A method for detecting the sphericity of a powder

Abstract

The application relates to a powder sphericity detection method and relates to the technical field of powder property detection, and solves the problem of poor accuracy of the existing powder sphericity detection method. The detection method comprises the following steps: randomly extracting a powder to be detected, and obtaining a contour descriptor of each powder particle; calculating a geometric shape factor and a mesoscopic descriptor of each powder particle according to the contour descriptor of each powder particle; classifying the powder to be detected according to the cross-section morphology of the powder particles, and counting the number of powder particles in different cross-section morphology types of powder; calculating the average sphericity value of each cross-section morphology type of powder according to the number of powder particles in each cross-section morphology type of powder and the geometric shape factor and the mesoscopic descriptor of each powder particle; and calculating the final sphericity of the powder to be detected based on the average sphericity value of the cross-section morphology type of powder. The application can guarantee the scientificity and accuracy of the powder sphericity detection result.

Description

Technical Field

[0001] This invention relates to the field of powder property testing technology, and in particular to a method for testing the sphericity of powder. Background Technology

[0002] Selective laser melting (SLM) is an additive manufacturing technology for metal materials based on powder bed deposition. First, the CAD model of the part is sliced ​​into layers. Using a pre-deposition powder method, a scanning galvanometer drives a laser beam, under computer control, to scan the selected area of ​​the alloy powder layer along a graphic trajectory. This melts and deposits a thin metal layer with the same thickness as the slice and the shape of a cross-section of the part, until a metal part identical to the CAD model is manufactured. Since metal powder is used as the raw material, the quality of the powder itself becomes particularly important. Among these, the sphericity of the powder directly affects the quality of the formed product and the stability of the forming process.

[0003] Currently, there are some domestic standards for testing the sphericity of powders. However, these standards have significant shortcomings in their understanding of the concept of sphericity and their testing methods, resulting in poor accuracy of current powder sphericity test results. In existing national or industry standards (GB / T 37406-2019 "Test Method for Sphericity of Spherical Silica Micropowder for Electronic Packaging - Particle Dynamic Photoelectric Projection Method", YS / T-1491-2021 "Determination Method for Sphericity of Nickel-Based High-Temperature Alloy Powder - Scanning Electron Microscopy Method", GB / T 39251-2020 "Characteristics Method for Performance of Additive Manufacturing Metal Powders"), sphericity is defined using a single descriptor (intermediate shape descriptor), which is the degree to which the planar projection image of a single particle approximates a standard circle (the ratio of the equivalent diameter of the maximum cross-sectional area of ​​the powder particle to the equivalent diameter of the maximum cross-sectional perimeter), calculated using the formula Q = rarea / Rperimeter.

[0004] Currently, the most accurate standard for defining powder shape and morphology is GB / T 15445.6-2014, "Expression of Particle Size Analysis Results Part 6: Qualitative and Quantitative Expression of Particle Shape and Morphology." This standard clearly shows that the sphericity defined in this way is essentially the roundness of the powder, not true sphericity. GB / T 15445.6-2014 reveals that the concept of roundness only applies to particles with smooth circumferences; that is, the concept of roundness is for near-spherical or elliptical individual particles. Based on this limitation, the calculation formula Q = rarea / Rperimeter is clearly reasonable. However, for additive manufacturing technology, the powders used often exhibit a large number of "satellite powders" (see...). Figure 1As shown in the diagram, the circumference of the powder at this point is no longer smooth, and it is essentially two or more powders stuck together. If the roundness calculation formula is still used, the "satellite powder" must first be assumed to be a smooth spherical powder to meet the calculation requirements. However, this assumption is clearly unreasonable. For example, as... Figure 2 As shown in Figures (a) and (b), the particles are clearly irregular at this point, but if calculated according to the concept of roundness, their sphericity has reached 90.8% and 91.1%, respectively, exhibiting the characteristics of high sphericity. Figure 2 In Figures (c) and (d), the particle morphology is significantly closer to spherical, but the calculated sphericity is only 90.4% and 90.6%, respectively. This shows that... Figure 2 In Figures (a) and (b), the actual sphericity of the particles is significantly lower than the calculated sphericity. If this powder is used for additive manufacturing, the low sphericity of the powder will inevitably lead to problems such as uneven powder spreading, agglomeration and bridging, resulting in defects such as pores, cracks or lack of fusion in the formed alloy. This will significantly reduce the mechanical properties (especially fatigue properties) of the formed parts and bring hidden dangers to the use of the formed parts.

