Journal of Power Sources 172 (2007) 358–362 Short communication The mathematical expression for kinetics of electrophoretic deposition and the effects of applied voltage Sian-Jie Ciou a , Kuan-Zong Fung a , Kai-Wei Chiang b,∗ a Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan b Department of Geomatics, National Cheng Kung University, Tainan 70101, Taiwan Received 17 July 2007; accepted 24 July 2007 Available online 28 July 2007 Abstract Electrophretic deposition (EPD) is a ceramic process. Although the kinetics for EPD have been established. However, there are still some ambiguities. In present study, a modified kinetic model was applied to describe the completely different behavior of EPD at -10 and -40 V respectively. The variation of the concentration profile during electrophoretical deposition at -10 and -40 V was simulated to explain what affected the EPD process. Based on the simulation, the depletion of colloidal particles near the electrode may be responsible for the EPD kinetic behaviors. © 2007 Elsevier B.V. All rights reserved. Keywords: Electrophoretic deposition; YSZ; LSM; Finite element method; Kinetics 1. Introduction Electrophoretic deposition (EPD) is a two-step process: First, the charged colloidal particles in the suspension migrate to the electrodes under an external electric field. This migration step involves the bulk properties of the colloidal suspension, such as conductivity, viscosity, particle concentration and dispersion, and the surface-charge density and the local field strength in the bath [1,2]. Secondly, the deposition step involves a complex combination of electrochemical and aggregation phenomena. Producing a dense and coherent deposition layer requires that the particles release their surface charge at the electrode [3]. Although several efforts have been devoted to study this pro- cess, there are still many parameters that must be considered to control the formation of EPD, leading to a highly nonlin- ear relationship between those parameters [4]. In the present study, a correction which describes the potential variation during electrophoretic deposition [5] was introduced into the proposed kinetic expression of EPD [6]. The kinetic behavior of EPD was explored using this modified kinetic model. Furthermore, differ- ent applied voltages were used to investigate their influence on EPD kinetics. ∗ Corresponding author. Tel.: +886 6 2757575x63829. E-mail address: kwchiang@mail.ncku.edu.tw (K.-W. Chiang). 2. Theoretical background 2.1. The factors affecting EPD The mechanisms of EPD include charged colloidal particles in solution moving under an applied external voltage, and a deposition of particles onto an electrode where charge transfer takes place. Two groups of parameters determine the charac- teristics of this process: (a) the specifics of suspensions and (b) the physico-chemical parameters of the electrochemical cells. For the EPD of particles, part of the current carries either the charged particles or free ions in the solution, so the number of deposited particles is not only relative to current. It is believed that the accumulated ions at the electrodes restrict subsequent deposition [7]. However, the number of free ions is generally small in organic suspensions, such as in ethanol. In this sense, the influence of the accumulation of ions is negligible in the initial period. The first attempt to correlate the number of particle with the affecting parameters of EPD was made by Hamaker and Avgustnik et al. [8]. The Hamaker law can be expressed as w =  t 1 t 2 fμEAC dt (1) 0378-7753/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2007.07.046