Zr-based ceramic modified C / C composite material as well as preparation method and application thereof

Abstract

The invention belongs to the field of material structure design, provides a Zr-based ceramic modified C / C composite material as well as a preparation method and application thereof, and aims to solve the problem that the mechanical property of the C / C composite material is damaged at high temperature by an existing reactive infiltration method. The method comprises the following steps: firstly, depositing pyrolytic carbon on a 2.5 D carbon fiber preform through a chemical vapor infiltration method to prepare a low-density C / C composite material, and carrying out trepanning design on the low-density C / C composite material; then Zr-Si alloy powder is adopted to carry out reactive infiltration on the perforated C / C composite material at 1800-1900 DEG C, the perforated design reduces erosion of an infiltration agent to a non-woven cloth layer of the composite material, interface bonding of carbon fibers and a ceramic phase is improved, the bending strength and the bending modulus of the composite material are remarkably improved, meanwhile, due to the fact that a pore channel structure can redistribute borne stress, the tensile strength of the composite material is improved, and the tensile strength of the composite material is improved. And the two components cooperate to improve the mechanical properties of the C / C-ZrC-SiC composite material. According to the method, the preparation process is simplified, complex interface layer deposition is avoided, and meanwhile the ablation performance and the room-temperature mechanical property of the material are guaranteed.

Description

Technical Field

[0001] The present invention belongs to the field of material structure design, and particularly relates to a Zr-based ceramic modified C / C composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of aerospace, aerospace vehicles are facing a more severe service environment. Therefore, the requirements for their thermal protection materials are becoming increasingly strict. However, traditional metal materials cannot meet the existing needs. As a composite material with the advantages of low density, low thermal expansion coefficient, high specific strength, and the mechanical properties increasing rather than decreasing with the increase of temperature, carbon / carbon (C / C) composite material is one of the candidate materials for the thermal structure components of the new generation of aircraft. However, C / C composite materials have strong mechanical sensitivity at high temperatures. When the weight loss percentage is 1%, its mechanical properties decrease by 10%. Introducing ultra-high temperature ceramics is an important technology that can currently achieve long-term effective protection for C / C composite materials. Currently, Zr-based and Hf-based ceramics are generally used for ultra-high temperature ceramics with a temperature resistance of ≥2000 °C. Among them, the melting point of Hf-based ultra-high temperature ceramics (UHTCs) is higher than that of Zr-based UHTCs, but its cost is high and the density is large. Zr-based UHTCs are widely used in the aerospace field due to their low density, low cost, etc.

[0003] Reaction Melt Infiltration (RMI) is to infiltrate the molten infiltrant into the porous matrix at high temperature, fill the pores or promote densification, and chemically react with the matrix or the surrounding environment to generate new phases, and finally form a dense and high-performance composite material. The RMI process has the characteristics of near-net shape forming, short preparation cycle, high densification degree, and is convenient for industrial application. It is the main method for introducing Zr-based ultra-high temperature ceramics at present. Currently, the infiltrants used for Zr-based UHTCs are mainly pure Zr or its silicide ZrSi 2 mainly, and its infiltration temperature is higher than 1800 °C. The preparation process temperature is relatively high, the high-temperature reaction is intense, and serious damage will be caused to the carbon fiber matrix during the infiltration process, damaging the mechanical properties of the carbon fiber.

