Method for avoiding brittle fracture in intermediate temperature zone of continuous fiber reinforced ceramic matrix composite

Abstract

The invention discloses a method for avoiding brittle fracture of a continuous fiber reinforced ceramic matrix composite in a medium-temperature zone, and relates to the technical field of high-temperature mechanical properties of materials. The method comprises the following steps: carrying out surface treatment on a transition section of a continuous fiber reinforced ceramic matrix composite sample by using two-component aluminosilicate inorganic high-temperature-resistant glue; the bi-component aluminosilicate inorganic high-temperature-resistant glue comprises a component A and a component B, according to the method, the surface of the prepared material is treated, so that the sample is effectively prevented from being in contact with oxygen in a medium-temperature zone, the sample is prevented from being broken due to oxidation in the medium-temperature zone, and the accuracy and reliability of a high-temperature mechanical experiment result of the continuous fiber reinforced ceramic matrix composite material are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature mechanical properties of materials, and particularly relates to a method for avoiding brittle fracture in the medium-temperature range of continuous fiber-reinforced ceramic matrix composites. Background Art

[0002] Continuous fiber-reinforced ceramic matrix composites have excellent properties such as low density, high specific strength, high modulus, good wear resistance, high temperature resistance, oxidation resistance, and creep resistance. Currently, they have become one of the popular materials for hot structural components of aerospace vehicles, and their mechanical properties at high temperatures are the focus and difficulty of research at home and abroad.

[0003] When conducting high-temperature tests on continuous fiber-reinforced ceramic composites, usually only the experimental section is in the heating furnace and subjected to the high-temperature zone (≥1000 °C), while the transition section of the specimen is at the edge and outside of the heating furnace and only subjected to the medium-temperature zone (500 °C - 800 °C). When the specimen is subjected to tension or creep, new cracks are generated on its surface and the original cracks expand, exposing the internal fibers of the specimen to the external atmosphere. At this time, more oxides will be generated in the experimental section subjected to high temperature, and the oxides will fill the cracks, thereby preventing the fibers from being oxidized; fewer oxides are generated in the transition section subjected to medium temperature. With the action of tensile stress, the surface cracks of the specimen expand, and oxygen enters the interior of the specimen to oxidize the fibers, resulting in a decrease in the properties of the specimen in the medium-temperature zone, which causes the specimen to fracture in the medium-temperature zone. This causes the specimen to fracture at an undesired temperature and stress level, obtaining invalid data, thereby affecting the accuracy of the high-temperature mechanical test results of continuous fiber-reinforced ceramic matrix composites.

[0004] The prior art discloses a method for detecting the room-temperature tensile properties of continuous fiber-reinforced ceramic matrix composites, which mainly re-cuts and processes the specimens according to the weaving direction of the specimens to make the specimens fracture at the correct position during the test. However, this invention is applicable to the room-temperature environment and is not applicable to the tensile test in a high-temperature environment; the prior art also discloses a coated inorganic fiber-reinforced MAX-phase ceramic composite material, its preparation method and uses, and adding a coating treatment during specimen preparation solves the problems of large brittleness and insufficient use reliability of MAX-phase ceramics, but there is still a problem of medium-temperature embrittlement in the high-temperature tensile test of specimens that are not coated during preparation. Summary of the Invention

[0005] Aiming at the deficiencies in the above-mentioned background technology, the present invention mainly solves the problem that existing continuous fiber-reinforced ceramic matrix composites undergo oxidation fracture in the medium-temperature region during high-temperature tension or creep, resulting in invalid results. The present invention provides a method for avoiding brittle fracture of continuous fiber-reinforced ceramic matrix composites in the medium-temperature region. This method effectively prevents the contact of the specimen with oxygen in the medium-temperature region, avoids the fracture of the specimen due to oxidation in the medium-temperature region, and greatly improves the accuracy and reliability of the high-temperature mechanical test results of continuous fiber-reinforced ceramic matrix composites. The purpose of the present invention is to provide a method for avoiding brittle fracture of continuous fiber-reinforced ceramic matrix composites in the medium-temperature region, including: surface-treating the transition section of the continuous fiber-reinforced ceramic matrix composite specimen with a two-component aluminosilicate inorganic high-temperature resistant adhesive. The two-component aluminosilicate inorganic high-temperature resistant adhesive includes component A and component B. Component A includes the following components by mass percentage: 60-70% of aluminosilicate powder with a purity of ≥99%, 15-20% of nano-aluminum oxide powder, 3-5% of potassium metaphosphate, 2-5% of zinc borate, 3-5% of silane coupling agent, and the sum of the mass percentages of each component is 100%. Component B includes the following components by mass percentage: 40-50% of potassium silicate solution, 10-15% of aluminum dihydrogen phosphate solution, 5-10% of organic amine curing agent, 15-20% of deionized water, 5-10% of ethanol, 3-5% of acrylate emulsion, 2-5% of organosilicon modifier containing reactive groups, and the sum of the mass percentages of each component is 100%.

