The effects of an electric field on the sintering of ceramics

Sintering is a method used to condense a solid powder material into a single solid mass allowing for the production of metal or ceramic parts. Different sintering techniques involve the manipulation of different processing variables. To fully exploit the processing variables, how they affect the sintering process must be fully understood. One such processing variable is an applied electric field, utilized in spark plasma sintering and flash sintering. Both techniques allow for densification to occur at lower temperatures and in shorter times when compared to other sintering techniques. Though various theories exist in literature for how the electric field affects the sintering process, not one has been universally agreed upon. In this work, the sintering of zinc oxide was characterized to determine its response to an electric field. Samples were sintered in a modified tube furnace under various strengths of an applied electric field ranging up to 112 V/cm. After sintering, densities and grain sizes were analyzed. For applied fields up to 112 V/cm, there was no change in the final density or final grain size with respect to the strength of the applied field. It can be concluded that while the field does not affect the final density and final grain size, it does affect when the material reaches those values during the sintering process. With increasing field strengths, less time and lower temperatures are required to reach final density and final grain size. Before the advantages of spark plasma sintering or flash sintering can be applied at the industrial level, more work is still needed to determine the specific effects of an electric field on the sintering of ceramic materials