A method for improving and predicting the room temperature bending fatigue life of ceramic parts containing microcracks

Abstract

The application discloses a room temperature bending fatigue life improvement and prediction method of a ceramic piece containing microcracks, and belongs to the technical field of mechanical structure strength. The method comprises the following steps: collecting the spatial information of microcracks on an original ceramic piece, testing the power index and critical fatigue life of the original ceramic piece; processing the microcracks into circular holes according to the spatial information of the microcracks, performing a polishing and cleaning process on the circular holes, obtaining a processed ceramic piece, and completing room temperature bending fatigue life improvement; performing size measurement on the circular holes to obtain the radius and cross-sectional area of the circular holes, calculating the stress limit of the processed ceramic piece under the action of static load by using the radius and the cross-sectional area; drawing an S-N curve of the processed ceramic piece by using the stress limit, the power index and the critical fatigue life; and testing the maximum bending stress of the processed ceramic piece, taking the corresponding abscissa of the maximum bending stress on the S-N curve as the prediction result of the room temperature bending fatigue life.

Description

TECHNICAL FIELD

[0001] The application relates to a room-temperature bending fatigue life improvement and prediction method for ceramic parts containing microcracks, and belongs to the technical field of mechanical structure strength. BACKGROUND

[0002] Ceramics are well known for their light weight, high strength, high hardness and high wear resistance, and can be used to replace metals to manufacture bearings, connecting rods, valves, sealing rings and cutting tools, etc., but the intrinsic brittleness and low damage tolerance of ceramics lead to cracks caused by microcracks, especially in the use scenarios of bearings, connecting rods, cutting tools, etc. under cyclic bending load, random fatigue failure of ceramic parts caused by microcracks is extremely serious, on the one hand, it is easy to break at a lower stress level, and on the other hand, the fatigue life is also greatly attenuated.

[0003] At present, there is little research on the improvement method and prediction method of the room-temperature bending fatigue life of ceramic parts, and the improvement effect is poor, and the prediction accuracy is low. SUMMARY

[0004] The purpose of the present application is to provide a room-temperature bending fatigue life improvement and prediction method for ceramic parts containing microcracks, to solve the problems of poor improvement effect and low prediction accuracy of room-temperature bending fatigue life in the prior art.

[0005] In order to achieve the above purpose, the application is realized by adopting the following technical scheme:

[0006] The application provides a room-temperature bending fatigue life improvement and prediction method for ceramic parts containing microcracks, comprising:

[0007] Collecting the spatial information of microcracks on the original ceramic part, testing the power index and the critical fatigue life of the original ceramic part;

[0008] According to the spatial information of the microcracks, the microcracks are processed into circular holes, and the circular holes are polished and cleaned to obtain a processed ceramic part, and the room-temperature bending fatigue life improvement is completed;

[0009] The size of the circular hole is measured to obtain its radius and cross-sectional area, and the stress limit of the processed ceramic part under static load is calculated by using the radius and the cross-sectional area;

[0010] The stress limit, the power index and the critical fatigue life are used to draw an S-N curve of the processed ceramic part;

[0011] The maximum bending stress of the processed ceramic part is tested, and the corresponding abscissa of the maximum bending stress on the S-N curve is taken as the prediction result of the room-temperature bending fatigue life.

[0012] Further, the spatial information includes length, depth and position coordinate parameters, and is collected by a non-destructive testing procedure.

[0013] Further, the micro-crack is processed into a circular hole according to the spatial information of the micro-crack, including:

[0014] The micro-crack is found according to the position coordinate parameter, and the micro-crack is processed into a circular hole by a femtosecond laser processing procedure, parameters of the femtosecond laser processing procedure are set according to the depth of the micro-crack, so as to ensure that the depth of the circular hole is between 80% and 110% of the depth of the micro-crack, and the diameter of the circular hole is 100-120% of the length of the micro-crack.

[0015] Further, the size of the circular hole is measured to obtain the radius and cross-sectional area, including:

[0016] The diameter of the circular hole is measured by an optical microscope, so as to obtain the radius of the circular hole;

[0017] The cross-sectional area of the circular hole is measured by a roughness analyzer, and the measured cross section is ensured to be parallel to the bending loading direction.

