Densification enhancement of alumina by sandwich process design

Abstract

Nano-particles densify faster than coarse (or submicron) particles. They also undergo higher volumetric shrinkage than coarse particles during sintering. By fabricating layered structure of coarse and nano particles of alumina powder having an interface of coarse particle/nano-particles, the volumetric shrinkage differential between the distinct layers constitute pressure on the coarse particles while sintering is in progress. The resulting dynamic compressive stress generated promotes mobility of the coarse particles, thus enhancing densification. By grinding off the outer tensile nano-particle layers after densification, the inner coarse particle layer is freed from residual stresses. Comparing the density obtained by this technique with the conventional pressureless sintering, significant enhancement of densification has been achieved, and it is shown that the higher the ratio of the thickness of the fine layer to the thickness of the coarse layer (the thickness ratio), the higher the densification enhancement.

Publication Title

Ceramic Engineering and Science Proceedings

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