Dimensional stability detection method of ceramic matrix composite connection transition piece

Abstract

The invention discloses a dimensional stability detection method for a ceramic matrix composite connection transition piece, which comprises the following steps: preparing a sample to be detected, and measuring and recording the initial size of the sample; drying the sample; in an environment of 20 DEG C, carrying out heat preservation on the dried sample for 20-25 minutes; carrying out hot-cold circulation treatment on the dried sample, and standing the sample in an environment of 20 DEG C after hot-cold circulation; measuring the size of the sample after standing in an environment of 20 DEG C, and calculating the size change rate of the sample according to the initial size of the sample; performing hot-cold circulation treatment on the sample for multiple times, and recording the size change rate of the sample after each time of hot-cold circulation treatment; calculating an average change rate according to the multiple dimensional change rates of the sample, and judging whether the stability of the sample meets the requirement or not according to the average change rate. According to the method, a cold and hot circulation method is adopted, a test sample is repeatedly placed at high temperature and low temperature, the size change of the test sample is measured after drying, and it is determined that the size change of the sample is in a controllable state after cold and hot circulation.

Description

Technical Field

[0001] The invention relates to the field of detection technology, and in particular to a method for detecting the dimensional stability of a ceramic-based composite material connecting transition piece. Background Art

[0002] The connection transition piece of ceramic matrix composite material has a round opening at one end and a square opening at the other end, and a hollow structure in the middle, which is used to connect two parts of different shapes. It is commonly known as a round-to-square structural piece. The round-to-square structural piece has a special position, and the requirements for its size are relatively complex. The working environment is complex and changeable. The meshing angle of the round-to-square structure needs to be kept fixed, but ceramic matrix composite materials inevitably have the performance characteristics of thermal expansion and contraction. Therefore, the detection of the dimensional stability of the connection transition piece is inevitable, but there is currently no more accurate method to detect the dimensional changes of the connection transition piece in a hot and cold alternating environment. Summary of the invention

[0003] The purpose of the present invention is to provide a method for detecting the dimensional stability of a ceramic-based composite material connecting transition piece, which adopts a hot and cold cycle method, repeatedly placing a test sample in high and low temperatures, measuring its dimensional change after drying, and determining whether the dimensional change of the sample after the hot and cold cycle is in a controllable state.

[0004] In order to solve the above technical problems, the present invention adopts the following solutions:

[0005] A method for detecting the dimensional stability of a ceramic matrix composite material connecting transition piece comprises the following steps:

[0006] S1: Prepare the sample to be tested, measure the initial size of the sample and record it;

[0007] S2: Dry the sample;

[0008] S3: Keep the dried sample warm for 20-25 minutes at 20℃.

[0009] S4: subject the dried samples to a hot and cold cycle treatment, and after the hot and cold cycle, place the samples in a 20°C environment for 20-25 minutes;

[0010] S5: Measure the size of the sample after it is left to stand in an environment of 20°C, and calculate the size change rate of the sample based on the initial size of the sample;

[0011] S6: Perform heat and cold cycle treatment on the sample multiple times, and record the dimensional change rate of the sample after each heat and cold cycle treatment and after the sample is left to stand in an environment at 20°C;

[0012] S7: Calculate the average change rate based on the multiple dimensional change rates of the sample, and determine whether the stability of the sample meets the requirements based on the average change rate.

[0013] In this method, the sample to be tested is prepared, and the initial size of the sample is measured and recorded. The purpose is to obtain the initial state data of the sample and provide a benchmark for the subsequent calculation of the size change rate. The purpose of drying the sample is to remove moisture or other volatile substances in the sample to ensure the accuracy of subsequent tests. In a 20°C environment, the dried sample is kept warm for 20-25 minutes to allow the sample to reach temperature equilibrium and eliminate the influence of temperature on subsequent tests. The dried sample is subjected to a hot and cold cycle treatment. After the hot and cold cycle, the sample is placed in a 20°C environment to stand still. The hot and cold cycle simulates extreme temperature conditions and observes the size changes of the sample under these conditions. The size of the sample after standing still in a 20°C environment is measured, and the size change rate of the sample is calculated based on the initial size of the sample. The purpose is to quantify the size change of the sample after the hot and cold cycle, and provide a basis for evaluating the stability of the sample. The sample is subjected to hot and cold cycle treatment multiple times, and the size change rate of the sample after each hot and cold cycle treatment and standing still in a 20°C environment is recorded. Through multiple tests, the stability of the sample size change is observed. Finally, the average change rate is calculated based on the multiple dimensional change rates of the sample, and the stability of the sample is determined based on the average change rate. The overall stability of the sample is evaluated by combining multiple test results. This method mainly uses the hot and cold cycle method, which repeatedly places the test sample in high and low temperatures, measures its dimensional change after drying, and determines that the dimensional change of the component after the hot and cold cycle is in a controllable state, providing a reference method for the dimensional stability detection of the connecting transition piece. The dimensional stability test can provide reference opinions on the design of the size and shape of the special-shaped ceramic matrix composite structural parts.

