Electrophoretic deposition is a colloidal processing method in which the charged particles dispersed in a liquid medium are attracted and deposited onto a conductive and oppositely charged electrode on application of a DC electric field. The technique with a wide range of novel applications in the processing of advanced ceramic materials and coatings, has recently gained increasing interest both in academia and industrial sector not only because of the high versatility of its use with different materials and their combinations but also because of its cost-effectiveness requiring simple apparatus, short formation time, little restriction in the shape of deposition substrate and suitability for mass production. In addition, there is no requirement of binder burnout because the green coating contains little or no organics. In particular, EPD offers easy control of the thickness and morphology of the deposited films through simple adjustment of the deposition time and applied potential. The principal driving force for electrophoretic deposition is the electric force exerted on charged particles on application of an electric field. The rate of electrophoretic deposition depends primarily on the charges on the particles, the electrophoretic mobility of the particles in the solvent, and the applied electric field.








Schematics of electrophoretic deposition process
We are utilizing the EPD technique to deposit submicron and nano-size particles from aqueous and non-aqueous suspension on a variety of electrically conducting substrates. We are studying the influence of primary particle properties as well as their secondary properties like surface charge in a liquid medium in addition to the process parameters for obtaining thin as well as thick films of Al2O3 on conducting substrates like steel, carbon, graphite etc. We have developed technique to prepare free-standing films of YSZ, thin and dense YSZ film on NiO and lanthanum strontium manganite [ La 0.85 Sr 0.15 MnO 3 (LSM) ] substrates as well as electrophoretic deposition on non-conducting NiO-YSZ composite substrates and other materials for wide range of applications such as solid oxide fuel cells, oxidation resistant coatings, multilayer composites and hybrid materials, laminates/layered ceramics etc. Work is also initiated on electrophoretic deposition of hydroxyapatite (HAp) on metal implants for biomedical applications, luminescent materials for field emission display (FED) applications, mixed ionic and electronics conductor (MIEC) materials on porous substrates for gas separation sensors etc. Presently our thrust has also been initiated towards template assisted electrophoretic deposition for preparation of 2-D as well as 3-D ordered nanostructured array for functional materials. Such ordered arrays of nanoparticles have attracted much attention because of their application as building blocks in many potential nanodevices and smart materials such as data storage media, photonic crystals, electronics, sensors (gas sensors, biosensors etc), catalysts, etching masks and many other advanced ceramic fields. We are contemplating to use templates made from block-copolymer films. Block copolymers consist of two or more polymer chains connected with covalent bonds. Most pairs of polymers are immiscible and blends of polymer tend to phase separate. But block polymers, when subjected to selective chemical etching or UV light treatment, the constituent polymers are unable to phase separate at macroscopic length scales and instead spontaneously form ordered structures at molecular scale. We are trying to incorporate nanoparticles into these ordered domains by electrophoretic deposition for making ordered arrays of desirable nanostructures.








Photograph of deposited electrophoretically alumina on
stainless steel from its suspension (20 wt%) in butan-1-ol at 250V, 5 min