Method and equipment for identifying hollow powder of ceramic material powder

Abstract

The invention discloses a method and equipment for identifying hollow powder of ceramic material powder, and the method comprises the following steps: putting a powder picking area of a bearing flat plate to which a powder sample to be detected is attached under an optical microscope, and picking out single powder to be observed in a specified transparency level by contacting the powder with a picking tool; the powder pressing area of the bearing flat plate is moved into the view field of the optical microscope, the selecting tool stained with the powder is placed on the bearing flat plate in the view field of the optical microscope, and the selecting tool is rolled and slightly moved back and forth so that the powder can be placed on the powder pressing area of the bearing flat plate from the selecting tool; the powder placed in the powder pressing area of the bearing flat plate is moved into a view field of an optical microscope to be crushed; the section of the crushed powder is observed and photographed, a proportional scale is selected according to the magnification times of the optical microscope, and the shell thickness of the crushed powder is measured through the proportional scale so as to judge whether the crushed powder is hollow powder or not. The method can intuitively and accurately verify the correctness of judging whether the powder is the hollow powder or not through the transparency.

Description

Technical Field

[0001] The present invention belongs to the technical field of hollow powder identification, and particularly relates to a method for identifying hollow powder of ceramic material powder. Background Art

[0002] Ceramic material powder can form a thermal barrier coating on the surface of a substrate through spraying means, thereby improving the high-temperature resistance and corrosion resistance of the substrate, and further improving its service life and safety. It is one of the research focuses in fields such as gas turbines and aero-engines.

[0003] Compared with solid powder, the hollow structure of hollow powder makes the droplets formed after heating have a longer diffusion and solidification time when sprayed onto the substrate, and the finally formed coating is more uniform, has a lower thickness, and has no continuous defects. This characteristic makes hollow powder a promising material form for developing high-performance thermal barrier coatings. However, for the hollow powder prepared by methods such as spray drying method, gas atomization method, and arc plasma spheroidization method, how to measure the proportion of hollow powder therein is a major problem.

[0004] As Figure 1 shown, at present, the mainstream measurement means is to prepare a sample of the powder to be measured by means of cold mounting or hot mounting (that is, embedding the powder in resin), then polish the prepared sample, and finally take an SEM of the polished surface. According to the obtained SEM image, the number of hollow powder and solid powder is manually counted. This technology takes a long time, has a high cost, has a large difficulty in getting started, and the randomness of sample grinding is large, and the credibility of the result is doubtful. It is necessary to develop a new technical solution for identifying hollow powder of ceramic material powder. Summary of the Invention

[0005] Therefore, the present invention provides a method for identifying hollow powder of ceramic material powder to solve the problems in the traditional technology, such as long time consumption, high cost, large difficulty in getting started, large randomness of sample grinding, and doubtful credibility of the result.

[0006] To achieve the above object, the present invention provides the following technical solution: A method for identifying hollow powder of ceramic material powder, comprising the following steps:

[0007] S1. Spread the powder to be detected on the powder picking area of the loading plate;

[0008] S2. Take a picture of the powder sample to be detected spread on the powder picking area of the loading plate to obtain an image of the powder sample to be detected, and divide the transparency level according to the transparency of the powder in the powder sample to be detected;

[0009] S3. Place the powder picking area of the carrier plate with the powder sample to be detected under an optical microscope. Use a picking tool to contact a single powder in the specified transparency level to be observed. Utilize the acting force at the contact interface between the powder and the picking tool to make the contacted powder adhere to the picking tool, so as to pick out the powder.

[0010] S4. Move the powder pressing area of the carrier plate into the field of view of the optical microscope. Place the picking tool with the adhered powder on the carrier plate within the microscope's field of view. Roll and slightly move the picking tool back and forth to place the powder from the picking tool onto the powder pressing area of the carrier plate.

[0011] S5. Move the powder placed on the powder pressing area of the carrier plate into the field of view of the optical microscope, and crush the powder moved into the field of view of the optical microscope.

[0012] S6. Observe and take a photo of the cross-section of the crushed powder. Select a scale according to the magnification of the optical microscope, and measure the shell thickness of the crushed powder through the scale to determine whether the crushed powder is a hollow powder.

[0013] As an optimized solution for the method of identifying hollow powders of ceramic material powders, in step S1, through vibration, shaking, and swaying, the hollow powders are laid on the plane of the powder picking area of the carrier plate in a single layer.

[0014] As an optimized solution for the method of identifying hollow powders of ceramic material powders, in step S2, the set transparency levels divided according to transparency include: transparent level, semi-transparent gloss - cavity observable level, semi-transparent gloss - cavity unobservable level, and opaque level.

[0015] Transparent level: See the color patches formed by the background color.

[0016] Semi-transparent gloss - cavity observable level: Part of the powder surface is transparent, see the color patches formed by the background color, and the remaining part shows a turbid transparent gloss, and the color patches formed by the background color cannot be seen.

[0017] Semi-transparent gloss - cavity unobservable level: The entire powder surface shows a turbid transparent gloss, and the color patches formed by the background color cannot be seen.

[0018] Opaque level: The whole powder completely shows white and has no transparent gloss.

[0019] As an optimized solution for the method of identifying hollow powders of ceramic material powders, in step S3, after placing the powder picking area of the carrier plate with the powder sample to be detected under an optical microscope, adjust the magnification of the optical microscope to 3 - 15 times, and adjust the shooting parameters of the optical microscope to make the number of powders in the field of view reach the specified quantity to compare and judge the transparency of the powders.

[0020] In step S3, the relationship between the diameter of the powder sample to be detected and the diameter of the selection tool is as follows:

[0021] 1.2D ≤ d1 ≤ 5D

[0022] In the formula, d1 is the diameter of the selection tool; D is the diameter of the powder sample to be detected.