[0018] Further, the stress limit of the processed ceramic piece under static load is calculated by using the radius and the cross-sectional area, and the calculation is performed by the following formula:

[0019]

[0020]

[0021]

[0022] wherein R0 is a mechanical constant solved based on Poisson's ratio, fracture toughness and original strength, v is Poisson's ratio, K Ic is the fracture toughness, σ0 is the original strength, σ f is the stress limit under pure I-type failure mode, n is a constant solved based on Poisson's ratio, area is the cross-sectional area of the circular hole, r is the radius of the circular hole, H is a constant solved based on Poisson's ratio, mechanical constant and radius of the circular hole, σ fm is the stress limit under mixed failure mode, L is the bending arm of the processed ceramic piece, B is the half width of the processed ceramic piece, x and y are respectively the offset of the center of the circular hole in the length and width directions of the processed ceramic piece, and are observed by an optical microscope;

[0023] The stress limit under the mixed failure mode is taken as the stress limit under the static load.

[0024] Further, the constant n is solved based on Poisson's ratio by the following method:

[0025] When the Poisson's ratio is 0 and 0.3 respectively, the constant n is 0.629 and 0.650 respectively;

[0026] When the Poisson's ratio is other values, the constant n is obtained by interpolation method.

[0027] Further, the constant H is solved based on the Poisson's ratio, the mechanical constant and the radius of the circular hole by the following method:

[0028] When the Poisson's ratio is 0.1, 0.15, 0.2, 0.25 and 0.3 respectively, if R0 / r is 0.0005, the constant H is 0.6294, 0.6215, 0.6104, 0.596 and 0.5785 respectively, if R0 / r is 0.001, the constant H is 0.6286, 0.6207, 0.6095, 0.5952 and 0.5777 respectively, if R0 / r is 0.005, the constant H is 0.6225, 0.6145, 0.6033, 0.5889 and 0.5714 respectively, if R0 / r is 0.01, the constant H is 0.6149, 0.6068, 0.5956, 0.5813 and 0.5638 respectively, if R0 / r is 0.05, the constant H is 0.5599, 0.5515, 0.5401, 0.5258 and 0.5086 respectively, if R0 / r is 0.1, the constant H is 0.5028, 0.4942, 0.4828, 0.4687 and 0.4518 respectively, if R0 / r is 0.3, the constant H is 0.3528, 0.3445, 0.3341, 0.3216 and 0.3069 respectively, if R0 / r is 0.5, the constant H is 0.2672, 0.2599, 0.2508, 0.2401 and 0.2276 respectively, if R0 / r is 1, the constant H is 0.159, 0.1537, 0.1473, 0.1399 and 0.1314 respectively;

[0029] When the Poisson's ratio and R0 / r are other values, the constant H is obtained by interpolation method.

[0030] Further, the power index k and the critical fatigue life N fc of the original ceramic piece are tested.

[0031] The S-N curve of the original ceramic piece is tested by using the room temperature bending fatigue test method at least 6 stress levels, and more than 3 odd samples are tested at each stress level, the test results are plotted into the S-N curve of the double logarithmic coordinate system, the power index of the original ceramic piece S-N curve is obtained by taking the median and linear fitting, and the critical fatigue life at the fatigue limit is obtained according to the S-N curve fitting result.

[0032] Further, the S-N curve of the processed ceramic part is drawn by using the stress limit, the power index and the critical fatigue life, comprising:

[0033] In the double logarithmic coordinate system, a coordinate point (1, σ fm ) is taken as a starting point, a power index k of the original ceramic part is taken as a slope to draw a slant line, a critical fatigue life N fc of the original ceramic part is taken as an end point of the slant line, and then a horizontal line is drawn, so as to draw the S-N curve of the processed ceramic part.

[0034] Wherein, σ fm is the stress limit of the processed ceramic part under the action of static load.

[0035] Further, the maximum bending stress is obtained by testing the processed ceramic part by the bending stress sensor.

