A method for nondestructive detection of lunar soil granularity

Abstract

The present application provides a method for detecting lunar soil particle size using computed tomography (CT) technology, which achieves non-contact, non-polluting and lossless detection. The present application also provides a method for detecting particle size of lunar soil samples using a combined three-dimensional X-ray microscope, an optical microscope and / or a scanning electron microscope, thereby making full use of the measurement advantages of different detection methods, effectively making up for the shortcomings of a single method, and improving the accuracy and reliability of particle size measurement.

Description

Technical Field

[0001] The present invention belongs to the field of detection, and specifically relates to a scanning-storage integrated container and method for non-destructive detection of lunar soil granularity, and their applications. Background Art

[0002] The particle size characteristic of rock and soil is a basic physical property, which is closely related to many physical and mechanical properties such as structural characteristics, mechanical properties, thermal properties, optical properties and seismic properties. It is of great significance for inverting geological causes and predicting physical and mechanical properties.

[0003] The moon has been transformed by meteorite impacts for billions of years. The unique and complex soil formation process has given the lunar soil a particle size distribution that is completely different from that of Earth's sediments. The particle size of the lunar soil is affected by a variety of factors, including the time of space exposure, the frequency and intensity of meteorite impacts, and the temperature changes on the lunar surface. Generally speaking, as the time of space exposure increases, the lunar soil will develop from immature to mature, and the particle size of the lunar soil particles will gradually become uniform and fine. By studying the particle size distribution characteristics of the lunar soil, we can not only get a glimpse of its space exposure time and maturity, but also infer the meteorite impact history and geological evolution process of the moon.

[0004] In the field of lunar engineering, in-depth research on the particle size distribution characteristics of lunar soil will help to fully understand the physical and mechanical properties of lunar soil and provide an important scientific basis for lunar exploration and in-situ resource utilization. For example, predicting the strength and compressibility of lunar soil based on the particle size characteristics of lunar soil, judging the bearing capacity and stability of the lunar foundation, is an important reference for selecting lunar landing sites and lunar rover driving paths; the particle size distribution of lunar soil profiles greatly affects the sampling effect of lunar surface drilling; the cohesiveness and biological toxicity of lunar dust (<20μm / 50μm) seriously threaten the health of astronauts and the safe operation of spacecraft systems, and the impact mechanism of lunar dust of different particle sizes on the human body is also significantly different; the particle size distribution of lunar soil can also indirectly affect the planting potential by affecting the pore structure); the radiation environment and temperature changes on the lunar surface are also closely related to the particle size characteristics. However, for the current particle size detection of lunar soil, a single measurement method is often only applicable to particles within a local particle size range, and inevitably causes sample loss. Therefore, it is urgent to develop a new non-destructive detection method for lunar soil particle size. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present application provides a method for detecting the particle size of lunar soil using computed tomography (CT) technology, which realizes non-contact, pollution-free and loss-free detection. Furthermore, the present application also provides a particle size detection method using multiple detection means for segmented splicing and fitting, thereby making full use of the measurement advantages of different detections, effectively making up for the shortcomings of a single method, improving the accuracy and reliability of particle size measurement, and providing an effective detection method for the particle size detection of lunar soil samples.

[0006] According to one aspect of the present application, there is provided an application of computed tomography (CT) technology in soil particle size detection.

[0007] In some embodiments, the CT is performed by three-dimensional X-ray microscopy.

[0008] In some embodiments, the soil is lunar soil.

[0009] According to another aspect of the present application, a scanning-storage integrated container is provided, which comprises a containing bottle and a sample cup which can be placed in the containing bottle, wherein the containing bottle comprises a bottle body and a bottle cap which is detachably connected to the bottle body, and the sample cup comprises a cup body and a cup cap which is detachably connected to the cup body, wherein the cup body is provided with a storage section, a gradual channel with a gradually decreasing diameter, and a detection section in sequence.

[0010] In some embodiments, a sealing gasket is provided between the containing bottle and the sample cup. Preferably, the number of the sealing gaskets is 1-5, for example, 1, 2, 3, 4 or 5.

[0011] In some embodiments, in the sample cup, a second internal thread is disposed at the lower portion of the cup cover, and a second external thread matching the second internal thread is disposed at the upper portion of the storage section of the cup body.

[0012] In some embodiments, in the containing bottle, a first internal thread is disposed at a lower portion of the bottle cap, and a first external thread matching the first internal thread is disposed at an upper portion of the bottle body.

[0013] In some embodiments, in the cup body of the sample cup, the height of the storage section is 5-15 mm, and the inner diameter of the storage section is 5-15 mm. In some specific embodiments, the height of the storage section is 5 mm, 7.5 mm, 10 mm, 12.5 mm, 15 mm, or any value therebetween. In some specific embodiments, the inner diameter of the storage section is 5 mm, 7.5 mm, 10 mm, 12.5 mm, 15 mm, or any value therebetween.