[0023] As an optimized scheme of the method for identifying hollow powder of ceramic material powder, in step S5, during the process of crushing the powder that has been moved to the center of the field of view of the optical microscope by the powder pressing mechanism, adjust the magnification of the optical microscope to 7 - 20 times. Increasing the magnification in this step is to observe the powder crushing process. However, since the powder will move during the crushing process, the magnification should not be too large;

[0024] In step S5, if the powder fragments after crushing are buckled on the powder pressing mechanism, use the selection tool to turn over the powder fragments buckled on the powder pressing mechanism and then observe.

[0025] The present invention also provides an apparatus for identifying hollow powder of ceramic material powder, characterized in that it adopts the method for identifying hollow powder of ceramic material powder described above.

[0026] Preferably, the powder that has been moved into the field of view of the optical microscope is crushed by the powder pressing mechanism;

[0027] The powder pressing mechanism includes a powder pressing mounting base, a driving device, a driving lead screw, a driving slider, and a clamping frame; the driving device is arranged on the upper part of the powder pressing mounting base, the driving shaft of the driving device is connected to the driving lead screw, the lower part of the driving lead screw is connected to the powder pressing mounting base through a bearing, the driving slider is connected to the driving lead screw, the clamping frame is connected to the driving slider, and a light-transmitting flat plate for crushing the powder at the center of the field of view of the optical microscope is fixed on the clamping frame.

[0028] The present invention also provides a method for calculating the hollow degree of powder of hollow powder, characterized in that the formula for calculating the hollow degree of powder is as follows:

[0029]

[0030] In the formula, c is the hollow degree, h is the measured shell thickness of the hollow powder, and d2 is the measured diameter of the hollow powder.

[0031] Preferably, it further includes:

[0032] Count the number of powders at a set transparency level on the image of the powder sample to be detected to obtain the statistical result of the number of powders at the set transparency level;

[0033] Calculate the proportion of hollow powder in the powder sample to be detected according to the statistical result of the powder quantity at the set transparency level;

[0034] The formula for calculating the proportion of hollow powder in the powder sample to be detected is:

[0035]

[0036] In the formula, K is the proportion of hollow powder obtained by the powder quantity method, n1 is the quantity of powder at the transparent level, n2 is the quantity of powder at the semi-transparent gloss - cavity observable level, n3 is the quantity of powder at the semi-transparent gloss - cavity unobservable level, and n4 is the quantity of powder at the opaque level.

[0037] Preferably, it further includes:

[0038] Identify and count the area of the powder image region at the set transparency level on the image of the powder sample to be detected, and obtain the area of the powder image region at the set transparency level on the image of the powder sample to be detected;

[0039] According to the obtained area of the powder image region at the set transparency level on the image of the powder sample to be detected, perform matching calculation on the proportion of hollow powder in the powder sample to be detected:

[0040]

[0041] In the formula, K' is the proportion of hollow powder obtained by the image recognition method, S1 is the area of the powder image region at the transparent level, S2 is the area of the powder image region at the semi-transparent gloss - cavity observable level, S3 is the area of the powder image region at the semi-transparent gloss - cavity unobservable level, and S4 is the area of the powder image region at the opaque level;

[0042] It also includes correcting the final result of the proportion of hollow powder:

[0043] K 修正 = ω1K + ω2K'

[0044] In the formula, K 修正 is the corrected proportion of hollow powder; ω1 + ω2 = 1, and ω1, ω2 are weights determined according to experience.

[0045] The present invention has the following advantages: The powder to be detected is laid flat in the powder picking area of the carrying plate; the powder sample to be detected laid flat in the powder picking area of the carrying plate is photographed to obtain an image of the powder sample to be detected, and the transparency level is divided according to the transparency of the powder in the powder sample to be detected; the powder picking area of the carrying plate with the powder sample to be detected attached is placed under an optical microscope, and a single powder in a specified transparency level to be observed is contacted by a picking tool, and the powder in contact is attached to the picking tool by the acting force at the contact interface between the powder and the picking tool, so as to pick out the powder; the powder pressing area of the carrying plate is moved into the field of view of the optical microscope, the picking tool stained with powder is placed on the carrying plate within the microscope field of view, and the picking tool is rolled and slightly moved back and forth to place the powder from the picking tool onto the powder pressing area of the carrying plate; the powder placed on the powder pressing area of the carrying plate is moved into the field of view of the optical microscope, and the powder moved into the field of view of the optical microscope is crushed; the cross-section of the crushed powder is observed and photographed, a scale is selected according to the magnification of the optical microscope, and the shell thickness of the crushed powder is measured through the scale to determine whether the crushed powder is a hollow powder. The present invention can obtain the shell thickness of a single powder, saving time and effort, with low operation difficulty and low cost; it can intuitively and accurately verify the correctness of judging whether a powder is a hollow powder through transparency, making the identification result of hollow powder more reliable. Description of the Drawings

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained based on the provided drawings.