[0004] Therefore, in order to avoid damage to carbon fibers caused by high-temperature infiltration, some researchers have adopted a Si-free system for low-temperature infiltration, using a Zr-Cu alloy as the infiltrant for reaction infiltration. The low temperature slows down the reaction rate between the infiltrant and the pyrolytic carbon, enabling the fibers to be protected from erosion by the high-temperature melt, avoiding fiber damage, and protecting the mechanical properties of the composite material. For example, in Document 1 "Y. Zhang et al. ZrC modified carbon / carbon composites using ZrSi 2and Zr-Cu alloys as reactive infiltrating materials: A comparative investigation, J. Alloys Compd, 1003(2024), 175515.” in which Zr-Cu alloys and ZrSi 2 were used as raw materials, and C / C-ZrC-Cu and C / C-ZrC-SiC composites were respectively prepared by reactive melt infiltration method. The mechanical properties were comparatively studied. The flexural strength of the C / C-ZrC-Cu composite reached 207.1 ± 22.7 Mpa, which was 152.1% higher than that of the C / C-ZrC-SiC composite prepared at high temperature. However, due to the poor wettability of the Cu melt and the carbon matrix, a higher furnace vacuum is required. When the vacuum is low, the melt infiltration reaction effect is poor. When the vacuum is high, the melt infiltration effect is high, but the residual Cu metal on the surface is difficult to peel off and easily damages the matrix. In the literature 2 "Wang S, Zhu Y L, Chen H M, et al. Effect of Cu on the ablation properties of C f / ZrC composites fabricated by infiltrating C f / C preforms with Zr-Cu alloys[J]. Ceramics International, 2015, 41(4): 5975-5983.", Zr-Cu and Zr 2 Cu alloys were infiltrated into the porous C / C composite at 1200 °C by reactive melt infiltration method to prepare the C / C-ZrC-Cu composite, and its ablation properties were tested by oxyacetylene flame. The results showed that: with the increase of the Cu content in the composite, its mass ablation rate gradually increased, mainly because of the volatilization of Cu during the ablation process. Thus, although the low-temperature infiltration with the Zr-Cu system infiltrant has a low temperature and a slow reaction rate, it can improve the mechanical properties of Zr-based ceramic modified C / C composites. However, due to the volatilization of Cu at high temperature, the ablation properties of Zr-based ceramic modified C / C composites decrease.

[0005] Although the Zr-Cu alloy as an infiltration agent can avoid the damage of the infiltration agent to the matrix material through low-temperature heat treatment, thus avoiding the reduction of the mechanical properties of the matrix, the Zr-Cu alloy inevitably introduces Cu elements into the Zr-based ceramic modified C / C composite material, which will affect its high-temperature ablation performance. Therefore, the low-temperature infiltration system with the Zr-Cu alloy as the infiltration agent cannot take into account both the mechanical properties and the ablation performance of the Zr-based ceramic modified C / C composite material.

[0006] Therefore, how to avoid the decline of mechanical properties in the Si-Zr infiltration agent system is a possible solution that can take into account both the ablation performance and the mechanical properties of the C / C composite material. Summary of the Invention

[0007] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for preparing a Zr-based ceramic modified C / C composite material, its preparation method and application. The Zr-Si alloy is used for reactive infiltration of the C / C composite material with an open-hole design to avoid the excessive erosion of the non-woven fabric layer in the C / C composite material during the high-temperature infiltration process, resulting in the serious decline of the mechanical properties after reactive infiltration in the prior art.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions: The first object of the present invention is to propose a method for preparing a Zr-based ceramic modified C / C composite material, which is characterized by including the following steps: S1: Pyrolytic carbon is deposited on a 2.5D carbon fiber preform by chemical vapor infiltration, and after cleaning and drying, a low-density C / C composite material is obtained; S2: Punch holes in the low-density C / C composite material, and clean and dry; S3: Adopt the reactive infiltration method to embed the low-density C / C composite material after punching, cleaning and drying in the ZrSi 2 alloy powder, and perform heat treatment under negative pressure. After the heat treatment is completed, clean and dry to obtain the Zr-based ceramic modified C / C composite material.

[0009] Preferably, in the step S2, holes are opened on the xz surface, yz surface or xy surface of the low-density C / C composite material.

[0010] Further preferably, xz the aperture of the hole opened on the surface or yz surface is 1 / 3 to 2 / 3 of the height of the low-density C / C composite material in the z direction at the opening, and the aperture of the hole opened on the xy surface is the low-density C / C composite material at the opening y1 / 15 to 1 / 10 of the directional length; the depth of the opening is the low-density C / C composite material at the opening position z 2 / 5 to 3 / 5 of the directional height.

[0011] Saint-Venant's principle states that the stress disturbance range caused by material openings is mainly concentrated within a range approximately 2 to 5 times the hole radius centered on the hole. Beyond this range, the stress distribution tends to be uniform. Within the 2 to 5 times radius region around the opening, significant stress concentration occurs due to geometric discontinuity in the material, which may trigger cracks or structural failure. In the matrix opening design proposed in this invention, an overly large hole diameter will lead to a decrease in the overall strength of the material. Especially when there are too many holes drilled, it may damage the material continuity. This invention restricts the hole diameter to narrow the stress concentration range and avoid damage caused by excessive stress around the hole. If the opening depth is too shallow, an effective seepage channel may not be formed, resulting in uneven melt distribution. If it is too deep, the mechanical properties of the material may be weakened. A depth of 1 / 2 height can not only provide sufficient penetration paths but also avoid excessive damage to the structural integrity. The opening diameter and opening depth proposed in this invention can ensure that the infiltrant can effectively penetrate into the pores to complete the formation and densification of the ceramic phase.