[0014] In some embodiments, the height of the gradient channel is 4-8 mm, for example, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or any value therebetween.

[0015] In some embodiments, the height of the detection section is 4-10 mm, and the inner diameter of the detection section is 1.5-4 mm. In some embodiments, the height of the detection section is 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any value therebetween. In some specific embodiments, the inner diameter of the detection section is 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or any value therebetween.

[0016] In some embodiments, the height of the cup cover of the sample cup is 5-10 mm, and the inner diameter of the cup cover is 10-20 mm. In some specific embodiments, the height of the cup cover is 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any value therebetween. In some specific embodiments, the inner diameter of the cup cover is 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, or any value therebetween.

[0017] In some embodiments, the containing bottle is a cylindrical structure.

[0018] In some embodiments, the inner diameter of the bottle is 15-25 mm, and the height of the bottle is 30-40 mm. In some specific embodiments, the inner diameter of the bottle is 15 mm, 17.5 mm, 20 mm, 22.5 mm, 25 mm, or any value therebetween. In some specific embodiments, the height of the bottle is 30 mm, 32 mm, 34 mm, 36 mm, 38 mm, 40 mm, or any value therebetween.

[0019] In some embodiments, the inner diameter of the bottle cap is 20-30 mm, and the height of the bottle cap is 5-10 mm. In some specific embodiments, the inner diameter of the bottle cap is 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, or any value therebetween. In some specific embodiments, the height of the bottle cap is 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any value therebetween.

[0020] In some embodiments, the sample cup is made of quartz glass.

[0021] In some embodiments, the material of the containing bottle is polytetrafluoroethylene.

[0022] According to another aspect of the present application, a method for detecting soil particle size is provided, comprising the following steps:

[0023] (1) the step of measuring the particle size of the soil sample using computed tomography (CT) technology; and optionally

[0024] (2) Performing image processing on the data obtained from the particle size detection to obtain a particle size distribution curve of the soil sample.

[0025] In some embodiments, the soil sample is a lunar soil sample.

[0026] In some embodiments, in step (1), the CT is performed by a three-dimensional X-ray microscope.

[0027] In some embodiments, the sample used for the three-dimensional X-ray microscopy detection is placed in the scanning-storage integrated container described in the present application.

[0028] In some embodiments, CT detection is performed on the detection section in the scanning-storage integrated container corresponding to the sample cup.

[0029] In some embodiments, the three-dimensional X-ray microscope is selected from the group consisting of a Xradia 620Versa three-dimensional X-ray microscope.

[0030] In some embodiments, the conditions for particle size detection using an Xradia 620Versa three-dimensional X-ray microscope include: scanning using phase contrast micro-tomography, the scanning voxel sizes are 2-4 μm and 0.5-1.5 μm, respectively, the X-ray tube energy is 85-95 kV and 10-14 W, the optical objective lens is 4X, and the exposure time of one projection is 3-5 s. In some specific embodiments, the scanning voxel sizes are 3 μm and 1 μm, respectively, the X-ray tube energy used is 90 kV and 12 W, respectively, the optical objective lens is 4X, and the exposure time of one projection is 4 s.

[0031] In some embodiments, image processing of data obtained by the Xradia 620Versa three-dimensional X-ray microscope includes: obtaining equivalent spherical volume diameters of different particles using Avizo 3D 2022.2 software.

[0032] In some embodiments, in step (1), the particle size detection further comprises performing particle size detection on the soil sample using an optical microscope and / or a scanning electron microscope.

[0033] In some embodiments, the soil sample for the optical microscope detection is placed on a glass slide. Preferably, the soil sample is mechanically shaken before the optical microscope detection.

[0034] In some embodiments, the soil sample for the scanning electron microscope detection is placed in epoxy resin, and the cross section is exposed by mechanical polishing. Preferably, before the scanning electron microscope detection, the soil sample is subjected to surface carbon coating treatment.

[0035] In some embodiments, the optical microscope is selected from a Smartzoom 5 microscope.

[0036] In some embodiments, the conditions for particle size detection using a Smartzoom 5 microscope include: a mixed mode, a resolution of 1-2.5 μm, preferably 1.5-2 μm, and an exposure time of 0.5-2 ms, preferably 0.5-1 ms. In some specific embodiments, the conditions for particle size detection using a Smartzoom 5 microscope include: a resolution of 1.7 μm, and an exposure time of 0.75 ms. In some embodiments, the mixed mode includes a mixture of 35-40% reflected light and 50-60% transmitted light sources, such as a mixture of 36.1% reflected light and 54.3% transmitted light sources.

