Spark plasma sintering (SPS) method
It was patented in America and later it was widely used, especially in Japan. In the case of this
process, the shaping proceeds simultaneously with the consolidation process of the ceramic
body, by the combined and simultaneous action of a pulsed direct current and a uniaxial
pressure applied during the heat treatment of the precursor powders introduced into a graphite
mold. The success of the SPS method has been attributed to the role of the plasma that is
generated between the powder particles, which involves the elimination of surface impurities
and the obtaining of an advanced densification, in conditions of significantly lower sintering
temperatures and levels than those required by conventional sintering performed through
thermal activation.
In addition to the influence of plasma, the SPS method has other advantages, such as a fast
heating rate and uniform heating conditions in the sample. The current can contribute to the
intensification of mass transport by electromigration or by its influence on the generation and
mobility of point defects. Rapid heating, as well as lower sintering temperatures and levels,
contribute to the inhibition of granular growth by diffusion mechanisms, which is why this
method of consolidation is one of the few that can lead to both obtaining nanostructured
unitary materials and composite materials without any unwanted secondary phases, generated
by possible reactions at the interface between the majority crystalline constituents, frequently
encountered in the case of conventional sintering.