[0047] Figure 1 SEM picture of the ground surface of the sample in the prior art provided by the present invention;

[0048] Figure 2 Schematic cross-sectional view of hollow powder and solid powder provided by the present invention;

[0049] Figure 3 Schematic flow chart of the method for identifying hollow powder of ceramic material powder provided in the embodiment of the present invention;

[0050] Figure 4 Picture of transparency grading in the method for identifying hollow powder of ceramic material powder provided in the embodiment of the present invention;

[0051] Figure 5 Schematic diagram of the equipment used in the method for identifying hollow powder of ceramic material powder provided in the embodiment of the present invention;

[0052] Figure 6 This is a comparison before and after crushing powders of different transparency levels in the method for identifying hollow powders of ceramic material powders provided in the embodiments of the present invention. Detailed implementation manners

[0053] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0054] See Figure 1 , currently the mainstream method for measuring the proportion of hollow powders is to use cold mounting or hot mounting to prepare the powders into samples (i.e., embedding the powders in resin), then polish the prepared samples, and finally take SEM images of the polished surface. According to the obtained SEM images, the number of hollow powders and solid powders is manually counted. However, the mainstream hollow powder detection method of "mounting → grinding → taking SEM → manual counting" has the following defects:

[0055] First, it is time-consuming. Generally, it takes about 20 minutes to make a sample by hot mounting, while it takes about 1.5 hours to make a sample by cold mounting; it takes about 15 - 30 minutes to complete the grinding of one sample; taking SEM requires reserving time, and when it is busy, one still needs to queue for machine time, so its detection cycle is very time-consuming.

[0056] Second, there is a certain learning curve. For mounting, the operation difficulty of hot mounting is not high, but it may have the problem of crushing hollow powders; while cold mounting has a certain operation difficulty, the types of resin and curing agent selected, the powder quality used to make one sample, the mixing ratio and stirring speed of the resin and curing agent, and the order of pouring the mixed resin and powder into the embedding mold will all affect the quality of the final sample (mainly bubbles); for grinding, if it is manual grinding, the grit number of the sandpaper selected, the grinding method, and the grinding time will all affect the flatness of the polished surface, thereby affecting the SEM shooting effect; if it is machine automatic grinding, parameters such as the rotation speed of the grinding disc, the applied pressure, and the grinding time also need to be carefully selected.

[0057] Third, the cost is relatively high. The cost of taking SEM is relatively high. Generally, 1 hour of SEM costs about 400 - 500 yuan, and only about 4 samples can be taken in 1 hour.

[0058] Fourth, the randomness of sample grinding is relatively large, and the credibility of the results is in doubt. Ideally, for all the powders on the ground plane after sample grinding, only when all the powders are cut from their own equatorial planes can the obtained results be closest to the actual situation. However, due to the extremely high randomness of the spatial distribution of the powders in the embedded resin samples, the ideal situation of cutting from the equatorial planes of the powders is very rare, and the cutting plane will also greatly affect the correctness of the final statistical results. As Figure 2 shown, for solid powders, the results obtained by cutting from any plane are the same. However, for hollow powders with a relatively large shell thickness, whether it is cutting plane 1 or cutting plane 3, this powder appears to be a solid powder, but it is only when cut from its equatorial plane (cutting plane 2) that it is found that this powder is actually a hollow powder.

[0059] In view of this, in order to solve the problems existing in the traditional technology, such as long time consumption, high cost, great difficulty in getting started, relatively large randomness of sample grinding, and doubtful credibility of the results, an identification method for hollow powders of ceramic material powders is provided in an embodiment of the present invention. The following are the specific contents of the embodiment of the present invention.

[0060] See Figure 3 , an identification method for hollow powders of ceramic material powders is provided in an embodiment of the present invention, including the following steps:

[0061] S1. Spread the powder to be detected on the powder picking area of the bearing plate;

[0062] S2. Take a picture of the powder sample to be detected spread on the powder picking area of the bearing plate to obtain an image of the powder sample to be detected, and divide the transparency level according to the transparency of the powders in the powder sample to be detected;

[0063] S3. Place the powder picking area of the bearing plate with the powder sample to be detected on an optical microscope, use a picking tool to contact a single powder in the specified transparency level to be observed, and make the contacted powder adhere to the picking tool by the acting force at the contact interface between the powder and the picking tool, so as to pick out the powder;

[0064] S4. Move the powder pressing area of the bearing plate into the field of view of the optical microscope, place the picking tool stained with powder on the bearing plate in the field of view of the microscope, roll and slightly move the picking tool back and forth to place the powder from the picking tool onto the powder pressing area of the bearing plate;

[0065] S5. Move the powder placed on the powder pressing area of the bearing plate into the field of view of the optical microscope, and crush the powder moved into the field of view of the optical microscope;

[0066] S6. Observe and photograph the cross-section of the crushed powder. Select a scale according to the magnification of the optical microscope, and measure the shell thickness of the crushed powder through the scale to determine whether the crushed powder is hollow powder.

[0067] In this embodiment, in step S1, the hollow powder is spread on the powder picking area plane of the bearing plate in a single layer by means of vibration, shaking and swaying. One hand can use a small spatula to take a very small amount of the prepared powder sample to be detected (the preparation techniques may be different), suspend it 2-3 cm above one end of the bearing plate, and gently pat the handle of the spatula with the other hand. Use vibration to make the powder fall and spread on the bearing plate as sparsely as possible.

[0068] Specifically, suspending the spatula containing the powder sample to be detected at a specified height above one end of the bearing plate can ensure that there is a certain space and distance when the powder falls, so that it can fall relatively evenly. Patting the handle of the spatula, the generated vibration and impact force are transmitted to the front end of the spatula, causing the powder sample to be detected to overcome the friction with the spatula and fall. During the powder falling process, it falls vertically due to the action of gravity and spreads at one end of the bearing plate. The specified height and the patting force can control the falling speed and dispersion degree of the powder, so as to form a relatively uniform distribution at one end of the bearing plate.

[0069] In this embodiment, in step S2, the set transparency levels divided according to transparency include: transparent level, semi-transparent gloss - cavity observable level, semi-transparent gloss - cavity unobservable level, and opaque level;

[0070] Transparent level: See the color patches formed by the background color;

[0071] Semi-transparent gloss - cavity observable level: Part of the powder surface is transparent, see the color patches formed by the background color, and the remaining part presents a turbid transparent gloss, and the color patches formed by the background color cannot be seen;

[0072] Semi-transparent gloss - cavity unobservable level: The whole powder surface presents a turbid transparent gloss, and the color patches formed by the background color cannot be seen;

[0073] Opaque level: The whole powder completely presents white and has no transparent gloss.