[0037] In some embodiments, performing image processing on data obtained by the Smartzoom 5 microscope includes: obtaining equivalent circular area diameters of different particles using Avizo 3D 2022.2.

[0038] In some embodiments, the scanning electron microscope is selected from a Sigma 360 field emission scanning electron microscope.

[0039] In some embodiments, the conditions for detection using a Sigma 360 field emission scanning electron microscope include: an accelerating voltage of 1.0-2.0 kV, a current of 1.5-2.5 nA, a working distance of 4-6 mm, and a resolution of 50-60 nm. In some embodiments, the conditions for detection using a Sigma 360 field emission scanning electron microscope include: an accelerating voltage of 1.5 kV, a current of 2.0 nA, a working distance of ~5 mm, and a resolution of 54.15 nm.

[0040] In some embodiments, image processing of data obtained by a Sigma 360 field emission scanning electron microscope includes: obtaining equivalent circular area diameters of different particles using Avizo 3D 2022.2.

[0041] In some embodiments, in step (2), the curve fitting characteristic values ​​obtained by the image processing are used to perform curve fitting to obtain the particle size distribution curve. Preferably, the curve fitting characteristic values ​​include an equivalent spherical volume diameter and / or an equivalent circular area diameter.

[0042] In some embodiments, the curve fitting is performed using formula (4):

[0043]

[0044] Among them, A1, A2, B, and D0 are curve fitting characteristic values, A1 is the value of the asymptote when D→-∞, A2 is the value of the asymptote when D→+∞, and the fitting curve is about point Symmetry, point The slope of the tangent line at is D1 and D2 are the particle size ranges of the soil samples. Different detection methods are suitable for different particle size fitting ranges, which are determined by the soil samples detected, and,

[0045] In some embodiments, the method includes using a three-dimensional X-ray microscope to detect the particle size of the soil sample, and using the curve fitting characteristic values ​​obtained by the three-dimensional X-ray microscope to perform curve fitting.

[0046] In some embodiments, a three-dimensional X-ray microscope and an optical microscope are used to detect the particle size of soil samples, and curve fitting is performed using the curve fitting characteristic values ​​obtained using the three-dimensional X-ray microscope. Then, for particle size data below 75 μm, the curve fitting characteristic values ​​obtained using the optical microscope are used to correct the fitting curve.

[0047] In some embodiments, a three-dimensional X-ray microscope, an optical microscope, and a scanning electron microscope are used to detect the particle size of a soil sample, and curve fitting is performed using the curve fitting characteristic values ​​obtained with the three-dimensional X-ray microscope. Then, for particle size data of 10-75 μm, the fitting curve is corrected using the curve fitting characteristic values ​​obtained with the optical microscope, and for particle size data less than 10 μm, the fitting curve is corrected using the curve fitting characteristic values ​​obtained with the scanning electron microscope.

[0048] According to another aspect of the present application, there is provided an application of the scanning-storage integrated container or the method described in the present application in the particle size detection of soil, especially lunar soil.

[0049] In some embodiments, the soil is lunar soil.

[0050] This application uses a three-dimensional X-ray microscope to detect lunar soil particle size, achieving non-contact, non-polluting and loss-free detection; and the scanning-storage integrated container used for detection can be used for CT detection of a three-dimensional X-ray microscope while storing lunar soil samples without the need for additional sample preparation. Furthermore, the use of multiple detection methods for combined detection fully utilizes the detection advantages of different methods, effectively makes up for the shortcomings of a single method, and significantly improves the accuracy and reliability of particle size measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A flow chart of a particle size detection method according to the present application is shown.

[0052] Figure 2 The structure of the containing bottle (a) and the sample cup (b) of the scanning-storage integrated container according to the present application is shown, wherein 1 is the bottle cover, 2 is the bottle body, 3 is the cup cover, 4 is the cup body, 5 is the storage section, 6 is the gradient channel, and 7 is the detection section.

[0053] Figure 3 The measurement results of different particle size detections are shown, where a is the number-particle size distribution result and b is the volume / area-particle size distribution result.

[0054] Figure 4 A comparison of the volume-size accumulation data fitting results from a laser particle size diffraction analyzer and a three-dimensional X-ray microscope is shown.

[0055] Figure 5 A comparison of the area / volume-particle size accumulation data fitting results from a laser particle size diffraction analyzer and an optical microscope is shown.

[0056] Figure 6 A comparison of the area / volume-particle size accumulation data fitting results from a laser particle size diffraction analyzer and a scanning electron microscope is shown.

[0057] Figure 7 A schematic diagram of the combined method for particle size detection is shown, where a is the measurement range and combined method of different detections, and b is a comparison of the fitting results of the combined measurement.