[0014] Optionally, in S4, the hot-cold cycle treatment needs to be carried out in the order of heating first and then cooling.

[0015] Optionally, the dried sample is first heated to 1300°C and kept at 1300°C for 10-15 minutes; then the heated sample is cooled to 15°C and kept at 15°C for 20-25 minutes.

[0016] Optionally, before the hot and cold cycle treatment, an inert gas needs to be introduced into the environment where the sample is located for protection.

[0017] Optionally, the appearance and material of the sample are consistent with those of the finished product, the size of the sample is a size proportionally reduced from the size of the finished product, and the initial length of the sample is set to 30-40 mm.

[0018] Optionally, the number of hot and cold cycles is not less than 15 times.

[0019] Optionally, the rate of change of size of the sample is the rate of change of length of the sample.

[0020] Optionally, after each heating and cooling cycle, the dimensional change rate of the sample is calculated based on the initial dimensions of the sample. First, the sample is horizontally placed on the support block in the heating container. There are baffles located inside the heating container on both sides of the sample, and there is a gap between the baffles and the ends of the sample that allows the sample to expand and contract. After the sample undergoes heating and cooling cycles, a photosensitive plate with a grid surface is placed on the lower side of the gap, with the grid surface facing up. A laser beam with a width greater than the width of the gap is emitted towards the gap position. The beam is centered on the width center point of the initial gap and vertically passes through the gap and irradiates on the photosensitive plate. The photosensitive plate receives the beam passing through the gap and generates an electrical signal that is transmitted to the controller. The controller calculates the initial width value of the gap, and then combines it with the grid surface to calculate the changed width value after heating and cooling cycles. Finally, the length change rate of the sample is calculated by combining the initial width value and the changed width value.

[0021] Optionally, in S2, the sample is placed in the dryer for no less than 24 hours, and the number of samples is no less than 3.

[0022] Optionally, among the multiple dimensional change rates of the sample, as long as one exceeds the threshold, then the sample is judged as unqualified.

[0023] The beneficial effects of the present invention are as follows:

[0024] In the present invention, the main method used is the heating and cooling cycle method. The test piece sample is repeatedly placed in high temperature and low temperature, and its dimensional change is measured after drying to determine that the dimensional change of the component is in a controllable state after heating and cooling cycles, providing a reference method for the dimensional stability detection of the connecting transition piece. The special-shaped ceramic matrix composite material structural member can provide reference opinions for the design of dimensions and shapes through dimensional stability inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic flow chart of the present invention;

[0026] Figure 2 is a structural diagram when the laser beam measures the change in the gap width value.

[0027] Reference numerals: 1 - heating container, 2 - baffle, 3 - photosensitive plate, 4 - support block, 5 - laser emission device, 6 - laser beam, 7 - sample. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following will further describe the present invention in detail in conjunction with embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0029] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inside", "outside", "front", "back", "top", "bottom" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0030] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed", "opened", "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Example

[0032] A method for detecting the dimensional stability of a ceramic matrix composite material connecting transition piece comprises the following steps:

[0033] S1: prepare the sample 7 to be tested, measure the initial size of the sample 7 and record it;

[0034] S2: drying the sample 7;

[0035] S3: Keep the dried sample 7 warm for 20-25 minutes in a 20°C environment;

[0036] S4: subjecting the dried sample 7 to a heat-cold cycle treatment, and placing the sample 7 in a 20°C environment for 20-25 minutes after the heat-cold cycle;

[0037] S5: measuring the size of the sample 7 after it is left to stand in an environment of 20° C., and calculating the size change rate of the sample 7 according to the initial size of the sample 7;

[0038] S6: Perform a heat-cold cycle treatment on sample 7 for multiple times, and record the dimensional change rate of sample 7 after each heat-cold cycle treatment and after it is left at rest in an environment at 20°C;

[0039] S7: Calculate the average change rate based on the multiple dimensional change rates of sample 7, and determine whether the stability of sample 7 meets the requirements based on the average change rate.