[0074] See Figure 4 , through human eye observation, four transparency levels are divided according to different transparencies: transparent level, semi-transparent gloss - cavity observable level, semi-transparent gloss - cavity unobservable level, and opaque level. The shell thickness affects the transparency, that is, the higher the transparency level, the smaller the shell thickness of the hollow powder. The pure white level is considered to be solid powder.

[0075] Specifically, when observing the powder sample to be detected, the judgment mainly relies on the human eye to determine the degree of light passing through the powder. For the "transparent level", the light can pass through the hollow powder almost unobstructed, indicating that its shell is very thin and hardly blocks or scatters the light, so it looks completely transparent. For the "semi-transparent gloss - cavity observable level", it shows that the shell of the hollow powder has a certain thickness, allowing the light to pass through and showing gloss, and at the same time, the internal cavity can be observed, meaning that the thickness of the shell is within a certain range, enabling some light to refract and reflect, so that the human eye can detect the existence of the cavity. For the "semi-transparent gloss - cavity unobservable level", it indicates that the thickness of the shell has increased, and the light can still pass through and present gloss, but the cavity is difficult to be directly observed, indicating that the refraction and reflection of light by the shell have enhanced, covering the visibility of the cavity. The "opaque level" is considered to be a solid powder because at this time the shell of the hollow powder is very thick, almost completely blocking the light from passing through, and all the light is scattered and reflected, presenting white, indicating that there is almost no cavity inside and it is close to the solid state. When detecting hollow powders under different batches or different processing conditions, through this classification of transparency levels, the thickness of the shell of the hollow powder can be quickly and preliminarily judged, and then its quality or process effect can be evaluated.

[0076] In this embodiment, in step S3, after placing the powder picking area of the carrier plate with the powder sample to be detected under the optical microscope, adjust the magnification of the optical microscope to 3 - 15 times, and adjust the shooting parameters of the optical microscope so that there are more powders in the field of view, which is convenient for comparing and judging the transparency of the powders. In step S3, the relationship between the diameter of the powder sample to be detected and the diameter of the picking tool is:

[0077] 1.2D ≤ d1 ≤ 5D

[0078] In the formula, d1 is the diameter of the picking tool; D is the diameter of the powder sample to be detected.

[0079] Then in step S4, move the other end of the carrier plate into the field of view of the optical microscope, place the needle tip with powder on the carrier plate within the field of view of the microscope, roll the thin needle and slightly move the thin needle back and forth to place the powder from the needle tip to the other end of the carrier plate.

[0080] Specifically, first, place the prepared sample carrier plate under an optical microscope and adjust it to an appropriate magnification (about 3 - 15 times) and shooting parameters to clearly observe the powder. Then, use a fine needle with a tip diameter of 50 - 80 μm to contact a single powder in a certain transparency level that you want to observe. Since the powder has a certain surface force, when the fine needle contacts the powder, this force enables the powder to adhere to the tip of the needle, thus realizing the picking out of a single powder from numerous powders. Next, move the other end of the carrier plate into the microscope field of view, and place the tip of the needle with the powder on the carrier plate within the microscope field of view. By rolling the fine needle and slightly moving the fine needle back and forth in all directions, the contact state and force between the tip of the needle and the powder are changed, causing the powder to fall off the tip of the needle and be placed on the carrier plate.

[0081] In this embodiment, in step S5, during the process of crushing the powder that has been moved into the field of view of the optical microscope by the powder pressing mechanism, adjust the magnification of the optical microscope to 7 - 20 times. In this step, increase the magnification to observe the powder crushing process. However, since the powder will move during the crushing process, the magnification should not be too large.

[0082] In step S5, if the powder fragments after crushing are buckled on the powder pressing mechanism, use a fine needle with a tip diameter of 20 μm to turn over the powder fragments buckled on the powder pressing mechanism and then observe.

[0083] See Figure 5 , wherein, the powder pressing mechanism includes a powder pressing mounting base, a driving motor, a driving lead screw, a driving slider, and a clamping frame; the driving motor is arranged on the upper part of the powder pressing mounting base, the driving shaft of the driving motor is connected to the driving lead screw, the lower part of the driving lead screw and the powder pressing mounting base are connected by a bearing, the driving slider is connected to the driving lead screw, the clamping frame is connected to the driving slider, and the clamping frame is fixed with a transparent plate for crushing the powder within the field of view of the optical microscope.

[0084] Specifically, the working principle of the powder pressing mechanism is that when the powder needs to be crushed, the drive motor starts and drives the drive screw to rotate. Since the drive screw is connected to the drive slider, the rotation of the screw is converted into the linear motion of the drive slider. The movement of the drive slider drives the clamping frame connected to it to move up and down. The transparent plate fixed on the clamping frame moves accordingly, applying pressure to the powder located in the center of the optical microscope field of view, thereby realizing the operation of crushing the powder. During the powder pressing process, the magnification of the optical microscope is adjusted to 7-20 times to observe the crushing process and details more clearly. If the crushed powder fragments are upside down on the powder pressing mechanism, use a fine needle with a needle tip diameter of 20μm to turn it over. This is because the tip of the fine needle is small enough to contact and manipulate the powder fragments more accurately, and it can be turned over by carefully flipping it for subsequent observation.