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] The present application provides a method for improving and predicting the room temperature bending fatigue life of ceramic parts containing micro-cracks, which can effectively reduce the fatigue failure probability of ceramic parts containing micro-cracks and greatly improve the fatigue life by processing the stress-sensitive micro-cracks into circular holes with low stress sensitivity to obtain processed ceramic parts; the prediction accuracy of the room temperature bending fatigue life of ceramic parts is improved by combining the force stress state analysis in the prediction process of the room temperature bending fatigue life through the calculation of the stress limit of the processed ceramic part under the action of static load and the test of the power index and the critical fatigue life of the original ceramic part, which provides technical support for the reliable application of ceramic bearings, connecting rods and other bending-resistant components. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a flowchart of a method for improving and predicting the room temperature bending fatigue life of ceramic parts containing micro-cracks provided by the present application;

[0039] Figure 2 is a schematic diagram of the position of the femtosecond laser processed circular hole provided by the present application;

[0040] Figure 3 is the S-N curve of 3Y-TZP ceramic parts under different conditions provided by the present application. DETAILED DESCRIPTION

[0041] The present application will be further described below in conjunction with the drawings, and the following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0042] Example 1

[0043] As Figure 1As shown, the embodiment of the application provides a method for improving and predicting the room temperature bending fatigue life of a ceramic part containing microcracks, which comprises the following steps:

[0044] S1, collect the spatial information of the microcracks on the original ceramic part, test the power index and critical fatigue life of the original ceramic part.

[0045] The spatial information of the microcracks on the surface of the original ceramic part is found by using a non-destructive testing process, and the spatial information includes the length, width and position coordinate parameters of the microcracks.

[0046] S2, according to the spatial information of the microcracks, the microcracks are processed into circular holes, and a polishing and cleaning process is performed on the circular holes to obtain a processed ceramic part, and the room temperature bending fatigue life is improved.

[0047] According to the position coordinate parameters, the microcracks are found, and the microcracks are processed into circular holes by using a femtosecond laser processing process. The parameters of the femtosecond laser processing process are set according to the depth of the microcracks, so that the depth of the circular hole is between 80% and 110% of the depth of the microcracks, and the diameter of the circular hole is 100-120% of the length of the microcracks.

[0048] The polishing and cleaning process is performed on the circular hole to remove the micro-burrs and remelted recrystallized residues in the femtosecond laser processing area, so as to ensure the accuracy of the subsequent size measurement of the circular hole.

[0049] The processed ceramic part obtained by completing this step can effectively reduce the fatigue failure probability of the ceramic part containing microcracks and greatly improve the fatigue life, thereby improving the room temperature bending fatigue life.

[0050] S3, measure the size of the circular hole to obtain its radius and cross-sectional area, and calculate the stress limit of the processed ceramic part under static load by using the radius and cross-sectional area.

[0051] The diameter 2r of the circular hole is measured by using an optical microscope, so as to obtain its radius r.

[0052] The cross-sectional area area of the circular hole is measured by using a roughness analyzer, and it is ensured that the measured cross section is parallel to the bending loading direction.

[0053] According to the national standards GB / T 37781-2019, GB / T 23806-2009 and GB / T 38897-2020, the original strength σ0, fracture toughness K Ic and Poisson's ratio v of the ceramic are measured, and the value of n is obtained by interpolation method according to v. When v is 0 and 0.3, n is 0.629 and 0.650, and when v is other values, the value of n is obtained by interpolation method.

[0054] R0 is calculated by the formula R0 is a mechanical constant solved based on Poisson's ratio, fracture toughness and original strength.

[0055] Using the values of R0 / r and v, the constant H is obtained:

[0056] When the Poisson's ratio is 0.1, 0.15, 0.2, 0.25 and 0.3 respectively, if R0 / r is 0.0005, the constant H is 0.6294, 0.6215, 0.6104, 0.596 and 0.5785 respectively, if R0 / r is 0.001, the constant H is 0.6286, 0.6207, 0.6095, 0.5952 and 0.5777 respectively, if R0 / r is 0.005, the constant H is 0.6225, 0.6145, 0.6033, 0.5889 and 0.5714 respectively, if R0 / r is 0.01, the constant H is 0.6149, 0.6068, 0.5956, 0.5813 and 0.5638 respectively, if R0 / r is 0.05, the constant H is 0.5599, 0.5515, 0.5401, 0.5258 and 0.5086 respectively, if R0 / r is 0.1, the constant H is 0.5028, 0.4942, 0.4828, 0.4687 and 0.4518 respectively, if R0 / r is 0.3, the constant H is 0.3528, 0.3445, 0.3341, 0.3216 and 0.3069 respectively, if R0 / r is 0.5, the constant H is 0.2672, 0.2599, 0.2508, 0.2401 and 0.2276 respectively, if R0 / r is 1, the constant H is 0.159, 0.1537, 0.1473, 0.1399 and 0.1314 respectively; when the Poisson's ratio and R0 / r are other values, the constant H is obtained by interpolation method.

