THERMAL EXPANSION BEHAVIOR OF THE Ba0.2Sr0.8Co0.8Fe0.2O3−δ (BSCF) WITH Sm0.2Ce0.8O1.9

Nanostructured perovskite oxides of Ba0.2Sr0.8Co0.8Fe0.2O3−δ (BSCF) were synthesized through the co-precipitation method. The thermal decomposition, phase formation and thermal expansion behavior of BSCF were characterized by thermogravimetric analysis, X-ray diffraction (XRD), and dilatometry, respectively. XRD peaks were indexed to a cubic perovskite structure with a Pm3m (221) space group. All the combined oxides produced the desired perovskite-phase BSCF. The microstructures were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The TEM analysis showed that BSCF powders had uniform nanoparticle sizes and high homogeneity. The cross-sectional SEM micrograph of BSCF exhibited a continuous and no delaminated layer from the electrolyte-supported cell. The thermal expansion coefficient (TEC) of BSCF was 16.2×10-6 K-1 at a temperature range of 600°C to 800°C. Additional experiments showed that the TEC of BSCF is comparable to that of Sm0.2Ce0.8O1.9 (SDC) within the same temperature range. The results demonstrate that BSFC is a promising cathode material for intermediate-temperature solid-oxide fuel cells

ELECTRICAL CONDUCTIVITY MODELS OF DIE CONFIGURATION FOR POLYPROPYLENE-REINFORCED MILLED CARBON FIBRE

Extrusion is one of the pre-mixing processes that produce a highly conductive polymer composite material when the appropriate die geometry is applied. However, the development of a conductivity model is still in the preliminary stage because the current model being used is unable to accurately predict the electrical conductivity. A generally effective media model and a modified fibre contact model were adapted in this study. To obtain a good agreement between the predicted model and the experimental data, the FCM model was modified by adapting the extrusion parameters, including the shear rate and rotational speed, into the equation. This was known as the MFCM with shear rate. This modified MFCM with shear rate showed a good correlation with the r-square of 0.99, as evidenced by the minimized gap between the predicted and experimental data. The MCF/PP composite produced using the rod die had the highest electrical conductivity of 3.7 S/cm as the fibre was aligned in the converging dies than in the sheet dies, which had an electrical conductivity of 1.3 S/cm

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

The microstructural and thermal characteristics of NiO-samarium-doped ceria carbonate (NiO-SDCC) 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 different NiO loadings (50-70 wt.%) and subjected to various pre-calcination temperatures (600-800°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°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 × 10-6 K-1