[0058] Figure 8 The area-particle size accumulation data obtained using a laser particle size diffraction analyzer for the samples before (LDPS1) and after (LDPS2) three-dimensional X-ray microscopy examination are shown. DETAILED DESCRIPTION

[0059] Particle size refers to the size of particles. The diameter of standard spherical particles is the particle size. Irregular particles often use equivalent particle diameter as the particle size. Equivalent particle diameter refers to the diameter of spherical particles with the same physical properties. According to different equivalent physical properties, equivalent particle diameter can be divided into equivalent volume diameter, equivalent sedimentation velocity diameter, equivalent resistance diameter and equivalent projection area diameter. In addition, Feretdiameter (the distance between the two parallel lines of the particle projection contour along a certain direction) is also often used to measure the size of irregular particles.

[0060] Various methods such as sieving, sedimentation, laser diffraction and image analysis are widely used to measure the particle size of rock and soil. Sieving is one of the traditional methods for particle size analysis. It usually requires a large sample (>50g) and works best when most particles are larger than 75μm. Therefore, it is most useful for coarser powders or granules. Sedimentation is usually used to measure particle sizes less than 75μm, but due to the influence of Brownian motion, the measurement results of particles less than 0.2μm are not ideal. In contrast, the measurement range of laser diffraction particle size (LDPS) analysis is quite wide, usually covering a particle size range of 10nm to 4mm. Sedimentation (10-40g) and LDPS analysis (0.1-0.5g) usually require a large sample and require the soil sample to be dispersed in a liquid. Imaging through various microscopy methods can not only directly measure the particle size, but also provide morphological characteristics of the particles. However, in order to obtain statistically significant analysis results, millions of particles need to be measured, and their accuracy may be affected by many factors such as test equipment, particle dispersion, operator and image processing methods.

[0061] The six Apollo missions brought back about 382 kg of lunar rocks, core samples, pebbles, sand and dust from the lunar surface, which is sufficient to allow particle size measurement (>31 μm) by sieving. In addition, more accurate particle size measurement methods have also been used, such as computer-coupled optical microscopy (≥10 μm), acoustic sieving (≥10 μm), Coulter counter and scanning electron microscopy (≤5 μm). The Chang'e-5 and Chang'e-6 missions brought back about 1731 g and 1935 g of lunar samples from the middle and high latitudes of the Northeast Ocean of Storms on the far side of the moon and the Apollo Basin in the South Pole-Aitken Basin, respectively. The limited and precious samples make the lunar soil particle size analysis extremely challenging. For the Chang'e-5 lunar soil samples, the particle size was measured by optical microscopy, laser diffraction coupled with image analysis, and a particle analysis system based on Raman spectroscopy. However, the particle size measurement methods of Apollo and Chang'e-5 lunar soil inevitably require contact and loss of samples, and the accuracy of the obtained particle size is limited to a specific range.

[0062] The present application uses a three-dimensional X-ray microscope for particle size analysis, achieving non-contact, non-polluting and lossless detection. At the same time, the present application also provides a scanning-storage integrated container with a special structure, which can be used to store lunar soil samples while enabling lunar soil samples to be used for particle size detection with a three-dimensional X-ray microscope, without the need for additional sample preparation operations, saving detection steps, and further ensuring non-polluting and lossless detection.

[0063] Furthermore, the more complex the particle shape, the greater the difference in results measured by different methods, which greatly increases the discreteness of different test results. The inventors of this application used simulated lunar soil and increased the range of sample particle size distribution as much as possible by adding grinding steps. After testing, it was found that within the measurable particle size range of different tests, only the volume / area cumulative data within a local range had good consistency with LDPS, thus proposing a particle size detection method that uses segmented splicing and fitting of data obtained from multiple tests. This method makes full use of the measurement advantages of different tests, effectively makes up for the shortcomings of a single method, improves the accuracy and reliability of particle size measurement, and makes full preparations for the particle size detection of lunar soil samples, including those from Chang'e 5 and Chang'e 6.

[0064] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to constitute any limitation to the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present disclosure. Such structures and technologies are also described in many publications.

[0065] Example

[0066] Example 1. Preparation of simulated lunar soil

[0067] The CAS-1 simulated lunar soil developed by the Institute of Geochemistry, Chinese Academy of Sciences (Guizhou) was used in this application. Its initial material is the black uniform basaltic volcanic slag in the Sihai volcanic slag layer. The chemical and mineral composition is similar to the Apollo 14 lunar sample. The main mineral components are pyroxene and olivine, containing 20%-40% glass material, the particle morphology is sharp and angular, and the median particle size is 85.938μm. In order to increase the sample particle size range and compare the applicability of different methods for particle size measurement, the CAS-1 simulated lunar soil was first ground twice using an agate mortar. Samples of similar mass were manually ground for 1h, 30min and 10min, and the ground samples were fully mixed and used as samples for this particle size test. According to the average value of the 6 measurement results of the laser diffraction particle size analyzer, the particle size range of the ground sample is between 0.04-1140μm.