[0085] In this embodiment, in step S6, during the observation of the crushed powder cross section, the magnification of the optical microscope is adjusted to 25-50 times, and a larger magnification can also be selected. The appropriate magnification should be selected according to the particle size of the powder and the broken cross-sectional structure to be observed. After step S6, it also includes repeating steps S3 to S6 to obtain the shell thickness of hollow noodles corresponding to all set transparency levels and the conclusion of whether the powder of the set transparency level is hollow noodles; the conclusion of whether the powder of the set transparency level is hollow noodles is:

[0086] Powders of transparent grade, translucent gloss - cavity observed grade, and translucent gloss - no cavity observed grade are all hollow powders, while powders of opaque grade are not hollow powders.

[0087] Specifically, when observing the crushed powder cross section, the magnification of the optical microscope is adjusted to 25-50 times. Such a high magnification can more clearly present the details of the powder cross section, including the structure and thickness of the shell and the internal conditions, which is helpful for accurate judgment and analysis.

[0088] Specifically, in step S2, four transparency levels are divided according to the transparency through human eye observation: transparent level, translucent gloss - cavity observed level, translucent gloss - no cavity observed level and opaque level. The shell thickness affects the transparency, that is, the higher the transparency level, the smaller the shell thickness of the hollow powder. The pure white level is considered to be solid powder. By repeating steps S3 to S6, the shell thickness of the hollow powder corresponding to the set transparency level in step S2 is verified. Figure 6 , the internal structure of powders with different transparency levels after being crushed is given: (a) transparent level; (b) translucent gloss - cavity observed level; (c) translucent gloss - no cavity observed level; (d) opaque level.

[0089] In a possible embodiment, the hollowness of the powder determined to be macaroni is calculated. The formula for calculating the powder hollowness is as follows:

[0090]

[0091] In the formula, c is the hollowness, h is the measured shell thickness of the macaroni, and d2 is the measured diameter of the macaroni.

[0092] Specifically, this formula reflects the proportion of the hollow part inside the macaroni in the entire powder volume through the ratio of the shell thickness to the diameter. The larger the hollowness value, the higher the proportion of the hollow part in the powder; conversely, the smaller the hollowness value, the thicker the shell relative to the hollow part and the lower the proportion of the hollow part. In the production process of ceramic material powders, hollowness is an important indicator for evaluating powder quality. Different application scenarios have specific requirements for the hollowness of macaroni. For example, in the preparation of thermal barrier coatings, an appropriate hollowness can ensure good performance of the coating. By calculating the hollowness, powders meeting the quality standards can be quickly screened out, unqualified products can be detected and processed in a timely manner, and the stability of product quality can be guaranteed.

[0093] In a possible embodiment, it further includes step S7:

[0094] Count the number of powders at the set transparency level on the image of the powder sample to be detected obtained in step S2 to obtain the statistical result of the number of powders at the set transparency level;

[0095] Calculate the proportion of macaroni in the powder sample to be detected based on the statistical result of the number of powders at the set transparency level and the conclusion on whether the powders at the set transparency level are macaroni;

[0096] The formula for calculating the proportion of macaroni in the powder sample to be detected is as follows:

[0097]

[0098] In the formula, K is the proportion of macaroni obtained by the powder quantity method, n1 is the number of powders at the transparent level, n2 is the number of powders at the semi-transparent gloss - cavity observable level, n3 is the number of powders at the semi-transparent gloss - cavity unobservable level, and n4 is the number of powders at the opaque level.

[0099] Specifically, count the number of powders with a set transparency level on the powder sample image obtained in step S2. By identifying and counting each powder with a different transparency level in the image one by one, and then, based on the previously obtained conclusion about whether the powder with the set transparency level is a hollow powder, that is, powders with a transparent level, a semi-transparent luster - cavity-observed level, and a semi-transparent luster - cavity-unobserved level are hollow powders, and powders with an opaque level are non-hollow powders, calculate the proportion of hollow powders by combining the statistical results of the number of powders at each level. Through this calculation of the proportion of hollow powders, obtain the proportion of hollow powders obtained by the powder quantity method in the entire sample. Thus, in actual analysis, count the specific number of powders at each transparency level, substitute them into the formula for calculation, and quickly understand the relative proportion of hollow powders in the sample, thereby obtaining a quantitative evaluation of the overall properties of the sample.

[0100] In a possible embodiment, in step S7, it further includes:

[0101] Use a computer vision algorithm or manual statistics method to identify and count the area of the powder image region with a set transparency level on the powder sample image obtained in step S2, and obtain the area of the powder image region with a set transparency level on the powder sample image to be detected;

[0102] Specifically, the steps of implementing with a computer vision algorithm are as follows:

[0103] (1) Extract target transparency-related features through grayscale conversion (if the original is an RGB image) or channel separation, and use Gaussian filtering and histogram equalization to eliminate noise and enhance the transparency level contrast.

[0104] (2) Establish a mapping relationship of transparency in the HSV / Lab color space (such as through interval division of the lightness channel L or saturation channel S), or set multi-level transparency thresholds based on the grayscale histogram (such as dividing the 0-255 grayscale values into 5 intervals).

[0105] (3) Segment the connected regions that meet the transparency thresholds at each level through adaptive threshold segmentation, the watershed algorithm, or a deep learning semantic segmentation model (such as U-Net, etc.), and label the pixel coordinates of each region.

[0106] (4) Calculate the pixel area of each level region according to the connected region mask (number of pixels × square of the actual size corresponding to a single pixel), and summarize by transparency level to generate an area statistical table and a visualized heat map.

[0107] Specifically, the steps of the manual statistics method are as follows:

[0108] (1) Use Photoshop, Meitu, Photoscape, or other similar software to load the image, manually adjust the color scale / curve tool to observe the distribution of different grayscale areas, and define the boundaries of the transparency range (e.g., define 0-50 as a highly transparent area and 51-100 as a semi-transparent area).

