3D Metal Powder:Research on Sphericity Detection Technology
1.Principle
1.1 Definition
The particle sphericity is defined as the ratio of the equivalent diameter of the perimeter of the particle to the equivalent diameter of the particle area, which is defined as a two-dimensional description
Q= d1/ da
Here dl: The perimeter equivalent diameter of the particle, The perimeter of the particle is l, than l=2πdl
Here da: The area equivalent diameter of the particle, the area of the particle is A, than A=πda2
1.2 The morphology of powder by SEM
The principle of scanning electron microscopy is that the electron beam with a diameter of 20μm~30μm emitted from the cathode of the electron gun is emitted to the lens barrel by the accelerated voltage between the cathode and the cathode, and is reduced to an electron probe with a diameter of about a few nanometers through the convergence of the condenser and the objective lens. Under the action of a scanning coil at the upper part of the objective, the electron probe scans the surface of the sample in a raster shape and excites a variety of electronic signals. These electronic signals are detected by the corresponding detectors, amplified, converted, and converted into voltage signals, and finally sent to the gate of the picture tube to modulate the brightness of the picture tube. The electron beam in the CRT is also grated on the phosphor screen, and this scanning motion is strictly synchronized with the scanning motion of the electron beam on the sample surface, so that the contrast corresponds to the intensity of the received signal to obtain a scanning electron image, which reflects the topography of the sample surface. Through this method, the surface morphology characteristics of the powder with different magnifications and different positions can be obtained.
1.3 IPP software/IPP
IPP software, short for Image-Pro Plus, is widely used in the fields of medicine, healthcare, pharmacy, and life sciences. Its powerful counting and measurement capabilities can rapidly segment light and dark areas in SEM images, obtain measurement results, and automatically classify and statistics based on the measurement results, thus improving work efficiency. This technology allows for the rapid partitioning of particles in SEM images, the removal of incomplete particles, and the calculation of equivalent diameters for the perimeter and area of complete particles, and the quick determination of the sphericity value of particles based on a formula.
2. Measurement and analysis
2.1 Measurement
According to the formula, as long as the perimeter of the complete particles in the measured particle group and the corresponding particle area are obtained, its sphericity can be calculated. Furthermore, the sphericity of the particles in the entire SEM image can be calculated. Figure 1 shows a set of SEM images, each at two different positions and the same magnification. It is visually evident from the images that the sphericity of Figure 1-a is worse than that of Figure 1-b, but it cannot be quantified.
Table 1 Software Statistical Information | |||
Number of Figures | 1-SEM-500X | 2-SEM-500X | |
Particles Total Count | 394 | 486 | |
Complete Particle Count | 120 | 95 | |
Average Sphericity | 91.12% | 90.17% | |
Deviation | 0.00498 | 0.00327 |
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