A method and system for detecting a plating loss rate of nickel-coated diamond powder

Abstract

The present application relates to the field of powder material surface modification, and discloses a kind of detection method and system of nickel-coated diamond powder plating loss rate, it includes the following steps: sample dispersion: the nickel-coated diamond powder sample to be measured is placed in dispersion medium, and is dispersed to form suspension;Magnetic separation: the suspension formed by dispersion is placed in magnetic field and is magnetically separated, so that magnetic particles are adsorbed;Acquire test solution: under the action of magnetic field, the supernatant of suspension is extracted as test solution;Suspension particle analysis: the test solution is introduced into particle analysis system, and the non-magnetic particles contained therein are counted and characterized;Result determination: according to the particle parameters output by the particle analysis system, the plating loss rate of the original nickel-coated diamond powder sample is evaluated.The present application completes the detection of a sample in a short time, and can output the absolute number concentration of plating loss particles, realize quantitative evaluation;It can detect trace or local plating loss particles that XRD method is difficult to identify.

Description

Technical Field

[0001] This invention relates to the field of powder material surface modification technology, and more specifically, to a method and system for detecting the plating failure rate of nickel-coated diamond powder. Background Technology

[0002] Nickel-coated diamond powder is a key raw material for preparing high-performance tools, and the integrity of its coating directly affects the performance of the final product. Currently, the main methods for detecting "missing coating" (i.e., exposed diamond) are scanning electron microscopy (SEM) observation and X-ray diffraction (XRD) analysis.

[0003] However, while SEM allows for direct observation of particle surfaces, it is a localized high-resolution observation with a limited field of view and poor statistical representativeness. Furthermore, the sample preparation and observation processes are cumbersome and time-consuming, failing to meet the demands for rapid, batch-based quality control.

[0004] XRD method: It indirectly reflects the degree of plating defects by detecting the characteristic diffraction peaks of exposed diamond, but its sensitivity is limited and it is not sensitive to trace, local or submicroscopic plating defects. Summary of the Invention

[0005] To address at least one of the aforementioned problems, the present invention first provides a method for detecting the plating failure rate of nickel-coated diamond powder, comprising the following steps:

[0006] Sample dispersion: The nickel-coated diamond powder sample to be tested is placed in a dispersion medium and dispersed to form a suspension;

[0007] Magnetic separation: The suspension formed by the dispersion treatment is placed in a magnetic field for magnetic separation, so that magnetic particles are adsorbed, and the strength of the magnetic field can be adjusted.

[0008] Obtaining the test solution: Under the influence of a magnetic field, the supernatant of the suspension is extracted as the test solution;

[0009] Suspended particle analysis: The test solution is introduced into a particle analysis system to count and analyze the characteristics of the non-magnetic particles contained therein;

[0010] Result determination: Based on the particle parameters output by the particle analysis system, the uncoated rate of the original nickel-coated diamond powder sample is evaluated.

[0011] Optionally, the dispersion medium is anhydrous ethanol; the dispersion treatment step includes one or more combinations of mechanical stirring, magnetic stirring, or ultrasonic dispersion.

[0012] Optionally, the magnetic separation includes the steps of: placing a container containing the suspension in the magnetic field of a permanent magnet or inserting a magnetic rod into the suspension and letting it stand for 1-30 minutes.

[0013] Optionally, the magnetic field strength is 0.3T-2T.

[0014] Optionally, when extracting the supernatant of the suspension, the extraction point is located 0.5cm-5cm below the liquid surface, and the extraction volume is 1ml-100ml.

[0015] Optionally, the result determination step includes the particle parameters including the total number of non-magnetic particles in a unit volume of test liquid, the number of particles within a specific particle size range, or the number of particles with specific morphological characteristics; by comparing the parameter with a preset quality standard threshold or standard sample test data, a quantitative value of the plating failure level or plating failure rate is output.