[0109] (2) Use the polygonal lasso or magic wand tool to select a continuous area that meets the set transparency (the tolerance value needs to be adjusted), read the pixel area of ​​the selected area through the software's built-in "histogram analysis" or "regional statistics" function, and accumulate and summarize to obtain a statistical table of the areas at each transparency level.

[0110] If you don't use software (Photoshop), you can consider the grid estimation method or manual measurement:

[0111] (1) After printing the image, cover it with transparent coordinate paper, and manually read the number of grids covered by each transparency level area, according to the preset grid unit area (e.g. 1 grid = 0.5mm 2 )Add up the estimated total area.

[0112] (2) Use a ruler to measure the diameter of each powder and manually determine its transparency level. Assuming that it is a circle, calculate the area according to the ruler in the upper left corner, and summarize to obtain a statistical table of the areas of each transparency level.

[0113] According to the area occupied by the powder image of the set transparency level on the obtained powder sample image to be detected, and the conclusion of whether the powder of the set transparency level is hollow powder, the proportion of hollow powder in the powder sample to be detected is matched and calculated:

[0114]

[0115] Where, K' is the hollow powder ratio obtained by the image recognition method, S1 is the transparent level powder image area, S2 is the semi-transparent gloss - cavity-observable level powder image area, S3 is the semi-transparent gloss - cavity-unobservable level powder image area, S4 is the opaque level powder image area;

[0116] It also includes the hollow powder ratio obtained by the powder quantity method and the image recognition method, and corrects the final result of the hollow powder ratio:

[0117] K 修正 =ω1K+ω2K`

[0118] In the formula, K 修正 is the corrected proportion of hollow noodles; ω1+ω2=1, ω1, ω2 are weights determined based on experience.

[0119] Specifically, in order to obtain a more accurate final result of the proportion of macaroni, the proportion of macaroni obtained by the powder quantity method and the proportion of macaroni obtained by the image recognition method are comprehensively considered. The proportion of macaroni is corrected by setting weights. The weights are determined based on past historical statistical experience to reflect the reliability and importance of the powder quantity method and the image recognition method under specific circumstances. In practical applications, if the image recognition method is more accurate and reliable in certain situations, the value of ω2 may be relatively large; conversely, if the powder quantity method is more representative, the value of ω1 may be large. Through this comprehensive correction, the accuracy and reliability of the macaroni proportion result can be improved.

[0120] In a possible embodiment, after identifying a certain ceramic material powder to be detected, the following steps are performed during the identification process of the same ceramic material powder in subsequent batches:

[0121] (1) Experiment preparation: Prepare a certain amount of ceramic material powder samples, select a suitable carrying plate, and ensure that its surface is flat and clean. Prepare an optical microscope and ensure that its magnification can be flexibly adjusted between 7 and 25 times and its shooting function is normal.

[0122] (2) Test steps and data recording

[0123] Powder spreading: Use a small spatula to take a small amount of powder, suspend it 2 - 3 cm above the carrying plate, and gently tap the spatula handle to evenly spread the powder in a single layer on the carrying plate.

[0124] Shooting: Adjust the magnification of the optical microscope to 10 times and take pictures of different areas on the carrying plate where there is powder to obtain 100 pictures.

[0125] Statistics: Process the pictures obtained in the previous step to obtain the number of powders included in each transparency level. Assume that in the statistical results, there are 849 powders at the transparent level, 1415 powders at the semi - transparent gloss - cavity observed level, 2398 powders at the semi - transparent gloss - cavity not observed level, and 406 powders at the opaque level.

[0126] Calculation of the proportion of hollow powder: According to the powder quantity method, the proportion of hollow powder \(K=(849 + 1415 + 2398)\div(849 + 1415 + 2398 + 406)\approx0.920\). Using computer vision algorithms to identify and count the area of the powder image region, assuming that the total area \(S1\) of the powder image region at the transparent level is \(2000\) pixels², the total area \(S2\) at the semi - transparent gloss - cavity observable level is \(3000\) pixels², the total area \(S3\) at the semi - transparent gloss - cavity unobservable level is \(4000\) pixels², and the total area \(S4\) at the opaque level is \(500\) pixels². The proportion of hollow powder \(K'\) by the image recognition method is \((2000 + 3000 + 4000)\div(2000 + 3000 + 4000 + 500)\approx0.947\). According to experience, the weights \(\omega1 = 0.6\) and \(\omega2 = 0.4\) are determined. The corrected proportion of hollow powder \(K_{corrected}=0.6\times0.920 + 0.4\times0.947 = 0.9308\).

[0127] Identification tests for hollow powder were carried out on a batch of ceramic material powders. The specific test process is as follows:

[0128] (1) Test preparation: Prepare a certain amount of ceramic material powder samples, select a suitable loading plate to ensure its surface is flat and clean. The picking tool selects a fine needle with a tip diameter of 60μm, prepare an optical microscope, and ensure that its magnification can be flexibly adjusted between 7 - 15 times and over 40 times, and its shooting function is normal. The powder pressing mechanism selects a device including a powder pressing mounting base, a driving motor, a driving lead screw, a driving slider, and a clamping frame. A light - transmitting flat plate is fixed on the clamping frame.

[0129] (2) Test steps and data recording

[0130] Powder spreading (S1): Use a small spatula to take a small amount of powder, suspend it 2 - 3 cm above the powder picking area of the loading plate, and gently tap the spatula handle to evenly spread the powder in a single layer on the picking area.

[0131] Photographing and transparency grading (S2): Take a photo of the powder in the picking area and divide the transparency levels by visual observation. Assume that 100 powders are counted, among which 15 are at the transparent level, 25 are at the semi - transparent gloss - cavity observable level, 30 are at the semi - transparent gloss - cavity unobservable level, and 30 are at the opaque level.