[0012] Preferably, in S3, the heat treatment temperature for reactive infiltration is 1800 - 1900 °C, the heat treatment pressure is below 50 Pa, and the reaction time is 1.5 - 2.5 h.

[0013] After the matrix is subjected to opening treatment, reactive infiltration in the temperature range of 1800 - 1900 °C avoids damage to the matrix structure by the infiltrant and avoids a decrease in mechanical properties.

[0014] Preferably, in S3, the ZrSi 2 alloy powder is ZrSi alloy powder sieved by a 325 - mesh sieve. 2

[0015] Preferably, after the low - density C / C composite material is embedded in the ZrSi 2 alloy powder, the embedded system is sealed and then heat - treated.

[0016] Preferably, after the heat treatment in S3 is completed, the low - density C / C composite material after reactive infiltration is polished, ultrasonically cleaned, and dried at 65 - 75 °C for 2 h.

[0017] Preferably, the initial density of the 2.5D carbon fiber preform is 0.48 g / cm 3 , the fiber used is carbon fiber, the fabric structure is a shallow cross - straight connection, the thickness of a single - layer fiber fabric is 0.8 - 2 mm, the number of warp yarn strands is 2, the number of weft yarn strands is 4, and the yarn density is 40% - 60%.

[0018] ​Preferably, the density of the low-density C / C composite material in S1 is 1.0 to 1.5 g / cm 3 .

[0019] The second object of the present invention is to disclose a Zr-based ceramic modified C / C composite material prepared by the preparation method of the above Zr-based ceramic modified C / C composite material.

[0020] The third object of the present invention is to disclose the application of the above Zr-based ceramic modified C / C composite material in the field of thermal protection materials.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a method for preparing a Zr-based ceramic modified carbon / carbon (C / C) composite material by reactive infiltration. By designing the open-hole structure of the C / C composite material matrix after pyrolytic carbon deposition, the presence of pores during the high-temperature infiltration process slows down the hindrance of the non-woven fabric layer to the high-temperature melt of the infiltrant, and the full reaction of the melt with PyC improves the interfacial bonding between the fiber and the ceramic phase; at the same time, a large amount of melt tends to flow from the pore channels, reducing the overall damage of the non-woven fabric layer. The flexural strength and flexural modulus of the prepared C / C-ZrC-SiC composite material can be increased by more than 200% compared with the C / C composite material matrix without hole punching design. This method can prepare a C / C-ZrC-SiC composite material with excellent mechanical properties at a relatively high infiltration temperature, that is, at a temperature of 1800 °C, without the need for complex interfacial layer deposition or low-temperature Si-free system infiltration, which may lead to deterioration of ablation performance.

[0022] Furthermore, holes are drilled in the x, y or / and z direction of the C / C composite material matrix. Through reasonable design of the hole positions, the potential impact of excessive damage to the C / C composite material matrix by the pore channels and the stress concentration generated by the geometric mutation of the matrix on the matrix strength can be avoided.

[0023] The prepared C / C-ZrC-SiC composite material has an approximate density and porosity compared with the C / C-ZrC-SiC without pore channel design. The presence of pore channels has no negative impact on the introduction of ultra-high temperature ceramics, ensuring the ablation performance of the specimen. The specimens with holes have good room temperature mechanical properties after reactive infiltration. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagrams of four pore channel structure designs in the embodiments of the present invention; Figure 2 Force-displacement curves of the C / C-ZrC-SiC composite materials prepared in the embodiments and comparative examples of the present invention; Figure 3Bending strength and bending modulus of C / C-ZrC-SiC composites prepared in each embodiment of the present invention and comparative examples Figure 4 Transverse strain DIC results of C / C-ZrC-SiC composites prepared in each embodiment of the present invention and comparative examples Figure 5 Longitudinal strain DIC results of C / C-ZrC-SiC composites prepared in each embodiment of the present invention and comparative examples Figure 6 Shear strain DIC results of C / C-ZrC-SiC composites prepared in each embodiment of the present invention and comparative examples Detailed implementation manners

