicon oxide is 1.0.

[0046] The acidic solution is dilute nitric acid.

[0047] (4) Impregnation: First, the low fiber volume content fabric is pretreated by boiling in acetone to remove the surface wetting agent. Then, the fabric is placed in a mold, vacuumed, and impregnated with the modified silica sol. Then, pressure is applied to allow the modified silica sol to further penetrate into the pores of the fabric.

[0048] The vacuum impregnation time is 1.5 hours, and the pressure holding time is 2 hours.

[0049] (5) Gel: The mold containing the sol and fabric is placed in an oven and heated to make the modified silica sol gel. After natural cooling, it is taken out to obtain a wet blank of quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material.

[0050] The heating rate is 3 min / ℃, the temperature is 80℃, and the holding time is 12 h.

[0051] (6) Drying: Place the wet blank of the thermal bridge blocking material in a forced-air drying oven for rapid drying, and take it out after it cools down to room temperature to obtain the dry blank of the thermal bridge blocking material.

[0052] The drying process employs a gradient heating method with a heating rate of 4℃ / min and a temperature control sequence of 50℃ for 1 hour, 100℃ for 1 hour, and 200℃ for 1 hour.

[0053] (7) Heat treatment: The alumina fiber reinforced oxide thermal bridge blocking blank was placed in a muffle furnace and held at 900°C for 1 hour. After cooling to room temperature, a quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material was obtained.

[0054] (8) Repeat steps (5) to (8) above 5 times until the density of the composite material reaches 1.52 g / cm³. 3 .

[0055] Example 2: A quartz fiber-reinforced silica / alumina / titanium oxide composite thermal bridge blocking material. The reinforcing structure of the material is a triaxial quartz fabric, and the main components of the composite matrix are silica, alumina, and titanium oxide. The silica / alumina / titanium oxide composite thermal bridge blocking material is prepared by a sol-gel process.

[0056] Table 1. Main performance parameters of the composite matrix thermal bridge blocking material prepared in Example 2

[0057]

[0058] A method for preparing a quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material includes the following steps:

[0059] (1) Prepare a low-density three-dimensional alumina fabric. The fabric has a three-dimensional orthogonal structure, a fiber volume content of 25%, and is woven using a loop-forming and ply-forming yarn weaving process.

[0060] (2) Prepare a triaxial orthogonal structure quartz fiber fabric with low fiber volume content. The warp and weft yarns are both 4 plies, with 2 plies having a longer length than the other 2 plies and a twist of 80 twists / m. The normal yarns are 2 plies, with 1 ply having a longer length than the other ply and a twist of 80 twists / m.

[0061] (3) Preparation of alumina and titanium dioxide modified silica sol: Prepare titanium compound modified silica sol and aluminum sol, and adjust the pH value of the titanium compound modified silica sol and aluminum sol to 3-4 using acidic solutions. Slowly drop the prepared titanium compound modified silica sol into the rapidly stirred aluminum sol to obtain alumina and titanium dioxide modified silica sol.

[0062] The preparation method of the titanium compound modified silica sol is disclosed in Chinese Patent CN115947346A, with a solid content of 15%.

[0063] (4) The aluminum sol has a pH of 4.0, a particle size range of 70-80 nm, and an aluminum oxide content of 10%.

[0064] (5) The mass ratio of alumina to silicon oxide is 0.2.

[0065] (6) The acidic solution is dilute nitric acid.

[0066] (7) Impregnation: First, the low fiber volume content fabric is pretreated by boiling in acetone to remove the surface wetting agent. Then, the fabric is placed in a mold, vacuumed, and impregnated with the modified silica sol. Then, pressure is applied to allow the modified silica sol to further penetrate into the pores of the fabric.

[0067] The vacuum impregnation time is 2 hours, and the pressure holding time is 8 hours.

[0068] (8) Gel: The mold containing the sol and fabric is placed in an oven and heated to make the modified silica sol gel. After natural cooling, it is taken out to obtain a wet blank of quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material.

[0069] The heating rate is 1 min / ℃, the temperature is 60℃, and the holding time is 24 h.

[0070] (9) Drying: Place the wet blank of the thermal bridge blocking material in a forced-air drying oven for rapid drying, and take it out after it cools down to room temperature to obtain the dry blank of the thermal bridge blocking material.

[0071] The drying process employs a gradient heating method with a heating rate of 4℃ / min and a temperature control sequence of 50℃ for 1 hour, 100℃ for 1 hour, and 200℃ for 1 hour.

[0072] (10) Heat treatment: The alumina fiber reinforced oxide thermal bridge blocking blank was placed in a muffle furnace and held at 1000℃ for 2 hours. After cooling to room temperature, a quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material was obtained.

[0073] (11) Repeat steps (5) to (8) above 10 times until the density of the composite material reaches 1.70 g / cm³. 3 .

