SiC / SiC composite material water-oxygen corrosion system and test method

Abstract

The application discloses a SiC / SiC composite material water-oxygen corrosion system and a testing method, and belongs to the field of ceramic matrix composite material high-temperature environment damage testing and interface performance characterization. The water-oxygen corrosion system comprises a gas supply unit, a humidification unit, a gas mixing unit, a flow control unit, a high-temperature corrosion furnace, a sample bearing unit, a tail gas exhaust unit and a control monitoring unit; the sample bearing unit bears the sample in an edge support mode, so that the contact area is minimized. The testing method comprises the following steps: sample pretreatment, water-oxygen corrosion treatment, test section preparation, fiber push-in testing, interface initial debonding critical load determination, interface shear strength calculation and result analysis and evaluation. The application can stably control the high-temperature high-water-vapor-pressure corrosion environment, and quantitatively characterize the interface shear strength of the fiber / matrix after corrosion through nanoindentation fiber push-in testing, thereby solving the problems of unstable corrosion environment control, unreasonable sample support and difficult quantitative testing of the interface bonding state after corrosion in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature environmental damage testing and interface performance characterization of ceramic matrix composites. Specifically, it relates to a water-oxygen corrosion system and testing method for SiC / SiC composites, and more particularly to a method suitable for corrosion testing of third-generation SiC fiber reinforced SiC / SiC composites in a high-temperature, high-water vapor partial pressure environment, and quantitatively testing the fiber / matrix interface shear strength after corrosion. Background Technology

[0002] Continuous silicon carbide fiber-reinforced silicon carbide composites (SiC / SiC) possess low density, excellent high-temperature mechanical properties, good oxidation resistance, and non-catastrophic fracture characteristics, making them promising candidates for applications in hot-end structural components of aero-engines, high-temperature components of gas turbines, and advanced energy equipment. For this type of composite material, the bonding state at the fiber / matrix interface directly affects toughening mechanisms such as crack deflection, interface debonding, and fiber pull-out, thereby influencing the material's residual strength and service life in complex environments.

[0003] Under high-temperature service conditions, the combustion environment typically contains a certain proportion of water vapor and oxygen. Especially in harsh local areas, high water vapor partial pressure environments can significantly alter the corrosion behavior of SiC / SiC composites. Existing research mainly focuses on oxidation kinetics and macroscopic mechanical properties in air or moderately humid oxygen environments, while lacking systematic experimental setups and quantitative testing methods for interfacial shear strength in extreme humid oxygen environments.

[0004] The existing technology has at least the following shortcomings:

[0005] Firstly, the atmosphere ratio and flow control of the water-oxygen corrosion test system are unstable, making it difficult to stably reproduce the high water vapor partial pressure condition.

[0006] Secondly, the way the samples are supported in the furnace often results in a large contact area, which can easily affect the uniformity of local corrosion.

[0007] Third, corrosion testing and interfacial mechanical property characterization are usually conducted separately, lacking an integrated technical approach from corrosion environment construction to quantitative evaluation of interfacial shear strength;

[0008] Fourth, there are insufficient methods for quantifying the bonding state of the fiber / matrix interface after corrosion, making it difficult to accurately identify strong bonding or interface degradation.

[0009] Therefore, a water-oxygen corrosion system for SiC / SiC composite materials is proposed, and a corresponding interfacial shear strength testing method is established. This is of great engineering significance for reproducing high-temperature and humid oxygen conditions in the laboratory, studying the evolution law of material interfaces, and quantitatively evaluating the impact of corrosion on interfacial properties. Summary of the Invention

[0010] The purpose of this invention is to provide a water-oxygen corrosion system for SiC / SiC composite materials and a method for testing interfacial shear strength, so as to solve the problems of unstable water-oxygen corrosion environment control, unreasonable sample support, and difficulty in quantitatively testing the interfacial bonding state after corrosion in the prior art.

[0011] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0012] A SiC / SiC composite water-oxygen corrosion system, comprising:

[0013] Gas supply unit for providing oxygen and / or inert carrier gas;

[0014] The humidification unit is used to generate water vapor;

[0015] The gas supply unit and the humidification unit are respectively connected to the inlet of the gas mixing unit;

[0016] The gas mixing unit is used to mix water vapor and oxygen in a set ratio before introducing them into the high-temperature corrosion furnace.