[0040] In this embodiment, Figure 1As shown, prepare the sample 7 to be tested, measure and record the initial size of the sample 7, with the aim of obtaining the initial state data of the sample 7 and providing a benchmark for calculating the size change rate in the subsequent process. The purpose of drying the sample 7 is to remove moisture or other volatile substances in the sample 7 to ensure the accuracy of subsequent tests. In an environment of 20 °C, keep the dried sample 7 warm for 20 - 25 minutes to make the sample 7 reach temperature equilibrium and eliminate the influence of temperature on subsequent tests. In this embodiment, the heat preservation time for the sample 7 is 20 minutes. Conduct thermal cycling on the dried sample 7. After thermal cycling, place the sample 7 in an environment of 20 °C and let it stand. Simulate extreme temperature conditions through thermal cycling and observe the size change of the sample 7 under these conditions. Measure the size of the sample 7 after it stands in an environment of 20 °C, and calculate the size change rate of the sample 7 based on the initial size of the sample 7. The purpose is to quantify the size change of the sample 7 after thermal cycling and provide a basis for evaluating the stability of the sample 7. Conduct thermal cycling on the sample 7 multiple times, and record the size change rate of the sample 7 after each thermal cycling and after it stands in an environment of 20 °C. Through multiple tests, observe the stability of the size change of the sample 7. After standing, it is necessary to dry the water stains on the surface of the sample 7. Finally, calculate the average change rate based on the multiple size change rates of the sample 7, and determine whether the stability of the sample 7 meets the requirements according to the average change rate. By comprehensively considering the results of multiple tests, evaluate the overall stability of the sample 7. This method mainly adopts the thermal cycling method, repeatedly place the test piece sample 7 in high temperature and low temperature, measure its size change after drying, and determine that the size change of the component is in a controllable state after thermal cycling, providing a reference method for the size stability detection of the connecting transition piece. The special-shaped ceramic matrix composite structure part can provide reference opinions for the design of size and shape through size stability inspection.

[0041] Further, in S4, the thermal cycling treatment needs to be carried out in the order of heating first and then cooling.

[0042] Further, first heat-treat the dried sample 7, heat it to 1300 °C, and keep it warm in an environment of 1300 °C for 10 - 15 minutes; then cool the heated sample 7, cool it to 15 °C, and keep it warm in an environment of 15 °C for 20 - 25 minutes.

[0043] Further, in S4, after the thermal cycling treatment, place the sample 7 in an environment of 20 °C and let it stand for 20 - 25 minutes. The standing time is 20 minutes.

[0044] Further, before the thermal cycling treatment, it is necessary to introduce an inert gas into the environment where the sample 7 is located for protection.

[0045] Furthermore, the appearance and material of the sample 7 are consistent with the finished product, the size of the sample 7 is the size of the finished product reduced in proportion, and the initial length of the sample 7 is set to 30-40 mm. In this embodiment, the initial length of the sample 7 is 30 mm.

[0046] Furthermore, the number of hot and cold cycles is not less than 15 times.

[0047] Furthermore, the dimensional change rate of sample 7 is the change rate of the length of sample 7.

[0048] Furthermore, after each hot and cold cycle, the size change rate of sample 7 is calculated based on the initial size of sample 7. First, sample 7 is placed horizontally on the support block 4 in the heating container 1. Baffles 2 located in the heating container 1 are provided on both sides of sample 7. There is a gap between the baffle 2 and the end of sample 7 to allow sample 7 to expand and contract. After the hot and cold cycle of sample 7, a photosensitive plate 3 with a grid surface is placed on the lower side of the gap with the grid surface facing upward. A laser beam 6 with a width greater than the gap width is emitted to the gap position. The beam uses the center point of the initial gap width as a reference, and the beam passes vertically downward through the gap and irradiates the photosensitive plate 3. The photosensitive plate 3 receives the beam passing through the gap and generates an electrical signal to transmit to the controller. The controller calculates the initial width value of the gap. The controller then calculates the changed width value after the hot and cold cycle in combination with the grid surface. Finally, the length change rate of sample 7 is calculated based on the initial width value and the changed width value.

