Method for detecting uniformity of mixed powder

Abstract

The invention relates to a method for detecting the uniformity of mixed powder, which comprises the following steps: mixing raw materials to obtain a mixture; sampling by using a powder sampler to obtain a detection sample; performing density detection on the detection sample to obtain detection density; calculating to obtain theoretical density according to the density and composition of the raw materials; and comparing the detection density with the theoretical density to obtain a relative deviation X, and judging the mixing uniformity. According to the method, the sample mixing uniformity is deduced by detecting the density of the detection sample in the mixed powder, the detection accuracy is high, the operation difficulty is low, the detection speed is high, the cost is low, and large-scale popularization is facilitated. The density is used as standard data, the density value of each raw material is fixed, and the theoretical density of the mixed powder is also fixed, so that the precision of the uniformity detection of the mixed powder can be further improved by taking the density detection as a measurement benchmark.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy, and relates to a mixed powder, and particularly relates to a method for detecting the uniformity of a mixed powder. Background Art

[0002] With the increasing demand for material properties, powder metallurgy technology has been applied to more and more material manufacturing fields. Powder metallurgy technology can prepare refractory metals, further improve the material utilization rate, and introduce fewer impurities. However, for materials used to prepare alloys, the powder metallurgy process involves a powder mixing process, and the mixing uniformity thereof is a key technical parameter, which directly affects the quality and performance of the final product. However, due to the characteristics of powders, such as small particle size, large specific surface area, easy agglomeration, etc., it is difficult to detect the uniformity of the mixed powder.

[0003] Mixing uniformity refers to the degree to which various powder bodies are mixed with each other under the action of an external force so that the powder body particles of each component are evenly distributed in any volume. The movement of the powder body during the mixing process is very complex, and how to correctly evaluate the mixing uniformity of the powder body has always been a research hotspot.

[0004] If the mixed powder is processed into a product and then the uniformity of the mixed powder is judged according to the performance of the product, not only the problem of uneven mixing cannot be detected in time, but also the performance of the product will be affected, and even the cost of the product may be further increased. Therefore, it is necessary to develop a method that can be detected at the sample mixing stage, on the one hand, to improve the uniformity of the mixed powder, and on the other hand, to reduce the detection and product costs.

[0005] CN109612888A proposes a method for detecting the mixing uniformity of powder based on image technology, including powder sample collection, powder image collection, image preprocessing, extracting characteristic parameters from the grayscale histogram, detecting the similarity of the grayscale distribution of the image, and setting a threshold according to the actual powder characteristics and processing requirements to judge the mixing uniformity. Among them, the collected powder image is subjected to image preprocessing, which successively includes image grayscaling, image downsampling, Gaussian filtering, and image sharpening. The grayscale histogram algorithm is used to extract the characteristic parameters of the preprocessed image. These characteristic parameters reflect the statistical relationship between each grayscale level and its occurrence frequency in the powder image. When analyzing the grayscale level of the image, first calculate the variable-weight Euclidean distance between the powder images at different sampling points according to the characteristic parameters, and characterize the similarity of the grayscale distribution of the image through the distance between each group of images. Since this method requires a digital microscope to collect powder images, the resolution of the digital microscope is limited, and it can only distinguish particles larger than 0.2 μm and cannot distinguish particles smaller than 0.2 μm. Moreover, the digital microscope cannot distinguish different components with the same particle size and color. Therefore, this method can only roughly characterize the mixing uniformity between powders with larger particles and significant color differences, and cannot accurately characterize the mixing uniformity between nano-scale particles or powders with the same or similar particle colors.

[0006] CN102661911A discloses a method for quickly detecting the mixing uniformity of powder materials, including the following steps: determining the particle size of each material in the mixed material, the mass percentage of each material in the mixed material, and whether the particle sizes of the mixed material are the same. If the particle sizes of the mixed material are the same, it is also necessary to determine the theoretical density ρ of each material. Here, the same particle size of the materials in the mixed material means that the difference in particle size is not greater than 10 microns; intercept the mixed material with a sampling circle with a radius of R in the mixed material, and then count the total number of particles contained in the circle; calculate the deviation value according to the number of particles, particle size, and theoretical density of the raw materials in the selected area; evaluate according to the deviation value. The smaller the deviation value, the better the mixing uniformity of the materials. When the deviation value is not greater than 10%, it is considered that the materials have been mixed evenly. If it is greater than 10%, it proves that the materials are not mixed evenly. This method requires a lot of data of the mixed material, not only the particle size and theoretical density of the mixed material, but also the total number of particles within the selected range, and the data accuracy is easily affected by the size of the sampling range, resulting in a low test accuracy for the mixing uniformity of the powder.