[0016] Optionally, the particle analysis system is an optical particle counter; the optical particle counter adopts the principle of optical obscuration and / or angular scattering, with a measurement range of 0.5-400μm, 4-100 detection channels, and an upper limit of concentration of not less than 45,000 particles / mL;

[0017] The counting and feature analysis of the non-magnetic particles contained therein includes the following steps: passing the particles in the test liquid through the detection zone to generate a pulse signal proportional to the particle size, and obtaining the particle number concentration and particle size distribution by analyzing the number and intensity of the pulse signal.

[0018] Optionally, the particle analysis system is a dynamic image analysis system; the dynamic image analysis system includes a high-speed camera and a telecentric lens, the particle recognition speed is not less than 10,000 particles / minute, and the measurement range is 2-10,000 μm;

[0019] The counting and feature analysis of the non-magnetic particles contained therein includes the following steps: allowing the particles in the test liquid to flow through the observation window, continuously acquiring particle images through the high-speed camera, and automatically identifying the morphological features of each particle, such as size, aspect ratio, and roundness, using an image processing algorithm; the exposure time of the high-speed camera is no more than 1 μs to eliminate particle motion trailing.

[0020] Optionally, the result determination includes the following steps: based on the morphological features, identifying particles with an aspect ratio greater than a preset threshold and a roundness less than a preset threshold as diamond particles that have not been deposited, and counting their quantity concentration.

[0021] The dimensions include X A (Area equivalent diameter) = and X P (Circumference equivalent diameter) = The X A Let A be the diameter of the circle whose projected area is equal to that of the particle, and let A be the area of ​​the circle whose projected area is equal to that of the particle; X PLet P be the diameter of the circle whose projected circumference is equal to that of the particle, and let P be the circumference of the circle whose projected circumference is equal to that of the particle; the roundness = The ratio of the major axis to the minor axis of the smallest circumscribed rectangle of the particle.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0023] 1. By creatively combining physical methods of magnetic separation with direct particle counting analysis technology for non-magnetic components, the problem of "missing plating" which is difficult to measure directly is transformed into the problem of "number of non-magnetic particles" which is easy to measure accurately. This eliminates the dependence on electron microscopes, allows for the detection of a sample in a short time, and can output the absolute number and concentration of missing plating particles for quantitative assessment. In addition, the analysis of thousands of particles in the supernatant provides more statistically representative results than local SEM observation, and can more objectively reflect the quality of the entire batch of powder.

[0024] 2. If the surface of diamond particles is completely coated with nickel, they will be more easily adsorbed in a magnetic field. If the surface of diamond particles is not completely coated with nickel, the nickel content will be less, and they will not be easily adsorbed under the same magnetic field, thus remaining in the upper clear liquid. If diamond particles are not coated with nickel during the nickel plating process, they are non-magnetic particles and will not be adsorbed in a magnetic field, also remaining in the upper clear liquid. Therefore, by controlling the magnetic field strength, the uniformity of nickel plating on particles can be detected, as well as non-magnetic unplated particles. This method has high sensitivity and can detect trace or local unplated particles that are difficult to identify by XRD.

[0025] 3. When using a dynamic image analysis system, it is not only possible to count the number and size of non-magnetic particles, but also to acquire particle images through a high-speed camera and automatically identify morphological features such as aspect ratio and roundness. Based on the typical morphological features of diamond particles, such as sharp edges, low roundness, and large aspect ratio, it can effectively distinguish between diamond particles that have not been plated and those that may be free nickel chips or other non-magnetic impurities, which significantly improves the accuracy of the determination of the plating failure rate and avoids misjudgment caused by impurity interference.

[0026] In addition, the present invention provides a powder plating failure rate detection system for performing the above-described method for detecting the plating failure rate of nickel-coated diamond powder, comprising:

[0027] The dispersion unit is used to mix and disperse the powder sample to be tested with the dispersion medium.

[0028] A magnetic separation unit, including a magnetic field generator and a container, is used for magnetic adsorption separation of dispersed suspensions.

