Reactions between Calcium- and Strontium-Substituted Lanthanum Cobaltite Ceramic Membranes and Calcium Silicate Sealing Materials

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• 作者：Sonia Faaland ; Mari-Ann Einarsrud ; and Tor Grande
• 刊名：Chemistry of Materials
• 出版年：2001
• 出版时间：March 2001
• 年：2001
• 卷：13
• 期：3
• 页码：723 - 732
• 全文大小：462K
• 年卷期：v.13,no.3(March 2001)
• ISSN：1520-5002

文摘

The reaction between Ca- and Sr-substituted LaCoO₃ and CaSiO₃/Ca₂SiO₄ has been studiedby electron microscopy (SEM and TEM) and X-ray diffraction. The aim was to investigatethe chemical stability of these materials as a model system for, respectively, a membraneand a sealing material in dense oxygen-permeable membrane systems. Sintered powdermixtures of the two materials were analyzed to gain information about coexistent phases inthe CaO/SrO-La₂O_3-CoO-SiO₂ system. The estimated phase composition along theCaSiO_3-LaCoO₃ line has been worked out. The chemical aspects of glass-ceramic sealingof dense perovskite membranes were studied by making diffusion couples. LaCoO₃ was foundto be kinetically more stable to calcium silicate than Ca- and Sr-substituted LaCoO₃. Theresults also revealed that Ca₂SiO₄ is a more suitable sealing material than CaSiO₃, due tolower reactivity. Thus, the stability of the membrane/sealant interface was observed to bequite sensitive to the O:Si ratio of the calcium silicate: 3 < O:Si < 4 will give rise to goodsealing properties and moderate reactivity to the membrane material. A suitable materialis a two-phase material with O:Si close to four, e.g. an orthosilicate glass-ceramic materialwith small amounts of metasilicate or disilicate glass.