[0007] CN112461717A discloses a method for detecting the mixing uniformity of dry powder, including the steps of: S1: uniformly mixing the powders to be mixed according to a preset ratio to obtain a mixed powder; S2: calculating the theoretical particle size of the mixed powder based on the particle size and ratio of the powders to be mixed; S3: randomly taking the powder in the mixed powder as a sample and spreading the sample flat; S4: testing the sample with a laser particle size analyzer to obtain the actual particle size of the mixed powder; S5: calculating the relative deviation between the actual particle size in step S4 and the theoretical particle size in step S2, and judging the mixing uniformity according to the relative deviation. Due to the non-uniformity of the particle size of the powder itself and the fluidity of the particle size distribution, the detection data error of the test sample is relatively large, which will also affect the accuracy of the detection of the mixing uniformity of the mixed powder.

[0008] There are defects of low detection accuracy in the prior art. Therefore, how to improve the detection of the mixing uniformity of mixed powder has become an urgent problem to be solved at present. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a method for detecting the mixing uniformity of mixed powder, which infers the mixing uniformity of the sample by detecting the density of the test sample in the mixed powder. It not only has high detection accuracy, low operation difficulty, fast detection speed and low cost, but also is conducive to large-scale promotion. And density is a standard data, the density value of each raw material is fixed, and the theoretical density of the mixed powder is also fixed. Therefore, taking density detection as a measurement benchmark can further improve the accuracy of detecting the mixing uniformity of mixed powder.

[0010] To achieve this purpose, the present invention adopts the following technical solutions:

[0011] In the first aspect, the present invention provides a method for detecting the mixing uniformity of mixed powder, and the method includes the following steps: after mixing the raw materials, obtaining a mixed powder; sampling with a powder sampler to obtain a test sample; performing density detection on the test sample to obtain a detected density; calculating the theoretical density according to the density and composition of the raw materials; comparing the detected density and the theoretical density to obtain a relative deviation X and judging the mixing uniformity.

[0012] The present invention infers the mixing uniformity of the sample by detecting the density of the test sample in the mixed powder. It not only has high detection accuracy, low operation difficulty, fast detection speed and low cost, but also is conducive to large-scale promotion. And density is a standard data, the density value of each raw material is fixed, and the theoretical density of the mixed powder is also fixed. Therefore, taking density detection as a measurement benchmark can further improve the accuracy of detecting the mixing uniformity of mixed powder.

[0013] A powder sampler is a tool or device used to collect representative samples from powdered or granular materials, and is widely used in industries such as chemical engineering, pharmaceuticals, food, and metallurgy to ensure product quality and production process control.

[0014] Preferably, the number of sampled samples is 9 - 18, for example, it can be 9, 12, 14, 16, or 18.

[0015] By further regulating the number of sampled samples in the present invention, not only can the accuracy of the detection method be further improved, but also the detection time can be further shortened and the powder mixing efficiency can be increased. Within the range of the preferred number of samples, the detection method has high accuracy, high detection precision, short detection time, and high powder mixing efficiency.

[0016] Preferably, the mixed material is evenly divided into nine regions, and the number of sampled samples in each region is 1 - 2, for example, it can be 1 or 2.

[0017] Preferably, the instrument for density detection includes a true density analyzer.

[0018] A true density analyzer is an instrument based on the gas displacement method or Archimedes' principle, used to measure the true density of solid, liquid, or slurry substances. True density refers to the actual density of solid substances within the volume of the material in an absolutely dense state, excluding internal pores.

[0019] Preferably, each test sample is tested 4 - 8 times, for example, it can be 4 tests, 5 tests, 6 tests, 7 tests, or 8 tests.

[0020] By further regulating the number of tests for each test sample in the present invention, not only can the influence of equipment detection fluctuations be excluded to avoid data errors, but also the detection time can be further shortened and the powder mixing efficiency can be increased. Within the range of the preferred number of tests, the detection method has high accuracy, high detection precision, short detection time, and high powder mixing efficiency.