[0005] Therefore, none of the above three standards can accurately detect the sphericity of powder. Although GB / T 15445.6-2014 accurately defines the shape of particles, it does not provide a method for detecting sphericity. Furthermore, YS / T1297-2019, "Method for Determination of Sphericity of Titanium and Titanium Alloy Powders," defines spherical particles (powder particles whose ratio of major axis length to minor axis length is not greater than 1.2). However, as can be seen from the definition, particles with a ratio of 1.2 are clearly non-spherical particles, and this standard can only calculate the sphericity ratio of powder, not its sphericity.

[0006] In summary, none of the aforementioned methods for detecting powder sphericity can guarantee the accuracy of the results, which has become a major bottleneck in the application of laser selective melting forming technology. Therefore, a new method for detecting powder sphericity is urgently needed to ensure the scientific validity and accuracy of the test results. Summary of the Invention

[0007] In view of this, the present invention provides a method for detecting the sphericity of powder, the main purpose of which is to improve the scientificity and accuracy of powder sphericity detection.

[0008] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0009] On one hand, embodiments of the present invention provide a method for detecting the sphericity of powder, which includes the following steps:

[0010] Steps for calculating geometry factor and mesoscopic descriptor: Randomly select the powder to be tested and obtain the contour descriptor of each powder particle; calculate the geometry factor and mesoscopic descriptor of each powder particle based on the contour descriptor of each powder particle.

[0011] Classification and statistical steps: Classify the powder to be tested according to the cross-sectional morphology of the powder particles, and count the number of powder particles in powders with different cross-sectional morphology types;

[0012] Steps for calculating the average sphericity value: Based on the number of powder particles in each cross-sectional morphology type of powder and the geometric shape factor and mesoscopic descriptor of each powder particle, calculate the average sphericity value of the powder for each cross-sectional morphology type.

[0013] The final sphericity calculation step is as follows: Based on the average sphericity value of powders of all cross-sectional morphology types, calculate the weighted average sphericity of the powder to be tested; wherein, the weighted average sphericity is the final sphericity of the powder to be tested.

[0014] Preferably, in the step of calculating the geometry factor and mesoscopic descriptor:

[0015] The contour descriptor of each powder particle is obtained by using any one of the following methods: dynamic imaging, metallography, and scanning electron microscopy.

[0016] Preferably, in the step of calculating the geometric shape factor and mesoscopic descriptor: the contour descriptor is the projected area A, roundness C, and minimum circumscribed circle diameter d. cmin The diameter of the largest inscribed circle d imax Thickness E, Quantity N, Perimeter P, Surface Area S, Volume V, Particle Area Equivalent Diameter x A Thickness x of elongated particles E Maximum Freette diameter x Fmax Minimum Freret diameter x Fmin The Freret diameter x perpendicular to the minimum Freret diameter LF The geodesic length x of the elongated particle LG The length of the major axis of the Legendre ellipse x Lmax The length of the minor axis of the Legendre ellipse x Lmin Particle perimeter equivalent diameter x P , Particle surface area equivalent diameter x S Particle volume equivalent diameter x V One or more of them.

[0017] Preferably, in the step of calculating the geometry factor and mesoscopic descriptor: the geometry factor is one or more of ellipticity, aspect ratio, modification ratio, and compactness; wherein, the ellipticity is x Lmin / x LmaxThe aspect ratio is x. Fmin / x Fmax The modification ratio is d. cmin / d imax The compactness is .

[0018] Preferably, in the step of calculating the geometry factor and mesoscopic descriptor: if the powder particles are smooth particles, the corresponding geometry factor is the ellipticity; if the powder particles are satellite powder particles, the corresponding geometry factor is the aspect ratio; if the powder particles are agglomerated particles, the corresponding geometry factor is the compactness; if the powder particles are irregular particles, the corresponding geometry factor is the modification ratio.

[0019] Preferably, in the step of calculating the geometry factor and mesoscopic descriptor: the mesoscopic descriptor is roundness; wherein, the roundness is x A / x P .