[0017] A flow control unit is disposed between the gas supply unit and the gas mixing unit and / or between the humidification unit and the gas mixing unit, for maintaining the stability of the flow rate of each gas;

[0018] A high-temperature corrosion furnace, the inlet of which is connected to the outlet of the gas mixing unit, and an internal sample corrosion zone is provided;

[0019] The sample support unit is located inside the high-temperature corrosion furnace and is used to support the SiC / SiC composite material sample in a rim support manner, and to minimize the contact area between the sample and the sample support unit.

[0020] The exhaust gas discharge unit is connected to the outlet of the high-temperature corrosion furnace and is used to discharge the exhaust gas inside the high-temperature corrosion furnace.

[0021] The system also includes a control and monitoring unit connected to at least one of the gas supply unit, humidification unit, gas mixing unit, flow control unit, high-temperature corrosion furnace, and exhaust gas discharge unit, for controlling and recording corrosion temperature, corrosion time, mixed atmosphere ratio, and total flow rate.

[0022] To optimize the above technical solution, the specific measures also include:

[0023] The sample support unit is a corundum clamp, and the SiC / SiC composite material sample is placed on the corundum clamp through its edges.

[0024] The ratio of water vapor partial pressure to oxygen partial pressure in the mixed atmosphere output by the mixing unit is P(H2O):P(O2)=88:12.

[0025] The high-temperature corrosion furnace is a tubular furnace, and the corrosion temperature controlled by the control and monitoring unit is 850℃ and / or 1350℃, and the corrosion time is 50h, 200h and / or 500h.

[0026] The method for testing the interfacial shear strength of SiC / SiC composite materials, using the aforementioned SiC / SiC composite material water-oxygen corrosion system, includes the following steps:

[0027] Step 1: Clean and dry the SiC / SiC composite material sample;

[0028] Step 2: Place the pretreated sample in the SiC / SiC composite water-oxygen corrosion system and perform corrosion treatment at the preset water-oxygen ratio, corrosion temperature and corrosion time.

[0029] Step 3: Prepare a cross-section of the corroded sample to obtain a flat surface suitable for micro-area mechanical testing;

[0030] Step 4: Use a nanoindentation device to push in a single fiber on the test section and record the load-displacement response curve during the loading process;

[0031] Step 5: Determine the initial debonding critical load of the interface based on the inflection point where the load-displacement curve transitions from the linear segment to the nonlinear deflection.

[0032] Step 6: Based on the initial debonding critical load at the interface, combined with the fiber radius and fiber elastic modulus, calculate the interface shear strength;

[0033] Step 7: Compare the interfacial shear strength under different corrosion conditions and evaluate the effect of water-oxygen corrosion on the interfacial bonding state of SiC / SiC composite materials.

[0034] The specific steps of step one are as follows: Select the SiC / SiC composite material sample to be tested, place it in anhydrous ethanol for ultrasonic cleaning for 15 minutes to fully remove residual particles and contaminants from the sample surface and pores; after cleaning, place the sample in an oven for drying until there is no residual liquid on the sample surface.

[0035] The specific steps of step three are as follows: embed the corroded sample in epoxy resin, select a section perpendicular to the weft direction of the composite material as the test section, and perform rough grinding, fine grinding and polishing treatment in sequence.

[0036] In step four, a flat-headed pressure head with a diameter of 10 μm is used to apply a normal load to a single fiber.

[0037] In step six, the Shear-lag model is used to calculate the interfacial shear strength. The calculation formula is:

[0038]

[0039] In the formula: It is the critical load value for interfacial debonding. The fiber radius; The parameters related to the elastic potential energy of the fiber and matrix and the fiber volume fraction are expressed as:

[0040]

[0041] In the formula: This represents the slope of the linear segment of the load-displacement curve. Given the fiber's elastic modulus, the final interfacial shear strength is:

[0042] .

[0043] After step two and before step three, the process also includes weighing the corroded sample and calculating the rate of change of mass.

[0044] The present invention has the following beneficial effects:

[0045] First, this invention constructs a system suitable for high-temperature extreme humid oxygen corrosion testing of SiC / SiC composite materials, which can stably control the ratio of water vapor to oxygen, corrosion temperature and total flow rate, and improve the repeatability of the test environment.