[0132] Powder picking (S3): Place the powder picking area of the loading plate under the optical microscope, adjust the magnification to 8 times, and adjust the shooting parameters. According to \(1.2D\leq d1\leq5D\), select powders with appropriate diameters for operation, use the fine needle to contact a single powder at the specified transparency level, and pick out the powder.

[0133] Powder transfer (S4): Move the powder pressing area of the loading plate to the microscope field of view, place the fine needle with the adhered powder on the flat plate in the field of view, roll and slightly move the fine needle to place the powder in the pressing area.

[0134] Powder pressing (S5): Move the powder to the center of the microscope field of view, start the drive motor of the powder pressing mechanism, the lead screw drives the drive slider and the clamping bracket, so that the light-transmitting flat plate presses down on the powder. When pressing the powder, the magnification of the microscope is adjusted to 12 times. If the powder fragments are upside down, use a 20μm fine needle to turn them over.

[0135] Observation and measurement (S6): Adjust the magnification of the microscope to 40 times, observe the cross-section of the crushed powder and take pictures. Select a scale, measure the shell thickness and diameter of powders with different transparency levels, and calculate the hollowness. Assume that 5 powders of the transparent level are measured, the average shell thickness h1 is 5μm, the average diameter D1 is 50μm, and the hollowness is 5÷50 = 0.1; semi-transparent gloss - cavity-observed level, 5 are measured, h2 is on average 8μm, D2 is on average 60μm, and the hollowness is 8÷60≈0.13; semi-transparent gloss - cavity-unobserved level, 5 are measured, h3 is on average 12μm, D3 is on average 70μm, and the hollowness is 12÷70≈0.17.

[0136] Calculation of the proportion of hollow powders (S7): According to the powder quantity method, the proportion of hollow powders K=(15 + 25 + 30)÷100 = 0.7. Use computer vision algorithms to identify and count the area of the powder image region. Assume that the total area S1 of the powder image regions of the transparent level powders is 1000 pixel², the semi-transparent gloss - cavity-observed level S2 is 1500 pixel², the semi-transparent gloss - cavity-unobserved level S3 is 2000 pixel², and the opaque level S4 is 1500 pixel². The proportion of hollow powders K` obtained by the image recognition method is (1000 + 1500 + 2000)÷(1000 + 1500 + 2000 + 1500)≈0.64. Determine the weights ω1 = 0.6, ω2 = 0.4 according to experience, and the corrected proportion of hollow powders Kcorrected = 0.6×0.7 + 0.4×0.64 = 0.676.

[0137] The proportion of hollow powders calculated by the powder quantity method is 0.7, the proportion of hollow powders obtained by the image recognition method is 0.64, and the proportion of hollow powders after weight correction is 0.676. This indicates that in this batch of ceramic material powder samples, the hollow powders account for a considerable proportion, reflecting that the content of hollow powders in the samples is at a medium to upper level, which may have a significant impact on relevant properties in practical applications. There are certain differences between the results of the powder quantity method and the image recognition method. The powder quantity method is based on the statistics of the quantities of powders with different transparency levels, while the image recognition method relies on the recognition and statistics of the areas of powder image regions. Due to the irregular shape of the powders, the area occupied in the image and the actual quantity do not have a strictly linear relationship, and partially overlapping or agglomerated powders may affect the accuracy of image recognition, resulting in different calculation results for the two methods.

[0138] Among them, the results of the two methods were corrected based on the weights determined empirically, and the result of 0.676 obtained comprehensively considered the characteristics of the two methods. The setting of the weights reflects the evaluation of the reliability of the two methods under the experimental conditions. Through correction, the accuracy and reliability of the hollow powder percentage results can be improved to a certain extent, and it is closer to the actual situation. The hollowness of transparent grade powder is 0.1, the hollowness of translucent gloss-observable cavity level is about 0.13, and the hollowness of translucent gloss-no cavity observable level is about 0.17. As the transparency level decreases, the hollowness gradually increases, which is consistent with theoretical expectations. Because the shell thickness affects the transparency, the higher the transparency level, the smaller the shell thickness and the smaller the hollowness, which shows that the method of preliminarily judging the shell thickness and hollowness by dividing the transparency level is feasible.

[0139] By actually measuring the thickness of the crushed powder shell to determine whether it is hollow powder, and combining the judgment results of powders with different transparency levels, the correctness of judging whether the powder is hollow powder by transparency can be intuitively and accurately verified. From the test results, there are obvious differences in the hollowness and hollow powder judgment results of powders with different transparency levels, which proves that the identification method has high accuracy in distinguishing hollow powder from solid powder. During the experiment, the identification operation of multiple powders was repeated and relatively stable results were obtained. This shows that the identification method has good repeatability and can obtain similar results when tested at different times and by different operators, providing reliable guarantee for large-scale powder quality detection.

[0140] In a possible embodiment, a ceramic material powder hollow powder identification device is also provided, which adopts the above-mentioned ceramic material powder hollow powder identification method. This identification device is easier to operate, and the operator only needs to operate the equipment according to the established process, without the need for complex skill training, which greatly reduces the operating threshold. At the same time, the equipment uses conventional tools such as optical microscopes to avoid expensive SEM shooting costs and effectively reduce costs. In terms of time cost, it gets rid of the lengthy process of mounting, grinding and waiting for SEM shooting, can quickly complete the identification, and improve work efficiency. In terms of the accuracy of the identification results, by directly observing the crushed powder cross-section to measure the shell thickness, the influence of the randomness of the cutting plane on the results is reduced, making the identification results more reliable.

