Metal powder properties

The metal powder is a loose material whose properties reflect the nature of the metal itself and the properties of the individual particles and the characteristics of the particle group. The properties of metal powders are generally classified into chemical properties, physical properties, and process properties. Chemical properties refer to metal content and impurity content. Physical properties include the average particle size and particle size distribution of the powder, the specific surface and true density of the powder, the shape of the particles, the surface topography and the internal microstructure. Process performance is a combination of properties including powder flow, bulk density, tap density, compressibility, formability and sintering dimensional changes. In addition, powders are required to have other chemical and physical properties, such as catalytic properties, electrochemical activity, corrosion resistance, electromagnetic properties, and internal friction coefficients, for certain special applications. The properties of the metal powder depend to a large extent on the method of production of the powder and its preparation process. The basic properties of the powder can be determined by specific standard test methods. There are many methods for measuring the particle size and distribution of the powder, and generally, sieve analysis (>44 μm), sedimentation analysis (0.5 to 100 μm), gas permeation, microscopy, and the like are used. Ultrafine powder (<0.5 μm) was measured by electron microscopy and X-ray small angle scattering. Metal powder is customarily divided into five grades of coarse powder, medium powder, fine powder, fine powder and ultrafine powder.