[0006] Preferably, the mass ratio of component A to component B is 2-3:1.

[0007] Preferably, the surface treatment process includes: coating the transition section surface of the continuous fiber-reinforced ceramic matrix composite specimen with the two-component aluminosilicate inorganic high-temperature resistant adhesive.

[0008] Preferably, after coating, the specimen is placed at room temperature for 12-24 hours for preliminary curing, and then placed in an environment of 80-120°C for 2-3 hours to complete the curing.

[0009] Preferably, the thickness of the transition section of the continuous fiber-reinforced ceramic matrix composite after surface treatment with the two-component aluminosilicate inorganic high-temperature resistant adhesive is 0.2-1 mm.

[0010] Preferably, the particle size of the high-purity aluminosilicate powder is 10-30 µm; the particle size of the nano-aluminum oxide powder is 50-100 nm.

[0011] Preferably, the modulus of the potassium silicate solution is 2.8-3.2, and the density is 1.38-1.45 g / cm³; The organic amine curing agent is ethylenediamine or diethylenetriamine.

[0012] Preferably, the organosilicon modifier containing reactive groups is methyl silicone resin.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for avoiding brittle fracture in the intermediate temperature range of continuous fiber reinforced ceramic matrix composites. The transition section of the continuous fiber reinforced ceramic matrix composite specimen is surface-treated with a two-component aluminosilicate inorganic high-temperature resistant adhesive. Component A is the framework, providing a basic heat-resistant structure, and component B plays a connecting role, promoting curing through reaction. After curing, an anti-oxidation layer is formed, effectively preventing the contact between the specimen surface and oxygen in the intermediate temperature range, avoiding fracture of the specimen due to oxidation in the intermediate temperature range, and greatly improving the accuracy and reliability of the high-temperature mechanical test results of continuous fiber reinforced ceramic matrix composites.

[0014] The treatment method of the present invention is simple, has a short treatment period, and low cost. Description of the Drawings

[0015] Figure 1 It is a schematic diagram of the structure and heat reception of a continuous fiber reinforced ceramic matrix composite specimen.

[0016] Figure 2 It is a schematic diagram of a continuous fiber reinforced ceramic matrix composite specimen after surface treatment.

[0017] Figure 3 It is a creep fracture photo of the specimen after surface treatment at 1100 °C / 65 MPa.

[0018] Figure 4 It is a creep fracture photo of the specimen without surface treatment at 1100 °C / 65 MPa.

[0019] Figure 5 It is a tensile creep curve at 1100 °C.

[0020] Figure 6 It is a tensile creep curve at 1000 °C.

[0021] Wherein: 1 - high temperature zone, 2 - intermediate temperature zone, 3 - specimen test section, 4 - specimen transition section, 5 - anti-oxidation layer. Detailed Embodiments

[0022] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments and drawings, but the specific embodiments cited do not limit the present invention.

[0023] The object of the present invention is to provide a method for avoiding brittle fracture in the medium-temperature zone of a continuous fiber-reinforced ceramic matrix composite. This method evenly coats a two-component aluminosilicate inorganic high-temperature resistant adhesive on the transition section of the continuous fiber-reinforced ceramic matrix composite specimen. After the high-temperature resistant adhesive cures, an anti-oxidation layer is formed on the surface of the specimen. By applying the adhesive coating treatment to the surface of the continuous fiber-reinforced ceramic matrix composite, the present invention avoids test errors caused by material fracture in the medium-temperature zone during tensile and creep processes, making the test results more reliable.

[0024] See Figure 1 As shown, when a high-temperature test is performed on a continuous fiber-reinforced ceramic matrix composite specimen, only the experimental section 3 is in the heating furnace and is subjected to the action of the high-temperature zone 1 (≥1000 °C), while the transition section 4 of the specimen is at the edge and outside of the heating furnace and is only subjected to the action of the medium-temperature zone 2 (500 °C - 800 °C). When the specimen is subjected to tension or creep, new crack generation and original crack expansion occur on its surface, exposing the internal fibers of the specimen to the external atmosphere. See Figure 2 As shown, the present invention coats a two-component aluminosilicate inorganic high-temperature resistant adhesive on the transition section 4 of the specimen to form an anti-oxidation layer 5, avoiding test errors caused by material fracture in the medium-temperature zone during tensile and creep processes, making the test results more reliable.

