Cathodic Electrodeposition of Ceramic Coatings for Oxidation Protection of Materials at Elevated Temperatures

Cathodic electrophoretic and electrolytic deposition have been utilized for preparation of ZrO2 and CeO2 coatings on stainless steel and graphite substrates. Thick coatings were obtained by multiple deposition or using electrochemical intercalation of a polyelectrolyte into the ceramic deposits. The use of poly(diallyldimethylammonium chloride) as an additive in bath formulation enabled coagulation of ceramic particles near the cathodic substrates to form adherent green deposits with enhanced resistance to cracking. The mechanisms of electrodeposition are discussed. Electron microscopy, thermogravimetric analysis and X-ray diffraction methods are used to examine the microstructure, composition and crystallization behaviour of the deposits prepared under various experimental conditions. Weight gain tests showed that sintered coatings provided good oxidation protection to stainless steel substrates at elevated temperatures.