[0046] Secondly, the present invention uses a corundum fixture and edge support method, which effectively reduces the contact influence between the sample and the bearing fixture and improves the uniformity of corrosion exposure.

[0047] Third, this invention establishes an integrated technical approach from high-temperature water-oxygen corrosion to quantitative characterization of interfacial shear strength, which can directly identify changes in interfacial bonding state under different corrosion conditions. Corresponding test results have shown significant differences in interfacial shear strength at 850℃ and 1350℃.

[0048] Fourth, the present invention uses a nano-indentation fiber pushing method to test the interfacial shear strength, which has the advantages of micro-area quantitative analysis, high sensitivity, and applicability to local interface evaluation after corrosion. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the water-oxygen corrosion system of the SiC / SiC composite material of the present invention.

[0050] Figure 2 This is a schematic diagram of the sample support unit structure of the present invention.

[0051] Figure 3 This is a flowchart of the interface shear strength testing method of the present invention.

[0052] Figure 4 This is a schematic diagram of the fiber insertion test in this invention.

[0053] Figure 5 This is a schematic diagram of a typical load-displacement curve in this invention.

[0054] Figure 6 This is the load-displacement curve of the interfacial shear strength test in this invention.

[0055] List of reference numerals in the attached diagram: 1-Gas supply unit, 2-Humidification unit, 3-Gas mixing unit, 4-Flow control unit, 5-High temperature corrosion furnace, 6-Sample bearing unit, 7-Tail gas discharge unit, 8-Control and monitoring unit. Detailed Implementation

[0056] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. For those skilled in the art, equivalent substitutions, simple modifications, improvements or combinations made to the technical solutions of the present invention without departing from the concept and essence of the present invention should all fall within the scope of protection of the present invention.

[0057] It should be noted that in the description of this invention, terms such as "upper," "lower," "inner," "outer," "front," and "rear," indicating or implying that the device or component must have a specific orientation, or be constructed and operated in a specific orientation, are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. The same or similar reference numerals in the accompanying drawings represent the same or similar structural units or components having the same or similar functions.

[0058] like Figure 1 As shown, this invention provides a water-oxygen corrosion system for SiC / SiC composite materials. The system includes an air supply unit 1, a humidification unit 2, an air mixing unit 3, a flow control unit 4, a high-temperature corrosion furnace 5, a sample carrying unit 6, an exhaust gas discharge unit 7, and a control and monitoring unit 8. These units function in concert to form an environmental simulation and testing platform suitable for high-temperature water-oxygen corrosion testing of SiC / SiC composite materials.

[0059] The gas supply unit 1 is used to stably supply oxygen and / or inert carrier gas to the system. The inert carrier gas is preferably one or more of argon and nitrogen, and its function is twofold: firstly, to assist in regulating the total flow rate and atmosphere composition entering the system; and secondly, to purge the system's gas path before and after the test to reduce the impact of residual environmental gases on the repeatability and reliability of the test. Preferably, the gas supply unit 1 may include a high-purity gas source, a pressure reducing valve, a pressure stabilizing device, and a gas path interface structure to ensure the purity and stability of the gas entering the system.

[0060] The humidification unit 2 is used to stably convert liquid water into water vapor and transport the generated water vapor to the mixing unit 3. Preferably, the humidification unit 2 can adopt a structure that can stably supply water vapor, such as isothermal evaporation, bubbling evaporation, carrier gas-carried evaporation, or other structures. More preferably, the humidification unit 2 is equipped with a temperature regulation module to control the evaporation rate of liquid water, thereby improving the stability of water vapor output. For high-temperature corrosion environment simulation, the stability of water vapor partial pressure directly affects the surface oxidation, interfacial phase change, and internal damage evolution behavior of SiC / SiC composite materials. Therefore, the humidification unit 2 is one of the key components in this invention to ensure the accuracy of experimental boundary conditions.