[0029] A sampling unit is used to quantitatively extract the supernatant from the container under the influence of a magnetic field;

[0030] The particle analysis unit is used to count and characterize particles in the extracted supernatant.

[0031] The data processing and judgment unit is connected to the particle analysis unit and is used to calculate and output the evaluation result of the plating failure rate based on the analysis results.

[0032] Compared with the prior art, the powder plating failure rate detection system of the present invention and the above-mentioned nickel-coated diamond powder plating failure rate detection method have the same advantages over the prior art, which will not be repeated here. Attached Figure Description

[0033] Figure 1 This is a flowchart of an embodiment of the present invention. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the following description is provided in conjunction with the accompanying drawings. Figure 1 This application will be described in further detail.

[0035] Firstly, referring to Figure 1 This invention provides a method for detecting the plating failure rate of nickel-coated diamond powder.

[0036] Example 1: The method for detecting the plating failure rate of nickel-coated diamond powder includes the following steps:

[0037] S100: Sample dispersion: The nickel-coated diamond powder sample to be tested is placed in a dispersion medium and dispersed to form a suspension.

[0038] Weigh 1.0 g of the nickel-coated diamond powder sample to be tested into a clean beaker, wherein the particle size of the powder is 0.5-30 μm. Then add 200 ml of dispersion medium to the beaker; in this embodiment, anhydrous ethanol is preferred. Next, place the beaker on a magnetic stirrer and stir the mixture in the beaker at 500 rpm for 10 minutes. Then transfer the beaker to an ultrasonic cleaner and ultrasonically disperse for 5 minutes to ensure that the powder particles do not agglomerate, achieving sufficient dispersion and forming a stable suspension. In another embodiment, the nickel-coated diamond powder sample mixed with anhydrous ethanol can also be stirred by mechanical stirring with a motor and paddles. In yet another embodiment, after stirring with a magnetic stirrer, ultrasonic dispersion is not performed using an ultrasonic cleaner.

[0039] S200: Magnetic separation: The suspension formed by dispersion treatment is placed in a magnetic field for magnetic separation, so that magnetic particles are adsorbed, and the strength of the magnetic field can be adjusted.

[0040] The beaker processed in step S100 is placed on a powerful permanent magnet, with the bottom of the beaker in close contact with the magnet. It is then left to stand for 1-30 minutes, preferably 5 minutes in this embodiment. Since diamond powder cannot be attracted by a magnetic field, while nickel can, the nickel-plated diamond particles can be attracted by the magnetic field. Therefore, during the standing period, most of the magnetic particles are observed to be attracted to the bottom of the beaker. The strength of the magnetic field can be adjusted by increasing or decreasing the number of powerful permanent magnets. This prevents particles with thin plating (weak magnetic particles) from being directly attracted by the strong magnet, which could lead to errors in the test results. The difference in the supernatant obtained with different magnetic field strengths can be compared to better assess the powder's plating failure rate. The magnetic field strength is 0.3T-2T, and in this embodiment, the magnetic field strength generated by the powerful permanent magnet is preferably 0.5T. If the magnetic field strength is 0.3T, diamond particles with an 80% nickel plating ratio will not be adsorbed; if the magnetic field strength is 2T, diamond particles with a 60% nickel plating ratio will be adsorbed. Therefore, the magnetic field strength of the corresponding high-strength permanent magnet can be controlled according to the detection requirements. In another embodiment, a magnetic rod with a corresponding magnetic field strength can be used instead of the high-strength permanent magnet. The magnetic rod needs to be inserted into the beaker, and it needs to be completely submerged in the suspension, after which it can be left to stand for the appropriate time.

[0041] S300: Obtain the test solution: Under the influence of a magnetic field, extract the supernatant of the suspension as the test solution.

[0042] Under the condition of maintaining a magnetic field, i.e., maintaining the adsorption state of a strong permanent magnet, carefully aspirate 1ml-100ml of the supernatant using a pipette at a distance of 0.5cm-5cm below the liquid surface. Then transfer it to a clean sample tube to obtain the test solution. In this embodiment, it is preferable to extract 20ml of the supernatant by pipetting at a distance of 1cm below the liquid surface.

