Apparent zeta potential of nano-porous Al2O3 film deposited on different substrates in streaming potential method

Abstract

19Al 2 O 3 films were coated on SUS304L stainless steel and fused silica substrates 20 using chemical solution deposition. Continuous pores with a diameter of 21 approximately 2 nm were observed through the measurement of the pore 22 J Mater Sci Ceramics Author Proof 52Zeta potential control is a method to suppress the 53 deposition of solid particles onto the surfaces of 54 parts. In this method, a film with the same zeta 55 potential sign as that of the solid particles in the fluid 56 is coated on the components, thereby creating a 57 repulsive force between the solid particles in the fluid 58 and the component surface [1][2][3][4][5][6]. This is a unique 59 and excellent method that takes advantage of the 60 intrinsic characteristics of the material and does not 61 consume energy to suppress deposition. 62The chemical solution deposition (CSD) method 63 considered in this study is a well-established practi-64 cal process to coat large parts [7][8][9][10][11]. In the CSD 65 method, a ceramic film is formed on a substrate by 66 first depositing a ceramic precursor solution on the 67 substrate surface and then applying heat treatment to 68 decompose the precursor. This process is advanta-69 geous in that it does not require special equipment 70 and is applicable to large parts with complex shapes. 71 However, films formed using CSD typically have a 72 characteristic microstructure with continuous pores 73 [22][23][24]. 74Many of the large parts that are considered in this 75 study are metallic. Therefore, accurate measurement 76 of the zeta potential of a film containing continuous 77 pores that is coated on a metal substrate is necessary. 78 Electrophoresis is also commonly used to evaluate 79 zeta potential, but this method involves the applica-80 tion of a high voltage to the electrolyte solution and is 81 therefore difficult to use in electrically conductive 82 substrate [13]. The streaming potential method [12] 83 can be used to measure the zeta potential of a film 84 coated on a metal substrate. In the streaming poten-85 tial method, an electrolyte solution is passed between 86 two specimens placed on either side of a narrow gap 87 and the resulting voltage or current is measured. A 88 voltage is not applied in this procedure, and thus, 89 evaluation of the zeta potential of a film on a metal 90 substrate should be possible. This method requires 91 the application of pressure to move the electrolyte 92 solution. As a result, the electrolyte solution may 93 penetrate the pores of the film, resulting in interac-94 tions between the electrolyte solution and the sub-95 strate that could affect the measured zeta potential. 96Very few reports discuss the zeta potential of a film 97 containing continuous pores that is coated on a metal 98 substrate by the use of the streaming potential 99 method to measure. Lorenzetti et al. [14] coated a 100 TiO 2 film with a thickness of 30 lm on a Ti metal 101 substrate via a hydrothermal method using a Ti deposition process. J Ceram Soc Jpn 124:448-454 609 [11] Brinker CJ, ...