Method and device for nondestructive measurement of density and porosity of material

Abstract

The invention relates to the technical field of physical properties of materials, and discloses a method and device for nondestructive measurement of density and porosity of a material, and the method comprises the following steps: obtaining material mass and material three-dimensional volume data; obtaining a material contour ROI material and a pore contour ROI pore according to the three-dimensional volume data of the material; obtaining a material volume V material and a pore volume V pore according to the material profile ROI material and the pore profile ROI pore; and obtaining the material density and porosity according to the material mass, the material volume Vmaterial and the pore volume Vpore. According to the invention, the density and porosity of the material can be measured at the same time, and both single-piece measurement and simultaneous measurement of multiple pieces are supported.

Description

Technical Field

[0001] The invention relates to the technical field of material physical properties, and in particular to a method and a device for non-destructively measuring material density and porosity. Background Art

[0002] Continuous fiber reinforced ceramic matrix composites have excellent properties such as low density, high temperature resistance, high specific strength, fatigue resistance, creep resistance and oxidation resistance, and have become one of the most promising thermal structural materials. However, pores are inevitably generated during its preparation process. Excessive porosity will not only reduce the density of the material, but also provide a direct channel for the external environment to enter the material, thereby causing the physical properties of the material to deteriorate and seriously affecting the service safety of the component. Therefore, the density and porosity of the material are important factors affecting the physical properties of the material.

[0003] However, the existing technology cannot meet the requirements of the density and porosity of the same material, and the detection accuracy is low. Therefore, it is necessary to develop a non-destructive method that can measure the density and porosity of ceramic matrix composites with high precision to ensure that the performance of the material meets the use requirements. Summary of the invention

[0004] The present invention aims to provide a method and device for non-destructive measurement of material density and porosity, which can simultaneously realize high-precision non-destructive measurement of material porosity and density.

[0005] To achieve the above object, the present invention provides a method for non-destructively measuring the density and porosity of a material, comprising:

[0006] Obtain material quality and material three-dimensional volume data;

[0007] Obtain material contour ROI based on material 3D volume data 材料 and pore outline ROI 孔隙 ;

[0008] ROI based on material contour 材料 and pore outline ROI 孔隙 , get the material volume V 材料 and the pore volume V 孔隙 ;

[0009] According to the material quality and material volume V 材料 and the pore volume V 孔隙 , obtain the material density and porosity.

[0010] The present invention also provides a device for non-destructively measuring material density and porosity, comprising:

[0011] A quality acquisition unit, used to obtain the quality of materials;

[0012] A volume data acquisition unit, used for acquiring three-dimensional volume data of a material;

[0013] The contour acquisition unit is used to obtain the material contour ROI based on the material's 3D volume data 材料 and pore outline ROI 孔隙 ;

[0014] Volume acquisition unit for ROI based on material contours 材料 and pore outline ROI 孔隙 , get the material volume V 材料 and the pore volume V 孔隙 ;

[0015] Density acquisition unit, used to obtain the density of the material according to the material mass, material volume V 材料 and the pore volume V 孔隙 , obtain the material density and porosity.

[0016] Technical effects and advantages of the present invention:

[0017] 1. The present invention can simultaneously measure the density and porosity of materials, and supports both single-piece measurement and simultaneous measurement of multiple pieces.

[0018] 2. The detection and data analysis in the non-destructive measurement process of the present invention can be easily automated, reducing human interference, and has the characteristics of simple operation, high precision and high reliability.

[0019] 3. The measuring method provided by the present invention has no special requirements on the preparation process, geometric shape and surface roughness of the object to be measured, has a wide range of applications and good versatility.

[0020] 4. The measurement method provided by the present invention does not destroy the object being measured. The object being measured can be used for experiments to test the performance of other materials, which is convenient for establishing the relationship between density and porosity parameters and other material performance parameters, and has good scalability.

[0021] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of a method for non-destructively measuring density and porosity of a material;

[0023] Figure 2 is a sample diagram of a continuous fiber reinforced ceramic matrix composite material in an embodiment;

[0024] Figure 3 This is a standard size diagram of a dumbbell-shaped ruby ​​ball in the embodiment;

[0025] Figure 4 It is the arrangement of CT transillumination of the sample in the embodiment;

[0026] Figure 5 is a projection image of a sample at a certain angle in the embodiment;

[0027] Figure 6 is the three-dimensional volume data reconstructed by CT scan of the sample in the embodiment;

[0028] Figure 7 is a cross section in the width direction of the CT volume data of the sample in the embodiment;