[0043] S400: Suspended Particle Analysis: The test solution is introduced into the particle analysis system to count and characterize the non-magnetic particles contained therein.

[0044] The particle analysis system is an optical particle counter. The test liquid is injected into the sample cell of the optical particle counter. The optical particle counter uses dual-optical-path technology of optical obscuration and angular scattering, resulting in higher detection accuracy. The measurement range is 0.5-400μm, the number of detection channels is 4-100, and the upper limit of concentration is not less than 45,000 particles / mL. The working principle of the optical particle counter is as follows: When particles in the test liquid pass through the detection area of ​​the flowing sample cell, they block (optical obscuration) or scatter a portion of the incident light, causing the detector to output two types of pulse signals—positive pulse signals are generated by light scattering, and their magnitude is proportional to the particle diameter; negative pulse signals are generated by optical obstruction (optical obscuration), and their magnitude is proportional to the cross-sectional area of ​​the particle. By analyzing the magnitude and number of the calibrated pulse signals, the particle size and the number and distribution of particles per unit volume can be calculated. Start the analysis program and set the detection channels to: 2-5μm, 5-10μm, 10-25μm, 25-50μm, 50-100μm, >100μm. An optical particle counter automatically measures and records the number of particles in each size range per milliliter of the test solution. After the test, the software outputs the total number of particles with a diameter >2 μm per milliliter of the test solution, N_total, and the number of particles with a diameter between 10-100 μm, N_core. Here, N_core is considered to mainly correspond to the diamond core particles that were not deposited. In this embodiment, N_core = 850 particles / mL. In another embodiment, the optical particle counter can also use only the optical obscuration method or the angular scattering method dual-optical-path technology.

[0045] S500: Result determination: Based on the particle parameters output by the particle analysis system, evaluate the plating failure rate of the original nickel-coated diamond powder sample.

[0046] The particle parameters include the total number of non-magnetic particles per unit volume of the test liquid, the number of particles within a specific particle size range, or the number of particles with specific morphological characteristics. By comparing this parameter with a preset quality standard threshold or standard sample test data, a quantitative value for the plating defect level or defect rate is output. That is, the measured N_core is compared with a pre-established quality standard. This quality standard is a comparison table developed by testing a large number of standard samples with known acceptable grades (such as qualified, first-class, and superior grades). For example, if N_core < 500 particles / mL, it is judged as "superior grade"; 500 ≤ N_core < 2000 particles / mL, it is judged as "qualified"; N_core ≥ 2000 particles / mL, it is judged as "unqualified". In this embodiment, the measured N_core is 850 particles / mL, therefore it is judged as "qualified". In addition, the optical particle counter can output a report format that conforms to the standard.

[0047] This application combines magnetic separation with particle analysis technology. The magnetic separation step effectively removes a large number of magnetically coated particles, and then the tens of thousands of non-magnetic particles in the supernatant are counted and analyzed as a whole, avoiding sampling bias caused by the limited field of view in traditional electron microscopy. It can quickly determine the undercoating rate of nickel-coated diamond powder. Compared to traditional methods that rely on localized observation with scanning electron microscopy, it can directly output the number concentration, particle size distribution, or proportion of particles with specific morphologies of non-magnetic particles per unit volume of the test solution, achieving rapid quantitative assessment of the degree of undercoating. This significantly improves detection efficiency and can more objectively and accurately reflect the undercoating status of the entire batch of powder samples, providing a reliable basis for product grading and quality judgment.