[0057] The stress limit σ of the machined ceramic part under pure I mode of failure is calculated by the formula f .

[0058] The bending arm L of the machined ceramic part and the half width B of the machined ceramic part are measured by using a caliper or a laser range finder and other range measuring instruments; the offset x of the center of the circular hole in the length direction of the ceramic part and the offset y in the width direction are measured by using an optical microscope, and in particular, the measurement accuracy needs to be one order of magnitude lower than the size of the ceramic part.

[0059] The stress limit σ of the machined ceramic part under mixed failure mode is calculated by the formula fm .

[0060] S4, drawing the S-N curve of the machined ceramic part by using the stress limit, the power index and the critical fatigue life.​​

[0061] The stress-life (SN) curves of original ceramic parts at at least six stress levels were tested using a room temperature bending fatigue test method, with an odd number of samples tested at each stress level (at least three). The test results were plotted as SN curves on a double logarithmic coordinate system. The power exponent k of the SN curve of the original ceramic parts was obtained by taking the median and linear fitting. At the same time, the critical fatigue life N at the fatigue limit was obtained based on the SN curve fitting results. fc .

[0062] σ obtained through calculation and testing fm , k and N fc In a double logarithmic coordinate system, with coordinates (1, σ) as the reference point. fm Starting from N, draw a diagonal line with the power exponent k as the slope, and then draw a line with N as the starting point. fc The endpoint of the diagonal line is marked by a horizontal line, which is then used to draw the SN curve for processing ceramic parts.

[0063] S5. Test the maximum bending stress of the processed ceramic part, and use the horizontal axis corresponding to the maximum bending stress on the SN curve as the prediction result of the room temperature bending fatigue life.

[0064] The actual maximum bending stress σ of the processed ceramic part was obtained by using a sensor test. max , with σ max Substituting the SN curve of the processed ceramic part into the vertical axis, we obtain the corresponding horizontal axis value, which is the room temperature cyclic fatigue life of the processed ceramic part under the corresponding conditions.

[0065] This invention utilizes high-precision femtosecond laser processing technology to transform stress-sensitive microcracks into stress-insensitive circular holes. This method can effectively reduce the fatigue failure probability of ceramic parts containing microcracks and significantly improve their fatigue life. In addition, this invention can effectively reduce the dispersion of fatigue failure life of ceramic parts from the current traditional 5-6 orders of magnitude to 1-2 orders of magnitude. Combined with stress state analysis, this invention can accurately predict the bending fatigue life of ceramic parts, providing technical support for the reliable application of bending-resistant components such as ceramic bearings and connecting rods.

[0066] Example 2

[0067] The present invention provides a method for improving and predicting the room temperature bending fatigue life of ceramic parts containing microcracks, which is implemented through the following process:

[0068] Microcracks were found on the surface of the 3Y-TZP ceramic part (the original ceramic part described in Example 1) using non-destructive testing. The length and depth of the microcracks were extracted to be 40 μm and 30 μm, respectively. For ease of subsequent comparison, the cross-sectional area of ​​the microcracks was also measured to be 715 μm.2 and position coordinate parameters.

[0069] The micro-crack region is processed into a circular hole by a femtosecond laser processing procedure, and the center wavelength, pulse width, repetition frequency, power, objective magnification and scanning speed of the femtosecond laser objective are 780 nm, 120 fs, 80 MHz, 20 mW, 20 times and 5 μm / s respectively.

[0070] The circular hole is polished by using 2000-mesh sandpaper and ultrasonic cleaning to remove the micro burrs and remelted recrystallized residues in the femtosecond laser processing region, and a processed ceramic part is obtained. The diameter 2r of the circular hole is measured by an optical microscope to be 40 μm, so the radius r is 20 μm. The cross-sectional area area of the circular hole parallel to the bending loading direction is measured by a roughness analyzer to be 1120 μm 2 .

