sintering, process of forming objects from a metal powder by heating the powder at a temperature below its melting point. In the production of small metal objects it is often not practical to cast them. Through chemical or mechanical procedures a fine powder of the metal can be produced. When the powder is compacted into the desired shape and heated, i.e., sintered, for up to three hours, the particles composing the powder join together to form a single solid object.

sintering

Welding together of small particles of metal by applying heat at temperatures below the melting point. The process is used to form complex shapes, to produce alloys, and to allow work on metals with very high melting points. Sintering is also used in the preliminary molding of ceramic or glass powders into forms that can then be permanently fixed by firing. See also powder metallurgy.

Making ceramic, plastic and metal objects by heating a powder. Sintering by laser is one of the additive fabrication methods used in rapid prototyping and manufacturing. See laser sintering and 3D printing.

Sintering

The welding together and growth of contact area between two or more initially distinct particles at temperatures below the melting point, but above one-half of the melting point in kelvins. Since the sintering rate is greater with smaller than with larger particles, the process is most important with powders, as in powder metallurgy and in firing of ceramic oxides.

Although sintering does occur in loose powders, it is greatly enhanced by compacting the powder, and most commercial sintering is done on compacts. Compacting is generally done at room temperature, and the resulting compact is subsequently sintered at elevated temperature without application of pressure. For special applications, the powders may be compacted at elevated temperatures and therefore simultaneously pressed and sintered. This is called hot pressing or sintering under pressure.

Certain compacts from a mixture of different component powders may be sintered under conditions where a limited amount of liquid, generally less than 25 vol%, is formed at the sintering temperature. This is called liquid-phase sintering, important in certain powder-metallurgy and ceramic applications. See Ceramics, Powder metallurgy