Carbon Deposition and Deformation of Ni-YSZ Cermet in Hydrocarbon-Containing Gases
From the backgrounds mentioned above, in this study, we quantitatively evaluated the carbon deposition and expansion of Ni-YSZ cermet during exposure to 10%CH4-N2, 1%CH4-N2, 1%C2H6-N2 or 1%C3H8-N2with S/C = 0.1 or 1.0 in the temperature range between 973 and 1173 K. The dilatometry and thermogravimetry measurements as well as posterior analyses by SEM/EDX and XRD were performed for blocks of Ni-YSZ cermet.
When S/C was 0.1, significant carbon deposition and expansion were observed during the exposure to hydrocarbon gases. The expansion reached 1% within 5 hours for 1%CH4-N2 and 1 hour for the others. According to SEM/EDX analyses, the amount of deposited carbon was found inside of the specimen after the exposure, although its distribution differed among hydrocarbon gas species. Carbon segregated in the near surface of the specimens for 1%C2H6-N2 and 1%C3H8-N2, while distributed in the whole parts of the specimens for 1% and 10%CH4-N2. The temperature dependency of the expansion was also quite deferent among hydrocarbon gas species. The expansion ratio was smallest at 973 K for 10%CH4-N2 and 1%CH4-N2, while smallest at 1173 K for 1%CH2H6-N2 and 1%C3H8-N2. In the presentation, the expansion mechanism will be discussed based on the obtained results.