[0061] The gas mixing unit 3 is connected to the gas supply unit 1 and the humidification unit 2. Its function is to fully mix the oxygen and / or inert carrier gas from the gas supply unit 1 with the water vapor from the humidification unit 2 in a predetermined ratio to form a high-temperature water-oxygen mixed atmosphere that meets the requirements of the target corrosion environment, and then introduce this mixed atmosphere into the high-temperature corrosion furnace 5. Preferably, the gas mixing unit 3 can be made of a gas mixing cavity or gas mixing pipeline made of high-temperature and corrosion-resistant materials, and a mixing buffer volume can be set to improve the uniformity and stability of each component gas. Through this gas mixing unit 3, the extreme humid oxygen environment can be accurately constructed, thereby more realistically simulating the high-temperature-water vapor-oxygen coupling environment faced by SiC / SiC composite materials under actual hot-end service conditions.

[0062] The flow control unit 4 is used to independently adjust and control the flow rate of each gas entering the high-temperature corrosion furnace 5 in real time, so as to ensure that the mixed atmosphere ratio and total flow rate remain stable during the corrosion test. Preferably, the flow control unit 4 can be a mass flow controller to precisely adjust the flow rate. By independently controlling the flow rates of oxygen, water vapor and inert carrier gas, different water-oxygen partial pressure conditions can be constructed within a wide parameter range, and the repeatability and comparability between different batches of tests can be improved.

[0063] The high-temperature corrosion furnace 5 provides a controlled high-temperature corrosion environment for the sample. Preferably, the high-temperature corrosion furnace 5 is a tube furnace. It has an internal sample corrosion zone to accommodate the sample support unit 6 and the sample body. The high-temperature corrosion furnace 5 is connected to a control and monitoring unit 8, which can automatically control the heating, holding, and cooling processes according to a preset program. The high-temperature corrosion furnace 5 allows the sample to undergo complex environmental processes such as oxidation, hydrolysis, volatilization, and interfacial structure reconstruction under a specific temperature field and atmosphere composition, providing the necessary environmental conditions for subsequent interfacial shear strength testing.

[0064] The sample-bearing unit 6 is disposed inside the high-temperature corrosion furnace 5 and is used to bear the SiC / SiC composite material sample to be tested. Optionally, in one embodiment of the present invention, as shown... Figure 2 As shown, the sample support unit 6 is a corundum fixture. The sample to be tested is placed on the corundum fixture with edge support, thereby minimizing the actual contact area between the sample and the fixture. Compared with the traditional surface contact support method, this low-contact support form can effectively reduce the interference of the fixture on local airflow distribution, local temperature field and local corrosion behavior, reduce the risk of local non-uniform corrosion caused by support contact, and improve the environmental consistency of the exposed surface of the sample and the representativeness of the test results. Furthermore, corundum material itself has good high temperature resistance, chemical stability and low reactivity. It is not prone to adverse reactions with SiC / SiC composite materials in high temperature water and oxygen environments, so it is suitable as a support component in corrosion tests.

[0065] The exhaust gas discharge unit 7 is used to discharge the exhaust gas after passing through the high-temperature corrosion furnace 5 during the corrosion test, so as to maintain the continuous renewal of the atmosphere inside the furnace and ensure the safe operation of the system. Preferably, the exhaust gas discharge unit 7 can be connected to an exhaust gas cooling, absorption, purification or emission device to perform necessary treatment on the discharged high-temperature humid oxygen exhaust gas.

[0066] The control and monitoring unit 8 is used to set, regulate, and monitor the system operating parameters in real time. Specifically, the control and monitoring unit 8 can be used to set the corrosion temperature, corrosion time, atmosphere composition ratio, and total flow rate, and can record these parameters in real time. Preferably, the control and monitoring unit 8 includes a temperature controller, a time controller, a flow display module, and an atmosphere parameter recording module. Through the control and monitoring unit 8, the entire corrosion test process can be programmed for control, improving the accuracy and reproducibility of the test conditions.

[0067] In a preferred embodiment of the present invention, the gas mixing unit 3 adjusts the corrosive atmosphere to...

[0068] The ratio of P(H₂O):P(O₂) was 88:12, and the total flow rate was kept constant. The control and monitoring unit 8 was set to corrosion temperatures of 850℃ and 1350℃, and corrosion times of 50h, 200h, and 500h, respectively. This parameter combination can characterize the interfacial evolution behavior of SiC / SiC composite materials in extreme humid oxygen environments under medium and high temperature conditions, and can be used to establish a comparative relationship between the effects of different environmental parameters on interfacial shear strength.