[0025] To achieve the above object, the present invention provides a method for avoiding brittle fracture in the medium-temperature zone of a continuous fiber-reinforced ceramic matrix composite, including: surface treating the transition section of the continuous fiber-reinforced ceramic matrix composite specimen with a two-component aluminosilicate inorganic high-temperature resistant adhesive; The two-component aluminosilicate inorganic high-temperature resistant adhesive includes component A and component B; Component A includes the following components by mass percentage: 60 - 70% of aluminosilicate powder with a purity of ≥99%, 15 - 20% of nano-aluminum oxide powder, 3 - 5% of potassium metaphosphate, 2 - 5% of zinc borate, 3 - 5% of silane coupling agent, and the mass percentages of each component add up to 100%; Component B includes the following components by mass percentage: 40 - 50% of potassium silicate solution, 10 - 15% of aluminum dihydrogen phosphate solution, 5 - 10% of organic amine curing agent, 15 - 20% of deionized water, 5 - 10% of ethanol, 3 - 5% of acrylate emulsion, 2 - 5% of organosilicon modifier containing active groups, and the mass percentages of each component add up to 100%.

[0026] In the present invention, the high-purity aluminosilicate powder in component A serves as a high-temperature resistant framework, providing a basic heat-resistant structure; the nano-aluminum oxide powder and silicon carbide micropowder fill the voids, enhancing heat conduction and mechanical strength, and improving the overall heat-resistant stability. The potassium silicate solution in component B forms a high-temperature resistant silicon-oxygen bond network after curing. Aluminum dihydrogen phosphate reacts with other components at high temperatures to form a high-temperature resistant aluminum phosphate salt, jointly constructing a stable high-temperature resistant system with component A, enabling the inorganic adhesive to maintain its structural integrity at a high temperature of 1000 °C without decomposition or softening. The high-temperature resistant adhesive layer formed by curing this invention reduces the contact between the surface of the specimen and oxygen in the environment, thereby preventing the oxidation of the specimen.

[0027] The mass ratio of component A to component B is 2 - 3:1.

[0028] The surface treatment process includes: coating a two-component aluminosilicate inorganic high-temperature resistant adhesive on the surface of the transition section of a continuous fiber reinforced ceramic matrix composite specimen.

[0029] After coating, the specimen is placed at room temperature for 12 - 24 hours for preliminary curing, and then placed in an environment of 80 - 120 °C for 2 - 3 hours to achieve complete curing.

[0030] The thickness of the transition section of the continuous fiber reinforced ceramic matrix composite after surface treatment with the two-component aluminosilicate inorganic high-temperature resistant adhesive is 0.2 - 1 mm.

[0031] The particle size of the high-purity aluminosilicate powder is 10 - 30 µm; the particle size of the nano-aluminum oxide powder is 50 - 100 nm.

[0032] The modulus of the potassium silicate solution is 2.8 - 3.2, and the density is 1.38 - 1.45 g / cm³; The organic amine curing agent is ethylenediamine or diethylenetriamine.

[0033] The organosilicon modifier containing reactive groups is methyl silicone resin.

[0034] It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used, unless otherwise specified, can be purchased on the market.

[0035] Example 1 First, high-purity silicate powder, nano-aluminum oxide powder, potassium metaphosphate, zinc borate, and silane coupling agent are uniformly mixed in a mass fraction of 13:4:1:1:1 to form component A. Then, potassium silicate solution, aluminum dihydrogen phosphate solution, ethylenediamine curing agent, deionized water, ethanol, acrylate emulsion, and methyl silicone resin are uniformly mixed in a mass fraction of 9:3:2:3:1:1:1 to form component B. Component A and component B are uniformly mixed in a mass fraction of 2:1, and coated on the transition sections at both ends of the specimen, cured at room temperature for 24 h and at 80 °C for 3 h to make the thickness of the anti-oxidation layer 1 mm.

[0036] After the curing is completed, the surface-treated specimens and the untreated original specimens are respectively subjected to tensile creep at 1100 °C / 65 MPa. Figure 3 The figure shows the fracture position diagram of the specimens after surface treatment in this embodiment. The specimens fracture in the experimental section in the figure; while as Figure 4 shown, the original specimens of the material without surface treatment all fracture in the transition section; by comparison, it can be obtained that brittle fracture of the specimens in the medium-temperature zone is avoided after surface treatment; Figure 5 is the tensile creep curve of the specimens. The fracture positions of the treated specimens and the untreated specimens are different, and the creep test results obtained are quite different.