[0074] The specific embodiments of the present invention disclosed above are intended to help understand the content of the present invention and to implement it accordingly. Those skilled in the art will understand that various substitutions, changes, and modifications are possible without departing from the spirit and scope of the present invention. The present invention should not be limited to the content disclosed in the embodiments of this specification; the scope of protection of the present invention is defined by the claims.

Claims

1. A silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material, characterized in that, The material comprises reinforcing fibers and a composite matrix. The reinforcing fibers are quartz fibers, and the composite matrix comprises silicon oxide, alumina, and titanium oxide. The silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material is prepared by a sol-gel process. This composite matrix thermal bridge blocking material is used to resolve the contradiction between low thermal conductivity and high strength at thermal bridge sites. The density of the silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material is 1.5-1.7 g / cm³. 3 The thermal conductivity at room temperature -300℃ is less than 0.6 W / m•K, the tensile strength at room temperature -1000℃ is above 30 MPa, and the compressive strength at room temperature -1000℃ is above 100 MPa. The silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material was prepared using the following steps: A three-dimensional quartz fiber fabric with low fiber volume content is prepared; the fiber volume content of the three-dimensional quartz fiber fabric with low fiber volume content is 25-35%; the three-dimensional quartz fiber fabric with low fiber volume content is prepared by a loop-forming and ply-forming process. Preparation of alumina and titanium dioxide modified silica sol; The low-fiber-volume-content three-dimensional quartz fiber fabric is impregnated with the alumina and titanium dioxide modified silica sol, and then gelled, dried and heat-treated to obtain a silica / alumina / titanium dioxide composite matrix thermal bridge blocking material. The loop-forming ply yarn process includes: when plying quartz fibers before weaving, using 1-2 strands of longer quartz fibers to ply and twist with other shorter quartz fibers. Under the premise that the ends of the ply yarn are aligned, the longer yarn after twisting is curled out from the ply yarn in the form of loops, so that the surface of the ply yarn is covered with looped yarns, forming a swollen ply yarn. The preparation of alumina and titanium oxide modified silica sol includes: preparing titanium compound modified silica sol and aluminum sol, adjusting the pH value of titanium compound modified silica sol and aluminum sol to 2-4 respectively using an acidic solution, and then slowly dripping the titanium compound modified silica sol into the rapidly stirred aluminum sol to obtain alumina and titanium oxide modified silica sol. The mass ratio of alumina to silicon oxide in the alumina-titanium oxide modified silica sol is 0.1 to 1.

0.

2. A method for preparing the silicon oxide / alumina / titanium oxide composite matrix thermal bridge blocking material according to claim 1, characterized in that, Includes the following steps: A three-dimensional quartz fiber fabric with low fiber volume content is prepared; the fiber volume content of the three-dimensional quartz fiber fabric with low fiber volume content is 25-35%; the three-dimensional quartz fiber fabric with low fiber volume content is prepared by a loop-forming and ply-forming process. Preparation of alumina and titanium dioxide modified silica sol; The low-fiber-volume-content three-dimensional quartz fiber fabric is impregnated with the alumina and titanium dioxide modified silica sol, and then gelled, dried and heat-treated to obtain a silica / alumina / titanium dioxide composite matrix thermal bridging material.

3. The method according to claim 2, characterized in that, The aluminum sol has a pH of 3.5–5, a particle size range of 5–100 nm, and an aluminum oxide content of 5–40%; the acidic solution is at least one of dilute nitric acid, dilute hydrochloric acid, acetic acid, and citric acid.

4. The method according to claim 2, characterized in that, The impregnation process includes: pretreating a low-fiber-volume-content fabric to remove its surface sizing agent, then placing the fabric in a mold, evacuating it, and impregnating it with modified silica sol, followed by applying pressure to allow the modified silica sol to enter the pores of the fabric; the impregnation time is 1 to 2 hours, and the pressure holding time is 2 to 8 hours.

5. The method according to claim 4, characterized in that, The gel comprises: placing the mold containing the sol and fabric in an oven and heating it to gel the modified silica sol, and then removing it after natural cooling to obtain a wet blank of a quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material; the heating rate is 1-3 min / ℃, the temperature is 60-90℃, and the holding time is 12-24 h.

6. The method according to claim 2, characterized in that, The drying process includes: placing the wet blank of the quartz fiber reinforced silica / alumina / titanium oxide composite matrix thermal bridge blocking material in a forced-air drying oven for drying, and then naturally cooling it to room temperature before removing it to obtain a dry blank of the thermal bridge blocking material; the drying process adopts a gradient heating drying method with a heating rate of 3-5℃ / min, and the temperature control process is 50℃ for 1-2h, 100℃ for 1-2h, and 200℃ for 1-2h; the heat treatment process includes: placing the thermal bridge blocking dry blank in a muffle furnace and holding it at 900-1000℃ for 0.5-2h.

7. The method according to any one of claims 2 to 6, characterized in that, Repeat the impregnation, gelation, drying, and heat treatment steps until the composite density reaches 1.5–1.7 g / cm³. 3 .

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