[0071] According to the national standards GB / T 37781-2019, GB / T 23806-2009 and GB / T 38897-2020, the original strength σ0, fracture toughness K Ic and Poisson's ratio v are measured to be 1100 MPa, 5.26 MPa·m 1 / 2 and 0.3 respectively. According to the solving rule in Example 1, n is 0.650.

[0072] The formula is used to calculate R0 / r to be 0.3. According to the solving rule in Example 1, the constant H is 0.3069.

[0073] The formula is used to calculate the stress limit σ f of the processed ceramic part under pure I-type failure mode to be 777 MPa. At the same time, the previously measured micro-crack cross-sectional area size 715 μm 2 and the crack tip radius r = 0 are substituted into the formula to calculate the stress limit σ crack of the ceramic part under the action of the micro-crack before processing to be 689 MPa.

[0074] The bending arm L of the processed ceramic part and the half-width B of the processed ceramic part are measured by a vernier caliper to be 30 mm and 5 mm respectively. The offset x in the length direction of the ceramic part and the offset y in the width direction of the circular hole center are measured by an optical microscope to be 0.87 mm and 0.42 mm respectively, as shown in Figure 2 .

[0075] The formula is used to calculate the stress limit σ fm of the processed ceramic part under mixed failure mode to be 874 MPa.

[0076] The SN curves of the original ceramic parts were obtained by room temperature bending fatigue testing. Six stress levels were tested, with an odd number of samples tested at each stress level (more than three). The test results were plotted as SN curves on a double logarithmic coordinate system. By taking the median and linear fitting, the power exponent k of the original ceramic SN curve was found to be -0.01277. Simultaneously, based on the SN curve (… Figure 3 The fitting results of Line 1) yield the critical fatigue life N at the fatigue limit. fc Approximately 10 5 .

[0077] σ obtained through calculation and testing fm =874MPa, k=-0.01277 and N fc =10 5 Plot the SN curve of the ceramic part containing circular holes. Figure 3 (Line 3), for comparison, according to σ crack =689MPa, k=-0.01277 and N fc =10 5 The SN curve of the ceramic part under the action of the microcrack before processing was plotted. Figure 3 (Line 2)

[0078] The actual maximum bending stress σ of the ceramic part containing circular holes was obtained by using sensor testing. max The pressure is 591 MPa. Substituting 591 MPa as the ordinate into the SN curve of the processed ceramic part, the corresponding abscissa value (i.e., fatigue life) is 35451 cycles. Actual testing yielded a fatigue life value of 156937 cycles (e.g., ...). Figure 3 As shown by the pentagram in the middle, the prediction error is on the order of magnitude, while the fatigue life of the ceramic part with microcracks before processing is only 64 cycles. After improvement, the fatigue life value of the ceramic part is increased by more than 2400 times, and the fatigue life of the ceramic part is greatly improved.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving and predicting the room temperature flexural fatigue life of a ceramic part containing microcracks, characterized in that, The application relates to a method for improving the room-temperature bending fatigue life of a ceramic piece. The spatial information of microcracks on the original ceramic piece is collected, and the power index and the critical fatigue life of the original ceramic piece are tested; The microcracks are processed into circular holes according to the spatial information of the microcracks, and the circular holes are polished and cleaned to obtain a processed ceramic piece, and the room-temperature bending fatigue life is improved; The radius and the cross-sectional area of the circular holes are measured, and the stress limit of the processed ceramic piece under static load is calculated by using the radius and the cross-sectional area; The S-N curve of the processed ceramic piece is drawn by using the stress limit, the power index and the critical fatigue life; The maximum bending stress of the processed ceramic piece is tested, and the corresponding abscissa on the S-N curve is taken as the prediction result of the room-temperature bending fatigue life; The radius of the circular hole is obtained by measuring the diameter of the circular hole by using an optical microscope; The cross-sectional area of the circular hole is measured by using a roughness analyzer, and the measured cross section is ensured to be parallel to the bending loading direction; The stress limit of the processed ceramic piece under static load is calculated by using the radius and the cross-sectional area according to the following formula: area ； ； ； wherein, R 0 is a mechanical constant solved based on a Poisson's ratio, a fracture toughness, and an original strength, v is a Poisson's ratio, K Ic is a fracture toughness, is an original strength, is a stress limit in a pure I mode of failure, n is a constant solved based on a Poisson's ratio, The S-N curve of the processed ceramic piece is drawn by using the stress limit, the power index and the critical fatigue life, and the spatial information includes length, depth and position coordinate parameters, which are collected by a non-destructive testing process. is a cross-sectional area of a circular hole, r is a radius of a circular hole, H is a constant solved based on a Poisson's ratio, a mechanical constant, and a radius of a circular hole, is a stress limit of a machined ceramic piece under a static load, L is a bending arm of a machined ceramic piece, B is a half width of a machined ceramic piece, x and y are offsets of a center of a circular hole in a length and a width direction of a machined ceramic piece, respectively, and are observed by an optical microscope. The microcracks are processed into circular holes according to the spatial information of the microcracks, and the spatial information includes length, depth and position coordinate parameters, which are collected by a non-destructive testing process. In a double logarithmic coordinate system, a straight line is plotted with the coordinate point (1, ) as the starting point, the power exponent of the original ceramic piece as the slope k , the critical fatigue life of the original ceramic piece as the end point of the straight line N fc , and a horizontal line thereafter, to obtain the S-N curve of the processed ceramic piece.

