EFFECTS OF NiO LOADING AND PRE-CALCINATION TEMPERATURE ON NiO-SDCC COMPOSITE ANODE POWDER FOR LOW-TEMPERATURE SOLID OXIDE FUEL CELLS

摘要

The microstructural and thermal characteristics of NiO-samarium-doped ceria carbonate (NiO-DCC) composite powders have been explored in terms of NiO loading and pre-calcination temperature. NiO SDCC composite powders were intimately mixed via fast ball-milling using dfferent NiO loadings (50 - 70 wt. %) and subjected to various pre-calcination temperatures (600 - 800 degrees C). Subsequently, the pre-calcined powders were then used to fabricate composite pellets using a uniaxial press and sintered at a low temperature of 600 degrees C. The crystalline phase, carbonate bonding, microstructure and thermal behaviour of the composite anode powders were investigated. The microstructure, porosity, and hardness of sintered composite pellets were also evaluated. All samples maintained their chemical compatibility and carbonate bonding after various processes. The findings indicated that the pre-calcination factor was more important than NiO loading in terms of powder and pellet morphologies as well as the thermal expansion behaviour. Moreover, the composite pellets prepared with composite powders pre-calcined at increasing temperatures exhibited an increase in porosity, but within an acceptable range (30 - 40 %). Overall, composite pellets fabricated with 50 wt. % NiO exhibited the optimum hardness values of 21 - 31 HV and the lowest thermal expansion of 12.2 - 12.7 x 10(-6) K-1.