Ionotec's fabrication technology for ceramic parts, coatings and thin films is based on electrodeposition or electrophoretic deposition. Electrodeposition involves plating of metals or alloys from a solution of salts and is most suited to thin film deposition. Electrophoretic deposition is used to build up thick films of ceramic material from suspensions of particles in a liquid. The principle is shown in the following diagram in which charged particles migrate to an electrode of opposite sign under an electric field. Usually one charge (+ or -) dominates so that only one electrode is coated or plated.
The main application for electrodeposition is the growth of photovoltaic semiconductor thin films on conductive glass substrates. Ionotec is leading a consortium on the development of an electrodeposition process for a novel design of thin-film solar cell invented by the Solar Energy Group at Sheffield Hallam University based on CdTe or CIGS (CuGaInSe2) absorber layers. For information about this research project see here.
The main applications for electrophoretic deposition are the fabrication of ion-conductive ceramic tubes and plates for batteries and other electrochemical cells and the formation of thin ion-conductive ceramic membranes for solid oxide fuel cells. The photograph at top left shows that quite large ceramic components can be fabricated by this method.
One of Ionotec's most frequent tasks for clients and for research and development projects concerns manufacturing scale-up. We have considerable experience in taking laboratory processes up to pilot scale manufacture and in building and commissioning equipment for this purpose. This is often a difficult stage in translating research ideas into industrial practice, so please contact us to discuss your needs since we may be able to help.
Pilot scale deposition facilities involve semi-automatic operation with load cells for thick-walled deposits. For thin coatings thickness is controlled by the time and deposition potential. Suspension and solution handling systems can be used with either water-based or flammable solvent-based fluids, and are designed to remove air bubbles that can cause defects. Uniform or graduated thickness as required is done by control of electric field strength and fluid flow to avoid stagnation points. Full sequencing of operations is provided by PLC. The unit shown at lower left was integrated into a continuous automatic production line capable of manufacturing 20,000 components per week.