[0020] Preferably, in the classification and statistical steps: the cross-sectional morphology of the powder particles includes one or more of the following: smooth particles, satellite particles, agglomerated particles, and irregular particles.

[0021] Preferably, in the step of calculating the average sphericity value:

[0022] For each cross-sectional morphology type of powder, the average sphericity value is calculated using the following formula:

[0023] Q_average = ∑(intermediate shape descriptor × geometric shape factor) / number of particles of powder corresponding to the cross-sectional morphology type;

[0024] Wherein, Q_average is the average sphericity value of powder for each cross-sectional morphology type.

[0025] Preferably, in the step of calculating the final sphericity:

[0026] Q-weighted = ∑{Q-average × (number of particles of each cross-sectional morphology type / total number of particles of all cross-sectional morphology types)};

[0027] Wherein, Q-weighted is the weighted average sphericity of the powder to be tested.

[0028] Preferably, the powder is a metal powder or a ceramic powder.

[0029] Preferably, the metal powder is a metal powder used in powder metallurgy or a metal powder used in additive manufacturing.

[0030] Compared with the prior art, the powder sphericity detection method of the present invention has at least the following beneficial effects:

[0031] This invention provides a method for detecting the sphericity of powder, mainly including the following steps: randomly selecting powder to be tested and obtaining the contour descriptor of each powder particle; calculating the geometric shape factor and mesoscopic descriptor of each powder particle based on the contour descriptor of each powder particle; classifying the powder to be tested according to the cross-sectional morphology of the powder particles and counting the number of powder particles in different cross-sectional morphology types; calculating the average sphericity value of each cross-sectional morphology type of powder based on the number of powder particles in each cross-sectional morphology type of powder and the geometric shape factor and mesoscopic descriptor of each powder particle; calculating the weighted average sphericity value of the powder to be tested based on the average sphericity value of all cross-sectional morphology types of powder; wherein, the weighted average sphericity value is the final sphericity of the powder to be tested. The following explanation is provided regarding the above scheme: Compared with existing detection methods, the above scheme of this invention innovatively proposes to use a composite shape descriptor (intermediate shape descriptor × geometric shape factor) to calculate powder sphericity. This composite descriptor comprehensively considers both the theoretically calculated value of powder sphericity and the actual shape deviation. Compared with the traditional single theoretical calculation result, the composite descriptor is closer to the actual situation and is therefore more scientific and accurate. At the same time, this method has the advantages of simple operation, high detection efficiency, and high accuracy.

[0032] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of satellite powder particles and normal powder particles mentioned in the background technology;

[0034] Figure 2 It is a cross-sectional morphology diagram of the powder particles mentioned in the background art;

[0035] Figure 3 It describes the powder morphology of smooth particles;

[0036] Figure 4 It refers to the powder morphology of satellite powder particles;

[0037] Figure 5 It is the morphology of the agglomerated particles;

[0038] Figure 6 It is an irregular particle powder morphology;

[0039] Figure 7 The morphology of the particulate powder is as shown in Example 1;

[0040] Figure 8 The morphology of the particles and powders in Example 2;

[0041] Figure 9 This is the morphology of the particulate powder in Example 3. Detailed Implementation

[0042] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0043] This invention is the first to propose using the concept of a composite shape descriptor (interrelated shape descriptor × geometric shape factor) to calculate powder sphericity, ensuring the scientific validity and accuracy of powder sphericity detection results. Furthermore, this method offers advantages such as ease of operation, high detection efficiency, and high accuracy. The specific solution of this invention is as follows:

[0044] This invention provides a method for detecting the sphericity of powder, which mainly includes the following steps:

[0045] Steps for calculating the geometry factor and mesoscopic descriptor: Randomly select the powder to be tested and obtain the contour descriptor of each powder particle; calculate the geometry factor and mesoscopic descriptor of each powder particle based on the contour descriptor of each powder particle.

[0046] In this step, the contour descriptor of each powder particle is obtained using any one of the following methods: dynamic imaging, metallography, and scanning electron microscopy.

