Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium Conference
Technical Report,04 Mar 2016,03 Sep 2016
Engineering Conferences International New York United States
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This overall objective of this conference, the first of its kind, is to discuss how electrical and electromagnetic fields can influence the generation and the movement of defects in ceramics. Mass transport in ionic ceramics is controlled by the diffusion of defects. Electrical conductivity depends on the transport of charged defects as well as holes and electrons. Recent research has shown that mass transport and electrical conductivity can change, together, and abruptly, under a critical combination of applied field and temperature. The mostremarkable evidence of this non-linearity is so-called flash sintering where ceramics sinter from a powder compact to a dense body in just a few seconds, at furnace temperatures that are hundreds of degrees below conventional sintering. That nearly half the mass can be transported by solid-state diffusion in mere seconds is striking. The phenomenon has been shown to occur in several oxide ceramics, and more recently, in non-oxides as well. The rise in electrical conductivity, which coincides with flash sintering, leads to Joule heating, adding considerable complexity to the fundamental understanding of this phenomenon. Spark Plasma Sintering SPS is another process which accelerates sintering. Whereas flash sintering is a low power process which employs fields of about 100 Vcm1 and currents that are much less than one Ampere, SPS is a high power, low voltage process. In SPS high currents are used to rapidly heat a graphite die. They produce very high heating rates, which combined with applied pressure achieve fast sintering. SPS is often used to sinter materials which are otherwise very difficult to fabricate. A third process for field assisted processing of ceramics is microwave sintering, which has been shown to induce high rates of sintering while preserving small grain size. It has been shown to apply to several ceramics.
- Ceramics, Refractories and Glass
- Electricity and Magnetism