[0021] Preferably, the average mass of each test sample is 0.1% - 1% of the mass of the mixed material, for example, it can be 0.1%, 0.3%, 0.5%, 0.8%, or 1%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0022] Preferably, the detected density is the average value of the detection data of all test samples.

[0023] Preferably, the calculation formula for the theoretical density is: ρ z =1 / Σ(N% / ρ n ), where ρ z is the theoretical density of the powder mixture, N% is the mass percentage content of the powder to be mixed, and ρn is the density of the powder to be mixed.

[0024] Specifically, if the mixed raw materials include raw material A and raw material B, where the density of raw material A is ρ A , the density of raw material B is ρ B , the mass percentage of raw material A is A%, and the mass percentage of raw material B is B%, then ρ z = 1 / (A% / ρ A + B% / ρ B ).

[0025] Preferably, the calculation formula for the relative deviation X is X = Δ 测 / ρ z , where Δ 测 = |ρ 测 - ρ z |.

[0026] Specifically, X = |ρ 测 - ρ z | / ρ z .

[0027] Preferably, the judgment criteria for the mixing uniformity are as follows:

[0028] When X = 0, it is absolutely uniformly mixed.

[0029] When 0 < X ≤ 0.01, it is first-level uniformly mixed. For example, the relative deviation X of the first-level uniformly mixed can be 0.001, 0.003, 0.005, 0.007, 0.009, or 0.01, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0030] When 0.01 < X ≤ 0.05, it is second-level uniformly mixed. For example, the relative deviation X of the second-level uniformly mixed can be 0.015, 0.02, 0.03, 0.04, or 0.05, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0031] When X > 0.05, it is non-uniformly mixed. For example, the relative deviation X of the non-uniformly mixed can be 0.15, 0.2, 0.3, 0.4, 0.45, or 0.5, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0032] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0033] (1) Mix different raw materials to obtain a mixed powder.

[0034] (2) Divide the mixture evenly into nine regions, and take 1 to 2 test samples from each region using a powder sampler to obtain 9 to 18 test samples. The average mass of each test sample is 0.1% - 1% of the mass of the mixture.

[0035] (3) Use a true density analyzer to perform 4 to 8 density tests on each test sample. After calculating the average value, obtain the test density.

[0036] (4) Calculate the theoretical density based on the density and composition of the raw materials. The calculation formula for the theoretical density is: ρ z = 1 / Σ(N% / ρ n ), where ρ z is the theoretical density of the mixed powder, N% is the mass percentage of the powder to be mixed, and ρ n is the density of the powder to be mixed.

[0037] (5) Compare the test density and the theoretical density, calculate the relative deviation X, and judge the mixing uniformity; where X = |ρ 测 - ρ z | / ρ z .

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] (1) By detecting the density of the test samples in the mixture, the present invention infers the mixing uniformity of the samples. It not only has high detection accuracy, low operation difficulty, but also fast detection speed and low cost, which is conducive to large-scale promotion.

[0040] (2) As a macroscopic value, the density value of each raw material is fixed, and the theoretical density of the mixed powder is also fixed. Therefore, taking density detection as the measurement benchmark can further improve the accuracy of detecting the mixing uniformity of the mixed powder. Specific embodiments

[0041] To facilitate the understanding of the present invention, the following embodiments are listed. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0042] Example 1

[0043] This example provides a method for detecting the mixing uniformity of mixed powder, and the method includes the following steps:

[0044] (1) Mix different raw materials to obtain mixed powder;

[0045] (2) Divide the mixed powder into nine regions on average, and take 1 test sample from each region using a powder sampler to obtain 9 test samples. The average mass of each test sample is 0.5% of the mass of the mixture.

[0046] (3) Use a true density analyzer to perform 6 density detections on each test sample. After calculating the average value, obtain the detected density and denote it as ρ 测 ;

[0047] (4) Calculate the theoretical density based on the density and composition of the raw materials. The calculation formula for the theoretical density is: ρ z = 1 / Σ(N% / ρ n ), where ρ z is the theoretical density of the mixed powder, N% is the mass percentage of the powder to be mixed, and ρ n is the density of the powder to be mixed.

