Development of Nondestructive Measurement Technique for the Characterization of Layer Properties in Solid Oxide Fuel Cells

• Main Authors: Sheng-Wei Tang, 湯盛瑋
• Other Authors: 楊哲化
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/7gu7wc

博士 === 國立臺北科技大學 === 機電科技研究所 === 97 === Solid oxide fuel cell (SOFC) has the advantage of high efficiency in converting the chemical energy to electricity. The main structure of SOFC is a three-layered structure with the electrolyte sandwiched by anode and cathode. Yttria stabilized zirconia (YSZ) is generally the material of electrolyte due to its high ionic conductivity and stable physical and chemical properties. However, YSZ has oxygen ionic conductivity only in the high operation temperature of 500℃ to 1000℃. The ceramic structure of YSZ also suffers the difficulties in the control of geometrical and mechanical properties. For example, thickness of the electrolyte is desired to be controlled within 15 micros with good uniformity. Mechanical properties of anode and cathode also subject to substantial variations during the manufacturing process. Therefore, monitoring of anode, electrolyte and cathode material properties is an important issue. This research is focused on the development of a nondestructive technique for the characterization of material properties and thickness of individual layer in solid oxide fuel cell (SOFC). A single cell of SOFC module is a three-layered ceramic structure, including layers of anode, electrolyte and cathode. For the ceramic layers in the SOFC, it is difficult to characterize their material properties with traditional material testing methods. In this research, a laser ultrasound technique is employed to obtain dispersion spectra of guided waves propagating (LGS) in the SOFC, and followed by an inversion algorism to calculated the material and geometrical properties. Good agreement is observed between the obtained properties and other available independent data sources. The current procedure is shown to be feasible in characterizing the ceramic SOFC layers, and currently being developed as an online characterization tool serving in the manufacturing process. While independent measurement using an optical microscope is used as a reference, the inversion-determined thicknesses are 0.341mm and 1.091 mm for the electrolyte and anode layers, respectively. The calculated thickness shows an accuracy of less than 1μm. Also, the obtained material properties are compared with those in the literature where destructive methods are employed, where E=212GPa, v=0.32 for the electrolyte and E=57GPa, v=0.28 for the anode. The determined Young''s modulus shows errors of 7.9% for the anode and 1.9% for the electrolyte.