[0068] Example 2. Particle size detection

[0069] The particle size of the simulated lunar soil of CAS-1 after secondary grinding was tested by laser diffraction particle size analyzer (LDPS), three-dimensional X-ray microscope (3D-XRM, hereinafter referred to as XRM), optical microscope (OM) and scanning electron microscope (SEM). Figure 1 shown.

[0070] (1) Laser diffraction particle size analyzer detection

[0071] The particle size test was performed using a LS13 320 laser diffraction particle size analyzer manufactured by BeckmanCoulter, which can measure particle sizes ranging from 0.04 to 2000 μm and provides volume / number percentages for 117 particle sizes in this measurement interval. Before analysis, a background measurement was performed on distilled water. Without any pretreatment, approximately 40-60 mg of soil sample was slowly poured into distilled water in the sample cell and dispersed using ultrasound. The same sample was analyzed six times in a row, each analysis lasting 1-2 minutes, and the average of the six measurements was finally used for discussion. The volume / number distribution data was directly exported using the software provided by the instrument.

[0072] (2) Three-dimensional X-ray microscopy (3D-XRM) detection

[0073] The 3D XRM test was conducted using a Zeiss Xradia 620Versa 3D X-ray microscope. About 40-60 mg of simulated lunar soil was placed in a scanning-storage integrated container and mounted on a Zeiss specimen holder for scanning using phase contrast micro-tomography. The scanning voxel sizes were 3μm and 1μm, respectively, the X-ray tube energies used were 90kV and 12W, and the optical objective was 4X. The exposure time for one projection was 4s, and 995 and 989 projections were collected, respectively. Avizo 3D 2022.2 was used to perform 3D reconstruction and particle segmentation on the slice data. The segmented data was measured in 3D using "label analysis". The "EqDiameter" parameter was selected to obtain the equivalent spherical volume diameters of more than 220,000 and more than 30,000 particles, respectively.

[0074] The scanning-storage integrated container for storing lunar soil samples includes a receiving bottle and a sample cup that can be placed in the receiving bottle, and the receiving bottle and the sample cup are sealed by a sealing gasket. The sample cup is made of quartz glass, and the receiving bottle is made of polytetrafluoroethylene.

[0075] The structures of the holding bottle and the sample cup are as follows: Figure 2 As shown in a and 2b.

[0076] The container bottle comprises a bottle body (2) and a bottle cap (1) detachably connected to the bottle body (2), the lower part of the bottle cap (1) is provided with a first internal thread, and the upper part of the bottle body (2) is provided with a first external thread matching the first internal thread. The container bottle is a cylindrical structure, the inner diameter of the bottle body (2) is 21 mm, the height is 33 mm, and the height of the bottle cap (1) is 8 mm, and the inner diameter is 25 mm.

[0077] The sample cup comprises a cup body (4) and a cup cover (3) detachably connected to the cup body (4), wherein the cup body (4) is provided with a storage section (5), a gradual change channel (6) with a gradually decreasing diameter, and a detection section (7) in sequence, wherein the lower part of the cup cover (3) is provided with a second internal thread, and the upper part of the storage section (5) of the cup body (4) is provided with a second external thread matching the second internal thread. The cup cover (3) of the sample cup has an inner diameter of 14 mm and a height of 8 mm, wherein the inner diameter of the storage section (5) of the cup body (4) is 10 mm and a height of 10 mm, the height of the gradual change channel (6) is 6 mm, and the inner diameter of the detection section (7) is 3 mm and a height of 6 mm.

[0078] (3) Optical microscope inspection

[0079] Optical microscopy was performed using a Zeiss Smartzoom 5 microscope. Before observation, the sample placed on the glass slide was mechanically shaken in order to better disperse the particles.

[0080] The sample with a range of about 17.60×13.17 mm was scanned using the hybrid mode of the Smartzoom 5 microscope (36.1% reflected light, 54.3% transmitted light source), with a resolution of 1.7 μm and an exposure time of 0.75 ms. Using Avizo3D2022.2 software, the "EqDiameter" parameter analysis was selected in the two-dimensional measurement, and the equivalent circular area diameter (EQPC) of a total of 27,052 particles was obtained.

[0081] (4) Scanning electron microscope detection

[0082] The scanning electron microscopy experiment used a Zeiss Sigma 360 field emission scanning electron microscope. Before the scanning electron microscopy observation, the simulated lunar soil was first evenly dispersed and embedded in an epoxy resin target with a diameter of 25.4 mm. The cross section was exposed by mechanical polishing, and the surface of the sample was carbon-plated to increase the surface conductivity.

