Electrophoretic Deposition of Aluminum Oxide Powders in Different Matrices for Alkali Bonded Coatings

Alkali bonded ceramics (geopolymers) have come into prominence as of recent in that they allow the production of cold-consolidated ceramic bodies endowed with a wide array of structural characteristics, making them useful in the production of many different materials. 3-D geopolymeric bodies are finding their way into many different industrial fields, such as cement, fire retardant, and refractory materials. The possibility of obtaining coatings by exploiting the unique features of the electrophoretic deposition process would in principle allow alkali bonded coatings to be directly fabricated onto conductive substrates of arbitrary geometry. Such a technology would significantly widen the application of alkali bonded ceramics. Cold consolidation pursued via the alkaline route may in principle be obtained by electrophoresis of powdered Al oxide feedstocks dispersed in a liquid matrix, in the presence of a suitable primer. However, it is not clear to what extent this is actually possible. In order to gain some understanding, we analyzed the deposition behavior of Al oxide feedstocks dispersed in different liquid matrices, also assessing the post-deposition behavior of the deposits as to consolidation and adhesion to the substrates.