[0049] like Figure 2As shown, the specific measurement method is: two support blocks 4 are installed in the heating container 1, the top of the support block 4 is adapted to the size of the sample 7, and the two ends of the sample 7 exceed the support block 4, so that the sample 7 can be prevented from falling off the support block 4 after being shortened, and baffles 2 with a certain thickness are placed at both ends of the sample 7, the baffles 2 are fixed on the side wall of the heating container 1, and the baffles 2 on both sides are basically flush with the two ends of the sample 7, and a gap is left between the sample 7 and the baffles 2 for the sample 7 to expand and contract, and a photosensitive plate 3 is placed directly below the gap, and the length of the photosensitive plate 3 is greater than the width of the gap, and a laser emitting device 5 is arranged directly above the gap, which can emit a laser beam 6 with a certain width. It is an existing product, which emits a laser beam 6 vertically downward from the top of the gap with the center point of the gap width as the reference. The width of the beam is greater than the width of the gap. Specifically, the beam needs to be greater than the gap width of the baffle 2 after the maximum shrinkage of the sample 7. The photosensitive plate 3 has a grid surface. At the same time, the photosensitive plate 3 is electrically connected to the controller to realize signal transmission. The size data of the photosensitive plate 3 and the grid surface are stored in the controller. The controller is a computer, and the photosensitive plate 3 can be displayed in the controller in the form of a picture. After the light beam passes through the gap and hits the grid surface of the photosensitive plate 3, an electrical signal is generated and output to the controller. The photosensitive plate 3 graphic in the controller will display the specific size of the light beam hitting the grid surface. The length of the position area is the width of the gap. At this time, the controller can obtain the initial width value of the gap between the sample 7 and the baffle 2. At this time, the length of the sample 7 is the initial length. Then, the sample 7 is subjected to a hot and cold cycle. After the sample 7 has undergone a hot and cold cycle, when the temperature in the heating container 1 drops to 15°C, the photosensitive plate 3 is placed under the gap again, and the laser beam 6 passes through the gap vertically downward again. The gaps at both ends of the sample 7 must be passed by the beam, and the beam is projected onto the grid surface of the photosensitive plate 3 again. The controller obtains the change in the width value of the gap at both ends of the sample 7 again and compares it with the initial width value. If it becomes larger, it means that the sample 7 has become shorter. If it becomes If the width of the sample 7 is smaller, it means that the sample 7 has been stretched, and the value after the difference with the initial width value is the change in the length of the sample 7. For example, the initial width value is a=6mm, the initial width value is the sum of the gap widths at both ends of the sample 7, and the initial width values ​​at both ends are 3mm respectively. The sum of the width changes after the hot and cold cycle is b=4mm, ab=2mm, and the gap width value is reduced, indicating that the sample 7 has been stretched by 2mm, and the elongation change rate of the sample 7 is 4 / 6=66%. If the sum of the width changes after the hot and cold cycle is 9mm, ab=-3mm, and the gap width value is increased, indicating that the sample 7 has been shortened by 3mm, and the shortening change rate of the sample 7 is 3 / 6=50%, and this cycle is repeated. When the present method is used for measurement, the change in the width of the gap can be detected in real time without waiting, and the real-time change rate of the sample length can be obtained.

[0050] Furthermore, in S2, sample 7 is placed in the dryer for not less than 24 hours, and the number of samples 7 is not less than 3.

[0051] Furthermore, among the multiple dimensional change rates of the sample 7, if any one exceeds the threshold value even once, then the sample 7 is judged as unqualified.

[0052] Specifically, the requirements for preparing the sample 7 to be tested are as follows: the appearance and material of the sample 7 are consistent with the finished product, and the size of the sample 7 is the size of the finished product reduced in proportion. In this embodiment, the initial length of the sample 7 is set to 30mm (range 30-40mm). Measure the initial size of the sample 7 and record it. The requirements for drying the sample 7 are as follows: the sample 7 is placed in the dryer for not less than 24h, and the number of samples 7 is not less than 3. The purpose is to remove moisture or other volatile substances in the sample 7 to ensure the accuracy of subsequent tests. In a 20°C environment, the dried sample 7 is kept warm for 20 minutes to allow the sample 7 to reach temperature equilibrium and eliminate the influence of temperature on subsequent tests. Preparation operations before hot and cold cycle treatment: Inert gas is introduced into the environment where the sample 7 is located for protection to prevent the sample 7 from oxidizing or undergoing other chemical reactions during heating. The heating stage of the hot-cold cycle treatment: heat sample 7 to 1300°C and keep it at 1300°C for 10 minutes. The cooling stage: cool the heated sample 7 to 15°C and keep it at 15°C for 20 minutes. The number of hot-cold cycles is not less than 15 times. After each hot and cold cycle, sample 7 is placed in a 20°C environment and allowed to stand for 20 minutes. After each hot and cold cycle treatment, and after standing in a 20°C environment for 20 minutes, the size of sample 7 is measured again, and the size change rate of sample 7 (the change rate of sample 7 length) is calculated based on the initial size of sample 7. After each hot and cold cycle, the size change rate of sample 7 is calculated based on the initial size of sample 7. The length of sample 7 can also be directly measured. Taking the length of sample 7 as 30mm as an example, the length of sample 7 after the first hot and cold cycle is 31mm, then sample 7 becomes 1mm longer, and the length change rate = 1 / 30 = 3.3%; after the second hot and cold cycle, the length of sample 7 is 2mm, then sample 7 becomes 2mm longer, and the length change rate = 2 / 30 = 6.6%; after the third hot and cold cycle, the length of sample 7 is 29mm, then sample 7 becomes 1mm shorter, and the length change rate = 1 / 30 = 3.3%. Each time the length change rate of sample 7 is calculated, it is calculated based on the initial length of sample 7. Finally, the average change rate is calculated based on the multiple dimensional change rates of sample 7, and then the average change rate is compared with the preset threshold to determine whether the stability of sample 7 meets the requirements. As long as the dimensional change rate exceeds the threshold once, the sample 7 is judged to be unqualified. The threshold is 20%, that is, as long as the length change rate of sample 7 exceeds 20% after one hot and cold cycle, the sample 7 is unqualified. During the entire test process, the processing conditions of sample 7 (such as heating temperature, insulation time, cooling rate, etc.) should be kept consistent to eliminate the influence of test conditions on the results. The number of samples 7 should be sufficient to reflect the stability of the overall sample 7. The test results should be accurately recorded, and necessary statistical analysis should be performed to draw reliable conclusions.