2. The method for improving and predicting the room temperature bending fatigue life of a ceramic component containing microcracks according to claim 1, characterized in that, The microcracks are processed into circular holes by using a femtosecond laser processing process according to the position coordinate parameters, and the parameters of the femtosecond laser processing process are set according to the depth of the microcracks, so that the depth of the circular hole is between 80% and 110% of the depth of the microcracks, and the diameter of the circular hole is 100-120% of the length of the microcracks.

3. The method for improving and predicting the room temperature bending fatigue life of a ceramic component containing microcracks according to claim 2, characterized in that, The power index and the critical fatigue life of the original ceramic piece are tested, and the maximum bending stress of the processed ceramic piece is obtained by testing the processed ceramic piece by using a bending stress sensor. ​ 4. The method for improving and predicting the room temperature bending fatigue life of a ceramic component containing microcracks according to claim 1, characterized in that, The constant is solved based on the Poisson's ratio by the following method n : The constant a is 0.5 when the Poisson's ratio is 0 and 0.3, respectively n are 0.629 and 0.650, respectively. When the Poisson's ratio is other values, the constant n Obtained by interpolation.

5. The method for improving and predicting the room temperature bending fatigue life of a ceramic component containing microcracks according to claim 1, characterized in that, Constants are solved based on Poisson's ratio, mechanical constants, and radius of circular hole by the following method H : When the Poisson ratio is 0.1, 0.15, 0.2, 0.25 and 0.3, respectively, if R 0 / r The constant H is 0.6294, 0.6215, 0.6104, 0.596 and 0.5785, respectively, if R 0 / r The constant H is 0.6286, 0.6207, 0.6095, 0.5952 and 0.5777, respectively, if R 0 / r The constant H is 0.6225, 0.6145, 0.6033, 0.5889 and 0.5714, respectively, if R 0 / r The constant H is 0.6149, 0.6068, 0.5956, 0.5813 and 0.5638, respectively, if R 0 / r The constant H is 0.5599, 0.5515, 0.5401, 0.5258 and 0.5086, respectively, if R 0 / r The constant H is 0.5028, 0.4942, 0.4828, 0.4687 and 0.4518, respectively, if R 0 / r The constant H is 0.3528, 0.3445, 0.3341, 0.3216 and 0.3069, respectively, if R 0 / r The constant H is 0.2672, 0.2599, 0.2508, 0.2401 and 0.2276, respectively, if R 0 / r The constant H is 0.159, 0.1537, 0.1473, 0.1399 and 0.1314, respectively, if When the Poisson's ratio and R 0 / r the constant H is obtained by interpolation.

6. The method for improving and predicting the room temperature bending fatigue life of a ceramic component containing microcracks according to claim 1, characterized in that, ​ S-N curve of the original ceramic piece at each stress level is plotted in a double logarithmic coordinate system, and a power index of the S-N curve of the original ceramic piece is obtained by taking a median value and linear fitting k At the same time, a critical fatigue life at the fatigue limit is obtained according to the S-N curve fitting result N fc .

7. The method for improving and predicting the room temperature flexural fatigue life of a ceramic component containing microcracks according to claim 1, characterized in that, ​

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