Preparation Of CaZr_1-xIn_xO_3-α And Its Use In Molten Aluminum

Since pervoskite proton conductors were found last century, its uses in solid oxide fuel cell (SOFC), gas sensors, hydrogen production from steam electrolysis, hydrogenation and dehydrogenization of organic compound etc. attracted a lot of researchers’attention. CaZrO3-based proton conductor had better chemical stability and physical property, showing promising prospect in aluminum industry. However, its preparation process and the opinion of relationship between conductivity and dopant concentration were not clear.In this paper, the synthesis temperature of CaZr1-xInxO3-α (0≤x≤0.15) through solid state reaction was obtained by DSC-TG analysis, and CaZr1-xInxO3-α(x=0,0.05,0.10,0.15) were prepared. Their properties were investigated through XRD, SEM and Electrochemical Impedances Spectroscopy. XRD patterns revealed that the pervoskite solid solution were synthesized after being calcined at1400℃for10h.. The conductivity results were δ(CaZrO3)<<δ(CaZr0.95In0.05O3-α)<δ(CaZr0.90In0.10O3-α)≈δ(CaZr0.85In0.15O3-α), and their conductive activation energy decreased with increase in dopant concentration. The relationship of the conductive activation energy with dopant concentration was gained by analytical modeling, as well as the relationship between the conductivity and dopant concentration and temperature. The condition when x was0.20was investigated under this model.CaZr0.90In0.10O3-α precursor was prepared through co-precipitation and the best synthesis temperature was also gained. Sever agglomeration happened during preparation, and EDS showed that In lost also occurred. During600～800℃temperature range, the conductivity was2.44X10-5～1.48×10-4S/cm, conductive activation energy0.81eV.Proton conductive tubes made form co-precipitation were gained by pressure the powder under200MPa for2h and sintered at1550℃for10h. Hydrogen sensor made from these tubes with standard hydrogen as reference electrode was used to pure molten aluminum. The process of CaZro.9oIno.io03-a tubes made from solid state reaction powder by hot pressure casting was investigated and the process parameters were also obtained. The green tubes were then sintered at1500℃for10h after the wax was removed, and deep gray green tubes with strength were obtained. Hydrogen sensor made from these tubes was investigated in molten6063alloy. In situ and continus determination of hydrogen in molten aluminum can be gained through these sensors.