[0029] Figure 8 In the embodiment, the local grayscale gradient edge detection material contour is based on subvoxel;

[0030] Fig. 9 is the inner and outer contours of the material of the unfilled pores being detected in the embodiment;

[0031] Fig.10 is the outer contour of the material filling the pores in the embodiment;

[0032] Fig.11 is the internal pore profile of the material in the embodiment;

[0033] Fig.12 It is the three-dimensional extraction result of the internal pores of the material being tested in the embodiment. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] To solve the deficiencies of the prior art, the present invention discloses a method for non-destructively measuring the density and porosity of a material, such as Figure 1 As shown, the method includes:

[0036] 1. Obtain material quality and material 3D volume data.

[0037] Specifically include: 1.1 Cut the ceramic matrix composite material samples whose density and porosity need to be measured from the furnace parts. The shape of the sample is arbitrary and the size should not be too large. Under the premise of being able to represent the material properties, the smaller the size, the better, so as to achieve subsequent high-resolution three-dimensional imaging.

[0038] The material is applicable to any material, and a ceramic-based composite material is used as an example for explanation below.

[0039] 1.2 Use a balance to weigh the weight of the dried sample and record the mass m of the sample. The measurement accuracy of the balance used should not be less than one thousandth of a gram.

[0040] 1.3 Use size standard parts to calibrate the voxel size of the industrial CT system. The industrial CT system is preferably a microfocus CT system.

[0041] In order to reduce the error of the industrial CT system and improve the measurement accuracy, the dimensional standard parts used should have a density similar to that of the sample to be tested (the error should not exceed 10%), and their dimensions should be calibrated with an accuracy of not less than 1μm.

[0042] 1.4 Install the sample at or near the rotation center of the turntable of the industrial CT system.

[0043] In order to avoid blurring and distortion of the sample contour in the CT image (ie, the three-dimensional volume data of the sample after CT reconstruction), the sample should be installed at an angle, and the angle θ between its surface normal and the CT rotation axis should not be less than 11°.

[0044] 1.5 Project the sample at different angles and optimize the exposure parameters such as tube voltage, tube current and integration time according to the grayscale distribution histogram of the projected image.

[0045] To ensure the signal-to-noise ratio of the sample CT image and improve the measurement accuracy, the exposure parameters should be optimized according to the following principles: adjust the energy of the radiation source to irradiate the sample, and when the sample rotates 360° around the CT rotation center, the ratio of the air grayscale peak to the sample material grayscale peak in the grayscale histogram of the sample projection image should be between 10% and 50%; adjust the radiation tube current and exposure time to irradiate the sample, and the signal-to-noise ratio of the air area in the projection image should be no less than 250.

[0046] 1.6 Move the sample out of the detection imaging field of view and perform air calibration on the detector after optimizing the exposure parameters to reduce the noise of the detector.

[0047] 1.7 After calibration, move the sample back into the detector imaging field of view, set the X, Y and Z coordinate parameters of the turntable center, and determine the geometric magnification of the sample and the imaging area in the detector.

[0048] 1.8 Optimize the number of projection image parameters according to the number of voxels contained in the longest distance perpendicular to the rotation axis in the projection of the sample at all sampling angles.

[0049] In order to achieve high-resolution CT imaging of the sample and improve the measurement accuracy, the Z coordinate setting in step 1.7 should ensure that the projected image of the sample has sufficient geometric magnification, and the voxel size of the projected image should not exceed 30 μm. At the same time, the voxel size of the projected image should not exceed the tube power value.

[0050] In order to avoid the occurrence of radial artifacts in the CT image that affect the measurement accuracy, the number of projection images should not be less than π / 4 times the number of voxels contained in the longest distance perpendicular to the rotation axis in the projection of the sample at all sampling angles.

[0051] 1.9 Set the optimized CT detection parameters, perform third-generation cone beam scanning on the sample, and obtain X-ray projection images of the sample at different angles.

[0052] 1.10 Use reconstruction software to calibrate and three-dimensionally reconstruct X-ray projection images at different angles to obtain three-dimensional volume data of the sample.

[0053] In order to avoid ghosting artifacts at the edge of the sample in the CT image that affect the measurement accuracy, the geometric rotation center of the projection image should be calibrated before reconstruction.

[0054] 2. Obtain material contour ROI based on the material's 3D volume data 材料 and pore outline ROI 孔隙 . Among them, ROI stands for region of interest, which is the abbreviation of region of interest.

[0055] Specifically include: 2.1 Use edge detection algorithm to detect material edges on the three-dimensional volume data of the sample and obtain material contour ROI 材料 .