[0037] Example 2 First, high-purity silicate powder, nano-aluminum oxide powder, potassium metaphosphate, zinc borate, and silane coupling agent are uniformly mixed in a mass fraction of 13:4:1:1:1 to form component A. Then, potassium silicate solution, aluminum dihydrogen phosphate solution, ethylenediamine curing agent, deionized water, ethanol, acrylate emulsion, and methyl silicone resin are uniformly mixed in a mass fraction of 9:3:2:3:1:1:1 to form component B. Component A and component B are uniformly mixed in a mass fraction of 2.5:1, and coated on the transition sections at both ends of the specimen, cured at room temperature for 24 h and at 80 °C for 3 h to make the thickness of the anti-oxidation layer 1 mm.

[0038] After the curing is completed, the surface-treated specimens and the untreated original specimens are respectively subjected to tensile creep at 1000 °C / 65 MPa. Figure 6 is the tensile creep curve of the specimens. The fracture positions of the treated specimens and the untreated specimens are different, and the creep test results obtained are quite different.

[0039] The present invention describes the preferred embodiments and their effects. However, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0040] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for avoiding brittle fracture in the intermediate temperature range of continuous fiber reinforced ceramic matrix composites, characterized in that, Comprising: Surface-treating the transition section of a continuous fiber reinforced ceramic matrix composite sample with a two-component aluminosilicate inorganic high-temperature resistant adhesive; The two-component aluminosilicate inorganic high-temperature resistant adhesive comprises component A and component B; Component A comprises components in the following mass percentages: 60 - 70% of aluminosilicate powder with a purity ≥ 99%, 15 - 20% of nano-aluminum oxide powder, 3 - 5% of potassium metaphosphate, 2 - 5% of zinc borate, 3 - 5% of silane coupling agent, and the sum of the mass percentages of each component is 100%; Component B comprises components in the following mass percentages: 40 - 50% of potassium silicate solution, 10 - 15% of aluminum dihydrogen phosphate solution, 5 - 10% of organic amine curing agent, 15 - 20% of deionized water, 5 - 10% of ethanol, 3 - 5% of acrylate emulsion, 2 - 5% of organosilicon modifier containing reactive groups, and the sum of the mass percentages of each component is 100%.

2. The method for avoiding brittle fracture in the intermediate temperature range of continuous fiber reinforced ceramic matrix composites according to claim 1, characterized in that The mass ratio of component A to component B is 2 - 3:

1.

3. The method for avoiding brittle fracture of continuous fiber reinforced ceramic matrix composites in the medium temperature range according to claim 1, characterized in that, The surface treatment process includes: coating the two-component aluminosilicate inorganic high-temperature resistant adhesive on the surface of the transition section of the continuous fiber reinforced ceramic matrix composite sample.

4. The method for avoiding brittle fracture in the intermediate temperature range of a continuous fiber reinforced ceramic matrix composite according to claim 3, characterized in that After coating, the sample is placed at room temperature for 12 - 24 hours for preliminary curing, and then placed in an environment of 80 - 120 °C for 2 - 3 hours to complete the curing.

5. The method for avoiding brittle fracture of continuous fiber reinforced ceramic matrix composites in the medium temperature range according to claim 1, wherein The thickness of the transition section of the continuous fiber reinforced ceramic matrix composite after surface treatment with the two-component aluminosilicate inorganic high-temperature resistant adhesive is 0.2 - 1 mm.

6. The method for avoiding brittle fracture of continuous fiber-reinforced ceramic matrix composites in the medium temperature range according to claim 1, characterized in that The particle size of the high-purity aluminosilicate powder is 10 - 30 µm; the particle size of the nano-aluminum oxide powder is 50 - 100 nm.

7. The method for avoiding brittle fracture of continuous fiber reinforced ceramic matrix composites in the medium temperature range according to claim 1, wherein The modulus of the potassium silicate solution is 2.8 - 3.2, and the density is 1.38 - 1.45 g / cm³; The organic amine curing agent is ethylenediamine or diethylenetriamine.

8. The method for avoiding brittle fracture of continuous fiber reinforced ceramic matrix composites in the medium temperature range according to claim 1, characterized in that The organosilicon modifier containing reactive groups is methyl silicone resin.

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