磁控溅射法制备磷灰石型硅酸镧中低温SOFCs电解质薄膜

发布时间：2018-03-21 11:47

  本文选题：中低温固体氧化物燃料电池　切入点：电解质薄膜　出处：《大连理工大学》2010年硕士论文　论文类型：学位论文

【摘要】： 固体氧化物燃料电池(SOFCs)是一种直接将储存在燃料和氧化剂中的化学能高效、环境友好地转化成电能的全固态化学发电装置。目前,SOFCs的发展趋势是中低温化。降低SOFCs运行温度的方法有：(1)电解质材料的薄膜化,(2)使用中低温下具有高电导率的电解质。磷灰石型硅酸镧因为具有高的中低温电导率,高的化学稳定性等优点而成为中低温固体氧化物燃料电池电解质的研究热点。磷灰石型硅酸镧一般采用固相反应法制备,但制备的磷灰石型硅酸镧存在的问题是烧结温度高和不易致密。采用磁控溅射法制备磷灰石型硅酸镧电解质薄膜有望解决在较低温度下制备的磷灰石型硅酸镧电解质很难致密的难题。而且电解质的薄膜化能降低其内阻,进一步降低SOFCs的运行温度。 本文首先采用固相反应法制备磷灰石型硅酸镧陶瓷靶材。使用精密天平,游标卡尺测量靶材的重量和尺寸,根据公式计算确定靶材致密度。采用XRD, SEM等测试方法表征了靶材的物相组成,表面形貌。实验结果表明,在1560℃下烧结,靶材的致密度为73.9%,靶材中主要是磷灰石相(La9.33Si6O26)；在1620℃下烧结靶材的致密度为83.5%,靶材主要相也为磷灰石相(La9.33Si6O26)。 使用磷灰石型硅酸镧靶磁控溅射制备磷灰石型硅酸镧电解质薄膜。首先实验中只使用磷灰石型硅酸镧单靶,制备的电解质薄膜中存在的问题是La含量严重不足。造成这种现象的原因为：(1)靶材中La成分不足；(2)La的溅射产额低。所以使用磷灰石型硅酸镧靶和镧靶共溅射制备磷灰石型硅酸镧电解质薄膜。磷灰石型硅酸镧靶采用射频溅射,镧靶采用直流溅射。通过EPMA,SEM,台阶仪等测试方法分别测量电解质薄膜的成分、表面形貌、薄膜厚度。实验结果表明,最佳的实验参数为：射频功率100W,直流功率11W,工作气压0.8Pa,偏压-45V。制备的电解质薄膜中最好成分为La 70.060wt%,Si 7.530wt%,Mg 0.063wt%,O 22.349wt%,La：Si摩尔比为10：5.32。电解质薄膜连续且致密。电解质薄膜的厚度为3μm-4μm,沉积速率为400nm／h-500 nm／h。 磁控溅射制备的电解质薄膜需退火以获得磷灰石相。通过XRD表征退火后电解质薄膜中的物相。结果表明,在1100℃下退火5h后,电解质薄膜中磷灰石(La9.33Si6O26)相的含量最多。另外,所有退火后的电解质薄膜中还含有La2Si207相和La2SiO5相。
[Abstract]:Solid oxide fuel cell (SOFCs) is a chemical energy that is stored directly in fuels and oxidants. An environmentally friendly all solid state chemical power plant that converts electricity into electrical energy. The current trend of development of SOFCs is moderate and low temperature. The method to reduce the operating temperature of SOFCs is: 1) thin film of electrolyte material, 2) use of medium and low temperature with high conductivity. Electrolytes. Apatite type lanthanum silicate, due to its high electrical conductivity at moderate and low temperatures, Because of its high chemical stability, lanthanum silicate is usually prepared by solid state reaction. However, the problems existed in the preparation of apatite type lanthanum silicate are that the sintering temperature is high and it is not easy to compact. The preparation of apatite type lanthanum silicate electrolyte film by magnetron sputtering is expected to solve the problem of apatite type lanthanum silicate electrolysis prepared at lower temperature. It is difficult to solve the problem of dense quality, and the thin film of electrolyte can reduce its internal resistance. Further reduce the operating temperature of SOFCs. In this paper, the apatite type lanthanum silicate ceramic target was prepared by solid state reaction method. The weight and size of the target were measured by using precision balance and Vernier caliper. According to the formula calculation, the target density was determined. The phase composition and surface morphology of the target were characterized by XRD, SEM, etc. The experimental results showed that the target was sintered at 1560 鈩，

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