Sintering

The sintering is a manufactoring process of parts consisting in heating a Poudre without carrying out it until the fusion. Under the effect of heat, the grains are welded between them, which forms the cohesion of the part. The most known case is that of the cooking of the Poterie S. Nowadays, sintering is used to obtain the thickening of ceramic materials:

  • it makes it possible to control the density of the matter; like one starts from a powder and that this one does not melt, one can control the size of the powder grains (Granulométrie) and the Densité of material, according to the degree of (compaction) initial of the powders and/or the use of doping agents, and/or the addition of binders…
  • it makes it possible to obtain hard but fragile materials, with porosity controlled, chemically inert (low chemical reactivity and good behavior with corrosions) and inert thermically;
  • it makes it possible to control dimensions of the produced parts: as there is no Changement of state, the variations of Volume, dimensions, are not very important compared to fusion (phenomenon of withdrawal).

Technical standards

Although there does not exist definition of the sintering achieving the unanimity, it can be described like a consolidation of a material (for example a powder), obtained by minimizing the energy of the system thanks to a contribution of energy (thermal, mechanical, with a Laser,…) but without fusion of at least one of the components.

Foot-note: not to confuse sintering and Hooping (assembly of two parts thanks to a tight adjustment).

For example, the cooking of the potteries is a sintering. Sintering is one of the best methods to obtain ceramics and prototypes of machine elements.

Here two more precise definitions of sintering:

“ the sintering is a process making evolve/move by heat treatment a system made up of individual particles (or a porous agglomerate), in the absence of exerted external pressure or under the effect of such a pressure, so that at least some of the properties of the system (if not all) are modified in the direction of a reduction of the total free energy of the system. In parallel, this evolution involves a major reduction (if not supplements) initial porosity. Lastly, the process supposes that at least a solid phase exists constantly during all the heat treatment, in order to preserve a certain stability of form and dimension at the system considered. ”

G. Cizeron, French ceramics Institute

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