[0025] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0027] The present invention proposes a method for preparing Zr-based ceramic modified C / C composites by reactive infiltration. The following further describes the present invention in detail with reference to the accompanying drawings: The initial density of the 2.5D carbon fiber preform used in the present invention is 0.48 g / cm 3 , the fibers used are carbon fibers, the fabric structure is a shallow cross-linked straight connection, the thickness of a single-layer fiber fabric is 0.8 - 2 mm, the number of warp yarns is 2, the number of weft yarns is 4, and the yarn density is 40% - 60%.

[0028] Step 1: Place the carbon fiber preform with a 2.5D braided structure in a chemical vapor infiltration furnace for pyrolytic carbon deposition. The pyrolytic carbon deposition process is as follows: Place the carbon fiber preform with a 2.5D braided structure in a mold, place the mold in the heating zone of the chemical vapor infiltration furnace, set the heating rate to 5 - 10 °C / min, the holding temperature to 1000 - 1200 °C, control the furnace pressure to 1 - 2 kPa, hold for 2 - 4 h, and take out the sample after cooling. After taking out, polish the pyrolytic carbon on the surface of the sample, then place the sample in deionized water and ultrasonically clean it in an ultrasonic machine for 4 - 6 h, and then place it in an oven at 70 °C for 6 - 8 h. Measure the density of the deposited sample, and select low-density carbon / carbon (C / C) composites with a density of about 1.0 - 1.5 g / cm 3 , preferably 1.3 g / cm 3 as the samples to be processed in the following comparative examples and Examples 2 - 5.

[0029] Step 2: The specific method for drilling holes in the matrix of the low-density carbon / carbon (C / C) composites in Examples 2 - 5 is as follows: For the 2.5D carbon fiber matrix, on the wide-height plane ( xz plane) and the long-height plane ( yz plane), the hole diameter should be 1 / 3 - 2 / 3 of the sample height and should not exceed 2 / 3 of the sample height to avoid excessive damage to the pore channels; for the hole diameter on the long-width plane ( xy plane), according to Saint-Venant's principle, when the distance from the center of the hole is 2 - 5 times the hole radius, obvious stress concentration will occur. To reduce the stress concentration in the central area and avoid excessive damage caused by over-drilling, the designed hole diameter is 1 / 15 - 1 / 10 of the sample length. To ensure the infiltration effect, the hole depth should be controlled at about 1 / 2 of the sample height.

[0030] Step 3: Weigh ZrSi 2 powder with a particle size of about 325 mesh. Lay a layer of carbon felt and a layer of graphite paper at the bottom of the crucible, spread 1 cm thick ZrSi 2 powder on the graphite paper, and compact it with a mold. Then place the low-density C / C composite with the above structural design in the graphite crucible on the ZrSi 2 powder, pour the remaining ZrSi 2 powder into the crucible and compact it. Then seal the crucible. Place the sealed crucible in the constant temperature zone of a vacuum sintering furnace and hold it in a vacuum environment at 1800 - 1900 °C for 1.5 - 2.5 h, preferably 2 h. After the holding is completed, turn off the heating power supply and let the sample cool with the furnace. Polish the ceramic phase on the surface of the sample after reaction infiltration, ultrasonically clean the sample, and then place it in an oven at 70 °C to dry for 2 h to obtain a C / C-ZrC-SiC composite with an optimized matrix structure design, that is, a Zr-based ceramic modified C / C composite.