[0047] The contour descriptor is the projected area A, roundness C, and minimum circumscribed circle diameter d. cmin The diameter of the largest inscribed circle d imax Thickness E, Quantity N, Perimeter P, Surface Area S, Volume V, Particle Area Equivalent Diameter x A Thickness x of elongated particles E Maximum Freette diameter x Fmax Minimum Freret diameter x Fmin The Freret diameter x perpendicular to the minimum Freret diameter LF The geodesic length x of the elongated particle LG The length of the major axis of the Legendre ellipse x Lmax The length of the minor axis of the Legendre ellipse x Lmin Particle perimeter equivalent diameter x P , Particle surface area equivalent diameter x S Particle volume equivalent diameter x V One or more of them.

[0048] In the step of calculating the geometry factor and mesoscopic descriptor: the geometry factor is one or more of ellipticity, aspect ratio, modification ratio, and compactness. The ellipticity is x... Lmin / x Lmax The aspect ratio is x. Fmin / x Fmax The modification ratio is d. cmin / d imax The relationship between the largest inscribed circle diameter and the smallest circumscribed circle diameter; the compactness is... This indicates the degree to which the particles are nearly round.

[0049] In the step of calculating the geometric shape factor and mesoscopic descriptor: the mesoscopic descriptor is roundness; the roundness is x. A / x P .

[0050] Classification and statistical steps: The powder to be tested is classified according to the cross-sectional morphology of the powder particles, and the number of powder particles in different cross-sectional morphology types is counted.

[0051] The cross-sectional morphology of the powder particles includes smooth particles (see...). Figure 3 As shown, surface roughness (e.g., profile arithmetic mean deviation Ra) < 0.1 μm, satellite powder particles (see...) Figure 4 As shown, primary and secondary particles are connected to each other, and the diameter of the secondary particle is less than 1 / 2 of the radius of the primary particle; and there are adhered particles (see...). Figure 5 As shown, the minimum circumscribed circle diameter of the particle aggregate is greater than 1.5 times the maximum diameter of a single primary particle) and irregular particles (see...). Figure 6 As shown, it is one or more of the following: particle roundness < 0.8 or aspect ratio > 3.

[0052] Steps for calculating the average sphericity value: Based on the number of powder particles in each cross-sectional morphology type of powder and the geometric shape factor and mesoscopic descriptor of each powder particle, calculate the average sphericity value of the powder for each cross-sectional morphology type.

[0053] Q_average = ∑(intermediate shape descriptor × geometric shape factor) / number of particles of powder corresponding to the cross-sectional morphology type;

[0054] Wherein, Q_average is the average sphericity value of powder for each cross-sectional morphology type.

[0055] The final sphericity calculation steps are as follows: Based on the average sphericity value of powders of all cross-sectional morphology types, calculate the weighted sphericity of the powder to be tested.

[0056] Q-weighted = ∑{Q-average × (number of particles of each cross-sectional morphology type / total number of particles of all cross-sectional morphology types)};

[0057] Wherein, Q-weighted is the weighted average sphericity of the powder to be tested.

[0058] Preferably, the powder is a metal powder or a ceramic powder.

[0059] Preferably, the metal powder is a metal powder used in powder metallurgy or a metal powder used in additive manufacturing.

[0060] The present invention will be further illustrated below with specific embodiments:

[0061] Example 1

[0062] This embodiment provides a method for detecting the sphericity of TC4 alloy powder used in additive manufacturing, including the following steps:

[0063] Steps for calculating the geometric shape factor and mesoscopic descriptor: Randomly select the powder to be tested, and use dynamic image analysis technology to obtain the contour descriptor of each powder particle. The contour descriptor includes: the minimum circumscribed circle diameter (d...). cmin ), the largest inscribed circle diameter (d) imax ), the length of the major axis of the Legendre ellipse (x) Lmax ), the length of the minor axis of the Legendre ellipse (x) Lmin ), maximum Feret diameter (x Fmax ), minimum Freette diameter (x Fmin The values ​​for the area (A) and the projected area are shown in Table 1.

[0064] The geometry factor and inter-descriptor of each powder particle are calculated based on the obtained contour descriptor of each powder particle, as shown in Table 2.

[0065] Classification and statistical steps: The powder to be tested is classified according to the cross-sectional morphology of the powder particles, and the number of powder particles in different cross-sectional morphology types is counted (as shown in Table 1).