[0069] like Figure 3 As shown, a method for testing the interfacial shear strength of SiC / SiC composite materials using the above system includes the following steps:

[0070] Step 1: Sample pretreatment;

[0071] Step 2: Water-oxygen corrosion treatment;

[0072] Step 3: Preparation of the test section;

[0073] Step 4: Fiber insertion test;

[0074] Step 5: Determine the initial debonding critical load at the interface;

[0075] Step 6: Calculation of interfacial shear strength;

[0076] Step 7: Analysis and evaluation of test results.

[0077] Optionally, in one embodiment of the present invention, step one includes the following steps:

[0078] The SiC / SiC composite material samples were ultrasonically cleaned in anhydrous ethanol for 15 minutes to remove dust, cutting residue, oil, and adhering impurities from the pores. After cleaning, the samples were dried in an oven until no visible liquid residue remained on the surface and the samples reached a stable state. This pretreatment step effectively improves the uniformity of the sample surface condition and reduces the impact of surface contaminants on corrosion uniformity, the accuracy of mass change measurement, and subsequent micro-area mechanical testing results.

[0079] Optionally, in one embodiment of the present invention, step two includes the following steps:

[0080] The pretreated sample is placed on the sample support unit 6 and then inserted into the high-temperature corrosion furnace 5 along with the fixture. Subsequently, a water-oxygen mixed atmosphere is continuously introduced into the high-temperature corrosion furnace 5 through the gas supply unit 1, humidification unit 2, gas mixing unit 3, and flow control unit 4 to ensure that the furnace environment meets the set water-oxygen partial pressure ratio conditions. Preferably, the corrosion atmosphere satisfies P(H2O):P(O2) = 88:12, the corrosion temperature is set to 850℃ and 1350℃, and the corrosion time is set to 50h, 200h, and 500h. After corrosion, the sample is removed after cooling to room temperature with the furnace.

[0081] Through this step, the sample undergoes surface oxidation, interfacial phase oxidation / hydrolysis, oxidation product migration, and internal pore structure evolution in a controlled high-temperature and humid oxygen environment, thereby changing the interfacial bonding state and providing environmental preconditions for subsequent interfacial shear strength testing.

[0082] Optionally, in one embodiment of the present invention, the following steps are included after step two and before step three:

[0083] The corroded samples were weighed, and the rate of change of mass was calculated based on the initial mass and the post-corrosion mass to characterize the macroscopic mass evolution behavior of the material during water-oxygen corrosion. Preferably, for samples with corrosion durations of 200 h and 500 h, an interrupted weighing method can be used, where samples are taken out and weighed at set time intervals to help determine the competition mechanism between weight gain and weight loss during the corrosion process. Through the analysis of the rate of change of mass, the combined effects of SiC oxidation product formation, interfacial phase volatilization loss, and corrosion product exfoliation on the material can be reflected from a macroscopic perspective, providing auxiliary basis for the subsequent interpretation of interfacial property changes.

[0084] Optionally, in one embodiment of the present invention, step three includes the following steps:

[0085] The etched sample is embedded in epoxy resin to improve the stability of small-sized samples during subsequent machining. Preferably, a section perpendicular to the weft direction of the composite material is selected for grinding and polishing to fully expose the fibers, matrix, and interface areas, resulting in a smooth test section free of obvious scratches and chipping. The grinding and polishing can employ a progressively finer process to meet the surface quality requirements of nanoindentation testing. Figure 4 As shown, a single fiber was selected as the subsequent loading target on the prepared test section.

[0086] This step provides a test area with well-defined geometric boundaries and stable surface conditions for fiber push-in testing, thereby improving the reliability of interface mechanical parameter inversion.

[0087] Optionally, in one embodiment of the present invention, steps four and five include the following steps:

[0088] A nanoindentation device was used to perform an indentation test on a single target fiber on the test section. - A flat-headed indenter with a diameter of 10 μm was used to apply a normal load to the fiber, and the load-displacement curve was recorded in real time.

[0089] like Figure 5 As shown, the standard load-displacement curve for fiber insertion typically exhibits a typical "S" shape and can be divided into three main stages:

[0090] The first stage is the initial contact stage. In this stage, the flat-head indenter gradually contacts the fiber surface. As the contact area is established, the load increases slowly, and the displacement response is relatively small. This stage mainly reflects the process of establishing the contact state between the indenter and the fiber.