[0056] Preferably, in order to improve the accuracy of edge detection, this step should use a subvoxel-based local grayscale gradient detection algorithm. The specific steps are as follows:

[0057] First, the initial contour of the sample is defined by the global grayscale threshold. The iso50 threshold method is usually used, that is, half of the sum of the average grayscale value of the material and the average grayscale value of the air is used as the detection threshold of the initial contour; then, along the normal direction of each point on the initial contour, a grayscale distribution curve is made within a certain distance ds on both sides. The distance ds should not be less than 2 voxel sizes; finally, the maximum grayscale gradient point of the curve is selected to define the final contour surface position of the sample. Through this algorithm, the material contour ROI can be obtained with sub-voxel accuracy 材料 .

[0058] 2.2 Use the pore filling algorithm to fill the pores inside the material contour ROI material and obtain the material contour ROI after the internal pores are filled 材料+孔隙 .

[0059] Preferably, obtain material contour ROI for fast pore filling 材料+孔隙 This step uses the morphological opening operation. The specific steps of this operation are as follows: First, the material contour ROI 材料Expand the area of ​​the specified number of voxels to fill the pores inside the material and eliminate the material ROI 材料 Inner contour, expanded material ROI 材料 The outer contour of the material; then immediately shrink the area of ​​the same number of voxels to restore the material contour ROI 材料 Outer contour.

[0060] 2.3 Material contour ROI after internal pore filling 材料+孔隙 Subtract material contour ROI 材料 , get the pore contour ROI 孔隙 .

[0061] 3. ROI based on material contour 材料 and pore outline ROI 孔隙 , get the material volume V 材料 and the pore volume V 孔隙 .

[0062] Specifically include: According to the ROI obtained 材料 and ROI 孔隙 , combined with the volume value of the calibrated voxel obtained when calibrating the industrial CT system with the size standard, calculate the material volume V 材料 and the pore volume V 孔隙 , as shown below:

[0063] V 材料 =N 材料 ×V voxel

[0064] V 孔隙 =N 孔隙 ×V voxel

[0065] Where N 材料 Represents material contour ROI 材料 The number of voxels occupied, N 孔隙 Represents the pore outline ROI 孔隙 The number of voxels occupied, V voxel Represents the volume value of the voxel after calibration.

[0066] 4. According to the material quality and material volume V 材料 and the pore volume V 孔隙 , obtain the material density and porosity.

[0067] Specifically include: calculating the porosity and density based on the mass m, material volume and pore volume of the obtained material sample,

[0068]

[0069] Where ρ represents the material density, m represents the material mass, V 材料 Represents the volume of the material, V 孔隙 Porosity represents the porosity of the material.

[0070] In order to better explain the present solution, embodiments are provided below.

[0071] Example

[0072] A method for continuously and non-destructively measuring the density and porosity of a fiber-reinforced ceramic matrix composite material comprises the following steps:

[0073] Step 1: Cut the ceramic matrix composite material sample from the furnace parts of a continuous fiber reinforced ceramic matrix composite material preparation process.

[0074] Among them, the continuous fiber reinforcement phase of the sample is Al2O3, and the matrix phase is also Al2O3. The material sample specifications are about 35.7mm long, 9.8mm wide, and 2.51mm thick. Figure 2 shown.

[0075] Step 2: Use a high-precision balance to weigh the dried sample, ensuring that the measurement error is less than 0.001g. Measure 5 times and take the average mass as 2.256g.

[0076] Step 3: Calibrate the voxel size of the industrial CT system using size standards.

[0077] The size standard used is a dumbbell-shaped ruby ​​ball with a length of 40.0774 mm ± 0.0010 mm, which has a similar density to the sample being measured, such as Figure 3 The industrial CT system used is a Phoenix Vtome|XM micro-nano focus industrial CT system.

[0078] Step 4: Install the sample on the rotating axis and adjust the angle of the sample so that the angle between the normal line of the sample surface and the rotating axis is about 15 degrees. The transillumination arrangement is as follows: Figure 4 shown.

[0079] Step 5: Set the tube voltage to 80KV, the tube current to 350uA, and the detector integration time to 1000ms.

[0080] Step 6: Remove the sample from the detector imaging field and perform detector air calibration for the above exposure parameters.

[0081] Step 7: After air calibration, move the sample into the detector imaging field of view and set the X, Y, and Z coordinates in the turntable to 0.000 mm, 202.516 mm, and 105.816 mm, respectively.