[0066] Steps for calculating the average sphericity value: Based on the concept of composite shape descriptors, the average sphericity value of powder for each cross-sectional morphology type is calculated according to the number of powder particles in each cross-sectional morphology type, the geometric shape factor of each powder particle, and the mesoscopic descriptor.

[0067] Q_average = ∑(intermediate shape descriptor × geometric shape factor) / number of particles of powder corresponding to cross-sectional morphology type.

[0068] Calculation results: The average sphericity of smooth particles is Q_average = 91.6%, the average sphericity of satellite powder particles is Q_average = 85.2%, the average sphericity of agglomerated particles is Q_average = 75.4%, and the average sphericity of irregular particles is Q_average = 48.0%.

[0069] The final sphericity calculation steps are as follows: Based on the average sphericity value of powders of all cross-sectional morphology types, calculate the weighted sphericity of the powder to be tested.

[0070] Q-weighted = ∑{Q-average × (number of particles of each cross-sectional morphology type / total number of particles of all cross-sectional morphology types)} = 91.6% × 10 / 20 + 85.2% × 5 / 20 + 75.4% × 2 / 20 + 48.0% × 3 / 20 = 81.8%, therefore the final sphericity of this batch of powder is 81.8%.

[0071] As can be seen from Table 2, if the traditional roundness (x) is used... A / x P If the sphericity is calculated using the concept of sphericity, the sphericity result of this batch of powder is 91.5%, while the calculation result in this embodiment is 81.8%. Figure 7 The morphology of the 20 powder particles in this embodiment is shown from... Figure 7 As can be seen from the data, the sphericity of this batch of powder is significantly lower. Therefore, the calculation results in this embodiment are closer to the actual situation of this batch of powder.

[0072] Table 1 shows the particle profile descriptors, particle type, and quantity of TC4 alloy powder used in additive manufacturing in Example 1.

[0073] Table 1

[0074]

[0075] Table 2 shows the geometry factor and related descriptors for each powder particle.

[0076] Table 2

[0077]

[0078] Example 2

[0079] This embodiment provides a method for detecting the sphericity of AlSi10Mg alloy powder for additive manufacturing, including the following steps:

[0080] Steps for calculating the geometric shape factor and mesoscopic descriptor: Randomly select the powder to be tested, and use dynamic image analysis technology to obtain the contour descriptor of each powder particle. The contour descriptor includes: the minimum circumscribed circle diameter (d...). cmin ), the largest inscribed circle diameter (d) imax ), the length of the major axis of the Legendre ellipse (x)Lmax ), the length of the minor axis of the Legendre ellipse (x) Lmin ), maximum Feret diameter (x Fmax ), minimum Freette diameter (x Fmin The values ​​for the area (A) and the projected area are shown in Table 3.

[0081] The geometry factor and inter-descriptor of each powder particle are calculated based on the obtained contour descriptor of each powder particle, as shown in Table 4.

[0082] Classification and statistical steps: The powder to be tested is classified according to the cross-sectional morphology of the powder particles, and the number of powder particles in different cross-sectional morphology types is counted (as shown in Table 3).

[0083] Steps for calculating the average sphericity value: Based on the concept of composite shape descriptors, the average sphericity value of powder for each cross-sectional morphology type is calculated according to the number of powder particles in each cross-sectional morphology type, the geometric shape factor of each powder particle, and the mesoscopic descriptor.

[0084] Q_average = ∑(intermediate shape descriptor × geometric shape factor) / number of particles of powder corresponding to cross-sectional morphology type.

[0085] Calculation results: The average sphericity of smooth particles is Q_average = 90.7%, the average sphericity of satellite particles is Q_average = 79.4%, the average sphericity of agglomerated particles is Q_average = 87.6%, and the average sphericity of irregular particles is Q_average = 54.7%.

[0086] The final sphericity calculation steps are as follows: Based on the average sphericity value of powders of all cross-sectional morphology types, calculate the weighted sphericity of the powder to be tested.

[0087] Q-weighted = ∑{Q-average × (number of particles of each cross-sectional morphology type / total number of particles of all cross-sectional morphology types)} = 90.7% × 13 / 20 + 79.4% × 4 / 20 + 87.6% × 2 / 20 + 54.7% × 1 / 20 = 86.4%, therefore the final sphericity of this batch of powder is 86.4%.

