| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 88 === This study is mainly focused on the fabrication of
potentiometric oxygen sensors by applying mixed ion-electronic conductor as material of electrode and YSZ as electrolyte. First, the YSZ/Pt composite powders obtained by an electroless deposition method was mixed with Pt paste by different ratios to form the slurry-like material. Next, we screen printed the slurry mentioned above onto one side of the sintered YSZ tablet. After undergoing high-temperature sintering, we got a porous working electrode. Besides, we screen printed Pt paste onto the other side of the YSZ tablet. And we got a porous counter electrode after undergoing high-temperature sintering.
According to the experimental results, Pt/YSZ powders increase the activation area of three-phase boundary and reduce the overpotential of the electrode. Therefore, the performance of the oxygen sensors made by YSZ/Pt composite powders is better than that made by Pt alone. For example, in the atmosphere of 8vol﹪O2＋92vol﹪N2 at 800℃, the sensitivity of the Pt/YSZ/Pt sensor, the 15﹪Pt-YSZ（Japan）/YSZ/Pt sensor and the 15﹪Pt-YSZ（Australia）/YSZ/Pt sensor are 15.39, 19.09 and 19.02 mv, respectively. Meanwhile, the increase of the sensitivity of oxygen sensor is proportional to the amount of composite powder. The performance of oxygen sensor made by using the YSZ powder from a Japanese company is superior to that made by using the YSZ powder from an Australia company. The sensitivity increases and response time decrease as the detected temperature is elevated.
The response time of the sensor decreases with an increase in the amount of composite powder in working electrode. For example, in the atmosphere of 8vol﹪O2＋92vol﹪N2 at 800℃, the response time of the Pt/YSZ/Pt sensor is 42 seconds, and the recovery time is 69 seconds. The response time of the 15﹪Pt-YSZ（Japan）/YSZ/Pt sensor is 25 seconds, and the recovery time is 35 seconds. The response time of the 15﹪Pt-YSZ（Australia） /YSZ/Pt sensor is 28 seconds, and the recovery time is 45 seconds.
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