[0083] The electron microscope scanning working distance was ~5 mm, and a total of 12,656 original images with a resolution of 54.15 nm were obtained at an accelerating voltage of 1.5 kV and a current of 2.0 nA. Avizo 3D 2022.2 software was also used, and the "EqDiameter" parameter in the two-dimensional measurement was selected to obtain the equivalent circular area diameter (EQPC) of 977,951 particles.

[0084] Example 3. Results of different detection methods

[0085] Laser diffraction particle size analyzer (LDPS) is widely used in particle size measurement due to its wide adaptability, good measurement reproducibility and high measurement accuracy. Therefore, this paper uses the data measured by laser diffraction particle size analyzer as a reference, compares the measurement results of other methods, and determines the applicable measurement range of each method.

[0086] (1) Laser diffraction particle size analyzer (LDPS) and three-dimensional X-ray microscope (3D-XRM) detection

[0087] The particle number distribution is Figure 3 a, XRM particle number distribution curve is rightward compared to LDPS curve, XRM-3μm number distribution curve is similar to LDPS and Smartzoom 5, showing rightward asymmetric distribution with prominent peak. Figure 3 b), 1μm voxels supplement the information of particles between 1-3μm, but have no significant effect on the particle size-volume distribution. The data of both below 10μm are almost 0, and the volume distribution data of 1μm voxels tend to have extremely high / low values ​​in the coarse particle range, and the curve is obviously ups and downs. The overall shape of the particle volume distribution curves of the two voxels is similar, both showing bimodal distribution characteristics. The main peak particle size and LDPS data are basically corresponding, and the secondary peak particle size has a slight deviation, which is in good agreement with the LDPS curve.

[0088] The Boltzmann function (Equation 1) can well characterize the S-shaped change of the area cumulative percentage with the particle size by performing nonlinear fitting on the area cumulative percentage data. Figure 4 ). The XRM curves of the two voxels have a high degree of overlap, and the XRM-1μm curve is slightly to the left of the XRM-3μm curve. The XRM-3μm curve is closer to the LDPS curve in the coarse-grained part. However, the morphological characteristics of both are similar to the LDPS curve, especially in the part above 75μm, which is very close and has considerable credibility, indicating the feasibility of XRM non-destructive measurement of particle size instead of LDPS lossy measurement.

[0089]

[0090] In formula (1), A1, A2, B, and D0 are curve fitting characteristic values, A1 is the value of the asymptote when D→-∞, A2 is the value of the asymptote when D→+∞, and the fitting curve is about point Symmetry, point The slope of the tangent line at is Reflects the steepness of the slope of the curve. Since the particle size distribution data are all positive, the fitting result only uses the positive part of the Boltzmann function, and Cum (%) | D = D min =0, Cum(%)|D=D max=100, so A2 should be a fixed value of 100, A1<0, and the specific value depends on the best fitting result.

[0091] (2) Test results of laser diffraction particle size analyzer (LDPS) and optical microscope (OM)

[0092] The particle number distribution is Figure 3 a, LDPS fine particles account for a significant percentage of the number, while OM coarse particles account for a significant percentage of the number, but the curves of the two are similar, both showing a right-skewed asymmetric distribution. Figure 3 b), the LDPS volume distribution curve is left-skewed and asymmetric, and the OM area distribution curve is overall left-skewed compared to the LDPS curve, showing an almost symmetrical single-peak distribution. The main peak position corresponds to the secondary peak position of the LDPS curve, but the peak value is higher.

[0093] The same fitting method was used to perform Boltzmann fitting on the XRM volume accumulation percentage data ( Figure 5 ). Taking XRM as a control, the coarse particle part (>75μm) is better detected. The OM curve is discrete from the LDPS curve above 75μm. As the particle size decreases, the OM curve below 75μm gradually approaches the LDPS curve, indicating that the OM curve has a narrow coverage range and is more suitable for the detection of medium and fine particles.

[0094] (3) Laser diffraction particle size analyzer (LDPS) and scanning microscope (SEM) detection

[0095] The particle number distribution is Figure 3 a, SEM particle size range is 0.10-386.80μm, the detection limit is coarser than LDPS, finer than OM and XRM, so the corresponding particle number distribution curve is between LDPS and OM / XRM, the curve is right-skewed asymmetric distribution, similar to LDPS. Figure 3 b), also limited by the scanning resolution and scanning range, SEM seriously underestimates the coarse particle fraction, and the maximum particle size detected is only 386.80μm. Therefore, the peak particle size of the particle area distribution curve of SEM is the smallest, and there is a lack of coarse particles. The main peak particle size of SEM is slightly different from the position of the secondary peak of LDPS, which may be due to the mechanical polishing in the preparation process of SEM samples, which will interfere with the particle distribution.