[0031] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples that do not specify specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, are conventional commercial products, and their specifications are conventional specifications in the art. The present invention is further described in conjunction with the embodiments and drawings: Comparative Example 1 The cleaned and polished low-density C / C composite material was cut into mechanical specimens of 40×7×3 mm using a cutting machine without any structural design. Weigh the ZrSi with a particle size of about 325 mesh 2 The powder is about 100 g. A layer of carbon felt and a layer of graphite paper are placed on the bottom of the crucible. A 1 cm thick ZrSi 2 The powder is then pressed with a mold. The low-density C / C composite material with the above structural design is then placed on the ZrSi 2 powder, and the remaining ZrSi 2 The powder was poured into a crucible and compacted, and then the crucible was sealed. The sealed crucible was placed in the constant temperature zone of the negative pressure sintering furnace and kept warm for 2 h in a vacuum environment of not less than 1800 ° C. After the insulation, the heating power was turned off and the sample was cooled with the furnace. The ceramic phase on the surface of the sample after the reaction infiltration was polished clean, and the sample was ultrasonically treated, and then placed in a 70 ° C oven for 2 h to obtain a C / C-ZrC-SiC composite material with optimized matrix structure, namely CZS1.

[0032] Example 2 like Figure 1 As shown in (a), the cleaned and polished low-density C / C composite material is cut into 40×7×3mm mechanical specimens using a cutting machine, and holes are punched using a drill bit with a diameter of 1.5 mm. Holes are punched at both ends of the front surface of the specimen. There are 3 holes on the left and right sides, with a hole spacing of 1 mm and a hole depth of 1.5 mm. The holes at the two ends are 1.5 mm away from the edge of the specimen.

[0033] Weigh the ZrSi with a particle size of about 325 mesh 2 The powder is about 100 g. A layer of carbon felt and a layer of graphite paper are placed on the bottom of the crucible. A 1 cm thick ZrSi 2 The powder is then pressed with a mold. The low-density C / C composite material with the above structural design is then placed on the ZrSi 2 powder, and the remaining ZrSi 2The powder is poured into the crucible and compacted, and then the crucible is sealed. The sealed crucible is placed in the constant temperature zone of a negative pressure sintering furnace and kept at a constant temperature for 2 h in a vacuum environment not lower than 1800 °C and not higher than 1900 °C. After the heat preservation is completed, the heating power supply is turned off, and the sample cools down with the furnace. The ceramic phase on the surface of the sample after reaction infiltration is polished clean, the sample is ultrasonically treated, and then placed in an oven at 70 °C for drying for 2 h, and the C / C-ZrC-SiC composite material with optimized matrix structure design, namely CZS2, can be obtained.

[0034] Example 3 As Figure 1 shown in (b) therein, the cleaned and polished low-density C / C composite material is cut into mechanical specimens of 40×7×3 mm by a cutting machine, and holes are drilled with a drill bit with a diameter of 1.5 mm. Holes are drilled on the wide and high surfaces on both sides of the specimen. The number of holes on the left and right sides is 2, the hole spacing is 0.5 mm, the hole depth is 1.5 mm, and the holes at both ends are 0.5 mm away from the edge of the specimen.

[0035] Weigh about 100 g of ZrSi 2 powder with a particle size of about 325 mesh. Lay a layer of carbon felt and a layer of graphite paper at the bottom of the crucible, and lay 1 cm thick ZrSi 2 powder on the graphite paper and compact it with a mold. Then place the low-density C / C composite material with the above structural design in the graphite crucible on the ZrSi 2 powder, and pour the remaining ZrSi 2 powder into the crucible and compact it. Then seal the crucible. Place the sealed crucible in the constant temperature zone of a negative pressure sintering furnace and keep it at a constant temperature for 2 h in a vacuum environment not lower than 1800 °C and not higher than 1900 °C. After the heat preservation is completed, turn off the heating power supply, and the sample cools down with the furnace. Polish the ceramic phase on the surface of the sample after reaction infiltration, ultrasonically treat the specimen, and then place it in an oven at 70 °C for drying for 2 h, and the C / C-ZrC-SiC composite material with optimized matrix structure design, namely CZS3, can be obtained.

[0036] Example 4 As Figure 1 shown in (c) therein, the cleaned and polished low-density C / C composite material is cut into mechanical specimens of 40×7×3 mm by a cutting machine, and holes are drilled with a drill bit with a diameter of 1.5 mm. The holes are drilled dispersedly on the upper surface of the specimen. The hole spacing is 15 mm, the hole depth is 1.5 mm, and the holes at both ends are 0.5 mm away from the edge of the specimen.

