Ceramic honeycombs based on homogeneous composites of zirconia and iron oxide are formed using polymer-based coextrusion for testing in thermochemical reactors to generate CO for renewable fuels. The honeycomb substrates possess controlled surface areas and are processed using zirconia with 3 and 8 mol % yttria additions to investigate the influence of surface area and oxygen conductivity of the substrate on the CO generation properties. CO generation was tested using a gas chromatography mass spectrometer and a laboratory scale thermochemical reactor capable of precisely controlling temperature and gas conditions. Results showed that reaction temperature and reactant gas flow rate effect CO generation. The yttria content of the zirconia support phase was also found to have a significant impact on the long-term CO generation, improving iron oxide conversion from 41 to 58%. Yttria content did not markedly impact the short-term reaction properties. Increasing the surface area of the substrates, from 2.6 up to 8.5 cm(2), did not result in improvements in CO generation within the resolution of the test equipment. The substrates reacted by two distinct mechanisms, an initial, spontaneous surface reaction that changed over time to a diffusion-based mechanism utilizing reaction material from the bulk. These substrate systems exhibit the high reactivity necessary for large-scale thermochemical reactors, while being based on common materials.
The 2014 aluminum alloy reinforced with 0.1 and 0.15 volume fraction of alumina particles (VFAP) have been solutionized for a range of time from 1.5 to 20 h at 813 K. The effect of solutionizing time (ST) on the age hardening response of the composites has been studied and compared with the characteristics exhibited by the monolith. The results indicate that increasing the ST decreases the time required to get the peak hardness (TPH) values in the monolith but the composites do not show a systematic monotonic behavior. The TPH values first decrease and then increase with an increase in ST at an aging temperature of 473 K for the composite. It has been speculated that the ST influences the concentration of quenched-in vacancies and continued heating may affect the bonding between particles and matrix which can generate additional dislocations throughout the solutionizing process due to curvature effects.
Age hardenable 2014 aluminum alloys and composites containing 0.10 and 0.15 volume fractions of alumina particles (VFAP) have been solutionized at 540 and 550 °C for up to 20 hours. The solutionized samples, heat treated for 5 and 20 hours, have been subjected to room temperature rolling until cracking develops. The work hardening curves have been compared to determine the effect of solutionizing time on the rolling characteristics from both hardness and the microstructural evolution points of view. Solutionizing at two different temperatures results in differences in the extent to which the composites can be rolled until fracture. The microstructural characterization by TEM has been performed to understand the room temperature rolling behavior.