[0082] Step 8: Set the number of projected images to 1000 frames.

[0083] Step 9: After the above parameters are set, start CT third-generation cone beam scanning on the sample to obtain X-ray projection images of the sample at different angles. Figure 5 It is the projection image of the sample at a certain angle.

[0084] Step 10: Use the reconstruction software that comes with the device to first perform geometric calibration of the rotation center of projection images at different angles, and then perform 3D reconstruction on the calibrated data to obtain the 3D volume data of the sample. The 3D visualization is as follows: Figure 6 shown.

[0085] Step 11: Use the subvoxel-based local grayscale gradient detection algorithm to define the edge of the material in the three-dimensional volume data of the sample. Specifically: First, based on the grayscale histogram of the three-dimensional volume data of the sample, use the iso50 threshold method and take half of the sum of the average grayscale value of the material and the average grayscale value of the air as the global threshold to obtain the initial contour of the material. Then, along the normal direction of each point on the initial contour, make a grayscale distribution curve within the distance of 4 voxels on both sides of the contour. Select the position of the maximum grayscale gradient on the curve to define it as the final surface contour of the sample, and obtain the precise contour of the edge of the material with subvoxel accuracy. Among them, Figure 7 is the cross section of the width direction of the three-dimensional volume data of the sample, Figure 8 Demonstrated the detection of material contours based on a subvoxel-based local grayscale gradient algorithm. Fig. 9 To obtain the material contour ROI 材料 (Material areas are rendered in red).

[0086] Step 12: Use morphological opening to fill the internal pores in the material contour. The specific process is as follows: first expand the material contour ROI by 3 voxels to fill the internal pores, and then immediately shrink the area by 3 voxels to restore the material edge contour ROI 材料 The original size of the outer contour, Fig.10 Material contour ROI for filling the internal pores of the material 材料+孔隙 .

[0087] Step 13: Material Contour ROI with Internal Porosity Fill 材料+孔隙 Subtract the material contour ROI containing internal pores 材料 , get the pore contour ROI inside the material 孔隙 , Fig.11 ROI is the contour of the pores inside the material 孔隙 (pore areas are rendered in red), Fig.12 Contour ROI of the pores inside the material 孔隙 3D extraction results (pore areas are rendered in red).

[0088] Step 14: Get the material contour ROI 材料 and pore outline ROI 孔隙 The number of voxels occupied N 材料 and N 孔隙 , combined with the calibrated voxel volume value V voxel , calculate the material volume V 材料 and the pore volume V 孔隙 .

[0089] V 材料 (mm 3 )=N 材料 ×V voxel =46079049.7×0.000017847

[0090] =822.373mm 3

[0091] V 孔隙 (mm 3 )=N 孔隙 ×V voxel =2478511.79×0.000017847=44.234mm 3

[0092] Step 15: Calculate the porosity based on the obtained material volume and pore volume.

[0093]

[0094] Based on the sample mass m and the apparent volume of the sample, the average density ρ of the material is calculated as follows:

[0095]

[0096] The present invention also provides a device for non-destructively measuring material density and porosity, comprising:

[0097] A quality acquisition unit, used to obtain the quality of materials;

[0098] A volume data acquisition unit, used for acquiring three-dimensional volume data of a material;

[0099] The contour acquisition unit is used to obtain the material contour ROI based on the material's 3D volume data 材料 and pore outline ROI 孔隙 ;

[0100] Volume acquisition unit for ROI based on material contours 材料 and pore outline ROI 孔隙 , get the material volume V 材料 and the pore volume V孔隙 ;

[0101] Density acquisition unit, used to obtain the density of the material according to the material mass, material volume V 材料 and the pore volume V 孔隙 , obtain the material density and porosity.

[0102] Since the content protected by this device is similar to that protected by the above method, no further introduction will be given here. Please refer to the discussion section of the above method for details.

[0103] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for non-destructively measuring material density and porosity, characterized in that: include: Obtain material quality and material 3D volume data; Obtain material contour ROI based on material 3D volume data 材料 and pore outline ROI 孔隙 ; ROI based on material contour 材料 and pore outline ROI 孔隙 , get the material volume V 材料 and the pore volume V 孔隙 ; According to the material quality and material volume V 材料 and the pore volume V 孔隙 , obtain the material density and porosity.

2. The method according to claim 1, characterized in that The obtaining of the material mass comprises: cutting and drying the original material, and weighing the material mass.