[0048] Example 2: The difference between this example and Example 1 is that the particle analysis system in step S400 is a dynamic image analysis system;

[0049] The dynamic image analysis system includes a high-speed camera and a telecentric lens, with a particle recognition speed of no less than 10,000 particles / minute and a measurement range of 2-10,000 μm. The exposure time of the high-speed camera is no more than 1 μs to eliminate particle motion blur. The counting and feature analysis of the non-magnetic particles includes the following steps: allowing particles in the test liquid to flow through an observation window, and continuously acquiring particle images using the high-speed camera. Image processing algorithms are then used to automatically identify the size, aspect ratio, and roundness of each particle. The system also features particle adhesion identification technology, which can filter out agglomerated or adhered particles to avoid affecting the test results.

[0050] The result determination includes the following steps: based on morphological characteristics, particles with an aspect ratio greater than a preset threshold and a roundness less than a preset threshold are identified as under-plated diamond particles, and their quantity concentration is counted. The particle size includes X... A (Area equivalent diameter) = and X P (Circumference equivalent diameter) = X A Let A be the diameter of the circle whose projected area is equal to that of the particle; X be the area of ​​the circle whose projected area is equal to that of the particle. P Let P be the diameter of the circle whose projected perimeter is equal to that of the particle, and let P be the circumference of the circle whose projected perimeter is equal to that of the particle; Circularity = The aspect ratio is the ratio of the major and minor axes of the smallest bounding rectangle of the particle. Diamond particles typically exhibit sharp, irregular polygonal shapes (lower roundness, larger aspect ratio), while nickel scrap or other impurities may appear as flakes or near-spherical shapes. The software sets identification rules: particles with an aspect ratio > 1.5 and roundness < 0.85 are identified as "suspected under-plated diamonds". The concentration of suspected under-plated diamonds, C_dia, is output per milliliter of the test solution. If C_dia exceeds a set threshold (e.g., 1000 particles / mL), the sample is considered to have an excessive under-plating rate. In this embodiment, C_dia was measured to be 320 particles / mL, which is considered acceptable. The system can simultaneously output particle size distribution (equivalent area diameter, major axis, minor axis), particle shape distribution (aspect ratio, roundness), and the original image of each particle for easy manual verification.

[0051] This embodiment can not only count the number and size of non-magnetic particles, but also automatically identify morphological features such as aspect ratio and roundness by acquiring particle images through a high-speed camera. Based on the typical morphological characteristics of diamond particles—sharp edges, low roundness, and large aspect ratio—it can effectively distinguish between under-plated diamond particles and possible free nickel flakes or other non-magnetic impurities, significantly improving the accuracy of under-plating rate determination and avoiding misjudgments caused by impurity interference.

[0052] Secondly, another embodiment of the present invention provides a powder plating failure rate detection system, comprising:

[0053] The dispersion unit is used to mix and disperse the powder sample to be tested with the dispersion medium.

[0054] A magnetic separation unit, including a magnetic field generator and a container, is used for magnetic adsorption separation of dispersed suspensions.

[0055] The sampling unit is used to quantitatively extract the supernatant from the container under the influence of a magnetic field.

[0056] The particle analysis unit is used to count and characterize particles in the extracted supernatant.

[0057] The data processing and judgment unit, connected to the particle analysis unit, is used to calculate and output the evaluation results of the plating failure rate based on the analysis results.

[0058] The above embodiments are merely illustrative of several implementation methods of this disclosure, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of this disclosure, and these modifications and improvements all fall within the protection scope of this disclosure.