[0053] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for detecting the dimensional stability of a ceramic matrix composite material connecting transition piece, characterized in that: The following steps are involved: S1: preparing a sample (7) to be tested, measuring and recording the initial size of the sample (7); S2: drying the sample (7); S3: keeping the dried sample (7) warm for 20-25 minutes at 20°C; S4: subjecting the dried sample (7) to a heat-cold cycle treatment, and placing the sample (7) in a 20° C. environment for 20-25 minutes after the heat-cold cycle; S5: measuring the size of the sample (7) after it has been left to stand in an environment at 20° C., and calculating the size change rate of the sample (7) based on the initial size of the sample (7); S6: performing a heat-cold cycle treatment on the sample (7) for multiple times, and recording the dimensional change rate of the sample (7) after each heat-cold cycle treatment and after the sample (7) is left to stand in an environment at 20° C.; S7: Calculate the average change rate based on the multiple dimensional change rates of the sample (7), and determine whether the stability of the sample (7) meets the requirements based on the average change rate.

2. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 1, characterized in that: In S4, the hot and cold cycle treatment needs to be carried out in the order of heating first and then cooling.

3. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 2, characterized in that: The heat-cold cycle treatment specifically involves first heating the dried sample (7) to 1300°C and keeping it at 1300°C for 10-15 minutes; then cooling the heated sample (7) to 15°C and keeping it at 15°C for 20-25 minutes.

4. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 2, characterized in that: Before the hot and cold cycle treatment, an inert gas needs to be introduced into the environment where the sample (7) is located for protection.

5. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 1, characterized in that: The appearance and material of the sample (7) are consistent with those of the finished product. The size of the sample (7) is proportionally reduced from the size of the finished product. The initial length of the sample (7) is set to 30-40 mm.

6. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 1, characterized in that: The number of hot and cold cycles is not less than 15 times.

7. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 1, characterized in that: The rate of change of the size of the sample (7) is the rate of change of the length of the sample (7).

8. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 1, characterized in that: After each hot and cold cycle, the size change rate of the sample (7) is calculated based on the initial size of the sample (7). First, the sample (7) is horizontally placed on a support block (4) in a heating container (1). Baffles (2) located in the heating container (1) are provided on both sides of the sample (7). A gap is provided between the baffles (2) and the ends of the sample (7) to allow the sample (7) to expand and contract. After the sample (7) is hot and cold cycled, a photosensitive plate (3) with a grid surface is placed under the gap, with the grid surface facing upward. A laser beam (6) having a width greater than the gap width is emitted to the gap position. The beam is based on the center point of the initial gap width. The beam passes through the gap vertically downward and irradiates the photosensitive plate (3). The photosensitive plate (3) receives the beam passing through the gap and generates an electrical signal to transmit to the controller. The controller calculates the initial width value of the gap. The controller then calculates the change width value after the hot and cold cycle in combination with the grid surface. Finally, the length change rate of the sample (7) is calculated based on the initial width value and the change width value.

9. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 1, characterized in that: In S2, the sample (7) is placed in the dryer for not less than 24 hours, and the number of samples (7) is not less than 3.

10. The method for detecting dimensional stability of a ceramic matrix composite material connecting transition piece according to claim 1, characterized in that: If any one of the multiple dimensional change rates of the sample (7) exceeds the threshold, the sample (7) is judged to be unqualified.

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