Material Analysis of Coated Siliconized Silicon Carbide (SiSiC) Honeycomb Structures for Thermochemical Hydrogen Production

Materials

Martina Neises-von Puttkamer²  Heike Simon¹  Martin Schm࿌ker¹  Martin Roeb²  Christian Sattler² 

[1]Institute of Materials Research, German Aerospace Center (DLR), Linder Hoehe, Köln 51170, Germany

[2] E-Mails:

[3]Institute of Solar Research, German Aerospace Center (DLR), Linder Hoehe, Köln 51170, Germany

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关键词: thermochemical cycle;    water splitting;    mixed iron oxides;    ferrite;    hydrogen;    silicon carbide;   

DOI  :  10.3390/ma6020421

来源: mdpi

【 摘 要 】

In the present work, thermochemical water splitting with siliconized silicon carbide (SiSiC) honeycombs coated with a zinc ferrite redox material was investigated. The small scale coated monoliths were tested in a laboratory test-rig and characterized by X-ray diffractometry (XRD) and Scanning Electron Microscopy (SEM) with corresponding micro analysis after testing in order to characterize the changes in morphology and composition. Comparison of several treated monoliths revealed the formation of various reaction products such as SiO₂, zircon (ZrSiO₄), iron silicide (FeSi) and hercynite (FeAl₂O₄) indicating the occurrence of various side reactions between the different phases of the coating as well as between the coating and the SiSiC substrate. The investigations showed that the ferrite is mainly reduced through reaction with silicon (Si), which is present in the SiSiC matrix, and silicon carbide (SiC). These results led to the formulation of a new redox mechanism for this system in which Zn-ferrite is reduced through Si forming silicon dioxide (SiO₂) and through SiC forming SiO₂ and carbon monoxide. A decline of hydrogen production within the first 20 cycles is suggested to be due to the growth of a silicon dioxide and zircon layer which acts as a diffusion barrier for the reacting specie.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.