Claims

1. A method for detecting the plating failure rate of nickel-coated diamond powder, characterized in that, Including the following steps: Sample dispersion: The nickel-coated diamond powder sample to be tested is placed in a dispersion medium and dispersed to form a suspension; Magnetic separation: The suspension formed by the dispersion treatment is placed in a magnetic field for magnetic separation, so that magnetic particles are adsorbed, and the strength of the magnetic field can be adjusted. Obtaining the test solution: Under the influence of a magnetic field, the supernatant of the suspension is extracted as the test solution; Suspended particle analysis: The test liquid is introduced into a particle analysis system to count and analyze the non-magnetic particles contained therein; the particle analysis system is a dynamic image analysis system; the dynamic image analysis system includes a high-speed camera and a telecentric lens, with a particle recognition speed of not less than 10,000 particles / minute and a measurement range of 2-10,000 μm; the counting and analysis of the non-magnetic particles includes the following steps: allowing the particles in the test liquid to flow through an observation window, continuously acquiring particle images through the high-speed camera, and automatically identifying the size, aspect ratio, and roundness morphological features of each particle using an image processing algorithm; the exposure time of the high-speed camera is not more than 1 μs to eliminate particle motion blur; Result determination: Based on the particle parameters output by the particle analysis system, evaluate the under-plating rate of the original nickel-coated diamond powder sample; the result determination includes the following steps: based on the morphological characteristics, identify particles with an aspect ratio greater than a preset threshold and a roundness less than a preset threshold as under-plated diamond particles, and count their quantity concentration.

2. The method for detecting the plating failure rate of nickel-coated diamond powder according to claim 1, characterized in that, The dispersion medium is anhydrous ethanol; the dispersion treatment step includes one or more combinations of mechanical stirring, magnetic stirring or ultrasonic dispersion.

3. The method for detecting the plating failure rate of nickel-coated diamond powder according to claim 1, characterized in that, The magnetic separation includes the steps of: placing a container containing the suspension in the magnetic field of a permanent magnet or inserting a magnetic rod into the suspension and letting it stand for 1-30 minutes.

4. The method for detecting the plating failure rate of nickel-coated diamond powder according to claim 1, characterized in that, The magnetic field strength is 0.3T-2T.

5. The method for detecting the plating failure rate of nickel-coated diamond powder according to claim 1, characterized in that, When extracting the supernatant of the suspension, the extraction point is located 0.5cm-5cm below the liquid surface, and the extraction volume is 1ml-100ml.

6. The method for detecting the plating failure rate of nickel-coated diamond powder according to claim 1, characterized in that, The particle parameters include the total number of non-magnetic particles in a unit volume of the test liquid, the number of particles within a specific particle size range, or the number of particles with specific morphological characteristics; by comparing this parameter with a preset quality standard threshold or standard sample test data, a quantitative value of the plating failure level or plating failure rate is output.

7. The method for detecting the plating failure rate of nickel-coated diamond powder according to any one of claims 1-6, characterized in that, The particle analysis system is an optical particle counter; the optical particle counter adopts the principle of optical obscuration and / or angular scattering, its measurement range is 0.5-400μm, the number of detection channels is 4-100, and the upper limit of concentration is not less than 45,000 particles / mL; The counting and feature analysis of the non-magnetic particles contained therein includes the following steps: passing the particles in the test liquid through the detection zone to generate a pulse signal proportional to the particle size, and obtaining the particle number concentration and particle size distribution by analyzing the number and intensity of the pulse signal.

8. The method for detecting the plating failure rate of nickel-coated diamond powder according to claim 1, characterized in that: The dimensions include X A (Area equivalent diameter) = and X P (Circumference equivalent diameter) = The X A Let A be the diameter of the circle whose projected area is equal to that of the particle, and let A be the area of ​​the circle whose projected area is equal to that of the particle; X P Let P be the diameter of the circle whose projected circumference is equal to that of the particle, and let P be the circumference of the circle whose projected circumference is equal to that of the particle; the roundness = The ratio of the major axis to the minor axis of the smallest circumscribed rectangle of the particle.

9. A powder plating failure rate detection system, used to perform the method described in any one of claims 1-8, characterized in that, include: The dispersion unit is used to mix and disperse the powder sample to be tested with the dispersion medium. A magnetic separation unit, including a magnetic field generator and a container, is used for magnetic adsorption separation of dispersed suspensions. A sampling unit is used to quantitatively extract the supernatant from the container under the influence of a magnetic field; The particle analysis unit is used to count and characterize particles in the extracted supernatant. The data processing and judgment unit is connected to the particle analysis unit and is used to calculate and output the evaluation result of the plating failure rate based on the analysis results.

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