The quality control items of diamond powder mainly include particle size distribution, particle shape, impurity content and so on.

• 1. Particle Size Distribution and Detection Methods:

Particle size refers to the diameter of a particle and is a value used to measure the size of a particle. For regular spherical particles, the particle size is simply the diameter of the sphere. However, diamond micropowder particles are not regular spheres but have irregular shapes, such as rod-like, needle-like, or flake-like shapes.

It is difficult to represent the size of such particles with a single value. Therefore, the concept of equivalent particle size has been introduced to represent the particle size of these particles. When a certain physical characteristic of a particle is similar to or the same as that of a homogeneous spherical particle, we use the diameter of the spherical particle to represent the diameter of this particle. The particle size of this spherical particle is the equivalent particle size of the particle.

There are several types of equivalent particle sizes: The equivalent projected area particle size is the diameter of a spherical particle that has the same projected area as the actual particle. The particle size measured by the image method is the equivalent projected area diameter. The equivalent volume-based particle size is the diameter of a sphere that has the same volume as the actual particle. Generally, the diameter measured by the laser method is considered to be the equivalent volume diameter.

The particle size distribution of diamond micropowder refers to the distribution ratio of diamond particles with various particle sizes. It is a very important parameter for measuring the quality of diamond micropowder. In various senses, the degree of concentration of the particle size distribution determines the level of product quality. In applications, products of various particle size specifications have corresponding grinding efficiencies and surface processing roughness. Users can select products of different particle size specifications according to different processing requirements.

Generally speaking, the coarse particles in diamond micropowder are strictly controlled. This is because the coarse particles can cause scratches on the processed devices during application, resulting in serious quality problems. Especially in some precision polishing fields, the scratches caused by coarse particles can directly lead to the scrapping of expensive processing devices and huge losses. The presence of fine particles can also cause corresponding problems. For example, it can reduce the grinding efficiency during grinding processing, so there are also clear requirements for it.

The main characteristic parameters of particle size distribution include D50, MV, D10, D95, etc.

D50：Also known as the median or median diameter, it is often used to represent the average particle size of powder. It is the particle size corresponding to the cumulative particle size distribution percentage of a sample reaching 50%. Its physical meaning is that particles with a particle size larger than it account for 50%, and particles with a particle size smaller than it also account for 50%.

MV： The average particle size based on volume distribution is another way to represent the average particle size. This value is more affected by large particles and is more indicative when controlling large particles.

D10：It is the particle size corresponding to the cumulative particle size distribution percentage of a sample reaching 10%. It is usually used to measure the particle index at the fine end of the sample.

D95：It is the particle size corresponding to the cumulative particle – size distribution percentage of a sample reaching 95%. It is usually used to measure the particle index at the coarse end of the sample.

The main detection methods for the particle size distribution of diamond micropowder are as follows:

The image method, the sedimentation method, the centrifugal method, the laser method, the resistance method, and so on.

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