How are particle size classified?

What is particle? What is powder?

A particle is a small object with a certain size and shape, and its macroscopic size is usually defined as above 1nm and below 1mm. In practice, it is difficult to see a single particle, see the accumulation of countless particles, also known as the separation. Broadly speaking, fog droplets dispersed in air, oil droplets dispersed in water, bubbles in solution, porous holes and so on can also be regarded as "particles", the first two are "particles" of liquid, the last two are "particles" of gas.

How are particle size classified?

Usually referred to as ultramicro particles or currently popular so-called nanoparticles, refers to 1~100nm scale particles. Strictly speaking, nanoparticles should be particles of 2~10nm, with obvious quantum effects, and below 2nm are called atomic groups: submicro nanoparticles refer to particles of 0.1~1 micron, and ultrafine particles are the general name of ultrafine particles and submicron particles. Fine powder refers to 1~100 micron powder; Coarse powder refers to the powder of 100~1000 microns. Different industries have different opinions about this, and harmonizing these opinions is good for technology exchange.