[0141] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A method for identifying hollow powder of ceramic material powder, characterized in that, It includes the following steps: S1. Spread the powder to be detected evenly on the powder picking area of the carrying plate; S2. Take a picture of the powder sample to be detected spread on the powder picking area of the carrying plate to obtain an image of the powder sample to be detected, and divide it into set transparency levels according to the transparency of the powder in the powder sample to be detected; S3. Place the powder picking area of the carrying plate with the powder sample to be detected attached under an optical microscope, use a picking tool to contact a single powder in the specified transparency level to be observed, and make the contacted powder adhere to the picking tool by the acting force at the contact interface between the powder and the picking tool, so as to pick out the powder; S4. Move the powder pressing area of the carrying plate into the field of view of the optical microscope, place the picking tool stained with powder on the carrying plate within the microscope field of view, roll and slightly move the picking tool back and forth to place the powder from the picking tool onto the powder pressing area of the carrying plate; S5. Move the powder placed in the powder pressing area of the carrying plate into the field of view of the optical microscope, and crush the powder moved into the field of view of the optical microscope; S6. Observe and take pictures of the cross-section of the crushed powder, select a scale according to the magnification of the optical microscope, and measure the shell thickness of the crushed powder through the scale to determine whether the crushed powder is a hollow powder.

2. The identification method of hollow powder of a ceramic material powder according to claim 1, characterized in that, In step S1, the hollow powder is spread in a single layer on the plane of the powder picking area of the carrying plate by means of vibration, shaking and swaying.

3. The identification method of hollow powder of a ceramic material powder according to claim 1, characterized in that, In step S2, the set transparency levels divided according to transparency include: transparent level, semi-transparent gloss - cavity observable level, semi-transparent gloss - cavity unobservable level, and opaque level; Transparent level: See the color patches formed by the background color; Semi-transparent gloss - cavity observable level: Part of the powder surface is transparent, see the color patches formed by the background color, and the remaining part presents a turbid transparent gloss, and the color patches formed by the background color cannot be seen; Semi-transparent gloss - cavity unobservable level: The whole powder surface presents a turbid transparent gloss, and the color patches formed by the background color cannot be seen; Opaque level: The whole powder completely presents white without transparent gloss.

4. A method for identifying hollow powder of a ceramic material powder according to claim 1, characterized in that, In step S3, after placing the powder picking area of the carrying plate with the powder sample to be detected attached under the optical microscope, adjust the magnification of the optical microscope to 3 - 15 times, and adjust the shooting parameters of the optical microscope to make the number of powders in the field of view reach the specified quantity to compare and judge the transparency of the powders; In step S3, the relationship between the diameter of the powder sample to be detected and the diameter of the picking tool is: 1.2D ≤ d1 ≤ 5D In the formula, d1 is the diameter of the picking tool; D is the diameter of the powder sample to be detected.

5. The method for identifying hollow powder of a ceramic material powder according to claim 1, characterized in that, In step S5, during the process of crushing the powder moved to the center of the field of view of the optical microscope by the powder pressing mechanism, adjust the magnification of the optical microscope to 7 - 20 times; In step S5, if the crushed powder fragments are buckled on the powder pressing mechanism, use a picking tool to turn over the powder fragments buckled on the powder pressing mechanism and then observe.

6. An identification device for hollow powder of ceramic material powder, characterized in that, Adopt the method for identifying hollow powder of a ceramic material powder according to any one of claims 1 to 5.

7. An identification device for hollow ceramic material powder, according to claim 6, It is characterized in that, breaking the powder moved into the field of view of the optical microscope through a powder pressing mechanism; The powder pressing mechanism includes a powder pressing mounting seat, a driving device, a driving screw rod, a driving slider and a clamping frame; the driving device is arranged on the upper part of the powder pressing mounting seat, the driving shaft of the driving device is connected to the driving screw rod, the lower part of the driving screw rod is connected to the powder pressing mounting seat through a bearing, the driving slider is connected to the driving screw rod, the clamping frame is connected to the driving slider, and a light-transmitting flat plate for breaking the powder at the exact center of the field of view of the optical microscope is fixed on the clamping frame.

8. A method for calculating the powder hollowness of macaroni, characterized in that, The formula for calculating the hollowness of the powder is: In the formula, c is the hollowness, h is the shell thickness of the measured hollow powder, and d2 is the diameter of the measured hollow powder.

9. A method for calculating the powder hollowness of macaroni according to claim 8, characterized in that, It further includes: counting the number of powders at a set transparency level on the image of the powder sample to be detected to obtain the statistical result of the number of powders at the set transparency level; calculating the proportion of hollow powders in the powder sample to be detected according to the statistical result of the number of powders at the set transparency level; The formula for calculating the proportion of hollow powders in the powder sample to be detected is: In the formula, K is the proportion of hollow powders obtained by the powder quantity method, n1 is the number of powders at the transparent level, n2 is the number of powders at the semi-transparent gloss - cavity observable level, n3 is the number of powders at the semi-transparent gloss - cavity unobservable level, and n4 is the number of powders at the opaque level.

10. A method for calculating the powder hollowness of macaroni according to claim 9, characterized in that, It further includes: identifying and counting the area of the powder image region at a set transparency level on the image of the powder sample to be detected to obtain the area of the powder image region at the set transparency level on the image of the powder sample to be detected; matching and calculating the proportion of hollow powders in the powder sample to be detected according to the area of the powder image region at the set transparency level obtained on the image of the powder sample to be detected: In the formula, K' is the proportion of hollow powders obtained by the image recognition method, S1 is the area of the powder image region at the transparent level, S2 is the area of the powder image region at the semi-transparent gloss - cavity observable level, S3 is the area of the powder image region at the semi-transparent gloss - cavity unobservable level, and S4 is the area of the powder image region at the opaque level; It further includes correcting the final result of the proportion of hollow powders. K 修正 = ω1K + ω2K` Where K 修正 is the proportion of penne after correction; ω1 + ω2 = 1, and ω1 and ω2 are weights determined according to experience.

Images