3. The method according to claim 1, characterized in that: The obtaining of three-dimensional volume data of the material comprises: Use dimension standards to calibrate industrial CT systems; Use the calibrated industrial CT system to perform industrial CT inspection on the material to obtain X-ray projection images of the material at different angles; The X-ray projection images of the material at different angles are calibrated and three-dimensionally reconstructed to obtain the three-dimensional volume data of the material.

4. The method according to claim 3, characterized in that: The error between the density of the size standard and the density of the material does not exceed 10%.

5. The method according to claim 3, characterized in that: The method of using the calibrated industrial CT system to perform industrial CT inspection on the material to obtain X-ray projection images of the material at different angles includes: Mount the material on the rotating axis of the industrial CT system turntable; Project the material at different angles and optimize the exposure parameters according to the grayscale distribution histogram of the projected image; Move the material out of the detection imaging field of view and perform air calibration on the detector for the optimized exposure parameters; Move the material back into the detector imaging field of view and set the X, Y and Z coordinate parameters of the turntable center to determine the geometric magnification of the material and the imaging area in the detector; Optimize the number of projection images according to the number of voxels contained in the longest distance perpendicular to the rotation axis in all sampling angle projections of the material; The optimized exposure parameters, X, Y and Z coordinate parameters and the optimized number of projection images were set, and the material was subjected to a third-generation cone beam scan to obtain X-ray projection images of the material at different angles.

6. The method according to claim 5, characterized in that The material is installed obliquely on the rotating axis of the turntable of the industrial CT system; The inclination angle is the angle θ between the normal line of the material surface and the rotation axis, and the angle θ is not less than 11°.

7. The method according to claim 5, characterized in that The method of optimizing exposure parameters according to the grayscale distribution histogram of the projection image includes: adjusting the energy of the radiation source to penetrate the material, so that when the material rotates 360° around the rotation center, the ratio of the air grayscale peak value to the material grayscale peak value in the grayscale histogram of the material projection image is 10%-50%; adjusting the radiation tube current and exposure time to penetrate the material, and controlling the signal-to-noise ratio of the air area in the material projection image to be not less than 250.

8. The method according to claim 5, characterized in that The setting of the Z coordinate parameter needs to satisfy the requirement that the voxel size of the material projection image does not exceed 30 μm.

9. The method according to claim 5, characterized in that The number of projection images is not less than π / 4 times the number of voxels contained in the longest distance perpendicular to the rotation axis in all sampling angle projections of the material.

10. The method according to claim 1, characterized in that The material contour ROI is obtained according to the three-dimensional volume data of the material 材料 and pore outline ROI 孔隙 ,include: Use edge detection algorithm to detect material edges on 3D volume data to obtain material contour ROI 材料 ; Use the pore filling algorithm to contour the material ROI 材料 Fill the internal pores to obtain the material contour ROI after the internal pores are filled 材料+孔隙 ; Material contour ROI after internal pore filling 材料+孔隙 Subtract material contour ROI 材料 , get the pore contour ROI 孔隙 .

11. The method according to claim 10, characterized in that The edge detection algorithm is a subvoxel-based local grayscale gradient detection algorithm.

12. The method according to claim 10, characterized in that The pore filling algorithm is a morphological opening operation.

13. The method according to claim 5, characterized in that The material volume V is obtained by the following formula 材料 and the pore volume V 孔隙 : V 材料 =N 材料 ×V voxel V 孔隙 =N 孔隙 ×V voxel Where N 材料 Represents material contour ROI 材料 The number of voxels occupied, N 孔隙 Represents the pore outline ROI 孔隙 The number of voxels occupied, V voxel Represents the volume value of the voxel after calibration.

14. The method according to claim 1, characterized in that The material density and porosity are obtained by the following formula; In the formula, ρ represents the material density, m represents the material mass, V 材料 Represents the volume of the material, V 孔隙 Porosity represents the porosity of the material.

15. The method according to claim 1, characterized in that The material is a continuous fiber reinforced ceramic matrix composite material.

16. A device for non-destructively measuring density and porosity of a material, characterized in that: include: A quality acquisition unit, used to obtain the quality of materials; A volume data acquisition unit, used for acquiring three-dimensional volume data of a material; The contour acquisition unit is used to obtain the material contour ROI based on the material's 3D volume data 材料 and pore outline ROI 孔隙 ; Volume acquisition unit for ROI based on material contours 材料 and pore outline ROI 孔隙 , get the material volume V 材料 and the pore volume V 孔隙 ; Density acquisition unit, used to obtain the density of the material according to the material mass, material volume V 材料 and the pore volume V 孔隙 , obtain the material density and porosity.

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