[0088] As can be seen from Table 4, if the traditional roundness (x) is used... A / x P The sphericity of the powder was calculated using the concept of sphericity, and the result was 93.7%, while the result calculated in this embodiment was 86.4%. Figure 8 The morphology of 20 powder particles, from Figure 8 As can be seen from the data, the sphericity of this batch of powder is significantly lower. Therefore, the calculation results of the example are closer to the actual situation of this batch of powder.

[0089] Table 3 shows the particle profile descriptors, particle type, and quantity of AlSi10Mg alloy powder for additive manufacturing.

[0090] Table 3

[0091]

[0092] Table 4 shows the geometry factors and interrelated descriptors for each particle.

[0093] Table 4

[0094]

[0095] Example 3

[0096] This embodiment provides a method for detecting the sphericity of GH4169 alloy powder for additive manufacturing, including the following steps:

[0097] Steps for calculating the geometric shape factor and mesoscopic descriptor: Randomly select the powder to be tested, and use dynamic image analysis technology to obtain the contour descriptor of each powder particle. The contour descriptor includes: the minimum circumscribed circle diameter (d...). cmin ), the largest inscribed circle diameter (d) imax ), the length of the major axis of the Legendre ellipse (x) Lmax ), the length of the minor axis of the Legendre ellipse (x) Lmin ), maximum Feret diameter (x Fmax ), minimum Freette diameter (x Fmin The values ​​for the area (A) and the projected area are shown in Table 5.

[0098] The geometry factor and inter-descriptor of each powder particle are calculated based on the obtained contour descriptor of each powder particle, as shown in Table 6.

[0099] Classification and statistical steps: The powder to be tested is classified according to the cross-sectional morphology of the powder particles, and the number of powder particles in different cross-sectional morphology types is counted (as shown in Table 5).

[0100] Steps for calculating the average sphericity value: Based on the concept of composite shape descriptors, the average sphericity value of powder for each cross-sectional morphology type is calculated according to the number of powder particles in each cross-sectional morphology type, the geometric shape factor of each powder particle, and the mesoscopic descriptor.

[0101] Q_average = ∑(intermediate shape descriptor × geometric shape factor) / number of particles of powder corresponding to cross-sectional morphology type.

[0102] Calculation results: The average sphericity of smooth particles is Q_average = 88.2%, and the average sphericity of satellite powder particles is Q_average = 85.7%.

[0103] The final sphericity calculation steps are as follows: Based on the average sphericity value of powders of all cross-sectional morphology types, calculate the weighted sphericity of the powder to be tested.

[0104] Q-weighted = ∑{Q-average × (number of particles of each cross-sectional morphology type / total number of particles of all cross-sectional morphology types)} = 88.2% × 16 / 20 + 85.7% × 4 / 20 = 87.7%, therefore the final sphericity of this batch of powder is 87.7%.

[0105] As can be seen from Table 6, if the traditional roundness (x) is used... A / x P If the sphericity is calculated using the concept of sphericity, the sphericity result of this batch of powder is 94.1%, while the calculation result in this embodiment is 87.7%. Figure 9 The morphology of the 20 powder particles in this embodiment is shown from... Figure 9 As can be seen from the data, the sphericity of this batch of powder is significantly lower. Therefore, the calculation results in this embodiment are closer to the actual situation of this batch of powder.

[0106] Table 5 shows the particle profile descriptor, particle type, and quantity of TC4 alloy powder for additive manufacturing.

[0107] Table 5

[0108]

[0109] Table 6 shows the geometry factors and interrelated descriptors for each particle.

[0110] Table 6

[0111]

[0112] In summary, the above description is merely a partial representation of the embodiments of the present invention and should not be construed as limiting the scope of the invention. For those skilled in the art, the settings and expressions of the particle profile descriptor acquisition method, particle profile descriptor content, particle classification method, particle quantity, particle geometric factors, and interrelated descriptors can be adjusted according to actual needs. Therefore, various other corresponding changes and modifications made based on the technical solutions and concepts of the present invention still fall within the scope of protection covered by the present invention.