[0091] The second stage is the near-linear elastic response stage. After the indenter and fiber form a stable contact, the fiber undergoes a response dominated by elastic deformation under the action of the indenter. Significant debonding has not yet occurred at the interface, and the load-displacement curve shows approximately linear growth. This stage reflects the stress characteristics when the fiber / matrix interface still possesses a relatively intact load-transfer capacity. The slope of the linear segment can serve as one of the important input parameters for subsequent solutions to the interface mechanical parameters.

[0092] The third stage is the interface debonding induction stage. As the load continues to increase, local shear stress at the fiber / matrix interface gradually accumulates. When the local stress at the interface reaches its debonding resistance limit, initial debonding begins, and the load-displacement curve gradually deviates from its original linear relationship, exhibiting obvious nonlinear characteristics. The load corresponding to the inflection point from the linear segment to the nonlinear deflection is defined as the critical load for initial interface debonding. This critical load is the core experimental parameter characterizing the interface's debonding resistance and can be directly used for subsequent calculations of the interface shear strength.

[0093] Optionally, in one embodiment of the present invention, step six includes the following steps:

[0094] The interfacial shear strength of the composite material can be calculated using the Shear-lag model.

[0095]

[0096] In the formula: It is the critical load value for interfacial debonding; The parameters related to the elastic potential energy of the fiber and matrix and the fiber volume fraction can be expressed as:

[0097]

[0098] In the formula: This represents the slope of the linear segment of the load-displacement curve. The final composite interfacial shear strength is:

[0099]

[0100] Optionally, in one embodiment of the present invention, step seven includes the following steps:

[0101] like Figure 6 As shown, the fiber push-in load-displacement curves of SiC / SiC composites after corrosion in air and humid oxygen environments at 850℃ and 1350℃ are presented. To further characterize the changes in the interfacial bonding state, the interfacial shear strength (ISS) under different corrosion conditions was measured by nanoindentation fiber push-in test, and the results are listed in Table 1.

[0102] Table 1 Micromechanical parameters of SiCf / BN / SiC composite materials

[0103] Test number <![CDATA[R f / μm]]> <![CDATA[E f / GPa]]> τ / MPa #1 (Air temperature 850℃) 6.49 267.37 112 #2 (Air temperature 1350℃) 5.74 271.91 101 #3 (Water Oxygen 850℃ 50h) 5.65 313.42 124 #4 (Water Oxygen 850℃ 200h) 6.59 295.05 127 #5 (Water Oxygen 850℃ 500h) 6.19 322.93 132 #6 (Water Oxygen 1350℃ 50h) 6.05 335.31 158 #7 (Water Oxygen 1350℃ 200h) 5.79 330.15 167 #8 (Water Oxygen 1350℃ 500h) 6.13 338.66 179

[0104] In air, the interfacial shear strengths were 112 MPa (850℃) and 101 MPa (1350℃). Under humid oxygen conditions, the ISS of the sample at 850℃ increased slowly from 124 MPa to 132 MPa with prolonged corrosion time, showing a relatively limited change; however, at 1350℃, the ISS increased significantly from 158 MPa to 179 MPa.

[0105] This result indicates that the interfacial bonding state undergoes more significant changes under high-temperature and humid oxygen conditions. In particular, at 1350℃, the continuous increase in interfacial shear strength is consistent with the aforementioned changes in the chemical composition of the interfacial phase and the reconstruction of the internal structure, and the interfacial region no longer maintains its original weak bonding state after long-term corrosion.