[0037] Weigh about 100 g of ZrSi 2 powder with a particle size of about 325 mesh. Lay a layer of carbon felt and a layer of graphite paper at the bottom of the crucible, and lay 1 cm thick ZrSi 2Powder, and compact it with a mold. Subsequently, place the low-density C / C composite material with the above structural design in a graphite crucible on the ZrSi 2 powder, and pour the remaining ZrSi 2 powder into the crucible and compact it. Then seal the crucible. Place the sealed crucible in the constant temperature zone of a negative pressure sintering furnace, and keep it warm for 2 h in a vacuum environment not lower than 1800 °C and not higher than 1900 °C. After the heat preservation is completed, turn off the heating power supply, and let the sample cool down with the furnace. Polish the ceramic phase on the surface of the sample after reaction infiltration, and ultrasonically treat the specimen, and then place it in an oven at 70 °C and dry it for 2 h to obtain the C / C-ZrC-SiC composite material with optimized matrix structure design, that is, CZS4.

[0038] Example 5 As Figure 1 shown in (d) therein, cut the cleaned and polished low-density C / C composite material into mechanical specimens of 40×7×3 mm with a cutting machine, and use a drill bit with a diameter of 1.5 mm to drill holes. Concentrate on drilling holes at both ends of the upper surface of the specimen. The number of holes on the left and right sides is 3 each, the hole spacing is 1 mm, the hole depth is 1.5 mm, and the holes at the two outermost ends are 1.5 mm away from the edge of the specimen.

[0039] Weigh about 100 g of ZrSi 2 powder with a particle size of about 325 mesh. Lay a layer of carbon felt and a layer of graphite paper at the bottom of the crucible. Lay 1 cm thick ZrSi 2 powder on the graphite paper, and compact it with a mold. Subsequently, place the low-density C / C composite material with the above structural design in a graphite crucible on the ZrSi 2 powder, and pour the remaining ZrSi 2 powder into the crucible and compact it. Then seal the crucible. Place the sealed crucible in the constant temperature zone of a negative pressure sintering furnace, and keep it warm for 2 h in a vacuum environment not lower than 1800 °C and not higher than 1900 °C. After the heat preservation is completed, turn off the heating power supply, and let the sample cool down with the furnace. Polish the ceramic phase on the surface of the sample after reaction infiltration, and ultrasonically treat the specimen, and then place it in an oven at 70 °C and dry it for 2 h to obtain the C / C-ZrC-SiC composite material with optimized matrix structure design, that is, CZS5.

[0040] Effect example It should be noted that Figure 3 、 4, the abscissa Time Pixel in 5 and 6 is the segmentation of the total time during the specimen bending test, that is, the entire bending process is evenly divided into 400 segments. The set pressing speed of the testing machine indenter is 0.5 mm / min. The bending process time is proportional to the displacement of the testing machine. Therefore, the strain and load during the bending process can be combined and analyzed through the strain-time segmentation curve and the force-displacement curve.

[0041] It should be noted that during the bending process of the material, under the condition of bearing the same force, the smaller the strain occurs, the stronger the ability of the material to resist deformation, and the more solid the structure of the material.

[0042] It should be noted that the ε extracted by the full-scene strain measurement system xx is the transverse strain of the specimen, and ε xy is the shear strain of the specimen, and ε yy is the longitudinal strain of the specimen.

[0043] Figure 1 Schematic diagrams of four kinds of pore structure designs. The figure shows the processing methods of specimens of four embodiments.

[0044] Figure 2 are the force-displacement curves of CZS1, CZS2, CZS3, CZS4, and CZS5. The figure shows that all five specimens exhibit pseudoplastic fracture, and the existence of pores improves the ultimate load-bearing capacity of the C / C-ZrC-SiC composite material.

[0045] Figure 3 are the bending strength and bending modulus of CZS1, CZS2, CZS3, CZS4, and CZS5. The average flexural strength and average bending modulus results of each test sample are shown in Table 1. Combining Figure 3 it can be seen that after the pore design, the bending strength and bending modulus of the C / C-ZrC-SiC composites CZS2, CZS3, CZS4, and CZS5 have been significantly improved.