[0048] (5) Compare the detected density with the theoretical density, calculate the relative deviation X, and judge the mixing uniformity. Among them, X = |ρ 测 - ρ z | / ρ z .

[0049] Example 2

[0050] This example provides a method for detecting the uniformity of a mixed powder. The method includes the following steps:

[0051] (1) Mix different raw materials to obtain a mixed powder;

[0052] (2) Divide the mixed powder into nine regions on average, and take 2 test samples from each region using a powder sampler to obtain 18 test samples. The average mass of each test sample is 0.1% of the mass of the mixture.

[0053] (3) Use a true density analyzer to perform 4 density detections on each test sample. After calculating the average value, obtain the detected density and denote it as ρ 测 ;

[0054] (4) Calculate the theoretical density based on the density and composition of the raw materials. The calculation formula for the theoretical density is: ρ z = 1 / Σ(N% / ρ n ), where ρ z is the theoretical density of the mixed powder, N% is the mass percentage of the powder to be mixed, and ρ n is the density of the powder to be mixed.

[0055] (5) Compare the detected density with the theoretical density, calculate the relative deviation X, and judge the mixing uniformity. Among them, X = |ρ 测-ρ z | / ρ z 。

[0056] Example 3

[0057] This example provides a method for detecting the uniformity of a mixed powder. The method includes the following steps:

[0058] (1) Mix different raw materials to obtain a mixed powder;

[0059] (2) Divide the mixed powder into nine regions on average and number them 1-9. Among them, one test sample is taken from the regions numbered 1, 3, 5, 7, and 9 using a powder sampler, and two test samples are taken from the regions numbered 2, 4, 6, and 8 using a powder sampler, obtaining 13 test samples. The average mass of each test sample is 1% of the mass of the mixture;

[0060] (3) Use a true density analyzer to perform 8 density detections on each test sample. After calculating the average value, obtain the detected density and denote it as ρ 测 ;

[0061] (4) Calculate the theoretical density according to the density and composition of the raw materials. The calculation formula for the theoretical density is: ρ z = 1 / Σ(N% / ρ n ), where ρ z is the theoretical density of the mixed powder, N% is the mass percentage of the powder to be mixed, and ρ n is the density of the powder to be mixed;

[0062] (5) Compare the detected density with the theoretical density, calculate the relative deviation X, and judge the mixing uniformity. Among them, X = |ρ 测 - ρ z | / ρ z 。

[0063] Example 4

[0064] The difference between this example and Example 1 is only that, except that one test sample is taken from the regions numbered 1, 3, 5, 7, and 9 in step (2) using a powder sampler, the rest are the same as Example 1.

[0065] Example 5

[0066] The difference between this example and Example 1 is only that, except that three test samples are taken from each of the nine regions in step (2) using a powder sampler, the rest are the same as Example 1.

[0067] Example 6

[0068] The difference between this embodiment and Embodiment 1 is only that, except that in step (3), each test sample is subjected to 3 density detections, the rest are the same as Embodiment 1.

[0069] Embodiment 7

[0070] The difference between this embodiment and Embodiment 1 is only that, except that in step (3), each test sample is subjected to 7 density detections, the rest are the same as Embodiment 1.

[0071] Comparative Example 1

[0072] This comparative example provides a method for detecting the uniformity of a mixed powder, and the method includes the following steps:

[0073] (1) Mix different raw materials to obtain a mixed powder;

[0074] (2) Divide the mixed powder into nine regions on average, and take 1 test sample from each region using a powder sampler to obtain 9 test samples;

[0075] (3) Use a laser particle size analyzer to perform 6 particle size detections on each test sample, calculate the average value, and obtain the detected particle size D50, denoted as H 测 ;

[0076] (4) Calculate the theoretical particle size D50 according to the particle size distribution and composition of the raw materials; the calculation formula for the theoretical particle size D50 is: H z = 1 / Σ(N% × H n ), where H z is the theoretical particle size D50 of the mixed powder, N% is the mass percentage of the powder to be mixed, and H n is the particle size D50 of the powder to be mixed;

[0077] (5) Compare the detected particle size D50 and the theoretical particle size D50, calculate the relative deviation X, and judge the mixing uniformity; where X = |H 测 - H z | / H z .