Claims

1. A method for detecting the sphericity of powder, characterized in that, It includes the following steps: Steps for calculating geometry factor and mesoscopic descriptor: Randomly select the powder to be tested and obtain the contour descriptor of each powder particle; calculate the geometry factor and mesoscopic descriptor of each powder particle based on the contour descriptor of each powder particle. Classification and statistical steps: Classify the powder to be tested according to the cross-sectional morphology of the powder particles, and count the number of powder particles in powders with different cross-sectional morphology types; Steps for calculating the average sphericity value: Based on the number of powder particles in each cross-sectional morphology type of powder and the geometric shape factor and mesoscopic descriptor of each powder particle, calculate the average sphericity value of the powder for each cross-sectional morphology type. The final sphericity calculation step is as follows: Based on the average sphericity value of powders of all cross-sectional morphology types, calculate the weighted average sphericity of the powder to be tested; wherein, the weighted average sphericity is the final sphericity of the powder to be tested.

2. The method for detecting powder sphericity according to claim 1, characterized in that, In the steps of calculating the geometry factor and mesoscopic descriptor: The contour descriptor of each powder particle is obtained by using any one of the following methods: dynamic imaging, metallography, and scanning electron microscopy.

3. The method for detecting powder sphericity according to claim 1, characterized in that, In the steps of calculating the geometry factor and mesoscopic descriptor: The contour descriptor is the projected area A, roundness C, and minimum circumscribed circle diameter. Maximum inscribed circle diameter Thickness E, Quantity N, Perimeter P, Surface Area S, Volume V, Equivalent Diameter of Particle Area x A Thickness of elongated particles x E Maximum Freette diameter x Fmax Minimum Freret diameter x Fmin The Freret diameter perpendicular to the minimum Freret diameter x LF Geodesic length of elongated particles x LG The length of the major axis of the Legendre inertial ellipse x Lmax The length of the minor axis of the Legendre inertial ellipse x Lmin Particle perimeter equivalent diameter x P Particle surface area equivalent diameter x S Particle volume equivalent diameter x V One or more of them.

4. The method for detecting powder sphericity according to claim 3, characterized in that, In the steps of calculating the geometry factor and mesoscopic descriptor: The geometric shape factor is one or more of ellipticity, aspect ratio, modification ratio, and compactness; Wherein, the ellipticity is x Lmin / x Lmax The aspect ratio is x Fmin / x Fmax The modification ratio is: d cmin / d imax The compactness is .

5. The method for detecting the sphericity of powder according to claim 4, characterized in that, In the steps of calculating the geometry factor and mesoscopic descriptor: If the powder particles are smooth, then the corresponding geometric shape factor is the ellipticity. If the powder particles are satellite powder particles, then the corresponding geometric shape factor is the aspect ratio; If the powder particles are agglomerated, the corresponding geometric shape factor is compactness. If the powder particles are irregular, the corresponding geometric shape factor is the modification ratio.

6. The method for detecting powder sphericity according to claim 3, characterized in that, In the steps of calculating the geometry factor and mesoscopic descriptor: The mesoscopic descriptor is roundness; Wherein, the roundness is x A / x P .

7. The method for detecting the sphericity of powder according to claim 1, characterized in that, In the classification and statistical steps: The cross-sectional morphology of the powder particles includes one or more of the following: smooth particles, satellite particles, agglomerated particles, and irregular particles.

8. The method for detecting the sphericity of powder according to claim 1, characterized in that, In the step of calculating the average sphericity value: For each cross-sectional morphology type of powder, the average sphericity value is calculated using the following formula: Q_average = ∑(intermediate shape descriptor × geometric shape factor) / number of particles of powder corresponding to the cross-sectional morphology type; Wherein, Q_average is the average sphericity value of powder for each cross-sectional morphology type.

9. The method for detecting the sphericity of powder according to claim 8, characterized in that, In the step of calculating the final sphericity: Q-weighted = ∑{Q-average × (number of particles of each cross-sectional morphology type / total number of particles of all cross-sectional morphology types)}; Wherein, Q-weighted is the weighted average sphericity of the powder to be tested.

10. The method for detecting the sphericity of powder according to any one of claims 1-9, characterized in that, The powder is a metal powder or a ceramic powder.

11. The method for detecting the sphericity of powder according to claim 10, characterized in that, The metal powder is a metal powder used in powder metallurgy or a metal powder used in additive manufacturing.

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