[0106] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A water-oxygen corrosion system for SiC / SiC composite materials, characterized in that, include: Gas supply unit (1) for providing oxygen and / or inert carrier gas; Humidification unit (2) is used to generate water vapor; The gas supply unit (1) and the humidification unit (2) are respectively connected to the inlet of the gas mixing unit (3); The gas mixing unit (3) is used to mix water vapor and oxygen in a set ratio and then pass them into the high-temperature corrosion furnace (5). A flow control unit (4) is disposed between the gas supply unit (1) and the gas mixing unit (3) and / or between the humidification unit (2) and the gas mixing unit (3) to maintain the stability of each gas flow rate; The high-temperature corrosion furnace (5) has its inlet connected to the outlet of the gas mixing unit (3) and has a sample corrosion zone inside. The sample support unit (6) is located inside the high-temperature corrosion furnace (5) and is used to support the SiC / SiC composite material sample in a rim support manner, and to minimize the contact area between the sample and the sample support unit (6). The exhaust gas discharge unit (7) is connected to the outlet of the high-temperature corrosion furnace (5) and is used to discharge the exhaust gas inside the high-temperature corrosion furnace (5); The control and monitoring unit (8) is connected to at least one of the gas supply unit (1), humidification unit (2), gas mixing unit (3), flow control unit (4), high-temperature corrosion furnace (5) and exhaust gas discharge unit (7) for controlling and recording corrosion temperature, corrosion time, mixed atmosphere ratio and total flow.

2. The SiC / SiC composite water-oxygen corrosion system according to claim 1, characterized in that, The sample support unit (6) is a corundum clamp, and the SiC / SiC composite material sample is placed on the corundum clamp through its edges.

3. The SiC / SiC composite water-oxygen corrosion system according to claim 1, characterized in that, The ratio of water vapor partial pressure to oxygen partial pressure in the mixed atmosphere output by the mixing unit (3) is P(H2O):P(O2)=88:

12.

4. The SiC / SiC composite water-oxygen corrosion system according to claim 1, characterized in that, The high-temperature corrosion furnace (5) is a tubular furnace, and the corrosion temperature controlled by the control and monitoring unit (8) is 850℃ and / or 1350℃, and the corrosion time is 50h, 200h and / or 500h.

5. A method for testing the interfacial shear strength of SiC / SiC composite materials, characterized in that, The SiC / SiC composite water-oxygen corrosion system as described in any one of claims 1-4 includes the following steps: Step 1: Clean and dry the SiC / SiC composite material sample; Step 2: Place the pretreated sample in the SiC / SiC composite water-oxygen corrosion system and perform corrosion treatment at the preset water-oxygen ratio, corrosion temperature and corrosion time. Step 3: Prepare a cross-section of the corroded sample to obtain a flat surface suitable for micro-area mechanical testing; Step 4: Use a nanoindentation device to push in a single fiber on the test section and record the load-displacement response curve during the loading process; Step 5: Determine the initial debonding critical load of the interface based on the inflection point in the load-displacement curve where the linear segment transitions to nonlinear deflection. Step 6: Based on the initial debonding critical load of the interface, combined with the fiber radius and fiber elastic modulus, calculate the interface shear strength; Step 7: Compare the interfacial shear strength under different corrosion conditions and evaluate the effect of water-oxygen corrosion on the interfacial bonding state of SiC / SiC composite materials.

6. The method for testing the interfacial shear strength of SiC / SiC composite materials according to claim 5, characterized in that, The specific steps of step one are as follows: Select the SiC / SiC composite material sample to be tested, place it in anhydrous ethanol for ultrasonic cleaning for 15 minutes to fully remove residual particles and contaminants from the sample surface and pores; after cleaning, place the sample in an oven for drying until there is no residual liquid on the sample surface.

7. The method for testing the interfacial shear strength of SiC / SiC composite materials according to claim 5, characterized in that, The specific steps of step three are as follows: embed the corroded sample in epoxy resin, select a section perpendicular to the weft direction of the composite material as the test section, and perform coarse grinding, fine grinding and polishing treatment in sequence.

8. The method for testing the interfacial shear strength of SiC / SiC composite materials according to claim 5, characterized in that, In step four, a flat-headed pressure head with a diameter of 10 μm is used to apply a normal load to a single fiber.

9. The method for testing the interfacial shear strength of SiC / SiC composite materials according to claim 5, characterized in that, In step six, the Shear-lag model is used to calculate the interfacial shear strength. The calculation formula is: ； In the formula: It is the critical load value for interfacial debonding. The fiber radius; The parameters related to the elastic potential energy of the fiber and matrix and the fiber volume fraction are expressed as: ； In the formula: This represents the slope of the linear segment of the load-displacement curve. Given the fiber's elastic modulus, the final interfacial shear strength is: 。 10. The method for testing the interfacial shear strength of SiC / SiC composite materials according to claim 5, characterized in that, The steps after step two and before step three include weighing the corroded sample and calculating the rate of mass change.

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