[0078] Testing method

[0079] Use a true density meter of the AccuPyc III model of Micromeritics to detect the true density of the mixed powders of Embodiments 1 - 7 and Comparative Example 1. Among them, taking the mixture of two different raw materials as an example, the calculation formula for the mass ratio of component 1 is N1% = [ρ1(ρ2 - ρ z )] / [ρ z(ρ2 - ρ1)], the calculation formula for the detection accuracy is: Detection accuracy = 1 - (|Calculated mass ratio of component 1 - Measured mass ratio of component 1| / Measured mass ratio), and record the result in Table 1.

[0080] Table 1

[0081]

[0082]

[0083] It can be seen from the test results that:

[0084] (1) It can be seen from Examples 1 - 7 and Comparative Example 1 that the present invention infers the uniformity of sample mixing by detecting the density of the test samples in the mixed powder, which not only has high detection accuracy, low operation difficulty, but also fast detection speed and low cost, and is conducive to large-scale promotion. And density, as a standard data, the density value of each raw material is fixed, and the theoretical density of the mixed powder is also fixed. Therefore, using density detection as a measurement benchmark can further improve the accuracy of the detection of the uniformity of the mixed powder.

[0085] (2) It can be seen from Examples 1 and 4 - 5 that the present invention can, on the one hand, improve the detection accuracy by regulating the number of test samples, and on the other hand, reduce the complexity of the operation and further improve the detection efficiency.

[0086] (3) It can be seen from Examples 1 and 6 - 7 that the present invention can, on the one hand, improve the detection accuracy by regulating the number of detections of each test sample, and on the other hand, reduce the complexity of the operation and further improve the detection efficiency.

[0087] (4) It can be seen from Examples 1 and Comparative Example 1 that the present invention can effectively avoid the influence of data fluctuations on the detection accuracy by selecting density detection as a measurement benchmark, thereby improving the detection accuracy of the uniformity of the mixed powder.

[0088] In summary, the present invention infers the uniformity of sample mixing by detecting the density of the test samples in the mixed powder, which not only has high detection accuracy, low operation difficulty, but also fast detection speed and low cost, and is conducive to large-scale promotion. And density, as a standard data, the density value of each raw material is fixed, and the theoretical density of the mixed powder is also fixed. Therefore, using density detection as a measurement benchmark can further improve the accuracy of the detection of the uniformity of the mixed powder.

[0089] The applicant declares that the above description is only a specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for detecting the uniformity of a mixed powder, characterized in that The method includes the following steps: After mixing the raw materials, a mixed powder is obtained; sampling is carried out with a powder sampler to obtain a test sample; the test sample is subjected to density detection to obtain a detected density; the theoretical density is calculated based on the density and composition of the raw materials; the detected density and the theoretical density are compared to obtain a relative deviation X and to judge the mixing uniformity.

2. The method according to claim 1, wherein The number of samples taken is 9 to 18.

3. The method according to claim 1 or 2, characterized in that, The mixed powder is evenly divided into nine regions, and the number of samples taken from each region is 1 to 2.

4. The method according to any one of claims 1 to 3, characterized in that The instrument for density detection includes a true density analyzer.

5. The method according to any one of claims 1-4, characterized in that, Each test sample is detected 4 to 8 times.

6. The method according to any one of claims 1-5, characterized in that, The average mass of each test sample is 0.1% - 1% of the mass of the mixed powder.

7. The method according to any one of claims 1-6, characterized in that, The detected density is the average value of all the detection data of the test sample.

8. The method according to any one of claims 1-7, characterized in that, The calculation formula for the theoretical density is: ρ z = 1 / Σ(N% / ρ n ), where ρ z is the theoretical density of the mixed powder, N% is the mass percentage of the powder to be mixed, and ρ n is the density of the powder to be mixed.

9. The method according to any one of claims 1-8, characterized in that, The calculation formula for the relative deviation X is X = Δ 测 / ρ z , where Δ 测 = |ρ 测 - ρ z |.

10. The method according to any one of claims 1-9, characterized in that, The judgment criteria for the mixing uniformity are as follows: When X = 0, it is absolutely uniformly mixed; When 0 < X ≤ 0.01, it is first-level uniformly mixed; When 0.01 < X ≤ 0.05, it is second-level uniformly mixed; When X > 0.05, it is non-uniformly mixed.

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