Control Of Diamond Fine Powder Size Distribution

Artificial diamond powder is mainly used in the grinding and polishing process of finish machining of workpiece. Users often require the lowest diamond concentration, the fastest cutting speed, the best surface finish and geometry of workpiece, and the smallest possible surface micro-damage. In order to meet such requirements, it is impractical to have proper micro-powder. Therefore, the following indexes must be strictly controlled: particle size distribution, particle shape, impurity content, diamond strength, etc.

 

Diamond powder size
Diamond powder diameter refers to the diameter of fine powder, which is a value to measure the particle size. For regular spherical particles, the particle size is the diameter of the sphere. However, diamond powder particles are not usually regular spheres but irregular shapes, such as rod-like, needle-like, etc.

 

Therefore, it is difficult to use a single value to represent the size of diamond powder particles. Therefore, the concept of equivalent particle size is introduced to represent the diameter of diamond powder particles. When a physical property of a particle is the same or similar to that of a homogeneous spherical particle, the diameter of the spherical particle is used to represent the diameter of the particle, which is the equivalent size of the particle.

 

There are several kinds of equivalent particle sizes: the equivalent projected area diameter is the same as the actual projected area diameter of spherical particles, and the image method measures the equivalent projected area diameter. Equivalent volume diameter is the same sphere diameter as the actual particle volume. It is generally considered that the diameter measured by laser method is equivalent particle size.

 

Grain size distribution of diamond powder

The size distribution of diamond powder refers to the distribution ratio of diamond particles with various sizes. It is a very important parameter to measure the quality of diamond powder. In a sense, the concentration of size distribution determines the quality of products.
In application, products with different grain sizes have corresponding grinding efficiency and surface finish.

 

Users can select products with different grain sizes according to different processing requirements. Generally speaking, the coarse particles in diamond powder will be strictly controlled, because the coarse particles will cause scratches of the processed parts in the application and cause serious quality problems.

 

Especially in some precision polishing fields, the scratches caused by the coarse particles will directly lead to the scrap of expensive processing devices and huge losses, and the existence of fine particles will also lead to corresponding problems, such as the reduction of grinding efficiency in grinding process. There are therefore clear requirements.

 

Main Characterizing Parameters of Grain Size Distribution
The main characterization parameters of particle size distribution are D50, Mv, D5, D95, etc.

D50: Also known as median or median diameter, commonly used to represent the average particle size of a powder, is the corresponding particle size when the accumulated percentage of particle size distribution of a sample reaches 50%. Its physical meaning is that the particle size larger than it accounts for 50%, and the particle smaller than it also accounts for 50%.

Mv: Average particle size distributed by volume. It is another way to represent the average particle size, which is more influenced by large particles and is more indicative when controlling large particles.

D5: The particle size corresponding to a sample whose accumulated percentage of particle size distribution reaches 5%, which is commonly used to measure the particle index at the fine end of the sample.

D95: The particle size corresponding to a sample whose accumulated percentage of particle size distribution reaches 95%, which is usually used to measure the particle index of the coarse end of the sample.