Preparation of Various Oxide Films by an Electrophoretic Deposition Method: A Study of the Mechanism

Abstract

The electrification mechanism of an oxide particle in a bath was analyzed. The zeta-potentials of various oxide particles in an acetone bath were found to be positive. The data suggested that H+ ions are generated in an acetone bath containing a small amount of added I2 and H2O by the keto-enol equilibrium reaction and then adsorbed on the oxide resulting in positively charged particles. The adsorption of H+ ions was assumed to be of the type of mono-molecular adsorption. Moreover, the electrodeposition flocculation mechanism for the particle was also investigated. On the basis of a relation of electrophoretic current with depositing time well described by the Cottrell equation, it was suggested that the electrochemical reaction proceeds on the cathode substrate surface and that the rate-determining step arises from the diffusion of H+ ions in the deposited film.

Electrophoretic deposition of dense BaCe0.9Y0.1O3−x electrolyte thick-films on Ni-based anodes for intermediate temperature solid oxide fuel cells

“…Iodine was used to positively charge the BCY10 particles since protons were formed according to the following reaction [15]: This reaction of iodine affects the suspension properties, such as its conductivity [26]. Thus, several suspensions were treated for 1 h in an ultrasonic bath and then steadied for different times ranging from 1 to 96 h. The sediments were always removed from the suspension to keep only the smaller BCY10 particles suspended for the EPD process.…”

YBa2Cu3O7−x dispersion in iodine acetone for electrophoretic deposition: Surface charging mechanism in a halogenated organic media

“…The mechanism widely used considers the formation of iodoacetone in the presence of H 2 O (equation 1), suggesting that particle surfaces become positive as a consequence of the proton formation during the acetone iodination [19,20,56]. A similar mechanism was proposed in other organic solvents [45,[49][50][51][52][53].…”

“…In acetone, a negative value of zeta potential for 0.01 g/l YBCO suspensions have been determined by Koura et al [20], while more concentrated suspensions promote a positive surface charge, leading to cathodic deposition [12, 21-35, 31, 32]. Other studies show that it is customary to use iodine (I 2 ) as stabiliser in acetone [10,12,19,20,[27][28][29][30]. Zeta-potentials of YBCO in acetone-I 2 solutions are always positive, forming also cathodic deposits.…”

“…Lee et al [50] and Chen et al [52] measured a decrease of the operational pH (7-2) with the I 2 addition (until 1 g/l) in YSZ suspensions prepared in isopropanol and acetone-ethanol, respectively. However, Koura et al [20] measured a slight variation of the proton concentration in acetone when adding I 2 until 8 g/l in YBCO suspensions. Moreover, suspensions conductivities measured were extremely different in ketones and alcoholic media for similar solid loadings, corresponding to differences among solvent dielectric constants [58].…”

“…acetone [10,12,[19][20][21][22][23][24][25][26][27][28][29][30][31][32], isobutylmethylketone [11], propanol and butanol [31,32], acetone being the most used solvent. In acetone, a negative value of zeta potential for 0.01 g/l YBCO suspensions have been determined by Koura et al [20], while more concentrated suspensions promote a positive surface charge, leading to cathodic deposition [12, 21-35, 31, 32]. Other studies show that it is customary to use iodine (I 2 ) as stabiliser in acetone [10,12,19,20,[27][28][29][30].…”