[0096] The same fitting method was used to perform Boltzmann fitting on the SEM area cumulative percentage data ( Figure 6 ), the SEM fitting curve only fits well with LDPS in the fine particle part (<10 μm).

[0097] Example 4. Combined method for detecting particle size

[0098] From the above, it can be seen that within the measurable particle size range of different tests, only the volume / area accumulation data in the local range are consistent with LDPS. The XRM curve has the best overall consistency with the LDPS curve, especially for coarse particles above 75μm. OM is more suitable for detecting medium and fine particles below 75μm, but SEM measurement is more reliable for particle sizes below 10μm.

[0099] In order to make full use of the measurement advantages of different tests, the data obtained from multiple tests are segmented and spliced ​​for fitting. Figure 7 a. Specifically:

[0100] 1) Single measurement method: XRM is used to measure particle size, which is suitable for samples that require no damage, no pollution, and no contact;

[0101] 2) Dual measurement method: XRM and OM measurements are used simultaneously, and OM correction is used for particle size data below 75 μm;

[0102] 3) Three measurement methods: XRM, OM and SEM are used for measurement at the same time, and SEM is used to correct the particle size data below 10μm. It is suitable for particles below 10μm that need to be accurately measured.

[0103] In the experiment of this application, XRM-3μm analyzed a larger sample volume than XRM-1μm, and the curve was closer to LDPS, so XRM-3μm was selected to represent the data of XRM for fitting. Figure 7 b shows the fitting results of single measurement method XRM, dual measurement method XRM (>75μm) + OM (<75μm), and triple measurement method XRM (>75μm) + OM (10-75μm) + SEM (<10μm). As the joint measurement method is continuously improved, the correction effect of the fine particle part is better, and the fitting curve gradually approaches the measurement result of LDPS. The joint measurement effectively makes up for the shortcomings of a single method, broadens the reliable measurement range, and improves the accuracy of particle size measurement.

[0104] The fitting curves of this test are shown in equations 2 and 3, where the values ​​of D1 and D2 depend on the particle size characteristics of the test sample. For any sample, the general fitting formula shown in equation 4 is used.

[0105]

[0106] Among them, A1, A2, B, and D0 are curve fitting characteristic values, and their physical meanings are the same as those in formula 1; D1 and D2 are fitting ranges applicable to different measurement methods, which are determined by the test sample.

[0107] Example 5. Validation of three-dimensional X-ray microscopy (3D-XRM) detection

[0108] The sample subjected to 3D-XRM detection in Example 2 was taken out from the scanning-storage integrated container, detected again using LDPS, and the volume / number distribution data (LDPS2) was directly derived using the software provided by 3D-XRM. Figure 8 The results show that the use of three-dimensional X-ray microscopy for particle size detection will not cause damage to the sample.

[0109] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for detecting soil particle size, comprising the following steps: (1) a step of measuring the particle size of soil samples using computer tomography; and optionally (2) performing image processing on the data obtained by the particle size detection to obtain a particle size distribution curve of the soil sample; in, In step (2), curve fitting is performed using the curve fitting characteristic values ​​obtained by the image processing to obtain the particle size distribution curve; The curve fitting characteristic values ​​include an equivalent spherical volume diameter and / or an equivalent circular area diameter; The curve fitting is performed using formula (4): Among them, A1, A2, B, and D0 are curve fitting characteristic values, A1 is the value of the asymptote when D→-∞, A2 is the value of the asymptote when D→+∞, and the fitting curve is about point Symmetry, point The slope of the tangent line at is D1 and D2 are the particle size ranges of the soil samples. and, 2. The method according to claim 1, characterized in that The soil sample is a lunar soil sample.

3. The method according to claim 1, characterized in that: In step (1), the computer tomography technique is performed by a three-dimensional X-ray microscope.

4. The method according to claim 3, characterized in that The sample used for detection by the three-dimensional X-ray microscope is placed in a scanning-storage integrated container, which includes a containing bottle and a sample cup that can be placed in the containing bottle, the containing bottle includes a bottle body and a bottle cap detachably connected to the bottle body, the sample cup includes a cup body and a cup cover detachably connected to the cup body, wherein the cup body is sequentially provided with a storage section, a gradual channel with a gradually decreasing diameter, and a detection section.