[0046] Table 1 Average flexural strength and average bending modulus of comparative and example samples

[0047] Figure 4It is the DIC result of the transverse strain during the bending process of CZS1, CZS2, CZS3, CZS4, and CZS5. Combining the force-displacement curve and the transverse strain curve, it can be seen from the figure that for the C / C-ZrC-SiC composites CZS2, CZS3, CZS4, and CZS5 with channel design, when bearing a relatively large force, the curves are below that of CZS1 without channel design. That is, compared with CZS1, CZS2, CZS3, CZS4, and CZS5 maintain a relatively small transverse strain, namely ε xx , indicating that for the C / C-ZrC-SiC composites with channel design, when the applied load is large, the transverse deformation is small, and the transverse structure is more stable than that of the C / C-ZrC-SiC composites without channel design.

[0048] Figure 5 It is the DIC result of the longitudinal strain of CZS1, CZS2, CZS3, CZS4, and CZS5. As shown in the figure, combining the force-displacement curve and the longitudinal strain curve, for the C / C-ZrC-SiC composites CZS2, CZS3, CZS4, and CZS5 with channel design, when bearing a large force, the curves are all below that of CZS1 without channel design, maintaining a small longitudinal strain, namely ε yy , indicating that the C / C-ZrC-SiC material after channel design is not prone to delamination failure longitudinally during the bending process, and the interfacial bonding force between layers is strong.

[0049] Figure 6 It is the DIC result of the shear strain of CZS1, CZS2, CZS3, CZS4, and CZS5. As shown in the figure, combining the force-displacement curve and the change of shear strain during the bending process, it can be seen that for the C / C-ZrC-SiC composites CZS2, CZS3, CZS4, and CZS5 with channel design, when bearing a large force, the curves are all below that of CZS1 without channel design, maintaining a relatively small shear strain compared with CZS1, namely ε xy , and a relatively strong bond is formed at the interface between the fibers and the ceramic phase of the C / C-ZrC-SiC after channel design.

[0050] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a Zr-based ceramic modified C / C composite material, characterized in that: The following steps are involved: S1: Pyrolytic carbon was deposited on a 2.5D carbon fiber preform by chemical vapor infiltration, and a low-density C / C composite material was prepared after washing and drying; S2: opening holes in the low-density C / C composite material, cleaning and drying; S3: The low-density C / C composite material after punching, cleaning and drying is embedded in ZrSi2 alloy powder by reactive infiltration method, and heat treated under negative pressure. After the heat treatment, it is cleaned and dried to obtain a Zr-based ceramic modified C / C composite material.

2. The method for preparing a Zr-based ceramic modified C / C composite material according to claim 1, characterized in that: In S2, in the low density C / C composite material xz noodle, yz Noodle or xy In-plane opening.

3. The method for preparing a Zr-based ceramic modified C / C composite material according to claim 2, characterized in that: xz Noodle or yz The diameter of the surface opening is z 1 / 3~2 / 3 of the direction height; xy The aperture of the surface is y 1 / 15~1 / 10 of the length in the direction; the depth of the opening is z 2 / 5~3 / 5 of the direction height; z Direction height, y The directional length is the material height and length of the low-density C / C composite material at the center of the opening.

4. The method for preparing a Zr-based ceramic modified C / C composite material according to claim 1, characterized in that: In S3, the heat treatment temperature of the reactive infiltration is 1800-1900° C., the heat treatment pressure is lower than 50 Pa, and the reaction time is 1.5-2.5 h.

5. The method for preparing a Zr-based ceramic modified C / C composite material according to claim 1, characterized in that: The ZrSi2 alloy powder in S3 is ZrSi2 alloy powder sieved through a 325-mesh sieve.

6. The method for preparing a Zr-based ceramic modified C / C composite material according to claim 1, characterized in that: After the S3 medium-low density C / C composite material is embedded in the ZrSi2 alloy powder, the embedding system is sealed and then heat treated.

7. The method for preparing a Zr-based ceramic modified C / C composite material according to claim 1, characterized in that: After the heat treatment in S3 is completed, the low-density C / C composite material after reaction infiltration is polished, ultrasonically cleaned, and then dried at 65-75° C. for 2 hours.

8. The method for preparing a Zr-based ceramic modified C / C composite material according to claim 1, characterized in that: The density of the low-density C / C composite material in S1 is 1.0-1.5 g / cm 3 .

9. A Zr-based ceramic modified C / C composite material obtained according to the method for preparing a Zr-based ceramic modified C / C composite material according to any one of claims 1 to 8.

10. Use of the Zr-based ceramic modified C / C composite material according to claim 9 in thermal protection materials.

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