5. The method according to claim 4, characterized in that A sealing gasket is provided between the containing bottle and the sample cup; and / or In the sample cup, a second internal thread is disposed at the lower portion of the cup cover, and a second external thread matching the second internal thread is disposed at the upper portion of the storage section of the cup body; and / or In the containing bottle, a first internal thread is disposed at the lower portion of the bottle cap, and a first external thread matching the first internal thread is disposed at the upper portion of the bottle body; and / or In the cup body of the sample cup, the height of the storage section is 5-15mm, and the inner diameter of the storage section is 5-15mm; the height of the gradual channel is 4-8mm; the height of the detection section is 4-10mm, and the inner diameter of the detection section is 1.5-4mm; the height of the cup cover of the sample cup is 5-10mm, and the inner diameter of the cup cover is 10-20mm; and / or The containing bottle is a cylindrical structure; and / or The sample cup is made of quartz glass; and / or The material of the containing bottle is polytetrafluoroethylene.

6. The method according to claim 5, characterized in that The number of the sealing pads is 1-5; and / or The inner diameter of the bottle body is 15-25 mm, and the height of the bottle body is 30-40 mm; the inner diameter of the bottle cap is 20-30 mm, and the height of the bottle cap is 5-10 mm.

7. The method according to claim 4, characterized in that The detection section in the scanning-storage integrated container corresponding to the sample cup is detected.

8. The method according to claim 3, characterized in that The three-dimensional X-ray microscope is selected from Xradia620Versa three-dimensional X-ray microscope.

9. The method according to claim 8, characterized in that The conditions for particle size detection using the Xradia 620Versa 3D X-ray microscope include: scanning using phase contrast micro-tomography, scanning voxel sizes of 2-4μm and 0.5-1.5μm, X-ray tube energies of 85-95kV and 10-14W, an optical objective lens of 4X, and an exposure time of 3-5s for one projection.

10. The method according to claim 8, characterized in that Image processing of data obtained by Xradia 620Versa 3D X-ray microscope includes: using Avizo 3D 2022.2 software to obtain the equivalent spherical volume diameter of different particles.

11. The method according to any one of claims 1 to 10, characterized in that In step (1), the particle size detection further comprises performing particle size detection on the soil sample using an optical microscope and / or a scanning electron microscope.

12. The method according to claim 11, characterized in that The soil samples for the optical microscopy examination were placed on glass slides.

13. The method according to claim 12, characterized in that The soil samples were mechanically shaken before testing.

14. The method according to claim 11, characterized in that The soil samples for the SEM examination were placed in epoxy resin, and the cross sections were exposed by mechanical polishing.

15. The method according to claim 14, characterized in that The soil samples were treated with carbon coating on the surface before testing.

16. The method according to claim 11, characterized in that The optical microscope is selected from a Smartzoom 5 microscope.

17. The method according to claim 11, characterized in that The scanning electron microscope was selected from a Sigma 360 field emission scanning electron microscope.

18. The method according to claim 16, characterized in that The conditions for particle size measurement using the Smartzoom 5 microscope include: mixed mode, resolution of 1-2.5 μm, and exposure time of 0.5-2 ms.

19. The method according to claim 16, characterized in that The conditions for particle size detection using the Smartzoom 5 microscope include: 35-40% reflected light and 50-60% transmitted light source mixture, resolution of 1.5-2μm, and exposure time of 0.5-1ms.

20. The method according to claim 17, characterized in that The conditions for detection using a Sigma 360 field emission scanning electron microscope include: accelerating voltage of 1.0-2.0 kV, current of 1.5-2.5 nA, working distance of 4-6 mm, and resolution of 50-60 nm.

21. The method according to claim 16, characterized in that Image processing of the data obtained by the Smartzoom 5 microscope included: using Avizo 3D 2022.2 to obtain the equivalent circular area diameters of different particles.

22. The method according to claim 17, characterized in that Image processing of data obtained by Sigma 360 field emission scanning electron microscope included: using Avizo 3D 2022.2 to obtain the equivalent circular area diameter of different particles.

23. The method according to claim 11, characterized in that The method comprises one of the following (AC): (A) The particle size of soil samples was detected using a three-dimensional X-ray microscope, and curve fitting was performed using the curve fitting characteristic values ​​obtained using the three-dimensional X-ray microscope; (B) using a three-dimensional X-ray microscope and an optical microscope to detect the particle size of the soil sample, using the particle size data obtained by the three-dimensional X-ray microscope to perform curve fitting, and then for the particle size data below 75 μm, using the particle size data obtained by the optical microscope to correct the fitting curve; (C) The particle size of soil samples was detected using a three-dimensional X-ray microscope, an optical microscope, and a scanning electron microscope. The particle size data obtained using the three-dimensional X-ray microscope were used to perform curve fitting. Then, for the particle size data of 10-75 μm, the particle size data obtained using the optical microscope were used to correct the fitting curve. For the particle size data of less than 10 μm, the particle size data obtained using the scanning electron microscope were used to correct the fitting curve.

24. Use of the method according to any one of claims 1 to 23 in detecting the particle size of soil.

25. The method according to claim 24, characterized in that The soil is lunar soil.

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